Q: A 2.00 L tank is evacuated and then filled with butane gas (C$$_4H$_{10}) at 2.20 $$atm and 25$$^ ext{o}C. $$What is the mass of butane in the tank? (R = 0.0821 L·atm/mol·K, molar mass of C$$_4H$_{10} = 58.12 g/$$mol)

$$m = \frac{PV}{RT} \times \text{MM} = \frac{2.20 \times 2.00}{0.0821 \times 298} \times 58.12 = 11.6\ \text{g}$$

Q: A mixture of gases contains 2.0 mol O$$_2$$ and 3.0 mol N$$_2 in a 10.0 L $$container at 25$$^ ext{o}C. $$What is the partial pressure of O$$_2$$? (R = 0.0821 L·atm/mol·K)

$$P_{O_2$} = \frac{nRT}{V} = \frac{2.0 \times 0.0821 \times 298}{10.0} = 4.89\ \text{atm}$$

Q: A sample of hydrogen gas is collected over water at 25$$^ ext{o}C $$and a total pressure of 755 mmHg. The vapor pressure of water at 25$$^ ext{o}C is 23.8 $$mmHg. What is the partial pressure of hydrogen gas?

$$P_{H_2$} = 755\ \text{mmHg} - 23.8\ \text{mmHg} = 731.2\ \text{mmHg}$$

Q: Which equation best represents the relationship between molar mass and rate of effusion according to Graham's Law?

$$\text{rate}_1 / \text{rate}_2 = \sqrt{\text{MM}_2 / \text{MM}_1}$$

Q: A 5.00 L sample of gas at 1.00 atm and 273 K is compressed to 2.50 L at constant temperature. What is the final pressure?

$$P_2$$ = \frac{$$P_1$$ $$V_1$$}{$$V_2$$} = \frac{1.00 \times 5.00}{2.50} = 2.00\ \text{atm}$$

Question 1

Which of the following statements best describes the kinetic molecular theory of gases?

Accepted Answer

Gas particles move in straight lines until they collide with another particle or the container wall.

Question 2

A 2.00 L tank is evacuated and then filled with butane gas (C$$_4H$_{10}) at 2.20 $$atm and 25$$^	ext{o}C. $$What is the mass of butane in the tank? (R = 0.0821 L·atm/mol·K, molar mass of C$$_4H$_{10} = 58.12 g/$$mol)

Accepted Answer

$$m = \frac{PV}{RT} 	imes 	ext{MM} = \frac{2.20 	imes 2.00}{0.0821 	imes 298} 	imes 58.12 = 11.6\ 	ext{g}$$

Question 3

Which of the following correctly expresses Boyle's Law?

Accepted Answer

$$V \propto \frac{1}{P} at $$constant $$T$$ and $$n$$

Question 4

A mixture of gases contains 2.0 mol O$$_2$$ and 3.0 mol N$$_2 in a 10.0 L $$container at 25$$^	ext{o}C. $$What is the partial pressure of O$$_2$$? (R = 0.0821 L·atm/mol·K)

Accepted Answer

$$P_{O_2$} = \frac{nRT}{V} = \frac{2.0 	imes 0.0821 	imes 298}{10.0} = 4.89\ 	ext{atm}$$

Question 5

Which of the following is NOT an assumption of the kinetic molecular theory of gases?

Accepted Answer

Gas particles are attracted to each other by strong intermolecular forces.

Question 6

A sample of hydrogen gas is collected over water at 25$$^	ext{o}C $$and a total pressure of 755 mmHg. The vapor pressure of water at 25$$^	ext{o}C is 23.8 $$mmHg. What is the partial pressure of hydrogen gas?

Accepted Answer

$$P_{H_2$} = 755\ 	ext{mmHg} - 23.8\ 	ext{mmHg} = 731.2\ 	ext{mmHg}$$

Question 7

Which equation best represents the relationship between molar mass and rate of effusion according to Graham's Law?

Accepted Answer

$$	ext{rate}_1 / 	ext{rate}_2 = \sqrt{	ext{MM}_2 / 	ext{MM}_1}$$

Question 8

A 5.00 L sample of gas at 1.00 atm and 273 K is compressed to 2.50 L at constant temperature. What is the final pressure?

Accepted Answer

$$P_2$$ = \frac{$$P_1$$ $$V_1$$}{$$V_2$$} = \frac{1.00 	imes 5.00}{2.50} = 2.00\ 	ext{atm}$$

Question 9

Which of the following best explains why real gases deviate from ideal behavior at high pressures?

Accepted Answer

The volume of gas particles becomes significant compared to the container volume.

Question 10

A balloon filled with helium and a balloon filled with air are left in a room. After several hours, which balloon will deflate faster and why?

Accepted Answer

The helium balloon will deflate faster because helium atoms effuse more rapidly due to their lower molar mass.

Question 11

Which equation is used to calculate the average kinetic energy of a gas particle?

Accepted Answer

$$	ext{KE}_{	ext{avg}} = \frac{3}{2} k_B T$$

Question 12

A sample of gas at STP occupies 22.4 L. How many moles of gas are present?

Accepted Answer

$$n = \frac{V}{22.4} = \frac{22.4}{22.4} = 1.00\ 	ext{mol}$$

Question 13

Which of the following is the correct form of the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 14

A 1.00 L sample of air contains 0.20 g of O$$_2 at 37$^	ext{o}C. $$What is the partial pressure of O$$_2$$? (Molar mass O$$_2 = 32.00 g/$$mol, R = 0.0821 L·atm/mol·K)

Accepted Answer

$$n = \frac{0.20}{32.00} = 0.00625\ 	ext{mol}$$; $$P = \frac{nRT}{V} = \frac{0.00625 	imes 0.0821 	imes 310}{1.00} = 0.16\ 	ext{atm}$$

Question 15

Which of the following modifications does the van der Waals equation make to the ideal gas law?

Accepted Answer

It accounts for intermolecular forces and the finite volume of gas particles.

Question 16

A 2.50 L flask, open to atmospheric pressure (1.01 atm), is filled with CO$$_2 at 25$^	ext{o}C. $$How many moles of CO$$_2$$ remain in the flask after it is sealed and the pressure increases to 1.50 atm at 75$$^	ext{o}C$$?

Accepted Answer

$$n = \frac{PV}{RT} = \frac{1.50 	imes 2.50}{0.0821 	imes 348} = 0.13\ 	ext{mol}$$

Question 17

Which of the following best describes the relationship between temperature and average kinetic energy of gas particles?

Accepted Answer

Average kinetic energy is directly proportional to temperature in Kelvin.

Question 18

A sample of gas contains 0.50 mol of O$$_2$$ and 1.50 mol of N$$_2. If $$the total pressure is 2.00 atm, what is the partial pressure of O$$_2$$?

Accepted Answer

Question 19

Which of the following is a correct statement about the mean free path of a gas molecule?

Accepted Answer

It is the average distance a molecule travels between collisions.

Comprehensive Study Notes: Gases and the Kinetic Molecular Theory

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