Question 1

A sample of nitrogen gas occupies 2.50 L at 1.00 atm and 300 K. If the pressure is increased to 2.00 atm and the temperature is decreased to 273 K, what will be the new volume of the gas? (Assume the amount of gas remains constant.)

Use the Combined Gas Law: 
$$\frac{P_1$ V_1$}{T_1$} = \frac{P_2$ V_2$}{T_2$}$$

Accepted Answer

1.13 L

Question 2

A weather balloon contains 60.0 L of helium at 1.00 atm. If the amount of helium is doubled while temperature and pressure remain constant, what will be the new volume?

Use Avogadro’s Law: 
$$\frac{V_1$}{n_1$} = \frac{V_2$}{n_2$}$$

Accepted Answer

120.0 L

Question 3

What is the molar mass of C2H6O (ethanol)?

(Atomic masses: C = 12.01 g/mol, H = 1.01 g/mol, O = 16.00 g/mol)

Accepted Answer

46.08 g/mol

Question 4

A 4.00 g sample of methane (CH4) is collected at STP. What is the volume of the gas?

(Molar mass of CH4 = 16.04 g/mol; 1 mole gas at STP = 22.4 L)

Accepted Answer

5.59 L

Question 5

A scuba tank contains a mixture of helium and oxygen at a total pressure of 8.00 atm. If the partial pressure of oxygen is 1280 mmHg, what is the partial pressure of helium? (1 atm = 760 mmHg)

Accepted Answer

6.32 atm

Question 6

Which of the following statements best describes Avogadro’s Law?

Accepted Answer

The volume of a gas is directly proportional to the number of moles of gas at constant temperature and pressure.

Question 7

If 3.0 moles of oxygen gas occupy 67.2 L at STP, what is the volume occupied by 1.0 mole of oxygen gas at STP?

Accepted Answer

22.4 L

Question 8

A gas sample has a pressure of 1.20 atm, a volume of 500 mL, and a temperature of 27°C. What will the pressure be if the volume is decreased to 250 mL and the temperature is increased to 327 K? (Use the Combined Gas Law.)

Accepted Answer

1.80 atm

Question 9

Which of the following is NOT a correct statement about STP?

Accepted Answer

At STP, 1 mole of gas occupies 1.00 L.

Question 10

A mixture of gases contains 2.0 atm of nitrogen, 1.0 atm of oxygen, and 0.5 atm of argon. What is the total pressure of the mixture according to Dalton’s Law?

Accepted Answer

3.5 atm

Question 11

Which of the following best explains why the total pressure of a gas mixture is the sum of the partial pressures of its components?

Accepted Answer

Each gas in the mixture behaves independently and exerts pressure as if it were alone in the container.

Question 12

A 10.0 L container holds 0.50 moles of neon gas at 300 K. If the amount of neon is increased to 1.00 mole at constant temperature and pressure, what will be the new volume?

Accepted Answer

20.0 L

Question 13

Which of the following is the correct formula for the Combined Gas Law?

Accepted Answer

$$\frac{P_1$ V_1$}{T_1$} = \frac{P_2$ V_2$}{T_2$}$$

Question 14

A 1.00 mole sample of an unknown gas occupies 30.0 L at STP. Which of the following is true about this gas?

Accepted Answer

It is less dense than a gas that occupies 22.4 L at STP.

Question 15

If the temperature of a gas is increased from 273 K to 546 K at constant pressure, what happens to the volume?

Accepted Answer

The volume doubles.

Question 16

Which of the following is the correct molar mass for lithium carbonate, Li2CO3? (Li = 6.94 g/mol, C = 12.01 g/mol, O = 16.00 g/mol)

Accepted Answer

73.89 g/mol

Question 17

A gas sample at 1.00 atm and 273 K has a volume of 5.00 L. If the pressure is increased to 2.00 atm and the temperature is increased to 546 K, what is the new volume?

Accepted Answer

10.0 L

Question 18

Which of the following is a correct conversion factor for molar volume at STP?

Accepted Answer

$$\frac{22.4\,L}{1\,mol}$$

Question 19

A mixture of gases contains 0.80 atm of CO2, 0.60 atm of N2, and 0.40 atm of O2. What is the total pressure of the mixture?

Accepted Answer

1.80 atm

Gas Laws, Molar Mass, and Dalton’s Law: Study Notes for GOB Chemistry

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