Question 1

Which of the following compounds will behave least like an ideal gas at low temperatures?

Accepted Answer

A)  Ar 
B)  CCl4 
C)  O2 
D)  Kr 
E)  F2 
A)  Ar 
B)  CCl4 
C)  O2 
D)  Kr 
E)  F2

Question 2

Explain what the term "mean free path" describes.How does it change with decreasing pressure?

Accepted Answer

Mean free path describes the distance th

Question 3

A 0.500 g sample containing Ag2O and inert material is heated,causing the silver oxide to decompose according to the following equation: 2 Ag2O(s)→ 4 Ag(s)+ O2(g)
If 13.8 mL of gas are collected over water at 27°C and 1.00 atm external pressure,what is the percentage of silver oxide in the sample? The partial pressure of water is 26.7 mm Hg at 27°C.

Accepted Answer

A)  12.5% 
B)  25.1% 
C)  50.1% 
D)  51.9% 
A)  12.5% 
B)  25.1% 
C)  50.1% 
D)  51.9%

Question 4

Calcium hydride (   )reacts with water to form hydrogen gas: CaH2(s)+ 2 H2O(l)→ Ca(OH)2(aq)+ 2 H2(g)
How many grams of   are needed to generate 45.0 L of   gas at a pressure of 0.888 atm and a temperature of 32°C?

Accepted Answer

A)  47.5 g 
B)  0.798 g 
C)  134 g 
D)  33.6 g 
E)  67.2 g 
A)  47.5 g 
B)  0.798 g 
C)  134 g 
D)  33.6 g 
E)  67.2 g

Question 5

A 5.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure.What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

Accepted Answer

A)  0.255 atm 
B)  0.987 atm 
C)  1.35 atm 
D)  1.84 atm 
A)  0.255 atm 
B)  0.987 atm 
C)  1.35 atm 
D)  1.84 atm

Question 6

A fixed amount of gas at 25.0°C occupies a volume of 10.0 L when the pressure is 629 torr.Use Charles's law to calculate the volume (L)the gas will occupy when the temperature is increased to   while maintaining the pressure at 629 torr.

Accepted Answer

A)  11.1 L 
B)  13.4 L 
C)  1.98 L 
D)  7.47 L 
E)  50.4 L 
A)  11.1 L 
B)  13.4 L 
C)  1.98 L 
D)  7.47 L 
E)  50.4 L

Question 7

What volume will 0.875 moles of Kr occupy at STP?

Accepted Answer

A)  22.4 L 
B)  80.0 L 
C)  43.7 atm 
D)  19.6 L 
E)  16.4 L 
A)  22.4 L 
B)  80.0 L 
C)  43.7 atm 
D)  19.6 L 
E)  16.4 L

Question 8

A mixture of 0.220 moles CO,0.350 moles F2 and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

Accepted Answer

A)  1.86 atm 
B)  0.649 atm 
C)  0.536 atm 
D)  1.54 atm 
E)  0.955 atm 
A)  1.86 atm 
B)  0.649 atm 
C)  0.536 atm 
D)  1.54 atm 
E)  0.955 atm

Question 9

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Accepted Answer

A)  0.08 moles gained 
B)  0.01 moles gained 
C)  0.01 moles lost 
D)  0.07 moles lost 
E)  1.40 moles gained 
A)  0.08 moles gained 
B)  0.01 moles gained 
C)  0.01 moles lost 
D)  0.07 moles lost 
E)  1.40 moles gained

Question 10

Identify the element or molecule that has the highest effusion rate.

Accepted Answer

A)  He  
B)  O2 
C)  HCl  
D)  SO2 
E)  Rn 
A)  He  
B)  O2 
C)  HCl  
D)  SO2 
E)  Rn

Question 11

How many molecules of XeF6 are formed from 12.9 L of F2 (at 298 K and 2.60 atm)according to the following reaction? Assume that there is excess Xe. Xe(g)+ 3 F2(g)→ XeF6(g)

Accepted Answer

A)  1.21 × 1023 molecules XeF6 
B)  8.25 × 1023 molecules XeF6 
C)  2.75 × 1023 molecules XeF6 
D)  7.29 × 1023 molecules XeF6 
E)  1.37 × 1023 molecules XeF6 
A)  1.21 × 1023 molecules XeF6 
B)  8.25 × 1023 molecules XeF6 
C)  2.75 × 1023 molecules XeF6 
D)  7.29 × 1023 molecules XeF6 
E)  1.37 × 1023 molecules XeF6

Question 12

Define effusion.

Accepted Answer

Effusion is the proc

Question 13

Define mean free path.

Accepted Answer

A)  average distance that a molecule travels between collisions 
B)  diameter of a molecule 
C)  distance between molecules in a gas 
D)  time for effusion 
E)  time for diffusion 
A)  average distance that a molecule travels between collisions 
B)  diameter of a molecule 
C)  distance between molecules in a gas 
D)  time for effusion 
E)  time for diffusion

Question 14

A mixture of Ar,H2 and SO2 has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H2 has a mole fraction of 0.23,what is the partial pressure of SO2?

Accepted Answer

A)  4.2 atm 
B)  3.7 atm 
C)  1.8 atm 
D)  5.5 atm 
E)  2.4 atm 
A)  4.2 atm 
B)  3.7 atm 
C)  1.8 atm 
D)  5.5 atm 
E)  2.4 atm

Question 15

The density of krypton gas at 1.35 atm and 54.1°C is ________ g/L.

Accepted Answer

A)  0.0503 
B)  0.237 
C)  0.304 
D)  4.21 
E)  8.42 
A)  0.0503 
B)  0.237 
C)  0.304 
D)  4.21 
E)  8.42

Question 16

The mole fraction of krypton in dry air near sea level is 0.00000114.The concentration of krypton is ________ molecules per liter,assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

Accepted Answer

A)  3.39 × 10-5 
B)  4.46 × 10-8 
C)  2.68 × 1016 
D)  2.04 × 1019 
E)  2.76 × 1017 
A)  3.39 × 10-5 
B)  4.46 × 10-8 
C)  2.68 × 1016 
D)  2.04 × 1019 
E)  2.76 × 1017

Question 17

The mole fraction of oxygen in dry air near sea level is 0.20948,where the molar mass of oxygen is 31.998.The partial pressure of oxygen when the total atmospheric pressure (dry air)is 97.5 kPa is

Accepted Answer

A)  471 
B)  14.7 
C)  20.7 
D)  661 
E)  0.646 
A)  471 
B)  14.7 
C)  20.7 
D)  661 
E)  0.646

Question 18

How many grams of calcium hydride are required to produce 1.14 L of hydrogen gas at 25.0°C and 0.975 atm pressure according to the chemical equation shown below? CaH2(s)+ 2 H2O(l)→ Ca(OH)2(aq)+ 2 H2(g)

Accepted Answer

A)  0.956 g 
B)  1.91 g 
C)  3.82 g 
D)  11.4 g 
A)  0.956 g 
B)  1.91 g 
C)  3.82 g 
D)  11.4 g

Question 19

A 0.334 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm.What is the identity of the halogen?

Accepted Answer

A)  Br2 
B)  F2 
C)  Cl2 
D)  I2 
E)  Ge 
A)  Br2 
B)  F2 
C)  Cl2 
D)  I2 
E)  Ge

Question 20

Identify the temperature at which O2 has the highest velocity.

Accepted Answer

A)  325 K 
B)  500 K 
C)  650 K 
D)  1000 K 
E)  900 K 
A)  325 K 
B)  500 K 
C)  650 K 
D)  1000 K 
E)  900 K

Exam 5: Gases

Which of the following compounds will behave least like an ideal gas at low temperatures?

Explain what the term "mean free path" describes.How does it change with decreasing pressure?

Calcium hydride ( )reacts with water to form hydrogen gas: CaH2(s)+ 2 H2O(l)→ Ca(OH)2(aq)+ 2 H2(g) How many grams of are needed to generate 45.0 L of gas at a pressure of 0.888 atm and a temperature of 32°C?

A 5.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure.What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

A fixed amount of gas at 25.0°C occupies a volume of 10.0 L when the pressure is 629 torr.Use Charles's law to calculate the volume (L)the gas will occupy when the temperature is increased to while maintaining the pressure at 629 torr.

What volume will 0.875 moles of Kr occupy at STP?

A mixture of 0.220 moles CO,0.350 moles F2 and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Identify the element or molecule that has the highest effusion rate.

How many molecules of XeF6 are formed from 12.9 L of F2 (at 298 K and 2.60 atm)according to the following reaction? Assume that there is excess Xe. Xe(g)+ 3 F2(g)→ XeF6(g)

Define effusion.

Define mean free path.

A mixture of Ar,H2 and SO2 has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H2 has a mole fraction of 0.23,what is the partial pressure of SO2?

The density of krypton gas at 1.35 atm and 54.1°C is ________ g/L.

The mole fraction of krypton in dry air near sea level is 0.00000114.The concentration of krypton is ________ molecules per liter,assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

The mole fraction of oxygen in dry air near sea level is 0.20948,where the molar mass of oxygen is 31.998.The partial pressure of oxygen when the total atmospheric pressure (dry air)is 97.5 kPa is

How many grams of calcium hydride are required to produce 1.14 L of hydrogen gas at 25.0°C and 0.975 atm pressure according to the chemical equation shown below? CaH2(s)+ 2 H2O(l)→ Ca(OH)2(aq)+ 2 H2(g)

A 0.334 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm.What is the identity of the halogen?

Identify the temperature at which O2 has the highest velocity.

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Calcium hydride ( )reacts with water to form hydrogen gas: CaH₂(s)+ 2 H₂O(l)→ Ca(OH)₂(aq)+ 2 H₂(g) How many grams of are needed to generate 45.0 L of gas at a pressure of 0.888 atm and a temperature of 32°C?

A 5.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure.What is the final pressure in the flask if an additional 2.00 g of N₂ gas is added to the flask and the flask cooled to -55°C?

A mixture of 0.220 moles CO,0.350 moles F₂ and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

How many molecules of XeF₆are formed from 12.9 L of F₂ (at 298 K and 2.60 atm)according to the following reaction? Assume that there is excess Xe. Xe(g)+ 3 F₂(g)→ XeF₆(g)

A mixture of Ar,H₂ and SO₂ has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H₂ has a mole fraction of 0.23,what is the partial pressure of SO₂?

How many grams of calcium hydride are required to produce 1.14 L of hydrogen gas at 25.0°C and 0.975 atm pressure according to the chemical equation shown below? CaH₂(s)+ 2 H₂O(l)→ Ca(OH)₂(aq)+ 2 H₂(g)

Identify the temperature at which O₂ has the highest velocity.