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BIG CHILL PROJECT 5%Goal: Build a container that keeps an ice cube from melting for the longest period of time.

Must be 15.0cm x 15.0cm x 15.0cm or smaller.Must operate at room temperature with no electricity.Must be an original creation.BIG CHILL PROJECTMust have a opening and chamber big enough to accommodate an ice cube.

BIG CHILL PROJECTGrade is two parts:1. Construction - 50 pts2. Efficiency - 50 ptsBonus points for being a top three finisher in your class, the best design in your class, ice cube lasting longer than 8 hours, and a parent signature on the blue form.

DUE THURSDAY MARCH 14OBJECTIVESDescribe the effect on a gas by a change in the amount of gas (moles), the pressure of gas, the volume of gas, and the temperature of gas.Be able to perform calculations using Boyles Law, Charles Law, and Gay-Lussacs Law.Be able to use Daltons Law of Partial Pressures in a calculationDistinguish between real and ideal gases. Be able to tell how real gases differ from ideal gases.State the ideal gas law and know what each symbol stands forPerform calculations using the ideal gas law and the combined gas law.State and use Grahams Law of Diffusion.Be able to calculate gas stoichiometry problems (volume volume, mass volume, volume mass).Be able to calculate density and molecular mass using the ideal gas law formula.GAS LAWSChapters 12-13

PRESSURE (Chapter 12)Pressure is the force per unit area. Gases exert pressure when they hit the walls of their container. To measure air pressure, you might use a barometer or a manometer. A barometer measures atmospheric pressure. A manometer measures the internal pressure of an enclosed gas.

PRESSUREThere is pressure exerted by the atmosphere. At sea level this pressure is equal to one atmosphere.

PRESSUREDEMOFig NewtonsPRESSUREPressure is measured in a variety of units.

UNITABBREVIATIONCOMPARE TO 1 ATMKilopascalkPa101.3 kPaMillimeters of mercurymmHg760.0 mmHgTorrtorr760.0 torrAtmosphereatm1.0 atmPounds per square inch*psi14.7 psi*We will use all of these but psi.VIDEODISCChapter 2 Racing Hot Air Balloons

Why is it easier for pilots to control the vertical direction of a balloons flight than the horizontal direction?Why did Julie say that a thermal is not a good word for balloonists?

GASES (Chapter 12)Physical Properties of Gases:Gases have mass.Gas particles do not attract or repel each other.It is easy to compress gases.Gas molecules are in constant motion Gases fill their containers completelyDifferent gases can move through each other quite rapidly. Gases exert pressure.The pressure of a gas depends on its temperature and volume.

GASESRemember that gases consist of very small particles, the particles have large distances between them, they are in constant, rapid, random motion and have elastic collisions.Actual gases (in real life) do not obey all the suppositions stated in the kinetic-molecular theory. In order to accurately measure a gas sample, you must know the quantity of particles (moles), pressure, temperature, and volume of a gas.

THE GAS LAWS (Chapter 13)Boyles Law:V and P; inversely proportional.Charles Law: T and V; directly proportional.Gay-Lussacs Law: P and T; directly proportional. Avogadro Principle: moles and P or V; directly proportional.

THE GAS LAWSDEMOS Boyles LawChapter 7 Breathing and Boyles Law1. Why does the balloon expand?2. What does this demo have to do with breathing?3. Have you ever heard the phrase nature abhors a vacuum? What do you think it means?Cartesian DiverWorld record diveBalloon and bottleArtificial lungBOYLES LAW

BOYLES LAWTHE LAW: For a given mass of gas, at a constant temperature, the volume varies inversely with the pressure:P1V1 = P2V2PRACTICE:The pressure in a 9.0 L balloon is 2.1 atm. If the volume is reduced to 5.0 L, what will the resulting pressure be? (Temperature does not change.)V1 = 9.0 LV2 = 5.0 LP1 = 2.1 atmP2 = ? atm

P1V1 = P2V2P2 = P1V1 = V2

REMINDEREVERY TIME you do a gas laws problem:

Write what you know and what you are trying to findWrite the formulaPlug in the numbers with units and solve with the correct number of sig figs.

GAS LAWSDEMOBalloon and temperature changeCHARLES LAW

CHARLES LAWTHE LAW: The volume of a fixed mass of a gas is directly proportional to its KELVIN temperature if the pressure is constant. If pressure is kept constant, then volume must change to keep temperature the same.V1 = V2T1 T2You must use the Kelvin temperature scale!K = C + 273PRACTICE:The temperature of a sample of gas is 300.0 K. The gas volume is 25.0 L. What will be the new volume of the gas if the temperature is dropped to 125.0 K?V1 = 25.0 L V2 = ? LV2 = T2V1 = T1 = 300.0 K T2 = 125.0 K T1

GAS LAWSVideodisc Chapter 5 - Imploding Can1. Why did the can implode?2. How does the demonstration you just saw relate to a barometer?3. How is a vacuum seal created on a jar of homemade preserves?Egg in a bottleBulb with pressure gaugeGAY-LUSSACS LAW

GAY-LUSSACS LAWTHE LAW: An increase in temperature increases the frequency of collisions between gas particles. In a given volume, raising the KELVIN temperature also raises the pressure.P1 = P2T1 T2You must use Kelvin temperature scale!PRACTICE:The temperature of a sample of gas is 300.0 K. The gas pressure is 1.4 atm. What will be the new pressure of the gas be if the temperature is dropped to 125.0 K?

P1 = 1.4 atm P2 = ? atmP2 = T2P1 = T1 = 300.0 K T2 = 125.0 K T1

REMINDEREVERY TIME you do a gas laws problem:

Write what you know and what you are trying to findWrite the formulaPlug in the numbers with units and solve with the correct number of sig figs.

DO NOWPick up handout due tomorrowCopy problem set info - due Feb. 25Ch. 12 #1, 2Ch. 13 #1, 2, 5, 6, 8, 9, 11,16, 21, 26, 27, 36, 38, 39, 42Paper towel drive ends Friday, 3:30.Balloons and Cans lab due Feb. 19.HINTPTVPUTTING IT ALL TOGETHERSimulation on gas laws:Structure and Properties of MatterAVOGADROS PRINCIPLE

Volume: 22.4L 22.4L 22.4LMass: 39.95g 32.00g 28.02gQuantity: 1 mol 1 mol 1 molPressure: 1 atm 1 atm 1 atmTemperature: 273K 273K 273KAVOGADROS PRINCIPLEDEMOBeach BallAVOGADROSS PRINCIPLEParticles of different gases vary greatly in sizes. But size is not a factor The Law: equal volumes of gases at the same temperature and same pressure contain equal number of particles. In gas law problems moles is designated by an n. One mole of a gas has a volume of 22.4 L (dm3) at standard temperature and pressure (STP). It also has 6.02 x 1023 particles of that gas.DALTONS LAW OF PARTIAL PRESSURES

DALTONS LAW OF PARTIAL PRESSURES THE LAW: The sum of the partial pressures of all components of a gas mixture is equal to the total pressure of the gas mixture.Ptotal = P1 + P2 + P3 + P4 +.....

PRACTICE (Easy Type):What is the atmospheric pressure if the partial pressures of nitrogen, oxygen, and argon are 604.5 mm Hg, 162.8 mm Hg, and 0.500 mm Hg, respectively?

Ptotal = P1 + P2 + P3Ptotal =

DALTONS LAW OF PARTIAL PRESSURES (Chapter 12)

DALTONS LAW OF PARTIAL PRESSURES PRACTICE (Hard Type):A quantity of oxygen gas is collected over water at 8C in a 0.353 L vessel. The pressure is 84.5 kPa. What volume would the DRY oxygen gas occupy at standard atmospheric pressure (101.3 kPa) and 8C. (The dry gas pressure of water at 8C is 1.1 kPa)

T1 = 8CT2 = 8CV1 = 0.353LV2 = ?P1 = 84.5 kPa 1.1 kPa = 83.4 kPaP2 = 101.3 kPaYou must correct the pressure so that you can have the DRY gas without the water pressure added in.P1V1 = P2V2V2 = P1V1 = P2GAS LAWSVideodisc Chapter 9Scuba DivingThink about your lungs as a flexible 6-liter container full of a gas at STP. How would lung volume change at a depth of 30 meters?Why not increase the oxygen to 100% and go really deep?What are the bends? How do divers avoid them?COMBINING THE LAWSFrom the Boyles, Charles, and Gay-Lussacs laws, we can derive the Combined Gas Law:

P1V1 = P2V2 T1 T2Mnemonic: Potato and Vegetable on top of the TableCOMBINED GAS LAWPRACTICE:The volume of a gas measured at 75.6 kPa pressure and 60.0C is to be corrected to correspond to the volume it would occupy at STP. The measured volume of the gas is 10.0 cm3.P1 = 75.6 kPaP2 = 101.3 kPaP1V1 = P2V2V1 = 0.0100 LV2 = ? T1 T2T1 = 333.0KT2 = 273 K V2 = P1V1T2 = ___________________________ T1P2

STANDARDST = 0C = 273 KV = 22.4 L (at STP)P = 1.00 atm = 101.3 kPa = 760.0 mm Hg = 760.0 torr

Remember only kPa has limited sigfigs.

COMBINED GAS LAWPRACTICE:Correct the volume for a gas at 7.51 m3 at 5.0C and 59.9 kPa to STP.

IDEAL GAS LAWIdeal Gas Equation:

PV = nRT

R is the universal gas constant.

UNIVERSAL GAS CONSTANTSR = 0.0821 L atm mol KR = 62.4 Lmm Hg mol KR = 62.4 L torr mol KR = 8.31 L kPa mol KWhy are there four constants?IDEAL GAS LAWRemember:Always change the temperature to KELVINS and convert volume to LITERSCheck the units of pressure to make sure they are consistent with the R constant given or convert the pressure to the gas constant (R) you want to use.

IDEAL GAS LAWPRACTICE:How many moles of a gas at 100.0C does it take to fill a 1.00 L flask to a pressure of 1.50 atm?

V = 1.00 L T = 100.0C = 373.0 KP = 1.50 atmR = 0.0821 atmLn = ? molKPV = nRT n = PV = ____________________________ = RT

IDEAL GAS LAWPRACTICE:What is the volume occupied by 9.45g of C2H2 at STP? Hint - convert grams to moles.....9.45g C2H2 1 mol C2H2 = 0.363 mol 26.04g C2H2P = 1.00 atmR = 0.0821 atmLV = ? molKn = 0.363 molT = 273.0K

PRACTICEP = 1.00 atmT = 273KV = ?R = 0.0821 L atmN = 0.363mol mol K

V = nRT = (0.363mol)(273K)(0.0821 L atm)= P (1.00 atm) (mol K)= 8.14L

GRAHAMS LAW OF EFFUSIONor DIFFUSION (Chapter 12)The rate of diffusion/effusion is inversely proportional to the square root of its molar mass under identical conditions of temperature and pressure.

If two bodies of different masses have the same kinetic energy, the lighter body moves faster.

DEMOAnise and CinnamonWhat can we assume about the temperatures of the two oils?How is temperature related to KE?How doe the KE of the two oils compare?What is the formula for KE?

CALCULATIONSKE = mv2 mava2 = mcvc2 mava2 = vc2 mc ma = vc2 mc va2 ma = vc2 mc va2

GRAHAMS LAW OF EFFUSIONor DIFFUSION (Chapter 12) Rate (velocity) a = Formula mass b Rate (velocity) b Formula mass a

Compare ammonia and hydrochloric acid:velocity NH3 = 36.45g/mol velocity HCl 17.04g/mol

= NH3 is 1.46 times faster than HCl

REAL vs. IDEAL GASESThe ideal gas equation, PV = nRT, is simple to use and accurately predicts gas behavior in many everyday situations. Under very high pressure, real gases have trouble compressing completely. The ideal gas law fails. Ideal gases have no volume, but real gases do.

REAL vs. IDEAL GASESAt very low temperatures, attractive forces between real gas molecules become significant and real gases liquefy.

The ideal gas law can be used under ordinary conditions only.

GAS STOICHIOMETRYWe are now going to add to our MOLE CITY diagram, adding volume of a mole of gas.VOLUME 1 mol 22.4 L @ STP

1 mole 1 molePARTICLES MOLE MASS6.02 x 1023 molar mass GAS STOICHIOMETRYPRACTICEDetermine the volume in 2.0 moles of H2.

?? volume = 2.0 mol H2 22.4 L H2 = 1 mol H2 = 45 L H2

GAS STOICHIOMETRYB. Determine the volume in 10.3 moles of CO2.?? volume =

GAS STOICHIOMETRYC. Determine the moles in 251 L of O2.?? moles =

GAS STOICHIOMETRYD. What volume of hydrogen gas is needed for the complete reaction between nitrogen gas and hydrogen gas to produce ammonia? You are given 5.0L of nitrogen gas. This problem involves not a mass to mass problem but a volume to volume problem.The balanced equation is N2 + 3H2 2NH3

? L H2 5.0L N2 N2 + 3H2 2NH3

GAS STOICHIOMETRYE. What volume of oxygen gas is needed for the complete reaction between oxygen gas and potassium chloride to produce potassium chlorate? You are given 45.0g KCl. This problem involves not a volume to volume problem but a mass to volume problem.The balanced equation is 2KCl + 3O2 2KClO3

?L O2 45.0g KCl 2KCl + 3O2 2KClO3

HOMEWORKCh. 13 #40-41, 43-44 due tomorrowGrahams Law handout due tomorrow.Quiz is now Monday March 3.Dry Ice lab will be Friday.Giant Problem set due March 4.Test is March 5.Get out Gas Diffusion labANALYSIS and CONCLUSION:1. Calculate the ratio of the distance moved. Since both gases moved through the glass tube in the same amount of time, the distances the gases moved can be used as a measure of the rates of diffusion of the gases. Substituting the distance (d) each gas moved for the velocity of the gas. Determine the ratio of the distance moved. Show your work. This is the experimental ratio. USE THE CLASS AVERAGE FOR THIS.d1 = m2 HCl = distance NH3 traveled d2 m1 NH3 distance HCl traveled

ANALYSIS and CONCLUSION

2. Determine the true rate of diffusion for ammonia (m1)to hydrochloric acid (m2). Use the masses from the periodic table. Write the formula and show your work.

3. How close is your experimental value to the molecular mass ratio? Calculate your percent error. Write the formula and show your work.

GAS LAW PROBLEMS DIRECTIONSBe sure to write:What you know and where you are going (V1, V2, P1, P2, T1, T2, etc.)The formulaRewrite the formula to solve for the unknown and fill in the known data.Show all units.Write the correct answer with sigfigs and units.

GAS LAW PROBLEMS DIRECTIONSFor stoichiometry: write what you know and where you are goingWrite the balanced equation if not given.Convert to moles, do the mole ratio, and convert to what is asked for.Gas Law Problems #11. A sample of oxygen gas occupies a volume of 250.0 mL at 740.0 torr pressure. What volume will it occupy at 800.0 torr pressure?

Gas Laws #1 AnswerV1 = 250.0mL V2 = ?P1 = 740.0 torrP2 = 800.0 torrBoyles Law

V2 = V1P1 = (250.0mL)(740.0torr) = P2 (800.0torr)= 231.25 = 231.3 mL

DETERMINING MOLAR MASS

We can use the ideal gas equation to calculate the molar mass of a gas from laboratory measurements.The molar mass formula is Molar mass, MM = mass, m/moles, nSo, n (moles) is equal to:moles, n = mass, m Molar mass, MM

DETERMINING MOLAR MASSSo, if n = m/M, substitute it in the formula.The ideal gas equation can be written asPV = mRT MM = mRT MMor P VPRACTICEWhat is the molar mass of a gas if 100.0 dm3 has a mass of 7.202g at 110C and 107.0 kPa?MM =T = V =P = m =R =

MM = mRT = P V

DETERMINING DENSITYThis modified version of the ideal gas equation can also be used to solve for the density of a gas.

PV = nRT bcomes D = PMM RT

DETERMINING DENSITYMM = mRT P V rewrite with m/V on one sidePMM = m RT V

D = m = PMMor D = PMM V RT RT

PRACTICEFind the density of NH3 in g/L at 752 mm Hg and 55C.MM = T = R = P =

D = PMM = RTPRACTICE1. Calculate the molar mass, MM, of a gas if 150.0 dm3 has a mass of 75.0 g at 100C and 95 kPa.

PRACTICE1. Calculate the molar mass, M, of a gas if 150.0 dm3 has a mass of 75.0 g at 100C and 95 kPa.MM =?T = 373KV =150.0LP = 95kPam =75.0gR = 8.31 L kpa mol KMM = mRT = (75.0g)(373K)(8.31L kpa) P V (95kPa)(150.0L)(mol K) = 16.31384 = 16g/mol

PRACTICE2. Determine the density of chloroform gas, CHCl3 if a sample massing is collected in a flask with at 37C and a pressure of 728 mm Hg.

PRACTICE2. Determine the density of chloroform gas, CHCl3 if a sample massing is collected in a flask with at 37C and a pressure of 728 mm Hg.MM = 119.37g/molT = 310KR = 62.4 L mmHgP = 728mmHgmol KD = PMM = (728mmHg)(119.37g)(mol K) RT (310K)(62.4 L mmHg)(mol)= 4.492419 = 4.5g/L

GAS LAWS QUIZ MONDAYThere will be six problems. Could be any from this list:Boyles/ Charles / Gay-LussacDaltons Law of Partial PressureCombined Gas LawIdeal Gas LawGrahams Law of DiffusionGas StoichiometryExtra Credit is Density or Molar Mass problem