Q: A sample of gas occupies 4.0 L at a pressure of 2.0 atm. If the pressure is increased to 8.0 atm at constant temperature, what will be the new volume of the gas?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{2.0 \times 4.0}{8.0} = 1.0\ \text{L}$$

Q: A manometer is used to measure the pressure of a gas sample. If the mercury level on the side open to the atmosphere is 20 mm higher than the side connected to the gas sample, and atmospheric pressure is 760 mmHg, what is the pressure of the gas sample?

$$P_{\text{gas}} = P_{\text{atm}} + h = 760\ \text{mmHg} + 20\ \text{mmHg} = 780\ \text{mmHg}$$

Q: A 2.0 L sample of gas at 300 K is heated to 600 K at constant pressure. What is the final volume?

$$V_2$$ = $$V_1$$ \frac{$$T_2$$}{$$T_1$$} = 2.0 \times \frac{600}{300} = 4.0\ \text{L}$$

Q: A gas has a density of $$1.96\ \text{g/L} at $$STP. What is its molar mass?

$$M = d \times 22.4 = 1.96 \times 22.4 = 43.9\ \text{g/mol}$$

Q: A mixture of gases contains $$2.0\ \text{mol} of$$ $$O_2$$, $$1.0\ \text{mol} of$$ $$N_2$$, and $$3.0\ \text{mol} of$$ $$CO_2. If $$the total pressure is $$6.0\ \text{atm}$$, what is the partial pressure of $$CO_2$$?

$$P_{CO_2$} = \frac{3.0}{6.0} \times 6.0 = 3.0\ \text{atm}$$

Q: A $$5.0\ \text{g}$$ sample of an unknown gas occupies $$2.0\ \text{L} at$$ $$1.0\ \text{atm}$$ and $$273\ \text{K}. $$What is the molar mass of the gas?

$$M = \frac{mRT}{PV} = \frac{5.0 \times 0.0821 \times 273}{1.0 \times 2.0} = 56.0\ \text{g/mol}$$

Question 1

Which of the following best explains why a diver ascending too quickly from deep water is at risk of decompression sickness?

Accepted Answer

Rapid ascent causes nitrogen dissolved in body tissues to form bubbles due to decreasing external pressure.

Question 2

A sample of gas occupies 4.0 L at a pressure of 2.0 atm. If the pressure is increased to 8.0 atm at constant temperature, what will be the new volume of the gas?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{2.0 	imes 4.0}{8.0} = 1.0\ 	ext{L}$$

Question 3

Which statement about the kinetic molecular theory is correct?

Accepted Answer

Gas particles move in random, straight-line motion and collisions with container walls create pressure.

Question 4

A manometer is used to measure the pressure of a gas sample. If the mercury level on the side open to the atmosphere is 20 mm higher than the side connected to the gas sample, and atmospheric pressure is 760 mmHg, what is the pressure of the gas sample?

Accepted Answer

$$P_{	ext{gas}} = P_{	ext{atm}} + h = 760\ 	ext{mmHg} + 20\ 	ext{mmHg} = 780\ 	ext{mmHg}$$

Question 5

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

Accepted Answer

$$V_1$$ $$T_2$$ = $$V_2$$ $$T_1$$

Question 6

A 2.0 L sample of gas at 300 K is heated to 600 K at constant pressure. What is the final volume?

Accepted Answer

$$V_2$$ = $$V_1$$ \frac{$$T_2$$}{$$T_1$$} = 2.0 	imes \frac{600}{300} = 4.0\ 	ext{L}$$

Question 7

Which of the following is the correct value for the molar volume of an ideal gas at STP?

Accepted Answer

$$22.4\ 	ext{L}$$

Question 8

A gas has a density of $$1.96\ 	ext{g/L} at $$STP. What is its molar mass?

Accepted Answer

$$M = d 	imes 22.4 = 1.96 	imes 22.4 = 43.9\ 	ext{g/mol}$$

Question 9

Which of the following best describes the relationship between pressure and the number of molecular collisions in a gas?

Accepted Answer

Pressure increases as the number of collisions increases.

Question 10

A mixture of gases contains $$2.0\ 	ext{mol} of$$ $$O_2$$, $$1.0\ 	ext{mol} of$$ $$N_2$$, and $$3.0\ 	ext{mol} of$$ $$CO_2. If $$the total pressure is $$6.0\ 	ext{atm}$$, what is the partial pressure of $$CO_2$$?

Accepted Answer

$$P_{CO_2$} = \frac{3.0}{6.0} 	imes 6.0 = 3.0\ 	ext{atm}$$

Question 11

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

Accepted Answer

$$PV = nRT$$

Question 12

A $$5.0\ 	ext{g}$$ sample of an unknown gas occupies $$2.0\ 	ext{L} at$$ $$1.0\ 	ext{atm}$$ and $$273\ 	ext{K}. $$What is the molar mass of the gas?

Accepted Answer

$$M = \frac{mRT}{PV} = \frac{5.0 	imes 0.0821 	imes 273}{1.0 	imes 2.0} = 56.0\ 	ext{g/mol}$$

Question 13

Which of the following statements about real gases is true?

Accepted Answer

Real gases deviate from ideal behavior due to intermolecular forces and finite molecular volume.

Question 14

Which equation is used to correct for the non-ideal behavior of real gases?

Accepted Answer

$$\left(P + a \frac{n^2$}{V^2$}\right)(V - nb) = nRT$$

Question 15

A gas sample at $$1.0\ 	ext{atm}$$ and $$273\ 	ext{K}$$ has a root mean square velocity of $$u_{rms}. If $$the temperature is doubled, what happens to $$u_{rms}$$?

Accepted Answer

$$u_{rms}$$ increases by a factor of $$\sqrt{2}$$

Question 16

Which of the following is the correct formula for pressure in terms of force and area?

Accepted Answer

$$P = \frac{F}{A}$$

Question 17

A scuba diver breathes air at a pressure of $$3.0\ 	ext{atm} at a $$depth of 20 meters. If the diver ascends to the surface ($$1.0\ 	ext{atm}) $$without exhaling, what happens to the volume of air in the diver's lungs?

Accepted Answer

The volume triples, according to Boyle's Law.

Question 18

Which of the following is NOT a unit of pressure?

Accepted Answer

Joule (J)

Gases: Properties, Laws, and Applications (Chapter 6 Study Notes)

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