Question 1

A scuba diver at a depth of 20 m breathes air at a pressure of 3 atm. If the diver fills his lungs with 5.0 L of air at this depth and then ascends to the surface (1 atm) without exhaling, what will be the volume of air in his lungs at the surface? (Assume temperature is constant.)

Accepted Answer

$$15.0\ \mathrm{L}$$

Question 2

Which of the following best explains why gases are compressible, but liquids are not?

Accepted Answer

Gas particles are much farther apart than liquid particles, leaving more empty space.

Question 3

A sample of gas has a volume of $$2.80\ \mathrm{L} at an $$unknown temperature. When the sample is cooled to $$0^\circ\mathrm{C}$$, its volume decreases to $$2.57\ \mathrm{L}. $$What was the initial temperature in Kelvin?

Accepted Answer

$$303\ \mathrm{K}$$

Question 4

Which of the following statements is NOT a postulate of the kinetic molecular theory of gases?

Accepted Answer

Gas particles attract each other strongly at short distances.

Question 5

A mixture of helium, neon, and argon has a total pressure of $$558\ \mathrm{mm\ Hg}. If $$the partial pressure of helium is $$341\ \mathrm{mm\ Hg}$$ and the partial pressure of neon is $$112\ \mathrm{mm\ Hg}$$, what is the partial pressure of argon?

Accepted Answer

$$105\ \mathrm{mm\ Hg}$$

Question 6

Which of the following best describes why a hot air balloon rises?

Accepted Answer

Heating the air inside the balloon decreases its density, causing it to float in cooler, denser air.

Question 7

Convert a pressure of $$0.311\ \mathrm{atm} to $$millimeters of mercury (mm Hg).

Accepted Answer

$$236\ \mathrm{mm\ Hg}$$

Question 8

A $$4.8\ \mathrm{L}$$ sample of helium gas contains $$0.22\ \mathrm{mol} of $$helium. How many additional moles of helium must be added to obtain a volume of $$6.4\ \mathrm{L} at $$constant temperature and pressure?

Accepted Answer

$$0.09\ \mathrm{mol}$$

Question 9

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

Accepted Answer

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

Question 10

A sample of gas has an initial volume of $$158\ \mathrm{mL} at a $$pressure of $$735\ \mathrm{mm\ Hg}$$ and a temperature of $$34^\circ\mathrm{C}. If $$the gas is compressed to a volume of $$108\ \mathrm{mL}$$ and heated to $$85^\circ\mathrm{C}$$, what is its final pressure in mm Hg? (Use the combined gas law.)

Accepted Answer

$$1,180\ \mathrm{mm\ Hg}$$

Question 11

Which of the following is NOT a property predicted by the kinetic molecular theory for gases?

Accepted Answer

Gases have high densities compared to solids and liquids.

Question 12

A sample of gas has a mass of $$0.136\ \mathrm{g}$$, a volume of $$0.112\ \mathrm{L}$$, a temperature of $$298\ \mathrm{K}$$, and a pressure of $$1.06\ \mathrm{atm}. $$What is the molar mass of the gas? (Use $$R = 0.0821\ \mathrm{L\ atm\ $$mol^{-1}$$\ K$$^{-1}$$})$$

Accepted Answer

$$31.5\ \mathrm{g\ $$mol^{-1}$$}$$

Question 13

Which of the following is the correct value for the molar volume of an ideal gas at standard temperature and pressure (STP)?

Accepted Answer

$$22.4\ \mathrm{L}$$

Question 14

A diver breathes a heliox mixture containing $$2.0\%$$ oxygen at a depth of $$90\ \mathrm{m}$$, where the total pressure is $$10.0\ \mathrm{atm}. $$What is the partial pressure of oxygen?

Accepted Answer

$$0.20\ \mathrm{atm}$$

Question 15

Which of the following is a real-world consequence of Boyle’s Law for scuba divers?

Accepted Answer

Ascending too quickly can cause lung overexpansion due to decreasing pressure and increasing gas volume.

Question 16

Which of the following is the correct equation for Avogadro’s Law?

Accepted Answer

$$\dfrac{V_1$}{n_1$} = \dfrac{V_2$}{n_2$}$$

Question 17

Which of the following is a major source of carbon monoxide (CO) pollution in the atmosphere?

Accepted Answer

Incomplete combustion of fossil fuels in motor vehicles.

Question 18

According to Dalton’s Law of Partial Pressures, which of the following is true?

Accepted Answer

The total pressure of a mixture of gases is the sum of the partial pressures of each component.

Chapter 11: Gases – Properties, Laws, and Applications

Guida di studio - Domande di pratica

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