Name___________________________________ Date___________________________

Study guide for Chem 1-2 Second Semester Final Exam ANSWERS

1. Read the following measuring devices. Don’t forget: You are required to estimate the digit of uncertainty.

_____63.5mL____ _____56.0mL_ ___________2.34cm__________ _____ 36.5mL___

2. List the name of the measuring device and the unit used for the following::

Measuring device Unit

The mass of a nail BALANCE grams (g)

Volume of a sample of water GRADUATED CYLINDER milliliters (mL)

Length of a pencil RULER centimeters(cm)

Temperature of oil THERMOMETER degrees Celsius (oC)

3. What is the definition of matter? ANYTHING THAT HAS VOLUME (OCCUPIES SPACE) AND HAS MASS.4. Draw molecular pictures (using circles to represent atoms) of a solid, a liquid and a ga

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5. What is an intermolecular force? A FORCE OF ATTRACTION BETWEEN MOLECULES. INCLUDE DIPOLE-DIPOLE FORCES, DISPERSION FORCES, AND HYDROGEN BONDING. HYDROGEN BONDING IS THE STRONGEST IMF AND INVOVES MOLECULAR COMPOUNDS THAT HAVE HYDROGEN BONDED TO EITHER FLUORINE, CHLORINE, OR NITROGEN.

6. Name a substance with strong intermolecular forces. Would this substance have a high or a low boiling point?

WATER. VERY STRONG IMF’S. HIGH BOILING POINT. LOW VAPOR PRESSURE.

7. What type of lab tests could you perform to see if a substance has a weak or a strong intermolecular force?

BOIL IT AND DETERMINE IF IT HAS A HIGH BOILING POINT. TIME HOW LONG IT TAKES FOR A SAMPLE TO EVAPORATE. DROP SOME ON WAX PAPER AND LOOK TO SEE HOW IT RESTS ON WAX PAPER. THE MORE IT PULLS ITSELF INWARD AND MAKES A CURVE, THE GREATER THE INTERMOLECULAR FORCES.

8. Define the term allotrope. Name the three common allotropes of carbon. What are the differences between these allotropes. DIFFERENT FORMS OF THE SAME ELEMENT DUE TO DIFFERENT BONDING PATTERNS. CARBON EXISTS AS GRAPHITE , DIAMOND, AND BUCKYBALLS. BUCKYBALLS BOND IN A SPHERICAL PATTERN (LIKE THE EPCOT CENTER DOME). DIAMONDS BOND WITH STRONG EVEN AND SHORT IDENTICAL BONDS. GRAPHITE BONDS TIGHTLY WITH EVEN BONDS AND ALSO WITH LONGER WEAKER BONDS. THIS CAUSES IT TO BREAK AT THE WEAK BONDS SO WE CAN USE IT TO WRITE WITH ON PAPER. CARBON CAN ALSO COME IN THE FORM OF NANOTUBES.

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9. What does the phrase “Like dissolves Like” refer to? POLAR SOLVENTS DISSOLVE POLAR SOLUTES AND IONIC SUBSTANCES. THIS EXPLAINS WHY WATER DISSOLVES OTHER NONPOLAR SUBSTANCES AND IONIC SUBSTANCES AS WELL. NONPOLAR SOLVENTS DISSOLVE NONPOLAR SOLUTES.

10. Why is a water molecule polar? Draw a picture of a water molecule showing the polarity.WATER IS A BENT SHAPE DUE TO TWO LONE PAIRS OF ELECTRONS ON THE CENTRAL ATOM. THE OXYGEN ATOM BONDS WITH THE HYDROGEN ATOMS UNFAIRLY. THE BOND IS CALLED POLAR. BECAUSE OF THE POLAR BONDING AND THE BENT SHAPE, WATER HAS ONE END THAT IS NEGATIVE (OXYGEN END) AND ONE END THAT IS POSITIVE(HYDROGEN END). THIS MAKES WATER MOLECULES ACT “STICKY’ TO ONE ANOTHER.

11. What is the law of conservation of mass?

THE MASS OF THE REACTANTS (PROVIDED THE MOLE RATIO IS PERFECT. NO LIMIITING REACTANT) WILL ALWAYS EQUAL THE MASS OF THE PRODUCTS. NO MASS IS CREATED OR DESTROYED IN ANY CHEMICAL OR PHYSICAL PROCESS.

12. Will the mass of a light stick after it is snapped and glowing be the same, lower, or higher than a light stick that is not snapped and glowing?

13. Density is mass/volume. If the volume of a metal is 6.0cm3 and the mass is 10.0g, what is the density?

D =m/v D = 10.0g/6.0cm3 = 1.7 g/cm3

14. Density is mass/volume. If the mass of an object is 60.0g and the density is 1.55 g/cm3, what is the volume?

V =m/D 60.0g/1.55g/cm3 = 38.7cm3

15. Density is mass/volume. If the density of a substance is 19.3g/cm3 and the volume is 2.00cm3, what is the mass?

m = v x D 2.00cm3 x 19.3g/cm3 = 38.6 g

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16. Aluminum has a density of 2.67g/cm3 and gold has a density of 19.3g/cm3. Draw pictures to represent the densities of these two metals. Use circles to represent atoms.

19.3g/cm3 2.67g/cm3

17. Water has a density of 1.0g/cm3. Vegetable oil has a density of 0.97g/cm3. Would the oil float or sink in the water? Lower density rests on top of higher density. Vegetable oil will float on top due to lower density.

18. Draw pictures to represent an atom, a compound, and a mixture. Use dark and light circles to represent atoms.

19. Which of the following are physical changes: boiling, dissolving, melting, burning, freezing, corroding

The shape, size, or texture might change, however, the properties of the substance remain.

20. Which of the following are chemical changes: boiling, dissolving, melting, burning, freezing, corroding

After a chemical change, the substance has changed into something else. The new substance has different properties.

21. Is the melting of ice endothermic or exothermic?22. Is the freezing of ice endothermic or exothermic?

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23. Is the vaporization of water endothermic or exothermic? 24. Is condensation of water endothermic or exothermic? 25. What type of substances would have low specific heats?

Metals. Low specific heats mean it takes only a small amount of energy to increase the temp of a gram of the substance. Specific heat has units of J/g x Co

26. Water has a specific heat of 4.184J/g x Co. What is the reason the specific heat of water is so large?

Strong intermolecular forces.

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27. Ice cubes and water are placed in a container of hot hard -boiled eggs. Explain the energy transfer that occurs.

Faster moving molecules transfer their energy to slower moving molecules. The energy from the hot eggs would transfer into the water and into the ice cubes.

28. Is energy released when bonds are broken or when bonds are formed?

Energy is NEEDED to BREAK bonds. Energy is RELEASED when bonds are FORMED.

29. Which has more potential energy: The products of an endothermic reaction or the reactants of an endothermic reaction. The reactants of an exothermic reaction or the products of an exothermic reaction.

30. A 50.0g piece of metal is boiled in a hot pot and reaches a temperature of 100.0oC. It is then placed into 75.0g of water that is at 20.0oC. The water is stirred and reaches a maximum temperature of 30.0oC. The specific heat of water is 4.184J/g Co. Calculate the following:The change in temperature of the water 30.0oC -20.0oC = 10.0oC The change in temperature of the piece of metal 30.0oC – 100.0oc = -70.0oCThe amount of Joules gained by the water (75.0g)(4.184J/g x oC)(10.0oC) = 3140J GainedThe amount of Joules lost by the metal -3140 J LostThe specific heat of the metal -3140 J = (50.0g)(x)(-70.0oC) = 0.900 J/g x oC

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31. What are the names of the following compounds? CaS CaSO4 NaNO3 Pb(OH)2

Calcium sulfide, calcium sulfate, sodium nitrate, lead(II)hydroxide

32. What are the names of the following compounds? SiO2 N2O5 CF4 N3O7 CO SCl6

silicon dioxide, dinitrogen pentaoxide, carbon tetrafluoride, trinitrogen heptaoxide, carbon monoxide, sulfur hexachloride. (prefixes of mono-di-tri-tetra-penta-hexa-hepta-octa-nona-deca are used when two nonmetals bond)

33. CH4 + 2O2 CO2 + 2H2O

List the reactants CH4 and O2 List the products CO2 and H2O

Balance the equation. What type of reaction does this equation represent? Complete combustion

What is the name given to the numbers used to balance an equation? Coefficients

34. Identify the reaction type.

A + B AB Synthesis/Composition AB A + B Decomposition

AB + C AC + B Single Replacement AB + CD AD + CB Double Replacement

35. H2SO4 + Mg H2 + MgSO4 This reaction takes 30.0 seconds to complete when 1.0M H2SO4 is used.

If 3.0M H2SO4 is used, would the reaction time period be the same, longer, or shorter? More concentrated acid

Would the rate of the reaction slow down, stay the same, or speed up if 0.5M acid is used? More dilute acid

36. Look at the Activity Series to answer the next questions.

Can chlorine replace fluorine? NO Can zinc replace hydrogen? YES Can copper replace silver YES

Which reactions WILL occur?

Ag + ZnNO3 AgNO3 + Zn NO Cu + AgNO3 CuNO3 + Ag YES

2HCl + Mg MgCl2 + H2 YES MgSO4 + Cu CuSO4 + Mg YES

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37. Which pairs will form a compound? N and F YES Ag and Cu (NO ) Cu and Cl YES H and O YES

TWO METALS WILL NOT MAKE A COMPOUND. NONMETALS CAN FORM COMPOUNDS WITH COVALENT BONDS.

A METAL AND A NONMETAL WILL MAKE AN IONIC BOND.

38. CO2 (g) + NaOH (aq) <==> NaHCO3(aq) + heat

Which of the following will increase the amount of NaHCO3?

Heat the reaction Add more CO2 Decrease the amount of NaOH Add pressure Add argon gas

39. Which situation would slow the rate of a reaction?

Cooling Heating Diluting the concentrations of the reactants Increasing the concentration of the reactants.

40. Define collision theory. Particles must collide at the proper angle and at the proper speed in order to react.

They must have effective collisions. The more collisions the faster the reaction occurs.

41. Which situation would cause particles to have more collisions? Note: The reactants are gases.

a. Heat the reaction container. b. Cool the reaction container.

a. Decrease the volume of the container. b. Increase the volume of the container.

a. Increase concentration of reactants. b. Decrease concentration of reactants.

42. How many molecules are in 2.0 moles of H2O?

2.0 moles x 6.02 x 1023 molecules/mol = 1.2 x 10 24 molecules of H2O

43. What is the molar mass of Mg3(PO4)2?

Mg = 3 x 24.30 = 72.9 + P = 2 x 30.97 = 61.94 + O = 8 x 16.0 = 128.00 ( 72.9 + 61.94 + 128.00 = 262.84g/mol)

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44. A piece of aluminum has a mass of 50.00g. How many moles does the piece of Al contain?

( grams to moles divide by the molar mass) 50.00g / 26.98g/mol = 1.853mol

45. A helium balloon has a volume of 30.50L at STP. How many atoms are inside the balloon?

30.50 L / 22.4 mol/L = 1.361607 mol of He x 6.02 x 1023 atoms /mol = 8.197 x 10 23 atoms of He

46. 2H2 + O2 2H2O

How many moles of hydrogen are needed to completely react with 6.0 moles of oxygen? The mole ratio of hydrogen to water is 2 : 1. Therefore 12.0 moles of hydrogen are needed to react with 6.0 moles of oxygen.

If 6.0 moles of water is formed, how many moles of hydrogen were used? The mole ratio of hydrogen to water is 1:1.

Therefore if 6.0 moles of water are formed, 6.0 moles of hydrogen were used in the reaction.

If 12.0 grams of hydrogen is reacted with excess oxygen, how many grams of water are produced?

12.0 grams H2 1mol H2 2mol H2O 18.0 g of H2O = 108 grams of H2O will be produced.

2.00grams H2 2 mol H2 1 mol H2O

47. What are the charge, relative mass and location of the following particles:

electron charge = -1 relative mass= 0 location = Outside nucleus

proton charge = +1 relative mass= 1 location = Inside nucleus

neutron charge = 0 relative mass= 1 location = inside nucleus

48. What is the mass number of an atom that has 20 protons, 20 electrons, and 21 neutrons?

Mass number = number of protons + number of neutrons (20 p + 21 n = 41)

49. What is the identity of the atom in problem #48? The number of protons identifies the atom. This is Ca.

50. Write the chemical symbol of an ion that has 11 protons, 10 electrons, and 11 neutrons

1+ (This is Na-22 with a charge of 1+)

22 Na

51. Write the chemical symbol of an ion that has 8 protons, 10 electrons, and 9 neutrons

2- (This is O-17 with a 2- charge (oxide)

17 O

52. What is the charge of a potassium ion? 1+ An oxide ion? 2- A sulfide ion? 2- A nitride ion? 3-A calcium ion? 2+ An aluminum ion? 3+ A zinc ion? 2+ A silver ion? 1+

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53. When oxygen forms an oxide ion, does it lose two electrons or gain two electrons? Gains two

54. When sodium forms an ion, does it gain one electron or lose one electron. Loses one

55. What is the name given to a positive ion? CATION What is the name given to a negative ion? ANION

56. Define the term line emission spectra.A specific band of colors that are emitted when the electrons of an atom are excited. The electrons JUMP up energy levels and emit light when they come DOWN creating a colorful banding pattern (when looked at through a diffraction grating) that is unique to that element.

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57. Can two elements have the same line emission spectra?

No. Every element emits its own emission spectra. It is the fingerprint of that particular element.

58. Define the term isotope. Atoms of the SAME element that have DIFFERENT numbers of NEUTRONS. They have different mass numbers but the same atomic number.

59. Which are isotopes? Li-7 and N-8 H-1 and H-2 Cu-63 and Zn-66

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60. Define the term fission. Where does fission occur? Does fission create more or less energy than fusion?

When a large unstable nucleus is split into two smaller nuclei. Three neutrons are emitted and LOTS of energy is emitted too. Fission is the reaction in a nuclear power plant

61. Define the term fusion. Where does fusion occur? Does fusion create more or less energy than fission?

Fusion is when two smaller nuclei combine into a bigger nucleus. An ENORMOUS amount of energy is released from this process. Fusion is what powers our sun. Fusion creates more energy compared to fission.

62. What happens during alpha decay?

A particle called an alpha particle is emitted from the nucleus. This particle consists of two protons and two neutrons. (It is a helium nucleus.) After the decay, the original element has changed into a DIFFERENT element that has two less protons and a mass number that is four less.

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63. What happens during beta decay?

This is when an electron is emitted from the nucleus. The electron is from a neutron. (Neutron is a proton + electron.) Once the electron is emitted, a proton is left behind. The original element has now changed into a DIFFERENT element. The new element has an atomic number ONE more than the original. The mass number of the NEW element is the SAME as the original element.

64. Identify the following as alpha decay or beta decay.

Beta decay Alpha decay Alpha decay Beta decay

65. Name an element with similar properties to neon. Any of the noble gases:He, Ne, Kr

66. Name an element with similar properties to oxygen. Any element in Group 16 (S, Se, Te, Po)

67. Name an element with similar properties to magnesium. Any element in Group 2 (Be, Ca, Sr, Ba)

68. List the properties of metals.

Shiny (lustrous), malleable, ductile, good conductors of heat and electricity. Most grey/silver in color.

69. List the properties of nonmetals Different colors, Not shiny, Not malleable, Not ductile, DO NOT conduct heat or electricity. Nonmetals shatter when you hit them (They are brittle).

70. List the properties of semimetals (metalloids)

A mix of properties from the metal list AND the nonmetal list. For example: Poor conductor of Heat. Great conductor of electricity.

71. How many valence electrons does oxygen have? (6) What is the charge of an oxide ion? 2-

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72. How many valence electrons does nitrogen have? (5) What is the charge of a nitride ion? 3-

73. How many valence electrons does sodium have? (1) What is the charge of a sodium ion? 1+

74. How many valence electrons does chlorine have? (7) What is the charge of a chloride ion? 1-

75. Name the seven common diatomic elements.

H2 N2 O2 F2 Cl2 Br2 I2 (HONClBrIF)

76. What type of covalent bonding does O2 have? Single, double, or triple

77. What type of covalent bonding does N2have? Single, double, or triple

78. What type of covalent bonding does Cl2 have? Single, double, or triple

79. Which type of atoms will form covalent bonds? Nonmetal bonded covalently with another nonmetal.

80. Which type of atoms will form ionic bonds? Metal cation bonded with a nonmetal anion

81. Which type of bond (covalent or ionic) involves a transfer of electrons?

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82. Which type of bond (covalent or ionic) involves a sharing of electrons?

83. Which type of particles will conduct a current If they are dissolved in water. Covalent or ionic?

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84. Draw the Lewis structures for the following molecular substances: H2O, CO2, NH3, and CH4

85. Sugar is dissolved in water. Name the solute and the solvent. SOLUTE is SUGAR SOLVENT is WATER

86. If 5.0 grams of sodium hydroxide (NaOH with a molar mass of 40.00g/mol) is dissolved in 0.500L of solution , what is the molarity of the solution?

Molarity = moles of solute/ Liters of solution 5.0 g NaOH/ 40.00g/mol = 0.125 moles of NaOH

M = 0.125mol solute/0.500L = 0.25M

87. You wish to increase the rate of dissolving of a solid substance in water. Which of the following will increase the dissolving rate?

a. crush the substance YES This increases the surface area. b. cool the water NO c. heat the water YES d. stir the water YES e. increase the pressure NO (pressure DOES NOT affect the way a solid will dissolve in a liquid. Pressure is a factor when you dissolve a GAS in a liquid.)

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88. Define the following terms:

Unsaturated At a particular temperature in a specific amount of solvent, there is still room for more dissolved solute.

Saturated At a particular temperature in a specific amount of solvent, there is NO more room for any more dissolved solute. It is at full capacity. Any more solute will not dissolve and will fall to the bottom of the solution.

Supersaturated This is a special situation where MORE solute is dissolved in a solution at a particular temperature than should be dissolved. This solution is unstable ,however all the solute is in a dissolved state. If this solution is disturbed, the excess solute will fall to the bottom.

89. What happens to the H+ (hydronium ion) concentration when the pH goes DOWN. A smaller pH means the solution is becoming MORE acidic. Therefore, the hydronium ion concentration is INCREASING. Hydronium is the ion that gives acids their properties.

What happens to the OH-(hydroxide ion) concentration when the pH goes DOWN. When the pH goes DOWN the solution is becoming MORE acidic. Therefore, the hydroxide ion concentration is DECREASING. When the pH goes UP the hydroxide concentration is also increasing.

90. What is the range of the pH scale? Which are acids? Which are bases?

The pH scale is from 0 to 14. Less than 7 is acidic and more than 7 is basic. If the hydronium ion concentration is equal to the hydroxide ion concentration the solution is neutral (pH of 7)

91. When the hydroxide ion increases in a solution, the hydronium (H+)ion : Goes up or Goes down

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92. Complete and balance the following neutralization reactions:

H2SO4 + 2NaOH 2H2O + Na2SO4 (water and a salt)

2HNO3 + Ca(OH)2 2H2O + Ca(NO3)2 (water and a salt)

93. What is Boyle’s Law? What is held constant? Temp and moles of gas Is this an inverse or direct relationship?

P1V1 = P2V2

94. What is Charles’ Law? What is held constant? Pressure and moles of gas Is this an inverse or direct relationship?

V1 = V2

T1 T2 (Remember to add 273 to oC. Kelvin temperatures are in ALL gas laws. NO EXCEPTIONS)

95. What is the combined gas law? What is held constant? Moles of Gas

P 1 V1 = P2 V2

T1 T2

96. . 50.0 L of a gas at 2.0 atm and 295K is compressed so it attains a pressure of 6.0atm at a temperature of 355K.

What is the new volume? SHOW ALL WORK.

P 1 V1 = P2 V2 (2.0atm) (50.0L) = (6.0atm) (xL)

T1 T2 295K 355K = 20.L

97. Which of the following are non-polar molecules? Oil (nonpolar) water(polar) gasoline(nonpolar)

98. Oil and water will not mix. (They are immiscible.) Why?

Like dissolves Like. Oil is nonpolar and water is polar. They are NOT alike. NO DISSOLVING/NO MIXING

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99. Which has the greatest penetrating power? Alpha particles, beta particles, or gamma rays

100. Which of the following represent a mixture of elements and compounds? F Which of the following represent molecules of the same compound? B and D

Which of the following represent molecules of a single element? A and E

Which of the following represent molecules of two different elements? C

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