Chapter 4: Reactions in Aqueous SolutionMultiple choice (only show examples) 2.What will happen to the height (h) of the column of mercury in the manometer shown below if the stopcock is opened?A)h will decreaseB)h will not changeC)h will increaseD)not enough information given to answer the questionAns:A Category:Medium Section:5.2

3.What will happen to the height (h) of the mercury column in the manometer shown below if the stopcock is opened, given that the atmospheric pressure is 755 mmHg?A)h will decreaseB)h will not changeC)h will increaseD)not enough information given to answer the questionAns:A Category:Medium Section:5.2

4.A pressure that will support a column of Hg to a height of 256 mm would support a column of water to what height? The density of mercury is 13.6 g/cm3; the density of water is 1.00 g/cm3.A) 1.00 102 ft B) 18.8 mm C) 33.8 ft D) 76.0 cm E) 348 cmAns:E Category:Medium Section:5.2

5.The pressure of a gas sample was measured to be 654 mmHg. What is the pressure in kPa? (1 atm = 1.01325 105 Pa)A)87.2 kPaD)8.72 104 kPaB)118 kPaE)8.72 107 kPaC)6.63 104 kPaAns:A Category:Medium Section:5.2

6.The pressure of a gas sample was measured to be 489 mmHg. Which of the following is not an equivalent statement of that pressure? (1 atm = 1.01325 105 Pa)A) 65.2 kPa B) 6.52 104 Pa C) 489 torr D) 0.811 atmAns:D Category:Medium Section:5.2

7.Which of these properties is/are characteristic(s) of gases?A)High compressibilityB)Relatively large distances between moleculesC)Formation of homogeneous mixtures regardless of the nature of gasesD)A and B.E)A, B, and C.Ans:E Category:Easy Section:5.1

8.A sample of a gas occupies 1.40 103 mL at 25C and 760 mmHg. What volume will it occupy at the same temperature and 380 mmHg?A) 2,800 mL B) 2,100 mL C) 1,400 mL D) 1,050 mL E) 700 mLAns:A Category:Medium Section:5.3

9.A sample of nitrogen gas has a volume of 32.4 L at 20C. The gas is heated to 220C at constant pressure. What is the final volume of nitrogen?A) 2.94 L B) 19.3 L C) 31.4 L D) 54.5 L E) 356 LAns:D Category:Medium Section:5.3

10.If 30.0 L of oxygen are cooled from 200C to 1C at constant pressure, what is the new volume of oxygen?A) 0.150 L B) 17.4 L C) 23.0 L D) 51.8 L E) 6.00 103 LAns:B Category:Medium Section:5.3

11.A sample of N2 gas occupies 2.40 L at 20C. If the gas is in a container that can contract or expand at constant pressure, at what temperature will the N2 occupy 4.80 L?A) 10C B) 40C C) 146C D) 313C E) 685CAns:D Category:Medium Section:5.3

12.The gas pressure in an aerosol can is 1.8 atm at 25C. If the gas is an ideal gas, what pressure would develop in the can if it were heated to 475C?A) 0.095 atm B) 0.717 atm C) 3.26 atm D) 4.52 atm E) 34.2 atmAns:D Category:Medium Section:5.3

13.If the pressure of a gas sample is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sample change?A) 8 B) 2 C) 1/2 D) 1/4 E) 1/8Ans:C Category:Medium Section:5.4

14.If the pressure on a gas sample is tripled and the absolute temperature is quadrupled, by what factor will the volume of the sample change?A) 12 B) 4/3 C) 3/4 D) 1/3 E) 4Ans:B Category:Medium Section:5.4

15.A small bubble rises from the bottom of a lake, where the temperature and pressure are 4C and 3.0 atm, to the water's surface, where the temperature is 25C and the pressure is 0.95 atm. Calculate the final volume of the bubble if its initial volume was 2.1 mL.A) 0.72 mL B) 6.2 mL C) 41.4 mL D) 22.4 mL E) 7.1 mLAns:E Category:Medium Section:5.4

16.The temperature of an ideal gas in a 5.00 L container originally at 1 atm pressure and 25C is lowered to 220 K. Calculate the new pressure of the gas.A) 1.0 atm B) 1.35 atm C) 8.8 atm D) 0.738 atm E) 0.114 atmAns:D Category:Medium Section:5.3

17.0.820 mole of hydrogen gas has a volume of 2.00 L at a certain temperature and pressure. What is the volume of 0.125 mol of this gas at the same temperature and pressure?A) 0.0512 L B) 0.250 L C) 0.305 L D) 4.01 L E) 19.5 LAns:C Category:Medium Section:5.3

18.At what temperature will a fixed amount of gas with a volume of 175 L at 15C and 760 mmHg occupy a volume of 198 L at a pressure of 640 mm Hg?A) 274C B) 214C C) 114C D) 1C E) 59CAns:D Category:Medium Section:5.4

19.At what temperature will a fixed mass of gas with a volume of 125 L at 15C and 750 mmHg occupy a volume of 101 L at a pressure of 645 mm Hg?A) 73C B) 10.4C C) 2C D) 34C E) 200CAns:A Category:Medium Section:5.4

20.Calculate the number of moles of gas contained in a 10.0 L tank at 22C and 105 atm. (R = 0.08206 Latm/Kmol)A) 1.71 103 mol B) 0.0231 mol C) 1.03 mol D) 43.4 mol E) 582 molAns:D Category:Medium Section:5.4

21.Calculate the volume occupied by 35.2 g of methane gas (CH4) at 25C and 1.0 atm. R = 0.08206 Latm/Kmol.A) 0.0186 L B) 4.5 L C) 11.2 L D) 49.2 L E) 53.7 LAns:E Category:Medium Section:5.4

22.Calculate the volume occupied by 25.2 g of CO2 at 0.84 atm and 25C. R = 0.08206 Latm/Kmol.A) 0.060 L B) 1.34 L C) 16.9 L D) 24.2 L E) 734 LAns:C Category:Medium Section:5.4

23.A gas evolved during the fermentation of sugar was collected. After purification its volume was found to be 25.0 L at 22.5C and 702 mmHg. How many moles of gas were collected?A) 0.95 mol B) 1.05 mol C) 12.5 mol D) 22.4 mol E) 724 molAns:A Category:Medium Section:5.4

24.How many molecules of N2 gas can be present in a 2.5 L flask at 50C and 650 mmHg?A)2.1 1023 moleculesD)3.6 1025 moleculesB)4.9 1022 moleculesE)0.081 moleculesC)3.1 1023 moleculesAns:B Category:Medium Section:5.4

25.Calculate the mass, in grams, of 2.74 L of CO gas measured at 33C and 945 mmHg.A) 0.263 g B) 2.46 g C) 3.80 g D) 35.2 g E) 206 gAns:C Category:Medium Section:5.4

26.A 1.2 L flask contains 0.500 mole of ammonia (NH3) at 150C. Calculate the pressure of the ammonia inside the flask.A) 6.91 102 atm B) 5.13 atm C) 12.2 atm D) 14.5 atm E) 22.4 atmAns:D Category:Easy Section:5.4

27.Gases are sold in large cylinders for laboratory use. What pressure, in atmospheres, will be exerted by 2,500 g of oxygen gas (O2) when stored at 22C in a 40.0 L cylinder?A) 3.55 atm B) 1,510 atm C) 47.3 atm D) 7.56 104 atm E) 10.2 atmAns:C Category:Medium Section:5.4

28.Calculate the density, in g/L, of CO2 gas at 27C and 0.50 atm pressure.A) 0.89 g/L B) 1.12 g/L C) 9.93 g/L D) 46.0 g/L E) 2.17 kg/LAns:A Category:Medium Section:5.4

29.Calculate the density of CO2(g) at 100C and 10.0 atm pressure.A) 1.44 g/L B) 134 g/L C) 44.0 g/L D) 53.6 g/L E) 14.4 g/LAns:E Category:Medium Section:5.4

30.Calculate the density of Br2(g) at 59.0C and 1.00 atm pressure.A) 27.2 g/L B) 5.83 g/L C) 769 g/L D) 22.4 g/L E) 3.45 g/LAns:B Category:Medium Section:5.4

31.Calculate the density, in g/L, of SF6 gas at 27C and 0.500 atm pressure.A) 3.38 103 g/L B) 2.96 g/L C) 22.4 g/L D) 32.9 g/L E) 3.38 kg/LAns:B Category:Medium Section:5.4

32.Calculate the density, in g/L, of chlorine (Cl2) gas at STP.A) 2.13 102 g/L B) 46.9 g/L C) 1.58 g/L D) 3.16 g/L E) 0.316 kg/LAns:D Category:Medium Section:5.4

33.Calculate the density of Ar(g) at 11C and 675 mmHg.A) 1.52 g/L B) 1.65 g/L C) 39.3 g/L D) 39.95 g/L E) 1254 g/LAns:B Category:Medium Section:5.4

34.Which of these gases will have the greatest density at the same specified temperature and pressure?A) H2 B) CClF3 C) CO2 D) C2H6 E) CF4Ans:B Category:Medium Section:5.4

35.Which one of these gases is "lighter-than-air"?A) Cl2 B) SO2 C) PH3 D) NO2 E) NeAns:E Category:Medium Section:5.4

36.Two moles of chlorine gas at 20.0C are heated to 350C while the volume is kept constant. The density of the gasA)increases.B)decreases.C)remains the same.D)Not enough information is given to correctly answer the question.Ans:C Category:Medium Section:5.4

37.Determine the molar mass of chloroform gas if a sample weighing 0.389 g is collected in a flask with a volume of 102 cm3 at 97C. The pressure of the chloroform is 728 mmHg.A)187 g/molD)31.6 g/molB)121 g/molE)8.28 10-3 g/molC)112 g/molAns:B Category:Medium Section:5.4

38.What is the molar mass of Freon-11 gas if its density is 6.13 g/L at STP?A) 0.274 g/mol B) 3.64 g/mol C) 78.2 g/mol D) 137 g/mol E) 365 g/molAns:D Category:Medium Section:5.4

39.Determine the molar mass of Freon-11 gas if a sample weighing 0.597 g occupies 100. cm3 at 95C, and 1,000. mmHg.A) 0.19 g/mol B) 35.3 g/mol C) 70.9 g/mol D) 137 g/mol E) 384 g/molAns:D Category:Medium Section:5.4

40.1.018 g of Freon-113 gas is trapped in a 145 mL container at 760. mmHg and 50.0C. What is the molar mass of Freon-113?A) 21.7 g/mol B) 28.8 g/mol C) 46.1 g/mol D) 186 g/mol E) 245 g/molAns:D Category:Medium Section:5.4

41.A 0.271 g sample of an unknown vapor occupies 294 mL at 140C and 847 mmHg. The empirical formula of the compound is CH2. What is the molecular formula of the compound?A) CH2 B) C2H4 C) C3H6 D) C4H8 E) C6H12Ans:B Category:Medium Section:5.4

42.A 1.17 g sample of an alkane hydrocarbon gas occupies a volume of 674 mL at 28C and 741 mmHg. Alkanes are known to have the general formula CnH2n+2. What is the molecular formula of the gas in this sample? (R = 0.08206 Latm/Kmol)A) CH4 B) C2H6 C) C3H8 D) C4H10 E) C5H12Ans:C Category:Medium Section:5.4

43.A 1.07 g sample of a Noble gas occupies a volume of 363 mL at 35C and 678 mmHg. Identify the Noble gas in this sample? (R = 0.08206 Latm/Kmol)A) He B) Ne C) Ar D) Kr E) XeAns:D Category:Medium Section:5.4

44.A gaseous compound is 30.4% nitrogen and 69.6% oxygen by mass. A 5.25-g sample of the gas occupies a volume of 1.00 L and exerts a pressure of 1.26 atm at 4.0C. Which of these choices is its molecular formula?A) NO B) NO2 C) N3O6 D) N2O4 E) N2O5Ans:D Category:Medium

45.A mixture of three gases has a total pressure of 1,380 mmHg at 298 K. The mixture is analyzed and is found to contain 1.27 mol CO2, 3.04 mol CO, and 1.50 mol Ar. What is the partial pressure of Ar?A)0.258 atmD)5,345 mmHgB)301 mmHgE)8,020 mmHgC)356 mmHgAns:C Category:Medium Section:5.6

46.A sample of hydrogen gas was collected over water at 21C and 685 mmHg. The volume of the container was 7.80 L. Calculate the mass of H2(g) collected. (Vapor pressure of water = 18.6 mmHg at 21C.)A) 0.283 g B) 0.572 g C) 0.589 g D) 7.14 g E) 435 gAns:B Category:Medium Section:5.6

47.A sample of carbon monoxide gas was collected in a 2.0 L flask by displacing water at 28C and 810 mmHg. Calculate the number of CO molecules in the flask. The vapor pressure of water at 28C is 28.3 mmHg.A) 5.0 1022 B) 5.2 1022 C) 3.8 1023 D) 5.4 1023 E) 3.8 1025Ans:A Category:Medium Section:5.6

48.Air contains 78% N2, 21% O2, and 1% Ar, by volume. What is the density of air at 1,000. torr and 10C?A) 1.0 g/L B) 6.1 g/L C) 1.3 g/L D) 1.8 g/L E) 0.56 g/LAns:D Category:Difficult Section:5.6

49.What volume of oxygen gas at 320 K and 680 torr will react completely with 2.50 L of NO gas at the same temperature and pressure?2NO(g) + O2(g) 2NO2(g)A) 1.25 L B) 2.50 L C) 3.00 L D) 1.00 L E) 5.00 LAns:A Category:Medium Section:5.5

50.2.0 L of gas A at 1.0 atm and 1.0 L of gas B at 1.0 atm are combined in a 3 L flask. The flask is sealed and over time they react to completely to give gas C according to the following chemical equation:2A(g) + B(g) C(g)Assuming the temperature stays constant, what will be the pressure after the reaction goes to completion?A) 0.33 atm B) 0.50 atm C) 0.67 atm D) 0.75 atm E) 1.0 atmAns:A Category:Medium Section:5.6

51.Gas A and gas B are combined in a flask at initial pressures of 1.0 atm each. The flask is sealed and over time they react to completion to give gas C according to the following chemical equation:2A(g) + B(g) C(g)Assuming the temperature stays constant, what will be the total pressure in the flask after the reaction goes to completion?A) 0.33 atm B) 0.50 atm C) 0.67 atm D) 0.75 atm E) 1.0 atmAns:E Category:Difficult Section:5.6

52.What volume of CO2 gas at 645 torr and 800 K could be produced by the reaction of 45 g of CaCO3 according to the equation?CaCO3(s) CaO(s) + CO2(g)A) 0.449 L B) 22.4 L C) 25.0 L D) 34.8 L E) 45.7 mLAns:D Category:Medium Section:5.5

53.How many liters of chlorine gas at 25C and 0.950 atm can be produced by the reaction of 12.0 g of MnO2 with excess HCl(aq) according to the following chemical equation?MnO2(s) + 4HCl(aq) MnCl2(aq) + 2H2O(l) + Cl2(g)A) 5.36 10-3 L B) 0.138 L C) 0.282 L D) 3.09 L E) 3.55 LAns:E Category:Medium Section:5.5

54.How many liters of oxygen gas at 153C and 0.820 atm can be produced by the decomposition of 22.4 g of solid KClO3? (The other decomposition product is solid potassium chloride.)A) 3.0 L B) 0.085 L C) 4.20 L D) 7.79 L E) 11.7 LAns:E Category:Difficult Section:5.5

55.When active metals such as magnesium are immersed in acid solution, hydrogen gas is evolved. Calculate the volume of H2(g) at 30.1C and 0.85 atm that can be formed when 275 mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.A) 3.4 10-3 L B) 2.2 L C) 2.9 L D) 5.8 L E) 11.7 LAns:C Category:Difficult Section:5.5

56.Calculate the volume of H2(g) at 273 K and 2.00 atm that will be formed when 275 mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.A) 0.56 L B) 1.12 L C) 2.23 L D) 4.47 L E) 3.54 LAns:B Category:Difficult Section:5.5

57.What mass of KClO3 must be decomposed to produce 126 L of oxygen gas at 133C and 0.880 atm? (The other reaction product is solid KCl.)A) 24.6 g B) 70.8 g C) 272 g D) 408 g E) 612 gAns:C Category:Difficult Section:5.5

58.Liquid nitrogen has a density of 0.807 g/mL at 195.8 C. If 1.00 L of N2(l) is allowed to warm to 25C at a pressure of 1.0 atm, what volume will the gas occupy? (R = 0.08206 Latm/Kmol)A) 59.1 L B) 182 L C) 705 L D) 1.41 103 L E) 1.97 104 LAns:C Category:Medium Section:5.5

59.Which statement is false?A)The average kinetic energies of molecules from samples of different "ideal" gases is the same at the same temperature.B)The molecules of an ideal gas are relatively far apart.C)All molecules of an ideal gas have the same kinetic energy at constant temperature.D)Molecules of a gas undergo many collisions with each other and the container walls.E)Molecules of greater mass have a lower average speed than those of less mass at the same temperature.Ans:C Category:Medium Section:5.7

60.The molecules of different samples of an ideal gas have the same average kinetic energies, at the sameA) pressure. B) temperature. C) volume. D) density.Ans:B Category:Easy Section:5.7

61.If equal masses of O2(g) and HBr(g) are in separate containers of equal volume and temperature, which one of these statements is true?A)The pressure in the O2 container is greater than that in the HBr container.B)There are more HBr molecules than O2 molecules.C)The average velocity of the O2 molecules is less than that of the HBr molecules.D)The average kinetic energy of HBr molecules is greater than that of O2 molecules.E)The pressures of both gases are the same.Ans:A Category:Medium Section:5.4

62.Which gas has molecules with the greatest average molecular speed at 25C?A) CH4 B) Kr C) N2 D) CO2 E) ArAns:A Category:Easy Section:5.7

63.Which of these gas molecules have the highest average kinetic energy at 25C?A)H2B)O2C)N2D)Cl2E)All the gases have the same average kinetic energy.Ans:E Category:Easy Section:5.7

64.Deviations from the ideal gas law are greater atA)low temperatures and low pressures.C)high temperatures and high pressures.B)low temperatures and high pressures.D)high temperatures and low pressures.Ans:B Category:Medium Section:5.8

65.For a substance that remains a gas under the conditions listed, deviation from the ideal gas law would be most pronounced atA)100C and 2.0 atm.D)100C and 4.0 atm.B)0C and 2.0 atm.E)100C and 4.0 atm.C)100C and 2.0 atm.Ans:D Category:Medium Section:5.8

66.What is the pressure of the gas trapped in the apparatus shown below when the atmospheric pressure is 720 mmHg?A) 12 mmHg B) 708 mmHg C) 720 mmHg D) 732 mmHg E) 760 mmHgAns:B Category:Medium Section:5.2

67.Determine the pressure of the gas trapped in the apparatus shown below when the atmospheric pressure is 695 mmHg. A) 45 mmHg B) 650 mmHg C) 695 mmHg D) 740 mmHg E) 760 mmHgAns:D Category:Medium Section:5.2

68.10.0 g of gaseous ammonia and 6.50 g of oxygen gas are introduced into a previously evacuated 5.50 L vessel. If the ammonia and oxygen then react to yield NO gas and water vapor, what is the final gas pressure inside the vessel at 23C?A) 1.79 atm B) 6.48 atm C) 3.50 atm D) 0.285 atm E) 3.67 atmAns:E Category:Difficult Section:5.6

69.5.00 g of hydrogen gas and 50.0 g of oxygen gas are introduced into an otherwise empty 9.00 L steel cylinder, and the hydrogen is ignited by an electric spark. If the reaction product is gaseous water and the temperature of the cylinder is maintained at 35C, what is the final gas pressure inside the cylinder?A) 7.86 atm B) 18.3 atm C) 2.58 atm D) 6.96 atm E) 0.92 atmAns:A Category:Difficult Section:5.6

70.9.45 g of liquid hexane (C6H14) is introduced into a 10.0 L vessel containing 13.15 atm of oxygen gas at 21C and ignited, yielding carbon dioxide and water. If the vessel is then cooled to 10C, what will be the gas pressure inside the vessel?A) 3.09 atm B) 13.15 atm C) 1.42 atm D) 10.9 atm E) 12.6 atmAns:D Category:Difficult Section:5.6

71.10.0 g of gaseous ammonia and 6.50 g of oxygen gas are introduced into a previously evacuated 5.50 L vessel. If the ammonia and oxygen then react to yield NO gas and water vapor, what is the final density of the gas mixture inside the vessel at 23C?A) 1.68 g/L B) 3.00 g/L C) 1.32 g/L D) 2.20 g/L E) 16.5 g/LAns:B Category:Difficult Section:5.6

72.A method of removing CO2 from a spacecraft is to allow the CO2 to react with sodium hydroxide. (The products of the reaction are sodium carbonate and water.) What volume of carbon dioxide at 25C and 749 mmHg can be removed per kilogram of sodium hydroxide that reacts?A) 301 L B) 284 L C) 276 L D) 310 L E) 620 LAns:D Category:Difficult Section:5.5

73.A spacecraft is filled with 0.500 atm of N2 and 0.500 atm of O2. Suppose a micrometeor strikes this spacecraft and puts a very small hole in it's side. Under these circumstances,A)O2 is lost from the craft 6.9% faster than N2 is lost.B)O2 is lost from the craft 14% faster than N2 is lost.C)N2 is lost from the craft 6.9% faster than O2 is lost.D)N2 is lost from the craft 14% faster than O2 is lost.E)N2 and O2 are lost from the craft at the same rate.Ans:C Category:Medium Section:5.7

74.A spacecraft is filled with 0.500 atm of O2 and 0.500 atm of He. If there is a very small hole in the side of this craft such that gas is lost slowly into outer space,A)He is lost 2.8 times faster than O2 is lost.B)He is lost 8 times faster than O2 is lost.C)He is lost twice as fast as O2 is lost.D)O2 is lost 2.8 times faster than He is lost.E)O2 is lost 8 times faster than He is lost.Ans:A Category:Medium Section:5.7

75.1.000 atm of dry nitrogen, placed in a container having a pinhole opening in its side, leaks from the container 3.55 times faster than does 1.000 atm of an unknown gas placed in this same apparatus. Which of these species could be the unknown gas?A) NH3 B) C4H10 C) SF6 D) UF6 E) RnAns:D Category:Medium Section:5.7

76.1.000 atm of oxygen gas, placed in a container having a pinhole opening in its side, leaks from the container 2.14 times faster than does 1.000 atm of an unknown gas placed in this same apparatus. Which of these species could be the unknown gas?A) Cl2 B) SF6 C) Kr D) UF6 E) XeAns:B Category:Medium Section:5.7

77.Samples of the following volatile liquids are opened simultaneously at one end of a room. If you are standing at the opposite end of this room, which species would you smell first? (Assume that your nose is equally sensitive to all these species.)A)ethyl acetate (CH3COOC2H5)D)naphthalene (C10H8)B)camphor (C10H16O)E)pentanethiol (C5H11SH)C)diethyl ether (C2H5OC2H5)Ans:C Category:Medium Section:5.7

78.A sample of mercury(II) oxide is placed in a 5.00 L evacuated container and heated until it decomposes entirely to mercury metal and oxygen gas. The container is then cooled to 25C. One now finds that the gas pressure inside the container is 1.73 atm. What mass of mercury(II) oxide was originally placed into the container?A) 913 g B) 76.6 g C) 1.51 g D) 45.6 g E) 153 gAns:E Category:Difficult Section:5.5

79.The mole fraction of oxygen molecules in dry air is 0.2095. What volume of dry air at 1.00 atm and 25C is required for burning 1.00 L of hexane (C6H14, density = 0.660 g/mL) completely, yielding carbon dioxide and water?A) 187 L B) 712 L C) 1780 L D) 894 L E) 8490Ans:E Category:Difficult Section:5.5

80.The mole fraction of oxygen molecules in dry air is 0.2095. What volume of dry air at 1.00 atm and 25C is required for burning 1.00 L of octane (C8H18, density = 0.7025 g/mL) completely, yielding carbon dioxide and water?A) 718 L B) 367 L C) 8980 L D) 1880 L E) 150 LAns:C Category:Difficult Section:5.5

81.A block of dry ice (solid CO2, density = 1.56 g/mL) of dimensions 25.0 cm 25.0 cm 25.0 cm is left to sublime (i.e. to pass from the solid phase to the gas phase) in a closed chamber of dimensions 4.00 m 5.00 m 3.00 m. The partial pressure of carbon dioxide in this chamber at 25C will beA)171 mmHgD)0.171 mmHgB)107 mmHgE)14.4 mmHgC)0.225 mmHgAns:A Category:Medium Section:5.5

82.A 2.50-L flask contains a mixture of methane (CH4) and propane (C3H8) at a pressure of 1.45 atm and 20C. When this gas mixture is then burned in excess oxygen, 8.60 g of carbon dioxide is formed. (The other product is water.) What is the mole fraction of methane in the original gas mixture?A) 0.341 B) 1.00 C) 0.659 D) 0.855 E) 0.145Ans:D Category:Difficult Section:5.7 7.An exothermic reaction causes the surroundings toA)warm up.D)decrease its temperature.B)become acidic.E)release CO2.C)expand.Ans:A Category:Easy Section:6.2

8.Copper metal has a specific heat of 0.385 J/gC. Calculate the amount of heat required to raise the temperature of 22.8 g of Cu from 20.0C to 875C.A) 1.97 105 J B) 1.0 102 J C) 329 J D) 7.51 kJ E) 10.5 kJAns:D Category:Medium Section:6.5

9.Calculate the amount of heat necessary to raise the temperature of 12.0 g of water from 15.4C to 93.0C. The specific heat of water = 4.18 J/gC.A) 0.027 J B) 324 J C) 389 J D) 931 J E) 3,890 JAns:E Category:Medium Section:6.5

10.How much heat is required to raise the temperature of 2,500 g of water from 27C to 72C? The specific heat of water is 4.184 J/gC.A) 0.19 kJ B) 10. kJ C) 280 kJ D) 470 kJ E) 750 kJAns:D Category:Medium Section:6.5

11.A beaker contains 115 g of ethanol at 18.2C. If the ethanol absorbs 1125 J of heat without losing heat to the surroundings, what will be the final temperature of the ethanol? The specific heat of ethanol is 2.46 J/gC.A) 4.08C B) 14.1C C) 18.4C D) 22.2C E) 36.4CAns:D Category:Medium Section:6.5

12.How many degrees of temperature rise will occur when a 25.0 g block of aluminum absorbs 10.0 kJ of heat? The specific heat of Al is 0.900 J/gC.A) 0.44C B) 22.5C C) 225C D) 360C E) 444CAns:E Category:Medium Section:6.5

13.If 325 g of water at 4.2C absorbs 12.28 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/gC.A) 4.21C B) 4.8C C) 9.0C D) 13.2C E) 2,938CAns:D Category:Medium Section:6.5

14.A glass containing 200. g of H2O at 20C was placed in a refrigerator. The water loses 11.7 kJ as it cools to a constant temperature. What is its new temperature? The specific heat of water is 4.184 J/gC.A) 0.013C B) 4C C) 6C D) 14C E) 34CAns:C Category:Medium Section:6.5

15.A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/C. What is the specific heat of copper?A)0.385 J/gCD)1.32 J/gCB)1.83 104 J/gCE)24.5 J/gCC)2.60 J/gCAns:A Category:Easy Section:6.5

16.The specific heat of gold is 0.129 J/gC. What is the molar heat capacity of gold?A)0.039 J/molCD)39.0 kJ/molCB)0.129 J/molCE)197 J/molCC)25.4 J/molCAns:C Category:Easy Section:6.5

17.Suppose a 50.0 g block of silver (specific heat = 0.2350 J/gC) at 100C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/gC) at 0C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocksA)will be higher than 50C.B)will be lower than 50C.C)will be exactly 50C.D)is unrelated to the composition of the blocks.E)cannot be predicted.Ans:B Category:Medium Section:6.5

18.When 0.7521 g of benzoic acid was burned in a calorimeter containing 1,000. g of water, a temperature rise of 3.60C was observed. What is the heat capacity of the bomb calorimeter, excluding the water? The heat of combustion of benzoic acid is 26.42 kJ/g.A)15.87 kJ/CD)1.34 kJ/CB)4.18 kJ/CE)752.1 kJ/CC)5.52 kJ/CAns:D Category:Medium Section:6.5

19.Naphthalene combustion can be used to calibrate the heat capacity of a bomb calorimeter. The heat of combustion of naphthalene is 40.1 kJ/g. When 0.8210 g of naphthalene was burned in a calorimeter containing 1,000. g of water, a temperature rise of 4.21C was observed. What is the heat capacity of the bomb calorimeter excluding the water?A) 32.9 kJ/C B) 7.8 kJ/C C) 3.64 kJ/C D) 1.76 kJ/C E) 15.3 kJ/CAns:C Category:Medium Section:6.5

20.Which of the following processes is endothermic?A)O2(g) + 2H2(g) 2H2O(g)B)H2O(g) H2O(l)C)3O2(g) + 2CH3OH(g) 2CO2(g) + 2H2O(g)D)H2O(s) H2O(l)Ans:D Category:Medium Section:6.4

21.A 100. mL sample of 0.200 M aqueous hydrochloric acid is added to 100. mL of 0.200 M aqueous ammonia in a calorimeter whose heat capacity (excluding any water) is 480. J/K. The following reaction occurs when the two solutions are mixed.HCl(aq) + NH3(aq) NH4Cl(aq)The temperature increase is 2.34C. Calculate H per mole of HCl and NH3 reacted.A)154 kJ/molD)1.96 kJ/molB)1.96 kJ/molE)154 kJ/molC)485 kJ/molAns:E Category:Difficult Section:6.5

22.A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/C. If the temperature rise of the calorimeter with water was 0.570C, calculate the enthalpy of combustion of magnesium.Mg(s) + 1/2O2(g) MgO(s)A)3280 kJ/molD)106 kJ/molB)24.8 kJ/molE)602 kJ/molC)435 kJ/molAns:E Category:Difficult Section:6.5

23.To which one of the following reactions occurring at 25C does the symbol Hf[H2SO4(l)] refer?A)2H(g) + S(g) + 4O(g) H2SO4(l)D)H2SO4(l) 2H(g) + S(s) + 4O(g)B)H2(g) + S(g) + 2O2(g) H2SO4(l)E)H2(g) + S(s) + 2O2(g) H2SO4(l)C)H2SO4(l) H2(g) + S(s) + 2O2(g)Ans:E Category:Medium Section:6.6

24.To which one of the following reactions occurring at 25C does the symbol Hf[HNO3(l)] refer?A)H(g) + N(g) + O3(g) HNO3(l)B)(1/2)H2(g) + (1/2)N2(g) + (3/2)O2(g) HNO3(l)C)HNO3(l) (1/2)H2(g) + (1/2)N2(g) + (3/2)O2(g)D)HNO3(l) H(g) + N(g) + 3O(g)E)H2(g) + N2(g) + O3(g) HNO3(l)Ans:B Category:Medium Section:6.6

25.When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (Hf) of NaF(s)?A)24.8 kJ/molD)7.8 kJ/molB)570 kJ/molE)-570 kJ/molC)24.8 kJ/molAns:E Category:Medium Section:6.6

26.When 18.5 g of HgO(s) is decomposed to form Hg(l) and O2(g), 7.75 kJ of heat is absorbed at standard-state conditions. What is the standard enthalpy of formation (Hf) of HgO(s)?A)90.7 kJ/molD)27.9 kJ/molB)7.75 kJ/molE)143 kJ/molC)0.419 kJ/molAns:A Category:Medium Section:6.6

27.Ethanol undergoes combustion in oxygen to produce carbon dioxide gas and liquid water. The standard heat of combustion of ethanol, C2H5OH(l), is 1366.8 kJ/mol. Given that Hf[CO2(g)] = 393.5 kJ/mol and Hf[H2O(l)] = 285.8 kJ/mol, what is the standard enthalpy of formation of ethanol?A)3,010 kJ/molD)687.6 kJ/molB)687.6 kJ/molE)1,367 kJ/molC)277.6 kJ/molAns:C Category:Difficult Section:6.6

28.Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: heat of combustion of C2H4(g) = 1411 kJ/mol; Hf[CO2(g)] = 393.5 kJ/mol; Hf[H2O(l)] = 285.8 kJ/mol.A)52 kJ/molD)1.41 103 kJ/molB)87 kJ/molE)2.77 103 kJ/molC)731 kJ/molAns:A Category:Difficult Section:6.6

29.Octane (C8H18) undergoes combustion according to the following thermochemical equation:2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) Hrxn = 11,020 kJ/mol.Given that Hf[CO2(g)] = 393.5 kJ/mol and Hf[H2O(l)] = 285.8 kJ/mol, calculate the standard enthalpy of formation of octane.A)210 kJ/molD)420 kJ/molB)11,230 kJ/molE)420 kJ/molC)22,040 kJ/molAns:A Category:Medium Section:6.6

30.Glycine, C2H5O2N, is important for biological energy. The combustion reaction of glycine is given by the equation4C2H5O2N(s) + 9O2(g) 8CO2(g) + 10H2O(l) + 2N2(g) Hrxn = 3857 kJ/molGiven that Hf[CO2(g)] = 393.5 kJ/mol and Hf[H2O(l)] = 285.8 kJ/mol, calculate the enthalpy of formation of glycine.A)537.2 kJ/molD)3,178 kJ/molB)268.2 kJ/molE)964 kJ/molC)2,149 kJ/molAns:A Category:Medium Section:6.6

31.Styrene, C8H8, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25C, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25C.(Given: Hf[CO2(g)] = 393.5 kJ/mol, Hf[H2O(l)] = 285.8 kJ/mol, Hf[H2O(g)] = 241.8 kJ/mol)A)323.8 kJ/molD)~636.7 kJ/molB)~4249 kJ/molE)147.8 kJ/molC)~8730 kJ/molAns:E Category:Difficult Section:6.6

32.Given 2Al(s) + (3/2)O2(g) Al2O3(s), Hf = 1,670 kJ/mol for Al2O3 (s).Determine H for the reaction 2Al2O3(s) 4Al(s) + 3O2(g).A)3,340 kJ/molD)1,670 kJ/molB)1,670 kJ/molE)835 kJ/molC)3,340 kJ/molAns:A Category:Easy Section:6.6

33.Calculate the standard enthalpy of formation of liquid methanol, CH3OH(l), using the following information:C(graph) + O2 CO2(g)H = 393.5 kJ/mol

H2(g) + (1/2)O2 H2O(l)H = 285.8 kJ/mol

CH3OH(l) + (3/2)O2(g) CO2(g) + 2H2O(l)H = 726.4 kJ/mol

A)1,691.5 kJ/molD)47.1 kJ/molB)238.7 kJ/molE)47.1 kJ/molC)1691.5 kJ/molAns:B Category:Difficult Section:6.6

34.Calculate the standard enthalpy change for the reaction2C8H18(l) + 17O2(g) 16CO(g) + 18H2O(l).Given:2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) H = 11,020 kJ/mol2CO(g) + O2(g) 2CO2(g) H = 566.0 kJ/molA)10,450 kJ/molD)6,492 kJ/molB)6,492 kJ/molE)10.450 kJ/molC)15,550 kJ/molAns:D Category:Medium Section:6.6

35.During volcanic eruptions, hydrogen sulfide gas is given off and oxidized by air according to the following chemical equation:2H2S(g) + 3O2(g) 2SO2(g) + 2H2O(g)Calculate the standard enthalpy change for the above reaction given:3S(s) + 2H2O(g) 2H2S(g) + SO2(g)H = 146.9 kJ/mol

S(s) + O2(g) SO2(g)H = 296.4 kJ/mol

A)1036.1 kJ/molD)443.3 kJ/molB)742.3 kJ/molE)742.3 kJ/molC)149.5 kJ/molAns:A Category:Medium Section:6.6

36.Calculate the standard enthalpy change for the reaction2C8H18(l) + 21O2(g) 8CO(g) + 8CO2(g) + 18H2O(l).Given:2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) H = 11,020 kJ/mol2CO(g) + O2(g) 2CO2(g) H = 566.0 kJ/molA)1.0454 104 kJ/molD)6,492 kJ/molB)8,756 kJ/molE)1.0454 104 kJ/molC)1.1586 104 kJ/molAns:B Category:Medium Section:6.6

37.Given the thermochemical equation 2SO2 + O2 2SO3, Hrxn = 198 kJ/mol,what is the standard enthalpy change for the decomposition of one mole of SO3?A)198 kJ/molD)396 kJ/molB)99 kJ/molE)198 kJ/molC)99 kJ/molAns:C Category:Medium Section:6.6

38.Given H2(g) + (1/2)O2(g) H2O(l), H = 286 kJ/mol, determine the standard enthalpy change for the reaction 2H2O(l) 2H2(g) + O2(g).A)H = 286 kJ/molD)H = +572 kJ/molB)H = +286 kJ/molE)H = 143 kJ/molC)H = 572 kJ/molAns:D Category:Easy Section:6.6

39.Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l). Calculate Hrxn for the combustion of 1 mol of B5H9.Hf[B2O3(s)] = 1,273.5 kJ/molHf[B5H9(s)] = 73.2 kJ/molHf[H2O(l)] = 285.8 kJ/molA)1,2735 kJ/molD)9,086 kJ/molB)4,543 kJ/molE)8,448 kJ/molC)18,170 kJ/molAns:B Category:Difficult Section:6.6

40.For the reactionC(graphite) + O2(g) CO2(g)H = 393 kJ/mol

how many grams of C(graphite) must be burned to release 275 kJ of heat?A) 22.3 g B) 0.70 g C) 12.0 g D) 17.1 g E) 8.40 gAns:E Category:Medium Section:6.4

41.The combustion of butane produces heat according to the equation2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) Hrxn = 5,314 kJ/molWhat is the heat of combustion per gram of butane?A)32.5 kJ/gD)2,656 kJ/gB)45.7 kJ/gE)15,440 kJ/gC)91.5 kJ/gAns:B Category:Medium Section:6.4

42.The combustion of octane produces heat according to the equation2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) Hrxn= 11,020 kJ/molWhat is the heat of combustion per gram of octane?A)5,510 kJ/gD)193 kJ/gB)96.5 kJ/gE)6.292 105 kJ/gC)48.2 kJ/gAns:C Category:Medium Section:6.4

43.The combustion of butane produces heat according to the equation2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) Hrxn= 5,314 kJ/molHow many grams of butane must be burned to release 1.00 104 kJ of heat?A) 30.9 g B) 61.8 g C) 109 g D) 153 g E) 219 gAns:E Category:Medium Section:6.4

44.The combustion of butane produces heat according to the equation2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) Hrxn= 5,314 kJ/molHow many grams of CO2 are produced per 1.00 104 kJ of heat released?A) 23.4 g B) 44.0 g C) 82.3 g D) 187 g E) 662 gAns:E Category:Medium Section:6.4

45.Given that CaO(s) + H2O(l) Ca(OH)2(s), Hrxn = 64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat?A) 6.92 g B) 56.1 g C) 455 g D) 606 g E) 3.40 104 gAns:C Category:Medium Section:6.4

46.The combustion of pentane produces heat according to the equationC5H12(l) + 8O2(g) 5CO2(g) + 6H2O(l) Hrxn= 3,510 kJ/molHow many grams of CO2 are produced per 2.50 103 kJ of heat released?A) 0.0809 g B) 3.56 g C) 31.3 g D) 157 g E) 309 gAns:D Category:Medium Section:6.4

47.An average home in Colorado requires 20. GJ of heat per month. How many grams of natural gas (methane) must be burned to supply this energy?CH4(g) + 2O2(g) CO2(g) + 2H2O(l) Hrxn= 890.4 kJ/molA)1.4 103 gD)2.2 104 gB)3.6 105 gE)1.4 104 gC)7.1 104 gAns:B Category:Medium Section:6.4

48.Given the thermochemical equation 2SO2(g) + O2(g) 2SO3(g), Hrxn= 198 kJ/mol, how much heat is evolved when 600. g of SO2 is burned?A)5.46 102 kJD)59,400 kJB)928 kJE)3.71 103 kJC)1.85 103 kJAns:B Category:Medium Section:6.4

49.Determine the heat given off to the surroundings when 9.0 g of aluminum reacts according to the equation 2Al + Fe2O3 Al2O3 + 2Fe, Hrxn= 849 kJ/mol.A)7.6 103 kJD)5.6 102 kJB)2.8 102 kJE)2.5 103 kJC)1.4 102 kJAns:C Category:Medium Section:6.4

50.Find the heat absorbed from the surroundings when 15 g of O2 reacts according to the equation O + O2 O3, Hrxn= 103 kJ/mol.A) 4.6 103 kJ B) 48 kJ C) 96 kJ D) 32 kJ E) 110 kJAns:B Category:Medium Section:6.4

51.Ethanol (C2H5OH) burns according to the equationC2H5OH(l) + 3O2(g) 2CO2(g) + 3H2O(l), Hrxn = 1367 kJ/mol.How much heat is released when 35.0 g of ethanol is burned?A) 1,797 kJ B) 1,367 kJ C) 9.61 104 kJ D) 4.78 104 kJ E) 1,040 kJAns:E Category:Medium Section:6.4

52.Methanol (CH3OH) burns according to the equation2CH3OH(l) + 3O2(g) 2CO2(g) + 4H2O(l), Hrxn = 1454 kJ/mol.How much heat, in kilojoules, is given off when 75.0 g of methanol is burned?A)727 kJD)1.70 103 kJB)3.22 103 kJE)3.41 103 kJC)1.45 103 kJAns:D Category:Medium Section:6.4

53.Calcium oxide and water react in an exothermic reaction:CaO(s) + H2O(l) Ca(OH)2(s) Hrxn = 64.8 kJ/molHow much heat would be liberated when 7.15 g CaO(s) is dropped into a beaker containing 152g H2O?A) 1.97 103 kJ B) 8.26 kJ C) 508 kJ D) 547 kJ E) 555 kJAns:B Category:Medium Section:6.4

54.Solid sodium peroxide (Na2O2) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released when 250.0 L of oxygen gas is produced from the reaction of sodium peroxide and water if the reaction is carried out in an open container at 1.000 atm pressure and 25C?(Given: Hf[Na2O2(s)] = 510.9 kJ/mol; Hf[NaOH(aq)] = 469.2 kJ/mol; Hf[H2O(l)] = 285.8 kJ/mol)A) 35,400 kJ B) 1740 kJ C) 141.7 kJ D) 3330 kJ E) 2900 kJAns:E Category:Difficult Section:6.6

55.At 25C, the standard enthalpy of formation of KCl(s) is 435.87 kJ/mol. When one mole of KCl(s) is formed by reacting potassium vapor and chlorine gas at 25C, the standard enthalpy of reaction is 525.86 kJ/mol. Find H for the sublimation of potassium, K(s) K(g), at 25C.A)345.88 kJ/molD)89.99 kJ/molB)45.00 kJ/molE)525.86 kJ/molC)345.88 kJ/molAns:D Category:Medium Section:6.6

56.At 25C, the standard enthalpy of formation of anhydrous sodium carbonate is 1130.9 kJ/mol, whereas the standard enthalpy of formation of sodium carbonate monohydrate is 1430.1 kJ/mol. Determine H at 25C for the reactionNa2CO3(s) + H2O(l) Na2CO3H2O(s).(Given: Hf[H2O(l)] = 285.8 kJ/mol)A)13.4 kJ/molD)299.2 kJ/molB)285.8 kJ/molE)156.3 kJ/molC)585.0 kJ/molAns:A Category:Medium Section:6.6

57.According to the first law of thermodynamics:A)Energy is neither lost nor gained in any energy transformations.B)Perpetual motion is possible.C)Energy is conserved in quality but not in quantity.D)Energy is being created as time passes. We have more energy in the universe now than when time began.Ans:A Category:Easy Section:6.3

58.The heat of solution of KCl is 17.2 kJ/mol and the lattice energy of KCl(s) is 701.2 kJ/mol. Calculate the total heat of hydration of 1 mol of gas phase K+ ions and Cl ions.A) 718 kJ B) 684 kJ C) 684 kJ D) 718 kJ E) None of these.Ans:C Category:Medium Section:6.7

59.The heat of solution of LiCl is 37.1 kJ/mol, and the lattice energy of LiCl(s) is 828 kJ/mol. Calculate the total heat of hydration of 1 mol of gas phase Li+ ions and Cl ions.A) 791 kJ B) 865 kJ C) 865 kJ D) 791 kJ E) None of these.Ans:C Category:Medium Section:6.7

60.The total heat of hydration of 1 mol of gas phase Li+ ions and Cl ions is 865 kJ. The lattice energy of LiCl(s) is 828 kJ/mol. Calculate the heat of solution of LiCl.A)37 kJ/molD)37 kJ/molB)1,693 kJ/molE)None of these.C)1,693 kJ/molAns:D Category:Medium Section:6.7

61.10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H2O at 18.0C.If the following reaction occurs, then what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat? (the specific heat of water = 4.18 J/gC)CaO(s) + H2O(l) Ca(OH)2(s) Hrxn = 64.8 kJ/molA) 18.02C B) 35.8C C) 311C D) 42.2C E) 117CAns:B Category:Medium Section:6.5

62.The enthalpy change when a strong acid is neutralized by strong base is 56.1 kJ/mol. If 135 mL of 0.450 M HI at 23.15C is mixed with 145 mL of 0.500 M NaOH, also at 23.15C, what will the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/gC, and that the density of the final solution is that of water.)A) 26.06C B) 29.19C C) 32.35C D) 20.24C E) 36.57CAns:A Category:Difficult Section:6.5

63.The enthalpy change when a strong acid is neutralized by strong base is 56.1 kJ/mol. If 12.0 mL of 6.00 M HBr at 21.30C is mixed with 300. mL of 0.250 M NaOH, also at 21.30C, what will the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/gC, and that the density of the final solution is that of water.)A) 18.20C B) 24.53C C) 101.8C D) 24.40C E) 34.25CAns:D Category:Difficult Section:6.5

64.Calculate the amount of work done, in joules, when 2.5 mole of H2O vaporizes at 1.0 atm and 25C. Assume the volume of liquid H2O is negligible compared to that of vapor. (1 Latm = 101.3 J)A) 6,190 kJ B) 6.19 kJ C) 61.1 J D) 5.66 kJ E) 518 JAns:B Category:Medium Section:6.3

65.A gas is compressed in a cylinder from a volume of 20.0 L to 2.0 L by a constant pressure of 10.0 atm. Calculate the amount of work done on the system.A) 1.01 104 J B) 180 J C) 1.81 104 J D) 1.81 104 J E) 180 JAns:C Category:Medium Section:6.3

66.Calculate the amount of work done against an atmospheric pressure of 1.00 atm when 500.0 g of zinc dissolves in excess acid at 30.0C.Zn(s) + 2H+(aq) Zn2+(aq) + H2(g)A)w = +22.4 kJD)w = 2.52 kJB)w = +24.9 kJE)w = 19.3 kJC)w = 0Ans:E Category:Medium Section:6.3

67.A gas is allowed to expand, at constant temperature, from a volume of 1.0 L to 10.1 L against an external pressure of 0.50 atm. If the gas absorbs 250 J of heat from the surroundings, what are the values of q, w, and E?Ans:ACategory:Medium Section:6.3

68.Which of the following processes always results in an increase in the energy of a system?A)The system loses heat and does work on the surroundings.B)The system gains heat and does work on the surroundings.C)The system loses heat and has work done on it by the surroundings.D)The system gains heat and has work done on it by the surroundings.E)None of these is always true.Ans:D Category:Medium Section:6.3

69.For which of these reactions will the difference between H and E be the greatest?A)2H2O2(l) 2H2O(l) + O2(g)B)CaCO3(s) CaO(s) +CO2(g)C)NO(g) + O3(g) NO2(g) + O2(g)D)2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(l)E)4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g)Ans:D Category:Medium Section:6.4

70.For which of these reactions will the difference between H and E be the smallest?A)N2(g) + 3H2(g) 2NH3(g)B)4PH3(g) P4(g) + 6H2(g)C)H2(g) + Cl2(g) 2HCl(g)D)CO2(g) + 2H2O(l) CH4(g) + 2O2(g)E)P4(s) + 10Cl2(g) 4PCl5(s)Ans:C Category:Medium Section:6.4

71.At 25C, the following heats of reaction are known:2ClF(g) + O2(g) Cl2O(g) + F2O(g)Hrxn = 167.4 kJ/mol

2ClF3(g) + 2O2(g) Cl2O(g) + 3F2O(g)Hrxn = 341.4 kJ/mol

2F2(g) + O2(g) 2F2O(g)Hrxn = 43.4 kJ/mol

At the same temperature, use Hess's law to calculate Hrxn for the reaction:ClF(g) + F2(g) ClF3(g)A)217.5 kJ/molD)108.7 kJ/molB)130.2 kJ/molE)465.4 kJ/molC)217.5 kJ/molAns:D Category:Medium Section:6.6

72.The bond enthalpy of the BrCl bond is equal to H for the reactionBrCl(g) Br(g) + Cl(g).Use the following data to find the bond enthalpy of the BrCl bond.Br2(l) Br2(g)H = 30.91 kJ/mol

Br2(g) 2Br(g) H = 192.9 kJ/mol

Cl2(g) 2Cl(g)H = 243.4 kJ/mol

Br2(l) + Cl2(g) 2BrCl(g)H = 29.2 kJ/mol

A)219.0 kJ/molD)438.0 kJ/molB)203.5 kJ/molE)407.0 kJ/molC)14.6 kJ/molAns:A Category:Medium Section:6.6

73.The heat of solution of ammonium nitrate is 26.2 kJ/mol. If a 5.368 g sample of NH4NO3 is added to 40.0 mL of water in a calorimeter at 23.5C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/gC; the heat capacity of the calorimeter = 650. J/C.)A) 14.3C B) 20.8C C) 7.7C D) 25.6C E) 21.4CAns:E Category:Difficult Section:6.5

74.The heat of solution of ammonium chloride is 15.2 kJ/mol. If a 6.134 g sample of NH4Cl is added to 65.0 mL of water in a calorimeter at 24.5C, what is the minimum temperature reached by the solution? (The specific heat of water = 4.18 J/gC; the heat capacity of the calorimeter = 365. J/C.)A) 27.1C B) 18.6C C) 19.7C D) 21.9C E) 30.4CAns:D Category:Difficult Section:6.5

75.Aluminum oxide can be reduced to aluminum metal using carbon, the other reaction product being carbon monoxide. Determine the enthalpy change when 12.5 g of aluminum is produced by this method. [Hf(carbon monoxide) = 110.5 kJ/mol; Hf(aluminum oxide) = 1669.8 kJ/mol]A) 725 kJ B) 697 kJ C) 310 kJ D) 361 kJ E) 1504 kJAns:C Category:Difficult Section:6.6

76.Ozone (O3) in the atmosphere can be converted to oxygen gas by reaction with nitric oxide (NO). Nitrogen dioxide is also produced in the reaction. What is the enthalpy change when 8.50L of ozone at a pressure of 1.00 atm and 25C reacts with 12.00 L of nitric oxide at the same initial pressure and temperature? [Hf(NO) = 90.4 kJ/mol; Hf(NO2) = 33.85 kJ/mol; Hf(O3) = 142.2 kJ/mol]A) 69.2 kJ B) 19.7 kJ C) 1690 kJ D) 97.6 kJ E) 167 kJAns:A Category:Difficult Section:6.69.Identify the major ionic species present in an aqueous solution of K2SO4.A)K2+, S6+, O48D)2K+, S6+, 4O2B)K2+, S6+, 4O2E)2K+, SO42C)2K+, S6+, O48Ans:E Category:Easy Section:4.1

10.The distinguishing characteristic of all electrolyte solutions is that theyA)contain molecules.D)always contain acids.B)conduct electricity.E)conduct heat.C)react with other solutions.Ans:B Category:Easy Section:4.1

11.Based on the solubility rules, which one of the following compounds should be insoluble in water?A) NaCl B) MgBr2 C) FeCl2 D) AgBr E) ZnCl2Ans:D Category:Easy Section:4.2

12.Based on the solubility rules, which one of the following compounds should be insoluble in water?A) Na2SO4 B) BaSO4 C) CuSO4 D) MgSO4 E) Rb2SO4Ans:B Category:Easy Section:4.2

13.Based on the solubility rules, which one of the following compounds should be insoluble in water?A) CaCO3 B) (NH4)2CO3 C) Na2CO3 D) K2CO3 E) KNO3Ans:A Category:Easy Section:4.2

14.Based on the solubility rules, which one of the following should be soluble in water?A) Hg2Cl2 B) Na2S C) Ag2CO3 D) Ag2S E) BaSO4Ans:B Category:Easy Section:4.2

15.Based on the solubility rules, which one of the following should be soluble in water?A) AgBr B) AgCl C) Ag2CO3 D) AgNO3 E) Ag2SAns:D Category:Easy Section:4.2

16.Based on the solubility rules, which one of the following should be soluble in water?A) (NH4)3PO4 B) Ca3(PO4)2 C) AlPO4 D) Ag3PO4 E) Mg3(PO4)2Ans:A Category:Easy Section:4.2

17.Based on the solubility rules, which one of the following should be soluble in water?A) CaSO4 B) BaSO4 C) PbSO4 D) K2SO4 E) AgClAns:D Category:Easy Section:4.2

18.Based on the solubility rules, which of the following will occur when a solution containing about 0.1 g of Pb(NO3)2(aq) is mixed with a solution containing 0.1 g of KI(aq) /100 mL?A)KNO3 will precipitate; Pb2+ and I are spectator ions.B)No precipitate will form.C)Pb(NO3)2 will precipitate; K+ and I are spectator ions.D)PbI2 will precipitate; K+ and NO3 are spectator ions.E)Pb2+ and I are spectator ions, and PbI2 will precipitate.Ans:D Category:Medium Section:4.2

19.Based on the solubility rules, which of the following will occur if solutions of CuSO4(aq) and BaCl2(aq) are mixed?A)CuCl2 will precipitate; Ba2+ and SO42 are spectator ions.B)CuSO4 will precipitate; Ba2+ and Cl are spectator ions.C)BaSO4 will precipitate; Cu2+ and Cl are spectator ions.D)BaCl2 will precipitate; Cu2+ and SO42 are spectator ions.E)No precipitate will form.Ans:C Category:Medium Section:4.2

20.Based on the solubility rules, which of the following will occur when solutions of ZnSO4(aq) and MgCl2(aq) are mixed?A)ZnCl2 will precipitate; Mg2+ and SO42 will be spectator ions.B)ZnSO4 will precipitate; Mg2+ and Cl will be spectator ions.C)MgSO4 will precipitate; Zn2+ and Cl will be spectator ions.D)MgCl2 will precipitate; Zn2+ and SO42 will be spectator ions.E)No precipitate will form.Ans:E Category:Medium Section:4.2

21.Which of the following is the correct net ionic equation for the reaction that occurs when solutions of Pb(NO3)2 and NH4Cl are mixed?A)Pb(NO3)2(aq) + 2NH4Cl(aq) NH4NO3(aq) + PbCl2(s)B)Pb2+(aq) + 2Cl(aq) PbCl2(s)

C)Pb2+(aq) + 2NO3 (aq) + 2NH(aq) + 2Cl(aq) 2NH(aq) + 2NO3 (aq) + PbCl2(s)D)NH4+(aq)+ NO3 (aq) 2NH4NO3(s)E)No reaction occurs when the solutions are mixed.Ans:B Category:Medium Section:4.2

22.The common constituent in all acid solutions isA) H2 B) H+ C) OH D) H2SO4 E) ClAns:B Category:Easy Section:4.3

23.Which of the following compounds is a weak acid?A) HF B) HCl C) HBr D) HI E) HClO4Ans:A Category:Easy Section:4.1

24.Identify the major ions present in an aqueous LiOH solution.A) Li2+, O, H B) Li+, OH C) LiO, H+ D) Li+, O2, H+ E) Li, OH+Ans:B Category:Easy Section:4.3

25.Identify the major ions present in an aqueous HNO3 solution.A) HN+, O2 B) OH, NO3 C) OH, NO D) H+, N3, O2 E) H+, NO3Ans:E Category:Easy Section:4.3

26.Identify the major ionic species present in an aqueous solution of H2SO4.A)S6+, O36 (plus H2O as a neutral species)B)H+, OH, S6+, 3O2C)2H+, S6+, 4O2D)H+, HSO4E)2H+, SO42Ans:D Category:Medium Section:4.3

27.What is the correct formula of the salt formed in the neutralization reaction of hydrochloric acid with calcium hydroxide?A) CaO B) CaCl2 C) CaH2 D) CaCl E) CaClHAns:B Category:Medium Section:4.3

28.What is the chemical formula of the salt produced by the neutralization of hydrobromic acid with magnesium hydroxide?A) MgBr B) Mg2Br3 C) Mg3Br2 D) Mg2Br E) MgBr2Ans:E Category:Medium Section:4.3

29.What is the chemical formula of the salt produced by the neutralization of nitric acid with calcium hydroxide?A) CaNO3 B) Ca2(NO3)3 C) Ca3(NO3)2 D) Ca2NO3 E) Ca(NO3)2Ans:E Category:Medium Section:4.3

30.What is the chemical formula of the salt produced by the complete neutralization of sodium hydroxide with sulfuric acid?A) Na2SO4 B) Na2(SO4)3 C) Na(SO4)2 D) NaSO3 E) Na3SO4Ans:A Category:Medium Section:4.3

31.What is the chemical formula of the salt produced by the neutralization of potassium hydroxide with sulfuric acid?A) KSO3 B) K2(SO4)3 C) K2SO4 D) K(SO4)2 E) KSO4Ans:C Category:Medium Section:4.3

32.The oxidation number of N in NaNO3 isA) +6 B) +5 C) +3 D) 3 E) None of the above.Ans:B Category:Medium Section:4.4

33.The oxidation number of S in K2SO4 isA) +6 B) +4 C) +2 D) 1 E) None of the above.Ans:A Category:Medium Section:4.4

34.The oxidation number of Mn in KMnO4 isA) +8 B) +7 C) +5 D) 7 E) 8Ans:B Category:Medium Section:4.4

35.The oxidation number of Fe in K3Fe(CN)6 isA) +3 B) +2 C) +1 D) 3 E) 4Ans:A Category:Medium Section:4.4

36.The oxidation number of Cr in Cr2O72 isA) 12 B) 7 C) 2 D) +6 E) +7Ans:D Category:Medium Section:4.4

37.The oxidation number of Cl in ClO3 isA) 1 B) +7 C) +5 D) +3 E) None of the above.Ans:C Category:Medium Section:4.4

38.The oxidation number of Cl in ClO4 isA) 1 B) +1 C) +3 D) +5 E) None of the above.Ans:E Category:Medium Section:4.4

39.The highest possible oxidation number of nitrogen isA) +8 B) +5 C) +3 D) +1 E) 3Ans:B Category:Medium Section:4.4

40.For which one of the following acids is chlorine in the +5 oxidation state?A) HCl B) HClO C) HClO2 D) HClO3 E) HClO4Ans:D Category:Medium Section:4.4

41.The highest possible oxidation number of carbon isA) +8 B) +6 C) +4 D) +2 E) 4Ans:C Category:Medium Section:4.4

42.Select the compound in which sulfur has its highest possible oxidation number.A) H2S B) SO2 C) SCl2 D) H2SO3 E) Na2SO4Ans:E Category:Medium Section:4.4

43.The oxidation number of N in N2H4 isA) +4 B) 4 C) +2 D) 2 E) 0Ans:D Category:Medium Section:4.4

44.Which choice gives the correct oxidation numbers for all three elements in Rb2SO3 in the order that the elements are shown in the formula?A) 2, +6, 2 B) 1, +4, 3 C) +2, +4, 2 D) +1, +4, 2 E) +1, +6, 6Ans:D Category:Medium Section:4.4

45.Which choice gives the correct oxidation numbers for all three elements in Ca(ClO)2 in the order that the elements are shown in the formula?A) +2, +1, 2 B) +2, 2, +1 C) +2, 3, +2 D) 2, +2, 1 E) 2, +3, 2Ans:A Category:Medium Section:4.4

46.In the following redox reaction4NH3 + 3Ca(ClO)2 2N2 + 6H2O + 3CaCl2which element is oxidized and which is reduced?A)H is oxidized and N is reducedD)Cl is oxidized and O is reducedB)N is oxidized and Cl is reducedE)Cl is oxidized and N is reducedC)N is oxidized and O is reducedAns:B Category:Medium Section:4.4

47.Which one of the following is a redox reaction?A)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)B)2KBr(aq) + Pb(NO3)2(aq) 2KNO3(aq) + PbBr2(s)C)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)D)H+(aq) + OH (aq) H2O(l)E)CO32 (aq) + HSO4(aq) HCO3 (aq) + SO42 (aq)Ans:A Category:Medium Section:4.4

48.Which of the following equations does not represent an oxidation-reduction reaction?A)3Al + 6HCl 3H2 + AlCl3B)2H2O 2H2 + O2C)2NaCl + Pb(NO3)2 PbCl2 + 3NaNO3D)2NaI + Br2 2NaBr + I2E)Cu(NO3)2 + Zn Zn(NO3)2 + CuAns:C Category:Medium Section:4.4

49.In the following chemical reaction the oxidizing agent is5H2O2 + 2MnO4 + 6H+ 2Mn2+ + 8H2O + 5O2A) H2O2 B) MnO4 C) H+ D) Mn2+ E) O2Ans:B Category:Difficult Section:4.4

50.In the following chemical reaction the oxidizing agent is5S + 6KNO3 + 2CaCO3 3K2SO4 + 2CaSO4 + CO2 + 3N2A) S B) N2 C) KNO3 D) CaSO4 E) CaCO3Ans:C Category:Difficult Section:4.4

51.Identify the oxidizing agent in the following chemical reaction.2MnO4 + 5H2SO3 2Mn2+ + 5SO42 + 4H+ + 3H2OA) MnO4 B) H2SO3 C) Mn2+ D) SO42 E) H+Ans:A Category:Difficult Section:4.4

52.Identify the reducing agent in the following chemical reaction.5Fe2+(aq) + MnO4(aq) + 8H+(aq) 5Fe3+(aq) + Mn2+(aq) + 4H2O(l)A) Fe2+ B) MnO4 C) H+ D) Mn2+ E) Fe3+Ans:A Category:Difficult Section:4.4

53.Identify the reducing agent in the following chemical reaction.Cd + NiO2 + 2H2O Cd(OH)2 + Ni(OH)2A) Cd B) NiO2 C) H2O D) Cd(OH)2 E) Ni(OH)2Ans:A Category:Difficult Section:4.4

54.What element is oxidized in the following chemical reaction?3Cu + 8HNO3 3Cu(NO3)2 + 2NO + 4H2OA) Cu B) H C) N D) O E) H2OAns:A Category:Medium Section:4.4

55.What element is oxidized in the following chemical reaction?NiO2 + Cd + 2H2O Ni(OH)2 + Cd(OH)2A) Ni B) Cd C) O D) H E) This is not a redox reaction.Ans:B Category:Medium Section:4.4

56.What element is oxidized in the following chemical reaction?H2SO4 + Cd(OH)2 2H2O + CdSO4A) H B) S C) O D) Cd E) this is not a redox reactionAns:E Category:Medium Section:4.4

57.What element is reduced in the following chemical reaction?Cu + 2H2SO4 CuSO4 + SO2 + 2H2OA) Cu B) H C) S D) O E) H2OAns:C Category:Medium Section:4.4

58.Identify the elements that are oxidized and reduced in the following reaction.KClO3(aq) + 6HBr(aq) KCl(aq) + 3Br2(l) + 3H2O(l)A)Br is oxidized and Cl is reducedD)O is oxidized and Cl is reducedB)Cl is oxidized and H is reducedE)Cl is oxidized and Br is reducedC)H is oxidized and O is reducedAns:A Category:Medium Section:4.4

59.Predict the products of the following single replacement reaction.Fe(s) + CuSO4(aq) A)Cu(s) + FeSO4(aq)D)FeCuSO4(aq)B)Fe(s) + Cu(s) + SO4(aq)E)FeO(s) + CuSO3(aq)C)CuS(s) + Fe2SO4(aq)Ans:A Category:Medium Section:4.4

60.Which of the following is an example of a disproportionation reaction?A)2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(l)B)2KBr(aq) + Cl2(g) 2KCl(aq) + Br2(l)C)2H2O2(aq) 2H2O(l) + O2(g)D)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)E)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)Ans:C Category:Medium Section:4.4

61.Which of the following represents a metal displacement reaction?A)2NaN3(s) 2Na(s) + 3N2(g)B)Fe2O3(s) + 2Al(s) 2Fe(s) + Al2O3(s)C)3NO2(g) + H2O(l) 2HNO3(aq) + NO(g)D)2P(s) + 3Cl2(g) 2PCl3(g)E)2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g)Ans:B Category:Easy Section:4.4

62.Which of the following represents a halogen displacement reaction?A)2KBr(aq) + Cl2(g) 2KCl(aq) + Br2(l)B)2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)C)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)D)2KNO3(s) 2KNO2(s) + O2(g)E)2LiOH(aq) + H2SO4(aq) Li2SO4(aq) + 2H2O(l)Ans:A Category:Easy Section:4.4

63.Which of the following represents a precipitation reaction?A)2H2(g) + O2(g) 2H2O(l)B)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)C)2KNO3(s) 2KNO2(s) + O2(g)D)2KBr(aq) + Cl2(g) 2KCl(aq) + Br2(l)E)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)Ans:B Category:Easy Section:4.2

64.Which of the following represents an acid-base neutralization reaction?A)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)B)SO2(g) + H2O(l) H2SO3(g)C)LiOH(aq) + HNO3(aq) LiNO3(aq) + H2O(l)D)2KBr(aq) + Cl2(g) 2KCl(aq) + Br2(l)E)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)Ans:C Category:Medium Section:4.4

65.Which of the following represents a hydrogen displacement reaction?A)2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(l)B)2KBr(aq) + Cl2(g) 2KCl(aq) + Br2(l)C)N2(g) + 3H2(g) 2NH3(g)D)CaBr2(aq) + H2SO4(aq) CaSO4(s) + 2HBr(g)E)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)Ans:E Category:Medium Section:4.4

66.Which of the following represents a combustion reaction?A)2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(l)B)LiOH(aq) + HNO3(aq) LiNO3(aq) + H2O(l)C)N2(g) + 3H2(g) 2NH3(g)D)2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)E)2Al(s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g)Ans:A Category:Easy Section:4.4

67.What mass of K2CO3 is needed to prepare 200. mL of a solution having a potassium ion concentration of 0.150 M?A) 4.15 g B) 10.4 g C) 13.8 g D) 2.07 g E) 1.49 gAns:D Category:Medium Section:4.5

68.What mass of Na2SO4 is needed to prepare 350. mL of a solution having a sodium ion concentration of 0.125 M?A) 3.11 g B) 24.9 g C) 12.4 g D) 6.21 g E) 8.88 gAns:A Category:Medium Section:4.5

69.What mass of Li3PO4 is needed to prepare 500. mL of a solution having a lithium ion concentration of 0.175 M?A) 6.75 g B) 10.1 g C) 19.3 g D) 30.4 g E) 3.38 gAns:E Category:Medium Section:4.5

70.A 50.0 mL sample of 0.436 M NH4NO3 is diluted with water to a total volume of 250.0 mL. What is the ammonium nitrate concentration in the resulting solution?A) 21.8 M B) 0.459 M C) 2.18 102 M D) 8.72 102 M E) 0.109 MAns:D Category:Medium Section:4.5

71.A 20.00 mL sample of 0.1015 M nitric acid is introduced into a flask, and water is added until the volume of the solution reaches 250. mL. What is the concentration of nitric acid in the final solution?A)1.27 MD)3.25 102 MB)8.12 103 ME)5.08 104 MC)0.406 MAns:B Category:Medium Section:4.5

72.A 3.682 g sample of KClO3 is dissolved in enough water to give 375. mL of solution. What is the chlorate ion concentration in this solution?A)3.00 102 MD)1.65 102 MB)4.41 102 ME)8.01 102 MC)0.118 MAns:E Category:Medium Section:4.5

73.A 4.691 g sample of MgCl2 is dissolved in enough water to give 750. mL of solution. What is the magnesium ion concentration in this solution?A)3.70 102 MD)4.93 102 MB)1.05 102 ME)0.131 MC)6.57 102 MAns:C Category:Medium Section:4.5

74.A 0.9182 g sample of CaBr2 is dissolved in enough water to give 500. mL of solution. What is the calcium ion concentration in this solution?A)9.19 103 MD)4.59 103 MB)2.30 103 ME)1.25 103 MC)2.72 103 MAns:A Category:Medium Section:4.5

75.35.0 mL of 0.255 M nitric acid is added to 45.0 mL of 0.328 M Mg(NO3)2. What is the concentration of nitrate ion in the final solution?A) 0.481 M B) 0.296 M C) 0.854 M D) 1.10 M E) 0.0295 MAns:A Category:Difficult Section:4.5

76.17.5 mL of a 0.1050 M Na2CO3 solution is added to 46.0 mL of 0.1250 M NaCl. What is the concentration of sodium ion in the final solution?A) 0.205 M B) 0.119 M C) 0.539 M D) 0.148 M E) 0.165 MAns:D Category:Difficult Section:4.5

77.25.0 mL of a 0.2450 M NH4Cl solution is added to 55.5 mL of 0.1655 M FeCl3. What is the concentration of chloride ion in the final solution?A) 0.607 M B) 0.418 M C) 1.35 M D) 0.190 M E) 0.276 MAns:B Category:Difficult Section:4.5

78.When 38.0 mL of 0.1250 M H2SO4 is added to 100. mL of a solution of PbI2, a precipitate of PbSO4 forms. The PbSO4 is then filtered from the solution, dried, and weighed. If the recovered PbSO4 is found to have a mass of 0.0471 g, what was the concentration of iodide ions in the original solution?A)3.10 104 MD)3.11 103 MB)1.55 104 ME)1.55 103 MC)6.20 103 MAns:D Category:Difficult Section:4.6

79.When 50.0 mL of a 0.3000 M AgNO3 solution is added to 50.0 mL of a solution of MgCl2, an AgCl precipitate forms immediately. The precipitate is then filtered from the solution, dried, and weighed. If the recovered AgCl is found to have a mass of 0.1183 g, what as the concentration of magnesium ions in the original MgCl2 solution?A)0.300 MD)2.06 105 MB)8.25 103 ME)4.13 103 MC)1.65 102 MAns:B Category:Difficult Section:4.6

80.When 20.0 mL of a 0.250 M (NH4)2S solution is added to 150.0 mL of a solution of Cu(NO3)2, a CuS precipitate forms. The precipitate is then filtered from the solution, dried, and weighed. If the recovered CuS is found to have a mass of 0.3491 g, what was the concentration of copper ions in the original Cu(NO3)2 solution?A)3.65 103 MD)4.87 102 MB)1.22 102 ME)2.43 102 MC)3.33 102 MAns:E Category:Difficult Section:4.6

81.34.62 mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H2SO4 solution. What is the concentration of the original sulfuric acid solution?A) 0.0229 M B) 0.218 M C) 0.0523 M D) 0.209 M E) 0.105 MAns:C Category:Medium Section:4.7

82.The concentration of oxalate ion (C2O42) in a sample can be determined by titration with a solution of permanganate ion (MnO4) of known concentration. The net ionic equation for this reaction is2MnO4 + 5C2O42 + 16H+ 2Mn2+ + 8H2O + 10CO2A 30.00 mL sample of an oxalate solution is found to react completely with 21.93 mL of a 0.1725 M solution of MnO4. What is the oxalate ion concentration in the sample?A) 0.02914 M B) 0.4312 M C) 0.1821 M D) 0.3152 M E) 0.05044 MAns:D Category:Medium Section:4.8

83.One method of determining the concentration of hydrogen peroxide (H2O2) in a solution is through titration with iodide ion. The net ionic equation for this reaction isH2O2 + 2I +2H+ I2 + 2H2OA 50.00 mL sample of a hydrogen peroxide solution is found to react completely with 37.12 mL of a 0.1500 M KI solution. What is the concentration of hydrogen peroxide in the sample?A)5.568 102 MD)0.4041 MB)0.2227 ME)0.1114 MC)0.1010 MAns:A Category:Medium Section:4.8

84.Zinc dissolves in hydrochloric acid to yield hydrogen gas:Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)What mass of hydrogen gas is produced when a 7.35 g chunk of zinc dissolves in 500. mL of 1.200M HCl?A) 0.605 g B) 0.113 g C) 0.302 g D) 0.453 g E) 0.227 gAns:E Category:Medium Section:4.8

85.Zinc dissolves in hydrochloric acid to yield hydrogen gas:Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)When a 12.7 g chunk of zinc dissolves in 500. mL of 1.450M HCl, what is the concentration of hydrogen ions remaining in the final solution?A) 0.776 M B) 0.388 M C) 0.674 M D) 1.06 M E) 0 MAns:C Category:Medium Section:4.8

86.Lithium metal dissolves in water to yield hydrogen gas and aqueous lithium hydroxide. What is the final concentration of hydroxide ions when 5.500 g of lithium metal is dropped into 750. mL of water?A) 1.06 M B) 0.528 M C) 2.11 M D) 0.792 M E) 0.943 MAns:A Category:Medium Section:4.8

87.When solid iron(II) hydroxide is added to water, the resulting solution contains 1.4103g of dissolved iron(II) hydroxide per liter of solution. What is the hydroxide ion concentration in this solution?A)7.8106 MD)3.1105 MB)1.6105 ME)4.0103 MC)2.51010 MAns:D Category:Difficult Section:4.5

88.A 250. mL sample of 0.0328M HCl is partially neutralized by the addition of 100. mL of 0.0245M NaOH. Find the concentration of hydrochloric acid in the resulting solution.A) 0.00700 M B) 0.0164 M C) 0.0383 M D) 0.0230 M E) 0.0575 MAns:B Category:Difficult Section:4.7

89.A 350. mL sample of 0.276M HNO3 is partially neutralized by 125 mL of 0.0120M Ca(OH)2. Find the concentration of nitric acid in the resulting solution.A) 0.210 M B) 0.00632 M C) 0.203 M D) 0.0240 M E) 0.197 MAns:E Category:Difficult Section:4.7

90.158 mL of a 0.148M NaCl solution is added to 228 mL of a 0.369M NH4NO3 solution. The concentration of ammonium ions in the resulting mixture isA) 0.157 M B) 0.218 M C) 0.625 M D) 0.369 M E) 0 MAns:B Category:Medium Section:4.5

91.1.40 g of silver nitrate is dissolved in 125 mL of water. To this solution is added 5.00 mL of 1.50M hydrochloric acid, and a precipitate forms. Find the concentration of silver ions remaining in solution.A)5.7103 MD)0.121MB)6.34102 ME)5.9103 MC)5.77102 MAns:A Category:Difficult Section:4.6

92.Calcium sulfate dihydrate (commonly known as gypsum) dissolves in cold water to the extent of 0.241 g per 100. cm3. What is the concentration of calcium ions in this solution?A)1.77102 MD)3.54102 MB)2.80102 ME)1,40102 MC)1.77103 MAns:E Category:Difficult Section:4.5

93.Calcium nitrate tetrahydrate dissolves in cold water to the extent of 266 g per 100. cm3. What is the concentration of nitrate ions in this solution?A) 32.4M B) 22.5M C) 11.3M D) 16.2M E) 8.10MAns:B Category:Difficult Section:4.5

94.Define solution, solute, and solvent.Ans:A solution is a homogeneous mixture of two or more substances.The substance present in a smaller amount is called the solute, while the substance present in the larger amount is called the solvent.Category:Easy Section:4.1

95.Identify the following compound as an electrolyte or nonelectrolyte: NaOH.Ans:electrolyteCategory:Easy Section:4.1

96.Identify the following compound as an electrolyte or nonelectrolyte: H2SO4.Ans:electrolyteCategory:Easy Section:4.1

97.Identify the following compound as an electrolyte or nonelectrolyte: Methanol (CH3OH).Ans:nonelectrolyteCategory:Easy Section:4.1

98.Identify the following compound as an electrolyte or nonelectrolyte: C12H22O11(sucrose).Ans:nonelectrolyteCategory:Easy Section:4.1

99.Identify the following compound as an electrolyte or nonelectrolyte: MgCl2.Ans:electrolyteCategory:Easy Section:4.1

100.Identify the following compound as a strong electrolyte, weak electrolyte, or nonelectrolyte: CH3OH (methanol).Ans:nonelectrolyteCategory:Easy Section:4.1

101.Identify the following compound as a strong electrolyte, weak electrolyte, or nonelectrolyte: CH3COOH.Ans:weak electrolyteCategory:Easy Section:4.1

102.Identify the following compounds as a strong electrolytes, weak electrolytes, or nonelectrolytes: KNO3, KNO2, HNO3, HNO2,Ans:KNO3, KNO2, and HNO3 are strong electrolytes; HNO2 is a weak electrolyte.Category:Medium Section:4.3

103.Identify the following compound as a strong electrolyte, weak electrolyte, or nonelectrolyte: NH3.Ans:weak electrolyteCategory:Medium Section:4.1

104.Identify the following compound as a strong electrolyte, weak electrolyte, or nonelectrolyte: NH4Cl.Ans:strong electrolyteCategory:Easy Section:4.1

105.Define and illustrate with an example the difference between an electrolyte and a nonelectrolyte.Ans:(Answers will vary.) An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity. An example is sodium hydrogen carbonate. A nonelectrolyte does not conduct electricity when dissolved in water. An example would be sugar.Category:Medium Section:4.1

106.Define precipitate and illustrate with an example.Ans:(Answers will vary.) A precipitate is an insoluble solid that separates from a solution.CoCl2 (aq) + Na2CO3(aq) CoCO3 (s) + 2NaCl (aq)In this reaction, CoCO3 is a precipitate.Category:Medium Section:4.2

107.Give an example of a monoprotic acid.Ans:HNO3 (for example)Category:Easy Section:4.3

108.Give an example of a diprotic acid.Ans:H2CO3 (for example)Category:Easy Section:4.3

109.Name and give the formulas for six strong acids.Ans:hydrochloric acid, HCl; hydrobromic acid, HBr; hydroiodic acid, HI; nitric acid, HNO3; sulfuric acid, H2SO4; perchloric acid, HClO4Category:Easy Section:4.3

110.Give an example of a triprotic acid.Ans:H3PO4Category:Easy Section:4.3

111.Write the net ionic equation for the following reaction. Aqueous iron(III) sulfate is added to aqueous sodium sulfide to produce solid iron(III) sulfide and aqueous sodium sulfate.Ans:2Fe3+(aq) + 3S2 (aq) Fe2S3(s)Category:Medium Section:4.2

112.Determine the oxidation number of each of the elements in Cs2Cr2O7?Ans:the oxidation number of Cs is +1; the oxidation number of Cr is +6; the oxidation number of O is 2Category:Easy Section:4.4

113.Identify the element being oxidized in the following reaction.4Al + 3O2 2Al2O3Ans:AlCategory:Medium Section:4.4

114.Identify the element being reduced in the following reaction.4Al + 3O2 2Al2O3Ans:OCategory:Medium Section:4.4

115.Identify the oxidizing agent in the following reaction.4Al + 3O2 2Al2O3Ans:O2Category:Medium Section:4.4

116.Identify the reducing agent in the following reaction.4Al + 3O2 2Al2O3Ans:AlCategory:Medium Section:4.4

117.Identify the element being oxidized in the following reaction.2KBr + F2 Br2 + 2KFAns:BrCategory:Medium Section:4.4

118.Identify the element being reduced in the following reaction.2KBr + F2 Br2 + 2KFAns:FCategory:Medium Section:4.4

119.Identify the oxidizing agent in the following reaction.2KBr + F2 Br2 + 2KFAns:F2Category:Medium Section:4.4

120.Identify the reducing agent in the following reaction.2KBr + F2 Br2 + 2KFAns:Br (or KBr)Category:Medium Section:4.4

121.Determine the oxidation number of each of the elements BaNaPO4?Ans:the oxidation number of Ba +2; the oxidation number of Na is +1; the oxidation number of P is +5; the oxidation number of O is 2Category:Easy Section:4.4

122.Determine the oxidation number of each of the elements in K2TaF7?Ans:the oxidation number of K is +1; the oxidation number of Ta is +5; the oxidation number of F is 1Category:Easy Section:4.4

123.Thorium metal is prepared by reacting thorium oxide with calcium.ThO2 + 2Ca Th + 2CaOWhich substance is reduced in this process?Ans:Th4+ is reducedCategory:Medium Section:4.4

124.Thorium metal is prepared by reacting thorium oxide with calcium.ThO2 + 2Ca Th + 2CaOWhat is the reducing agent in this process?Ans:CaCategory:Medium Section:4.4

125.Thorium metal is prepared by reacting thorium oxide with calcium.ThO2 + 2Ca Th + 2CaOWhich substance is oxidized in this process?Ans:CaCategory:Medium Section:4.4

126.Thorium metal is prepared by reacting thorium oxide with calcium.ThO2 + 2Ca Th + 2CaOWhat is the oxidizing agent in this process?Ans:ThO4Category:Medium Section:4.4

127.Batteries in our cars generate electricity by the following chemical reaction.Pb + PbO2 + 2H2SO4 2PbSO4 + 2H2OWhich substance is reduced in this process?Ans:Pb4+Category:Medium Section:4.4

128.Batteries in our cars generate electricity by the following chemical reaction.Pb + PbO2 + 2H2SO4 2PbSO4 + 2H2OWhat is the reducing agent in this process?Ans:PbCategory:Medium

129.Batteries in our cars generate electricity by the following chemical reaction.Pb + PbO2 + 2H2SO4 2PbSO4 + 2H2OWhich substance is oxidized in this process?Ans:PbCategory:Medium Section:4.4

130.Batteries in our cars generate electricity by the following chemical reaction.Pb + PbO2 + 2H2SO4 2PbSO4 + 2H2OWhat is the oxidizing agent in this process?Ans:PbO2Category:Medium Section:4.4

131.Describe the procedure used to make 3.0 liters of a 2.0 M KCl solution, starting with solid KCl and water.Ans:Determine the molar mass of KCl, which is 74.55 g/mol; weigh out 447.3 grams (6 mol) of KCl; dissolve the KCl in enough water to form exactly 3 liters of solution.Category:Medium Section:4.5

132.What is the molarity of a solution that contains 5.0 moles of solute in 2.00 liters of solution?Ans:2.5 MCategory:Easy Section:4.5

133.The solubility of Ba(NO3)2 is 130.5 grams per liter at 0C. How many moles of dissolved salt are present in 4.0 liters of a saturated solution of Ba(NO3)2 at 0C?Ans:2.0 molesCategory:Medium Section:4.5

134.What is the molar concentration of chloride ions in a solution prepared by mixing 100. mL of 2.0 M KCl with 50. mL of a 1.5 M CaCl2 solution?Ans:2.3 MCategory:Difficult

135.What volume of concentrated nitric acid (15.0 M) is required to make 100. mL of a 3.0 M nitric acid solution?Ans:20. mLCategory:Medium Section:4.5

136.During a titration the following data were collected. A 10. mL portion of an unknown monoprotic acid solution was titrated with 1.0 M NaOH; 40. mL of the base were required to neutralize the sample. What is the molarity of the acid solution?Ans:4.0 MCategory:Medium Section:4.7

137.During a titration the following data were collected. A 10. mL portion of an unknown monoprotic acid solution was titrated with 1.0 M NaOH; 40. mL of the base were required to neutralize the sample. How many moles of acid are present in 2.0 liters of this unknown solution?Ans:8.0 molesCategory:Medium Section:4.7

138.If 145 grams of potassium nitrate were added to water to make 1,500 mL of solution, what would be the molarity of the resulting solution?Ans:0.956 MCategory:Medium Section:4.5

139.During a titration the following data were collected. A 50.0 mL portion of an HCl solution was titrated with 0.500 M NaOH; 200. mL of the base was required to neutralize the sample. How many grams of HCl are present in 500. mL of this acid solution?Ans:36.5 gCategory:Medium Section:4.7

140.Identify the following as either a good or poor conductor of electricity: a crystal of Na2SO4.Ans:poorCategory:Easy Section:4.1

141.Identify the following as either a good or poor conductor of electricity: an aqueous solution of Na2SO4.Ans:goodCategory:Easy Section:4.1

142.Identify the following as either a good or poor conductor of electricity: gasoline (C8H18).Ans:poorCategory:Easy Section:4.1

143.Which substance is acting as a Brnsted acid in the following reaction?HSO4 + NH4+ H2SO4 + NH3Ans:NH4+Category:Medium Section:4.3

144.Identify the Brnsted acid in the following reaction.NH3 + H2O NH4+ + OHAns:H2OCategory:Medium Section:4.3

145.Write balanced molecular and net ionic equations for the reaction that would occur between CaCl2(aq) and Na2CO3(aq). Be sure to include the correct states in your final equations. If no reaction is expected, write no reaction.Ans:Molecular equation: CaCl2(aq) + Na2CO3(aq) CaCO3(s) + 2NaCl(aq)Net ionic equation: Ca2+(aq) + CO32(aq) CaCO3(s)Category:Medium Section:4.2

146.Write balanced molecular and net ionic equations for the acid-base neutralization reaction between H3PO4(aq) and Ba(OH)2(aq). Be sure to include the correct states in your final equations. If no reaction is expected, write no reaction.Ans:Molecular equation: 2H3PO4(aq) + 3Ba(OH)2(aq) Ba3(PO4)2(s) + 6H2O(l)Net ionic equation: 2H3PO4(aq) + 3Ba2+(aq) + 6OH(aq) Ba3(PO4)2(s) + 6H2O(l)Category:Difficult Section:4.3

147.Write balanced molecular and net ionic equations for the reaction that would occur between Al(s) and Co(NO3)2(aq). Be sure to include the correct states in your final equations. If no reaction is expected, write no reaction.Ans:Molecular equation: 2Al(s) + 3Co(NO3)2(aq) 2Al(NO3)3(aq) + 3Co(s)Net ionic equation: 2Al(s) + 3Co2+(aq) 2Al3+(aq) + 3Co(s)Category:Medium Section:4.4

148.Write balanced molecular and net ionic equations for the reaction that would occur between CuCl2(aq) and Pb(s). Be sure to include the correct states in your final equations. If no reaction is expected, write no reaction.Ans:Molecular equation: CuCl2(aq) + Pb(s) Cu(s) + PbCl2(s)Net ionic equation: Cu2+(aq) + 2Cl(aq) + Pb(s) Cu(s) + PbCl2(s)Category:Difficult Section:4.4

149.A piece of copper metal was added to an aqueous solution of silver nitrate, and within a few minutes it was observed that a grey crystalline solid formed on surface of the copper and the solution turned a blue color characteristic of copper(II) ions.Write the balanced chemical equation for this reaction.Ans:Cu(s) + 2AgNO3(aq) 2Ag(s) + Cu(NO3)2(aq)Category:Medium Section:4.4

150.A piece of copper metal was added to an aqueous solution of silver nitrate, and within a few minutes it was observed that a grey crystalline solid formed on surface of the copper and the solution turned a blue color characteristic of copper(II) ions.Write the net ionic equation for this reaction.Ans:Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s)Category:Medium Section:4.4

151.A piece of lead metal was added to an aqueous solution of copper(II) nitrate, and within a few minutes it was observed that the lead turned black and crumbled, and the blue solution characteristic of copper(II) ions faded. (NOTE: Lead forms a 2+ ion when it reacts.)Write the balanced chemical equation for this reaction.Ans:Pb(s) + Cu(NO3)2(aq) Cu(s) + Pb(NO3)2(aq)Category:Medium Section:4.4

152.A piece of lead metal was added to an aqueous solution of copper(II) nitrate, and within a few minutes it was observed that the lead turned black and crumbled, and the blue solution characteristic of copper(II) ions faded. (NOTE: Lead forms a 2+ ion when it reacts.)Write the net ionic equation for this reaction.Ans:Pb(s) + Cu2+(aq) Pb2+(aq) + Cu(s)Category:Medium Section:4.4

153.A piece of zinc metal was added to an aqueous solution of lead(II) nitrate. After some time it was observed that the zinc metal had appeared to fall apart and a solid had accumulated at the bottom of the reaction vessel.Write the balanced chemical equation for this reaction.Ans:Zn(s) + Pb(NO3)2(aq) Pb(s) + Zn(NO3)2(aq)Category:Difficult Section:4.4

154.A piece of zinc metal was added to an aqueous solution of lead(II) nitrate. After some time it was observed that the zinc metal had appeared to fall apart and a solid had accumulated at the bottom of the reaction vessel.Write the net ionic equation for this reaction.Ans:Zn(s) + Pb2+(aq) Zn2+(aq) + Pb(s)Category:Difficult Section:4.4

155.The following experiments were carried out and observations recorded. Expt. #1: copper metal was added to an aqueous solution of silver nitrateObservation: The copper become coated with a substance.Expt. #2: lead metal was added to an aqueous solution of copper(II) nitrateObservation: The lead turned black and crumbled.Expt. #3: zinc metal was added to an aqueous solution of lead(II) nitrateObservation: The zinc appeared to fall apart. Rank the metals from most active to least active.Ans:most active Zn, next most active Pb, next most active Cu, least active AgCategory:Difficult Section:4.4

156.Write a balanced molecular equation for the reaction that occurs when aqueous solutions of potassium iodide and lead(II) nitrate are combined.Ans:2KI(aq) + Pb(NO3)2(aq) PbI2(s) + 2KNO3(aq)Category:Medium Section:4.2

157.If 73.5 mL of 0.200 M KI(aq) was required to precipitate all of the lead(II) ion from an aqueous solution of lead(II) nitrate, how many moles of Pb2+ were originally in the solution?Ans:7.35 103 moles of Pb2+Category:Medium Section:4.6

158.Sugar dissolves in water, therefore it is a strong electrolyte.Ans:False Category:Medium Section:4.1

159.Silver chloride (AgCl) has an extremely low solubility in water; therefore, it is a weak electrolyte.Ans:False Category:Medium Section:4.1

160.Most compounds containing chlorides, bromides, and iodides are soluble except those containing Ag+, Hg22+, and Pb2+.Ans:True Category:Easy Section:4.2

161.The following reaction is an acid-base neutralization reaction.H2SO4(aq) + CaBr2(aq) CaSO4(s) + 2HBr(g)Ans:False Category:Easy Section:4.3

162.The oxidation number of N in NO is +7.Ans:False Category:Easy Section:4.4

163.Hydrogen is oxidized in the following chemical reaction.H2 + Cl2 2HClAns:True Category:Medium Section:4.4

164.The following equation is an example of a net ionic equation.Na+(aq) + Br(aq) + Ag+(aq) + NO3(aq) AgBr(s) + Na+(aq) + NO3(aq)Ans:False Category:Medium Section:4.2

165.The oxidation number of iodine increases by 6 in the following reaction.2MnO4 + I + H2O 2MnO2 + IO3 + 2OHAns:True Category:Medium Section:4.4

166.A weak acid or a weak base ionizes completely.Ans:False Category:Medium Section:4.3

167.The following reaction is a redox reaction.CaC2(s) + H2O(l) HCCH(g) + CaO(s)Ans:False Category:Medium Section:4.4

Definitions (only examples)83.What is the definition of a gas?Ans:A gas is a substance in which the molecules are separated on the average by distances that are large compared with the sizes of the molecules.Category:Easy Section:5.1

84.What is standard temperature and standard pressure?Ans:0C and 1 atm pressureCategory:Easy Section:5.2

Comprehensive questions/ Calculations(only show examples)85.What is the pressure of the sample of gas trapped in the open-tube mercury manometer shown below if atmospheric pressure is 742 mmHg and h = 16.7 cm?Ans:575 mmHgCategory:Easy Section:5.2

86.What is the pressure (in atmospheres) of the sample of gas trapped in the open-tube mercury manometer shown below if atmospheric pressure is 735 mmHg and h = 8.3 cm?Ans:0.858 atmCategory:Easy Section:5.2

87.What is the pressure (in atmospheres) of the sample of gas trapped in the closed-tube mercury manometer shown below if h = 23.6 cm?Ans:0.311 atmCategory:Easy Section:5.2

88.What is the pressure of the sample of gas trapped in the closed-tube mercury manometer shown below if atmospheric pressure is 751 mmHg and h = 17.3 cm?Ans:173 mmHg (or 0.228 atm)Category:Easy Section:5.2

89.What is the significance of the magnitude of the van der Waals a constant?Ans:The magnitude of the van der Waals a constant reflects the strength of the attractions between molecules of a given type of gas.Category:Easy Section:5.8

90.How many grams of N2O, nitrous oxide, are contained in 500. mL of the gas at STP?Ans:0.982 gCategory:Easy Section:5.2

91.Calculate the density of N2O gas, in grams per liter, at 110C and 12 atm.Ans:16.8 g/LCategory:Medium Section:5.4

92.Calculate the molar mass of a gaseous substance if 0.125 g of the gas occupies 93.3 mL at STP.Ans:30.0 g/molCategory:Medium Section:5.4

93.An aerosol can with a volume of 0.50 L has a bursting point of 2.6 atm. If the can contains 1.0 g CO2 and is heated to 400C, will it burst?Ans:NoCategory:Medium Section:5.4

94.Phosgene, a chemical warfare agent used in World War I, consists of 12.41% C, 16.17% O, and 71.69% Cl. 1.00 L of this gas at STP has a mass of 4.42 g. What is the molecular formula of phosgene?Ans:COCl2Category:Medium Section:5.4

95.The van der Waals equation is a modification of the ideal gas equation. For what two facts does this equation account?Ans:(1) Real gas molecules exert forces on each other. (2) Gas molecules have volume.Category:Easy Section:5.8

96.On a spring morning (20C) you fill your tires to a pressure of 2.25 atmospheres. As you ride along, the tire heats up to 45C from the friction on the road. What is the pressure in your tires now?Ans:2.44 atmospheresCategory:Medium Section:5.4

97.A gas-filled balloon with a volume of 12.5 L at 0.90 atm and 21C is allowed to rise to the stratosphere where the temperature is 5C and the pressure is 1.0 millibar. What is the final volume of the balloon? 1.000 atm = 1.013 bar.Ans:1.0 104 LCategory:Medium Section:5.4

98.What volume of H2 is formed at STP when 6.0 g of Al is treated with excess NaOH?2NaOH + 2Al + 6H2O 2NaAl(OH)4 + 3H2(g)Ans:7.5 LCategory:Medium Section:5.5

99.A convenient way to produce very high purity oxygen in the laboratory is to decompose KMnO4(s) at high temperature according to the following chemical equation:2KMnO4(s) K2MnO4(s) + MnO2(s) + O2(g)If 2.50 L of O2(g) is needed at 1.00 atm and 20C, what mass of KMnO4(s) should be decomposed? Assume the decomposition of KMnO4(s) goes to completion.Ans:32.8 gCategory:Medium Section:5.5

100.What is V in the table below? PVT

initial:1,420 torr75 mL200. K

final:760 torrV360. K

Ans:250 mLCategory:Medium Section:5.4

101.What is P in the table below? PV

initial:14 atm1.0 L

final:P50. L

Ans:0.28 LCategory:Medium Section:5.3

102.What is T in the table below? VT

initial: 91.8 mL365 K

final: 45.8 mLT

Ans:182 K or 91.0CCategory:Medium Section:5.3

103.What is P in the table below? VP

initial:91.8 mL1 atm

final:45.8 mLP

Ans:2 atmCategory:Medium Section:5.3

104.Today is a beautiful day for a picnic in the mountains, so we seal our peanut butter sandwich in a plastic sandwich bag at the base of the mountain. The approximate volume of the sandwich bag not occupied by the sandwich is 200. mL. The pressure at the base of the mountain is 1.0 atm. If the pressure at the top of the mountain is 0.80 atm, what is the final volume of gas in our sandwich bag?Ans:250 mLCategory:Medium Section:5.3

105.Give five examples of elements that occur as gases at room temperature and pressure?Ans:(Answers will vary.) Oxygen, nitrogen, helium, hydrogen, argon, chlorineCategory:Easy Section:5.1

106.Give five examples of compounds that exist as gases at room temperatu