# CHEM 1045 QUIZ CHAPTER 5

Exercise 5.54: Problems by Topic – Ideal Gas Law

Part A

Use the molar volume of a gas at STP to calculate the density (in g/L ) of carbon dioxide gas at STP.

ANSWER:

Correct

Exercise 5.37: Problems by Topic – Simple Gas Laws

A 48.2- mL sample of gas in a cylinder is warmed from 22 ∘ C to 85 ∘ C .

Part A

What is its volume at the final temperature? (Assume constant pressure.)

ANSWER:

Correct

Exercise 5.43: Problems by Topic – Ideal Gas Law

A cylinder contains 30.5 L of oxygen gas at a pressure of 2.0 atm and a temperature of 310 K .

Part A

How much gas (in moles) is in the cylinder?

Express your answer using two significant figures.

ANSWER:

Correct

Exercise 5.46: Problems by Topic – Ideal Gas Law

A weather balloon is inflated to a volume of 29.9 L at a pressure of 733 mmHg and a temperature of 31.5 ∘ C . The balloon rises in the atmosphere to an altitude, where the pressure is 375 mmHg and the temperature is -15.3 ∘ C .

Part A

Assuming the balloon can freely expand, calculate the volume of the balloon at this altitude.

ANSWER:

Exercise 5.53: Problems by Topic – Ideal Gas Law

Part A

Use the molar volume of a gas at STP to determine the volume (in L ) occupied by 14.0 g of neon at STP.

Exercise 5.57: Problems by Topic – Molar Volume, Density, and Molar Mass of a Gas

An experiment shows that a 247 −mL gas sample has a mass of 0.436 g at a pressure of 748 mmHg and a temperature of 26 ∘ C .

Part A

What is the molar mass of the gas?

ANSWER:

Exercise 5.62: Problems by Topic – Partial Pressure

A gas mixture with a total pressure of 770 mmHg contains each of the following gases at the indicated partial pressures: CO 2 , 253 mmHg ; Ar , 114 mmHg ; and O 2 , 165 mmHg . The mixture also contains helium gas.

Part A

What is the partial pressure of the helium gas?

Part B

What mass of helium gas is present in a 13.1- L sample of this mixture at 279 K ?

ANSWER:

Exercise 5.65: Problems by Topic – Partial Pressure

A gas mixture contains 1.17 g N 2 and 0.88 g O 2 in a 1.45- L container at 20 ∘ C .

Part A

Calculate the mole fraction of N 2 .

Express your answer using two significant figures.

Correct

Part B

Calculate the mole fraction of O 2 .

Express your answer using two significant figures.

ANSWER:

Part C

Calculate the partial pressure of N 2 .

Express your answer using two significant figures.

ANSWER:

Part D

Calculate the partial pressure of O 2 .

Express your answer using two significant figures.

ANSWER:

Exercise 5.67: Problems by Topic – Partial Pressure

The hydrogen gas formed in a chemical reaction is collected over water at 30.0 ∘ C at a total pressure of 730 mmHg .

Part A

What is the partial pressure of the hydrogen gas collected in this way?

ANSWER:

Part B

If the total volume of gas collected is 720 mL , what mass of hydrogen gas is collected?

ANSWER:

Exercise 5.77: Problems by Topic – Reaction Stiochiometry Involving Gases

Hydrogen gas (a potential future fuel) can be formed by the reaction of methane with water according to the following equation:

CH 4 ( g )+H 2 O( g )→CO( g )+3H 2 ( g )

In a particular reaction, 26.5 L of methane gas (measured at a pressure of 736 torr and a temperature of 25 ∘ C ) is mixed with 22.2 L of water vapor (measured at a pressure of 704 torr and a temperature of 125 ∘ C ). The reaction produces 26.8 L of hydrogen gas measured at STP.

Part A

What is the percent yield of the reaction?

ANSWER: