Q: A manometer is used to measure the pressure of a gas in a vessel. If the atmospheric pressure is 760 mm Hg and the height difference in the manometer is 50 mm (with the gas side higher), what is the pressure of the gas in mm Hg?

$$P_{\text{gas}} = 710\ \text{mm Hg}$$

Question 1

Which of the following statements best explains why gases are highly compressible compared to solids and liquids?

Accepted Answer

Gases are composed of particles with significant empty space between them.

Question 2

A manometer is used to measure the pressure of a gas in a vessel. If the atmospheric pressure is 760 mm Hg and the height difference in the manometer is 50 mm (with the gas side higher), what is the pressure of the gas in mm Hg?

Accepted Answer

$$P_{	ext{gas}} = 710\ 	ext{mm Hg}$$

Question 3

Which of the following is the correct mathematical expression for Boyle's Law?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 4

A 2.0 L sample of gas at 1.0 atm and 300 K is compressed to 1.0 L at constant temperature. What is the final pressure?

Accepted Answer

$$2.0\ 	ext{atm}$$

Question 5

Which of the following best describes Avogadro's Law?

Accepted Answer

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

Question 6

A sample of gas occupies 5.0 L at 27°C and 2.0 atm. How many moles of gas are present? (Use $$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$n = 0.41\ 	ext{mol}$$

Question 7

Which of the following is the correct expression for the density of a gas using the ideal gas law?

Accepted Answer

$$d = \frac{MP}{RT}$$

Question 8

A mixture contains 2.0 mol O$$_2$$ and 3.0 mol N$$_2 in a 10.0 L $$container at 300 K. What is the total pressure of the mixture? ($$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P = 1.23\ 	ext{atm}$$

Question 9

According to the kinetic-molecular theory, which of the following statements is true?

Accepted Answer

The average kinetic energy of gas molecules is proportional to the absolute temperature.

Question 10

A 1.0 L flask contains 0.5 mol of He and 0.5 mol of Ne at 300 K. What is the mole fraction of Ne in the mixture?

Accepted Answer

$$X_{	ext{Ne}} = 0.50$$

Question 11

A gas sample effuses through a small hole at a rate that is 0.707 times the rate of O$$_2$$ under the same conditions. What is the molar mass of the unknown gas?

Accepted Answer

$$M = 64.0\ 	ext{g/mol}$$

Question 12

Which of the following best describes Graham's Law of Effusion?

Accepted Answer

The rate of effusion of a gas is inversely proportional to the square root of its molar mass.

Question 13

A 5.0 g sample of an unknown gas occupies 2.5 L at 1.0 atm and 300 K. What is the molar mass of the gas? ($$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$M = 49.2\ 	ext{g/mol}$$

Question 14

If the temperature of a gas in a rigid container is doubled, what happens to the pressure?

Accepted Answer

The pressure doubles.

Question 15

A 10.0 L tank contains 2.0 mol of H$$_2 at 300 K. $$What is the pressure inside the tank? ($$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P = 4.92\ 	ext{atm}$$

Question 16

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

Accepted Answer

Gas molecules experience significant attractive and repulsive forces.

Question 17

A 36 L automobile airbag is to be filled with N$$_2$$ gas at 1.15 atm and 26°C. How many grams of NaN$$_3 ($$sodium azide, $$M = 65.0\ 	ext{g/mol}) $$must be decomposed to produce the required N$$_2$$? (Use $$2	ext{NaN}_3(s) ightarrow 2	ext{Na}(s) + 3	ext{N}_2(g)$$ and $$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$74.9\ 	ext{g}$$

Question 18

Which of the following is the correct formula for the root-mean-square speed ($$u_{rms}) of a $$gas molecule?

Accepted Answer

$$u_{rms} = \sqrt{\frac{3RT}{M}}$$

Chapter 10: Gases – General Chemistry Study Notes

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