Gas Laws. Boyle s Law Charle s law Gay-Lussac s Law Avogadro s Law Dalton s Law Henry s Law

Gas Laws Boyle s Law Charle s law Gay-Lussac s Law Avogadro s Law Dalton s Law Henry s Law 1 1

What is Pressure? Gas molecules cause pressure 2 2

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same as 3 3

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same as Less particles will hit the sides of the container less often, causing less pressure. 4 4

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same 5 5

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same As counterintuitive as this may be, the size and mass of the gas particles do not affect the pressure, only the number of moles of particles affect the pressure. (more on this later.) 6 6

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same as 7 7

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same as Particles moving faster will hit the sides of the container more often, AND hit with more force causing greater pressure. 8 8

Air molecules cause air pressure The weight of all the air on top of us causes the pressure. Since air is a fluid, it pushes all around, not just from the top. you will study fluid dynamics when you go to physics 1&2 Air Pressure 9 9

Barometer Standard air pressure 760 mm of Hg 760 torr 29.92 inches of Hg 1 atm 101.3 kpa 10 10

Which graph below best represent the relationship between moles of gas and volume of container? (holding pressure and temperature constant.) Volume 1 2 3 4 Volume Volume Volume moles moles moles moles 11 11

number of molecules and volume moles and volume n & V increase the number of moles, (while pressure & temp remain constant) and the volume will increase. This is a direct relationship n is proportional to V V n = k k = a constant 13 13

There is gas in the flask, and more gas is added with the syringe. What would the pressure gauge read in the second picture?? 1 2 3 14 14

There is gas in the flask, and more gas is added with the syringe. What would the pressure gauge read in the second picture?? 1 2 3 15 15

number of molecules and pressure moles and pressure n & P increase the number of moles (while maintaining constant volume and temp) and the pressure increases. this is a direct relationship n is proportional to P P n = k k = a constant 16 16

The height of the piston in the container on the right would be the height of the gas in the container on the left.?? 1. higher than 2. lower than 3. the same as 17 17

The height of the piston in the container on the right would be the height of the gas in the container on the left. 1. higher than 2. lower than 3. the same as 18 18

temperature and volume T & V increase the temperature (while pressure remains constant) and the volume increases. this is a direct relationship V is proportional to T V T = k k = a constant 19 19

The pressure of the gas in the container on the right would be the pressure of the gas in the container on the left. (Temperature and moles remain constant.)?? 1. higher than 2. lower than 3. the same as 20 20

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same as 21 21

pressure and volume P & V increase the volume (while temp and number of moles remains constant) and the pressure decreases. this is an inverse relationship P is inversely proportional to V PV = k k = a constant 22 22

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. (volume and moles remain constant) 1. higher 2. lower 3. the same 23 23

The pressure of the gas in the container on the right would be as the pressure of the gas in the container on the left. 1. higher 2. lower 3. the same 24 24

P & T pressure and temperature increase the temperature (while volume and moles remains constant) and the pressure increases. atm this is an direct relationship P is directly proportional to T P T = k k = a constant 25 25

Gas Relationships Together All the k s are different PV P V n = T = k Squish the k s all together, let s call kcombined, R PV nt = R and since R = R The Combined Gas Law P 1 V 1 n 1 T 1 = P 2 V 2 n 2 T 2 26 26

Gas Relationships Together All the k s are different PV P V n = T = k Squish the k s all together, let s call kcombined, R PV nt = R and since R = R The Combined Gas Law P 1 V 1 n 1 T 1 = P 2 V 2 n 2 T 2 27 27

pressure and temperature Double the temp, does not double the pressure as you might expect. 1 atm 2 atm The temperature must reach 373ºC before the pressure doubles. Why? 28 28

Break out the Graph Paper Sketch a graph of the following pressure and temp data collected for a tank of helium. For reasons that might not make sense yet, set the range of your x-axis from -300ºC to 100ºC hold the paper landscape make the graph as large as is reasonable Temp (ºC) Pressure (units) 0 15 30 16.7 50 17.9 100 20.7-25 13.8-50 12.3-140 7.5 29 29

Absolute Zero As gases cool, they slow down and cause less pressure....slow molecules more = less pressure...more = even less......finally the molecules stop, don t cause any pressure and can t go any slower. this is as slow as the molecules can go, thus this is the coldest the molecules can get. 30 30

Kelvin the Absolute Temp Scale Absolute zero, 0 = -273ºC 0 K = -273ºC Pressure vs Temperature 25 20 Pressure (units) -273ºC = 0 K 15 10 5 0-300 -280-260 -240-220 -200-180 -160-140 -120-100 -80-60 -40-20 0 20 40 60 80 100 120 Temp (deg C) 31 31

Manometers measuring gas Closed-end harder to build, but easier to use Open-end easy to build (set up), but require a barometer reading and an addition or subtration to determine the pressure in the gas tank The outside barometer reads 760 mmhg 380 mm 380 mm P = 0.5 atm P = 1.5 atm 32 32

Put some gas in a container at certain conditions... It just so happens that air pressure 32 g of oxygen, (1 mole) 22.4 L sealed in a piston cylinder, plunged into ice water, barometric air pressure of 760, The measured volume of the gas will = 22.4 L 33 33

Put a different gas in a container at certain conditions... It just so happens that 2 g of helium, (½ mole) 11.2 L sealed in a piston cylinder, plunged into ice water, barometric air pressure of 760, The measured volume of the gas will = 11.2 L 22.4 L Again! If increased to 4 g, the volume of the gas = 22.4 L 34 34

Just what about gas constant, R? It just so happens that 44 g of CO2, (1 mole) sealed in a piston cylinder, plunged into ice water, PV nt = R barometric air pressure of 760, The measured volume of the gas will = 22.4 L, yet again! Plug these values into the Gas Law, and solve for R 760mmHg 22.4L 1mol 273K = 62.4mmHg i L i mol 1 K 1 35 35

Just what about gas constant, R? The units on the constant R are very important. If we plug the values into the gas law as different PV nt = R units, R will be different. 760mmHg 22.4L 1mol 273K = 62.4mmHg i L i mol 1 K 1 1atm 22.4L 1mol 273K = 0.0821atm i L i mol 1 K 1 36 36

Manometer Open-end and closed-end height height 37 37

Dalton s Law of Partial Pressures P Total = P A + P B + P C +... 38 38

The red gas is 2.0 atm, the blue gas is 2.0 atm, when combined together in one of the containers, the pressure would be 1. 4.0 atm 2. less than 4.0 atm 3. more than 4.0 atm 4. no way of knowing because it depends on the molar mass of each of the gases. 5. 2.0 atm 39 39

The red gas is 20 atm, the blue gas is 20 atm, when combined together in one of the containers, the pressure would be 1. 4.0 atm Dalton s Law of Partial Pressures Ptotal = P1 + P2 + P3 +... For ideal gases, their identity does not matter 2. less than 4.0 atm 3. more than 4.0 atm 4. no way of knowing because it depends on the molar mass of each of the gases. 40 40

A rigid flask contains 0.3 moles He, 0.4 moles H2, and 0.5 moles Ne. The total pressure is 15 atm. What is the partial pressure of the H2? (No calculator.) Input a numeric answer. 41 41

A rigid flask contains 0.3 moles He, 0.4 moles H2, and 0.5 moles Ne. The total pressure is 15 atm. What is the partial pressure of the H2? (No calculator.) the mole fraction: 0.4H 2 = 0.3 1.2total (a percentage without multiplying by 100) 0.4H 2 (15atm) = 5atm 1.2total Let s look for this on the formula sheet. 42 42

If the gas from the two blue containers were put into the empty gold container. What would be the total pressure? 1. 1 atm 2. 1.5 atm 3. 2 atm 4. 2.5 atm 5. 3 atm 6. 4 atm 1L 1 atm 500 ml 1 atm 1L 7. unable to be determined 43 43

If the gas from the two blue containers were put into the empty gold container. What would be the total pressure? 1. 1 atm 2. 1.5 atm, assuming temp and remained constant. 1L 1 atm 500 ml 1 atm the large blue container would be 1atm in same size container the small blue container, PV = PV thus double vol = half pressure = 1L 0.5 atm sum for the total = 1.5 atm 44 44

Consider the containers with blue and gold gas. Assume the number of atoms corresponds to the number of moles of each gas. If the total pressure is 1 atm. In which container(s) does the gold gas have a partial pressure of 0.6 atm? 1 2 3 4 5 6. The gold gas can not have a higher pressure than blue gas since they are smaller molecules 45 45

Consider the diagrams of mixtures of blue and gold gas. If the total pressure is 1 atm. Which drawing(s) corresponds to the mixture(s) in which gold gas has a partial pressure of 0.6 atm? 1 2 3 4 5 The mole fraction must be 0.6 since total pressure = 1 atm 6gold #2 and #4 (1atm) 10total 3gold (1atm) 5total 46 46

Equal masses of three gases were placed in a rigid, sealed 3 L container. The total pressure is 2 atm. Which gas has the highest partial pressure? 1. He 2. Ne 3. Ar 4. All three gases cause the same partial pressure because they all have the same mass. 47 47

Equal masses of three gases were placed in a rigid, sealed 3 L container. The total pressure is 2 atm. Which gas has the highest partial pressure? 1. He The gas with the lower molar mass will be more moles and thus cause greater pressure. It is a valid assumption that the pressure is low enough and temperature is high enough to allow the gases to behave ideally. 2. Ne 3. Ar 4. All three gases cause the same partial pressure. 48 48

The Combined Gas Law Consider 0.5 L of gas in syringe in a 50ºC water bath with a pressure of 200 mmhg. The syringe is compressed to 0.1 L, what will be the new pressure? P1 V1 n1 T1 = P2 V2 n2 T2 2 L of oxygen gas in a sealed, rigid metal cylinder is at 0.80 atm at 25ºC. To what temperature, in Celsius should the gas be changed to reduce the pressure to 0.20 atm? P1 V1 n1 T1 = P2 V2 n2 T2 49 49

Correcting to STP 42.0 ml of hydrogen gas was collected at 21.0ºC over water. The barometer read 757.5 mmhg. Calculate the volume that this hydrogen would fill at STP? P1 V1 n1 T1 = P2 V2 n2 T2 Equilibrium Vapor Pressure 17 14.53 18 15.48 19 16.48 20 17.54 21 18.65 22 19.83 23 21.07 24 22.38 50 50

Ideally, Chemistry s a Gas! PV = nrt 51 51

From data we previously considered: 1 atm and 0ºC are considered standard conditions (STP). The Ideal Gas Law PV = nrt (1atm)(2.24L) What is the volume of 1 mole of gas? Depends on the conditions. (0.1mol)(273K) = R 22.4 L is the volume of 1 mole of any gas at STP (0ºC, 273 K and 1atm, 760 mmhg) Molar volume: 22.4 L mol 52 52

Using the Ideal Gas Law PV = nrt If you have 1500 ml of oxygen gas at a pressure of 624 mmhg and at 27.0ºC, calculate the moles of gas in this container. n = PV RT n = 624mmHg 1.5L 62.4 mmhg i L mol i K 300K n = 0.05mol 53 53

The Ideal Gas Law PV = nrt If you have 1500 ml of oxygen gas at a pressure of 624 mmhg and at 27.0ºC, calculate the moles of gas in this container. n = 0.05mol What is the mass? What is the density? What volume of hydrogen would you need to react completely with this oxygen? What mass of water would be produced? 55 55

The Ideal Gas Law PV = nrt If you have 1500 ml of oxygen gas at a pressure of 624 mmhg and at 27.0ºC, calculate the moles of gas in this container. n = 0.05mol What is the mass? What is the density? m = 0.05mol 32g 1mol = 1.6g D = 1.6g 1.5L = 1.07g i L 1 56 56

The Ideal Gas Law PV = nrt If you have 1500 ml of oxygen gas at a pressure of 624 mmhg and at 27.0ºC, calculate the moles of gas in this container. n = 0.05mol What volume of hydrogen (assume same P, T) would you need to react completely with this oxygen? 2 H2 + O2 2 H2O 1.5L 2H 2 1O 2 = 3.0L What mass of water would be produced? 0.05molO 2 2H 2O 1O 2 18g 1mol = 1.8gH 2O 57 57

Remember LAD D.1? Calculating the MM of Butane PV = nrt and n = m MM PV = m MM RT rearrange MM = mrt VP While this is just a rearrangement of the Ideal Gas Law, it s easy to remember. the molar mass kitty kat MM = DRT MM P D = m V 58 58

Let s do some algebra. Determine the molar mass of a Noble gas that has been heated to 300ºC and has a pressure of 25 atm with a density of 21.3 g/l. 59 59

Calculate the density of nitrogen gas at STP. 60 60

Which Equation to Use? What would be the identity of 0.896 g of some diatomic gas in a 3.0 L container that was at 58.5 mmhg of pressure and had a temp of 50.0ºC 61 61

Which Equation to Use? If you have a 5 L container of air at STP, what is the (partial) pressure of oxygen? 62 62

Which Equation to Use? If you have a 5 L container that is 20% (by mass) hydrogen and 80% nitrogen (by mass) at STP, what is the (partial) pressure of hydrogen? 63 63

Which Equation to Use? O2 gas in a freely moveable piston container has a volume of 750 ml at 15ºC. If the container is heated to 30ºC what will be the new volume of the gas? 64 64

When calcium carbonate is heated strongly, carbon dioxide gas is released CaCO3(s) CaO(s) + CO2(g) What volume of CO2(g), measured at STP, will be produced if 15.2 g of CaCO3(s) is heated? 65 65

Consider the following unbalanced chemical equation for the combustion of propane. C3H8(g) + O2(g) CO2(g) + H2O What volume of oxygen gas at 25ºC and 745 atm is needed for the complete combustion of 1.54 g of propane? 66 66

Ammonia and gaseous hydrogen chloride combine to form ammonia chloride. NH3(g) + HCl(g) NH4Cl(s) If 12.0 L of NH3(g) at 20.0ºC and 0.945 atm is combined with 15.0 L of HCl(g) at 26ºC and 1.04 atm, what mass of NH4Cl(s) will be produced? Which gas is the limiting reactant? Which gas is present in excess? 67 67

If water is added to magnesium nitride, ammonia gas is produced when the mixture is heated. Mg3N2(g) + 3H2O(L) 3MgO(s) + 2NH3(g) If 6.50 g of magnesium nitride is treated with water, what volume of ammonia gas would be collected at 22.0ºC and 755 mm Hg? 68 68

Pre LAD D.1 Gas in a Tube 69 69

Predict: As you lift the eudiometer up in the? cylinder, the vol of the gas in the eudiometer will measure 1. larger in 1 1 2 2. larger in 2 3. the same volume 70 70

As you lift the eudiometer up in the cylinder, the vol of the gas in the eudiometer is larger in The weight of the volume of water 1 2 above the gas in the eudiometer will squish the gas into a smaller volume. Thus the volume will be larger in #2 71 71

As you lift the eudiometer up in the? cylinder, the pressure of the gas in the eudiometer will 1. stay the same 2. get smaller 3. get larger 72 72

As you lift the eudiometer up in the cylinder, the pressure of the gas in the eudiometer will 1. stay the same 2. get smaller PV = P V Since we just learned that the Volume gets larger, the pressure must get smaller Or...consider the setup as a manometer, and the gas is winning (higher pressure than air) on the left, and the gas on the right is losing (lower pressure than air). 3. get larger 73 73

In the eudiometer pictured, the pressure of the air inside 1. is the same as the air pressure 2. is more than air pressure 3. is less than the air pressure 74 74

In the eudiometer pictured, the pressure of the air inside 1. is the same as the air pressure 2. is more than air pressure 3. is less than the air pressure The pressure in the eudiometer is the same as the air pressure, however, two gases are causing the equal pressure - gas and water vapor, thus the gas must be less than the outside air pressure. 75 75

Exactly what is in the gas space of the eudiometer? 1. just the gas that I put in with the hose as demonstrated 2. the gas that I put in and some other gas as well 76 76

H2O as a gas All liquids evaporate. Evaporated liquid causes pressure like any other gas. If the flask is left open the water would all eventually evaporate? 1. Yes 2. No 3. Maybe 77 77

H2O as a gas All liquids evaporate. Evaporated liquid causes pressure like any other gas. If the flask is left open the water would all eventually evaporate? 1. Yes Evaporation is a surface phenomenon. It may take a long time since there is 2. No such a small opening in the flask. 3. Maybe 78 78

If the flask is sealed, will all the water evaporate? 1. Yes 2. No 3. Maybe 79 79

If the flask is sealed, will all the water evaporate? 1. Yes 2. Not likely The image shows a larger amount of water than can completely evaporate into the space, thus it is likely to reach equilibrium. The amount of liquid evaporating will be equal to the amount of vapor condensing. 3. Maybe 80 80

If there is enough liquid water in the flask, equilibrium will result. The resulting pressure in the flask is called the equlibrium vapor pressure. 81 81

Which flask will achieve a higher equilibrium vapor pressure? 1. Flask A 2. Flask B 3. The same, since it appears that the flasks are the same size and the amount of liquid water appears to be the Flask A Flask B Hot same. 82 82

Which flask will achieve a higher equilibrium vapor pressure? 1. Flask A 2. Flask B Higher temp cause greater equilibrium vapor pressure. 3. The same, since it appears that the flasks are the same size and the amount of liquid water appears to be the Flask A Flask B Hot same. 83 83

Vapor Pressure Vapor pressure increases with temperature. This is not a linear relationship. The pressure is independent of the size of the container and the other gases present. Vapor Pressure of Water at Various Temps 84 84

Consider the equilibrium vapor pressure of alcohol 1. Blue Line 2. Same, black line Vapor Pressure of Water at Various Temps 3. Red Line 85 85

Consider the equilibrium vapor pressure of alcohol 1. Blue Line Since alcohol is not as sticky to Vapor Pressure of Water at Various Temps itself as water is to itself, it vaporizes more easily. 2. Same, black line 3. Red Line 86 86

Collecting gas over water Water vapor as well as the gas formed from the reaction will end up in a gas collection container. 87 87

A sealed container is manipulated such that the absolute temp is doubled, and the pressure is tripled. How will the number of moles of molecules be affected? (Do not use a calculator.) 1. increase 2. decrease 3. stay the same The problem tells you that the container is sealed, thus heat and volume changes must be what is used to change the temp and pressure 89 89

A hydrocarbon with an empirical formula of has a density of CH2 2.5 g/l at STP. A possible formula of the hydrocarbon is 1. CH2 2. C2H4 3. C3H6 4. C4H8 5. C5H10 90 90

A hydrocarbon with an empirical formula of has a density of CH2 2.5 g/l at STP. A possible formula of the hydrocarbon is 1. CH2 2. C2H4 3. C3H6 2.5g 22.4L 56g 4. C4H8 L mol = mol 5. C5H10 91 91

Select the gas with the greatest density at STP. 1. H2 2. He 3. H2O 4. CO2 5. O2 6. They all have the same density, since the pressure and temperature conditions are the same. 92 92

Select the gas with the greatest density at STP. 1. H2 2. He 3. H2O 4. CO2 (MolarMass)(MolarVolume) = density thus the gas with the larger molar mass will have the larger density when the conditions are the same for each gas. 44g 1mol 1mol = 22.4L 5. O2 6. They all have the same density, since the conditions are the same. 93 93

How would you calculate the pressure of the gas in this open-end manometer in mm Hg? There is mercury in the tube. 1. Pgas = h 2. Pgas = Pair 3. Pgas = h + Pair 4. Pgas = h - Pair 5. Pgas = Pair - h 6. Pgas =Pair + 2h 94 94

How would you calculate the pressure of the gas in this open-end manometer in mm Hg? There is mercury in the tube. 1. Pgas = h 2. Pgas = Patm 3. Pgas = h + Patm 4. Pgas = h - Patm 5. Pgas = Patm - h 6. Pgas =Patm + 2h 95 95

How would you calculate the pressure of the gas in this closed-end manometer in mm Hg? There is mercury in the tube. 1. Pgas = h Closed 2. Pgas = Patm 3. Pgas = h + Patm 4. Pgas = h - Patm 5. Pgas = Patm - h 6. Pgas =Patm + 2h 98 98

The temp of a container of He is held constant, and the volume is doubled, thus the pressure changes. If the gas were carbon dioxide instead of helium, the change in pressure would be 1. the same as the He Avogadro s Law At a fixed temperature and pressure, equal volumes of any ideal gas have the same number of moles. Thus changing volume will result in the same pressure changes regardless of the gas, since it will be same number of molecules. 101 101

The volume of the container is reduced to half it s size, but the pressure remains constant. What can be true about the gas inside. Select all that apply. 1. The gas must now weigh half as much. 2. The temp was reduced from 100 to 50. 3. The gas molecules were switched to a gas with half the molar mass. 4. Half of the molecules may have leaked out. 5. No specifics are possible without knowing the identity of the gas. 102 102

The volume of the container is reduced to half it s size, but the pressure remains constant. What can be true about the gas inside. Select all that apply. 1. The gas must now weigh half as much. 2. The temp was reduced from 100 to 50 If assumed to be Kelvin 3. The gas molecules were switched to a gas with half the molar mass. 4. Half of the molecules may have leaked out 5. No specifics are possible without knowing the identity of the gas. 103 103

The y-axis could be labeled 1. pressure 2. temperature? 3. moles 4. any of the above Volume 104 104

The y-axis could be labeled 1. pressure inverse relationship 2. temperature? 3. moles 4. any of the above Volume 105 105

The y-axis could be labeled Select all that apply. 1. pressure? 2. moles 3. volume temp 4. any of the above 106 106

The y-axis could be labeled 1. pressure direct relationship? 2. moles 3. volume temp direct relationship 4. any of the above 107 107

What is the density of CO2 in a 4 L container at 1 atm and 273 K closest to? No calculator 1. 88 g/l 2. 44 g/l 3. 22 g/l 4. 11 g/l 5. 5 g/l 6. 2 g/l 7. 0.5 g/l 8. no way of knowing 108 108

What is the density of CO2 in a 4 L container at 1 atm and 273 K closest to? No calculator 1. 88 g/l 2. 44 g/l 3. 22 g/l 4. 11 g/l 5. 5 g/l 6. 2 g/l 7. 0.5 g/l 8. no way of knowing 109 109

When nitrogen gas and hydrogen gas react, ammonia gas results. Write a balanced equation for this reaction. Is this picture stoichiometrically correct? During the course of the reaction, 1. the pressure increases. 2. the pressure decreases. 3. the pressure stays the same. 4. can not be determined 110 110

3. the pressure stays the same. 111 When nitrogen gas and hydrogen gas react, ammonia gas results. Write a balanced equation for this reaction. Is this picture stoichiometrically correct? During the course of the reaction, 1. the pressure increases. 2. the pressure decreases. 111

Problem Types Gas Laws 112 112

An excess of Al(s) is added to 100. ml of 0.400 M HCl. At 0 C and 1 atm pressure, what volume of H2 gas can be obtained? 113 113

An excess of Al(s) is added to 100. ml of 0.400 M HCl. At 0 C and 1 atm pressure, what volume of H2 gas can be obtained? 2 Al + 6 HCl 2AlCl3 + 3 H2 Woo Hoo M V = moles 0.4M 0.1L = 0.04mol 3H 2 6HCl = 0.02mol 22.4L 1mol = 0.448L 114 114

A 4.0 L container that holds 3.0 g of gas at STP will contain which gas? 1. O2 2. NH3 3. C2H6 4. CO2 5. SO2 115 115

A 4.0 L container that holds 3.0 g of gas at STP will contain which gas? 1. O2 Woo Hoo 2. NH3 3. C2H6 4. CO2 5. SO2 the molar mass kitty kat MM = DRT MM P 3g 0.0821 273Κ MM = 4L 1atm MM = 16.8g / mol MM = 3g 4L 22.4L 1mol MM = 16.8g / mol 116 116

A flask that has a total pressure of 500 mmhg contains 0.40 mole of SO2, 0.50 mole of N2, and 0.10 mole of He. Determine the partial pressure of SO2 Report your answer to the 1 s place NO Calculators 117 117

A flask that has a total pressure of 500 mmhg contains 0.40 mole of SO2, 0.50 mole of N2, and 0.10 mole of He. Determine the partial pressure of SO2 Report your answer to the 1 s place 1 mole of gas in total NO Calculators SO is 40% of the gas, thus 40% of 500 = 200 mm 118 118

NH4NO3(s) N2O(g) + 2 H2O(g) When 8.0 g of ammonium nitrate is sealed in a 2.0 L flask and heated to 300ºC, it completely decomposes. Calculate the total pressure in the flask. 1. input your answer 0.8gNH 4 NO 3 1mol 80g 3product 1NH 4 NO 3 = 0.3mol P = nrt V 0.3mol 0.0821 573Κ 2.0L = 7.1atm 120 120

When the stopcock is opened, and the two gases mix, the temperature remains constant, calculate the total pressure in the apparatus? O2 4 L 0.5 atm N2 1 L 1.5 atm 1. Input your answer 121 121

When the stopcock is opened, and the two gases mix, the temperature remains constant, calculate the total pressure in the apparatus? PV = PV 0.5 4 = P O2 5 P O2 = 0.4 atm 1 1.5 = P N2 5 P N2 = 0.3 atm P O2 + P N2 = 0.7atm O2 4 L 0.5 atm N2 1 L 1.5 atm 1. 0.7 atm 122 122

Air pressure is 752 mmhg today open valve A O2 4 L valve B valve D N2 1 L 1.5 atm valve C closed v 200mm 2.5 L empty 1. Valve A is open, what is the oxygen pressure? 2. Valve C is open, draw on the mercury levels and label height? 123 123

Air pressure is 752 mmh today closed open valve A O2 4 L valve B valve D N2 1 L 1.5 atm valve C v 200mm 2.5 L empty 1. Open valve B and recalculate the pressure then resketch and label each mercury height. 124 124

Air pressure is 752 mmh today closed open valve A O2 4 L valve B valve D N2 1 L 1.5 atm valve C v 200mm 2.5 L empty 1. Valve D is opened. Recalculate the pressure then resketch and label each mercury height. 125 125

Iron oxide and carbon monoxide react together according to the equation shown below. If you had 112 L of CO at STP and 240 g of Fe2O3 what volume of CO2 can you produce at STP? 3 CO(g) + Fe2O3(g) 2 Fe(s) + 6 CO2(g) 126 126

If 3.21 mole of a gas occupies 56.2 L at some temperature and pressure, 5.29 mole of this gas will occupy what volume under these same conditions. 1. 606 ml 2. 1.65 L 3. 34.1 L 4. 92.6 L 5. You can not determine the volume without knowing the temperature and pressure. 127 127

If 3.21 mole of a gas occupies 56.2 L at some temperature and pressure, 5.29 mole of this gas will occupy what volume under these same conditions. 1. 606 ml 2. 1.65 L V n = V n 56.2L 3.21mol = V 5.29mol V = 92.6 3. 34.1 L 4. 92.6 L 5. You can not determine the volume without knowing the temperature and pressure. 128 128

If 50.0 g of a gas occupies 10.0 L at STP, 150 g of this gas will occupy what volume at STP? 1. 3.92 L Woo Hoo 2. 50.8 L 3. 12.9 L 4. 25.5 L 5. 5.08 L 6. 30.0 L 7. cannot be determined without knowing who the gas is. 129 129

According to kinetic molecular theory, molecules of different gases at the same temperature always have the same. (Select as many as apply.) 1. average kinetic energy 2. molecular mass 3. pressure 4. molecular speed 5. average density 130 130

When 100 ml of nitrogen gas is added to 150 ml of hydrogen gas and reacted to form ammonia, as in the equation below, at a constant temperature and pressure, what volume of ammonia will be produced? N2(g) + 3 H2(g) 2 NH3(g) 1. 350 ml 2. 250 ml 3. 200 ml 4. 100 ml 5. Can not determine the volume without more temperature and pressure information. 131 131

What is the temperature of 0.444 mole of CO gas in a 11.8 L container at 889 torr. 1. 106ºC 2. 73ºC 3. 14ºC 4. 32ºC 5. 379ºC 132 132

In a 3.0 L container at 20ºC that contains 5 g of gas, which gas will have the greatest pressure? 1. He 2. Ne 3. Ar 4. Kr 5. They will all have the same pressure because they are all monatomic noble gases. 133 133

The volume of a 2.49 g sample of gas was 752 ml at 1.98 atm and 62 C. The gas is 1. SO2 2. SO3 3. NH3 4. NO2 5. Ne 134 134

Determine the molar mass of a gas that has a density of 6.7 g/l at STP. 1. 496 g/mole 2. 150 g/mole 3. 73.0 g/mole 4. 3.35 g/mole 5. 0.298 g/mole 135 135

Automobile air bags use the decomposition of sodium azide as their sources of gas for rapid inflation, represented in the reaction below. What mass of NaN3 is required to provide 40.0 L of N2 at 25 C and 763 torr? 2 NaN3(s) 2 Na(s) + 3 N2(g) 1. 16.4 g 2. 1.09 g 3. 160 g 4. 71.1 g 5. 107 g 136 136

Potassium chlorate can be decomposed to produce oxygen gas in the laboratory by the reaction below. What volume of dry oxygen gas at 25 C and 1.00 atm pressure is produced by the decomposition of 7.5 g of KClO3(s)? 2 KClO3(s) 2 KCl(s) + 3 O2(g) 1. 4.5 L 2. 7.5 L 3. 2.2 L 4. 3.7 L 5. 11 L 137 137

Determine the total pressure in a 12.2 L vessel that contains 2.34 g of carbon dioxide, 1.73 g of sulfur dioxide, and 3.33 g of argon, at 42 C. 1. 263 mmhg 2. 134 mmhg 3. 395 mmhg 4. 116 mmhg 5. 0.347 mmhg 138 138

A gas mixture of Ne and Ar has a total pressure of 4.00 atm and contains 16.0 moles of gas. If the partial pressure of Ne is 2.75 atm, how many moles of Ar are in the mixture? 1. 5.00 moles 2. 6.75 moles 3. 9.25 moles 4. 11.0 moles 5. 12.0 moles 139 139

According to the kinetic molecular theory, if the temperature of a gas were raised from 100 C to 200ºC, the average kinetic energy if the gas will 1. double 2. increase by a factor of 1.27 3. increase by a factor of 100 4. decrease by half 5. decrease by a factor of 100 6. remain the same 140 140

Speed of Gases 141 141

Boltzman Distribution Curve. Temperature, and therefore kinetic energy is an average. Probability of the various speeds for a container of a single gas. 142 142

The two graphs represent the same gas at different temps. Which gas is hotter? #1 #2 143 143

The two graphs represent the same gas at different temps. Which gas is hotter? #1 As the temperature rises, the graph #2 shifts to the right and becomes flatter The root mean square speed is marked by u. This is nearly the same as the average speed. Notice that the average speed increases as the temperature increases. 144 144

Boltzman Distribution Curve Probability of gases moving at two different temperatures. 145 145

The white powder will form a ring 1. closer to the NH3 2. closer to the HCl 3. in the middle 4. wherever by chance 5. no way of knowing 146 146

The white powder will form a ring 1. closer to the NH3 Graham s Law of effusion says that the rates of effusion for two gases is inversely proportional to the square roots of their molar masses Check your blue sheets for an equation (Though you may be asked this on MC as well.) 2. closer to the HCl 3. in the middle 4. wherever by chance 5. no way of knowing 147 147

Compare the speed of helium compared to carbon dioxide. 1. He is faster 2. CO2 is faster 3. He and CO2 travel at the same speed 148 148

Compare the speed of helium compared to carbon dioxide. 1. He is faster 2. CO2 is faster Graham s Law of effusion says that the rates of effusion for two gases is inversely proportional to their molar masses 149 149

Since T α KE = ½mv 2 If gases are at the same temp and therefore have the same average KE, the equation above indicates that lighter gases (smaller molar mass) must have a larger speed (v). The bottom line? Low MM gasses go fast High MM gases go slower 150 150

This is a graph of different gases all at 25ºC. The blue line is water vapor. Which gas can be He? (Select all that apply.) #1 #2 #3 #4 151 151

This is a graph of different gases all at 25ºC. The blue line is water vapor. Which gas is He? Without more information either 3 or 4 could be He. Light gases have higher velocity since KE = ½mu 2. Thus at the same temp lower mass means higher speed. #1 #2 #3 #4 152 152

Select the gas that has an average speed closest to Ne. All gases at same temp & pressure. 1. H2 2. He 3. H2O 4. CO2 5. O2 6. They all have the same speed, since the conditions are the same. 153 153

Select the gas that has an average speed closest to Ne at STP. 1. H2 2. He 3. H2O 4. CO2 the mass of the gas will affect the speed. thus the gas with the most similar molar mass will be the gas with the closest speed. 5. O2 6. They all have the same speed, since the conditions are the same. 154 154

Select the gas that has the highest average kinetic energy. All gases at STP. 1. H2 2. He 3. H2O 4. CO2 5. O2 6. All of these gases have the same KE 7. None of the gases have kinetic energy since they are all at 0ºC. 155 155

Select the gas that has the highest kinetic energy at STP. 1. H2 2. He 3. H2O 4. CO2 5. O2 T α KE All of the gases have the same kinetic energy since they are at the same temperature. 6. None of the gases have kinetic energy since they are all at 0ºC. 156 156

Effusion and Diffusion Effusion The escape of gas molecules through a tiny hole into an evacuated space. Diffusion The spread of one substance throughout a space or throughout a second substance. 157 157

What s so Ideal about the Ideal Gas Law? PV = nrt 158 158

The Ideal Gas Law 1. Kinetic Molecular Theory the temperature of a gas is propotional to its kinetic energy. 2. KMT is dependent upon a gas behaving as if the gas particles have NO IMFs. 3. KMT also considers gases to be point masses. That is to say, the size of each atom is insignificant. If the statements above are true, the gases will behave ideally. However, we know the 2 nd & 3 rd statements aren t always so perfectly true. 159 159

Graphing PV/RT at various pressures PV=nRT, thus for 1 mole of any gas,»pv/rt = 1 The graph of PV/RT vs P for one mole of an ideal gas would be the dashed line. at ~300K Ideal Gas 160 160

Real Gases Deviate from the Ideal For one mole of the gases shown, the graph of PV/nT vs P actually looks like this. at ~300K 161 161

The not so ideal Ideal Gas Law If n is larger than 1, then at the pressure measured, V must be at ~300K bigger than it ideally should be. n = PV RT If n is smaller than 1, at the measured pressure, V must be smaller than it ideally should be. 162 162

What would make V smaller than it should ideally be at a given pressure? If ratio is below the 1 line, IMFs are having an effect. The V is smaller because the IMFs are playing a role. The darker molecule is feeling the love and thus not pushing out as hard as it ideally should and causing less volume (if in a flexible container). 163 163

What would make V larger than it should ideally be at a given pressure? Usually molecules are far apart and their personal particle size is irrelevant, however when cramped together, the particle s personal size begins to matter. At higher pressures, the volume of each individual molecule begins to matter and actually takes up some space, causing the volume to record as larger. 164 164

Put the gases in order of increasing intermolecular forces. 1. N2 < H2 < CH4 < CO2 at ~300K 2. CO2 < H2 < N2 < CH4 3. CO2 < CH4 < H2 < N2 4. H2 < N2 < CH4 < CO2 5. H2 < CH4 < N2 < CO2 6. CO2 < CH4 < N2 < H2 165 165

Put the gases in order of increasing intermolecular forces. at ~300K 1. N2 < H2 < CH4 < CO2 2. CO2 < H2 < N2 < CH4 3. CO2 < CH4 < H2 < N2 4. H2 < N2 < CH4 < CO2 5. H2 < CH4 < N2 < CO2 6. CO2 < CH4 < N2 < H2 IMFs increase with increasing molar mass The molecule with the smallest IMFs deviates least below the line. The deviation below the line increases with increasing IMFs 166 166

Variations from the Ideal as a function of Temperature Which line represents the highest Varying Temps for N2 temperature? 1. green 2. red 3. blue 167 167

Variations from the Ideal as a function of Temperature Which line represents the highest Varying Temp for N2 temperature? 1. green 2. red 3. blue Turn to your mate, and tell them why. 168 168

Variations from the Ideal as a function of Temperature Remember that deviations below the Varying Temps for N2 line arise from intermolecular forces. At higher temperatures, IMFs have less effect, thus the line does not dip below as much or at all. 169 169

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The van der Waals Equation Predicting Real Gas Pressures PV = nrt P + n2 a V 2 (V nb) = nrt correction for IMFs correction for volume of molecules written this way in your text: P = nrt V nb n2 a V 2 171 171

P + n2 a V 2 (V nb) = nrt correction for IMFs correction for volume of molecules 172 172