Question 1

Which of the following best explains why gases are easily compressed compared to liquids and solids?

Accepted Answer

Gases have much lower densities and their particles are far apart, allowing their volume to decrease significantly under pressure.

Question 2

A barometer is used to measure atmospheric pressure. If the height of the mercury column is 760 mm, what is the atmospheric pressure in pascals ($$Pa$$)?

Accepted Answer

$$101,325\ Pa$$

Question 3

Which of the following statements about pressure is correct?

Accepted Answer

Pressure is defined as the force exerted per unit area: $$P = \frac{F}{A}.$$

Question 4

A sample of gas occupies $$2.50\ L at$$ $$1.00\ atm. If $$the pressure is increased to $$2.00\ atm at $$constant temperature, what is the new volume?

Accepted Answer

$$1.25\ L$$

Question 5

Which of the following is a correct statement of Boyle's Law?

Accepted Answer

At constant temperature, the volume of a gas is inversely proportional to its pressure: $$PV = 	ext{constant}.$$

Question 6

A weather balloon contains $$5.00\ L of $$helium at $$1.00\ atm$$ and $$300\ K. If $$the balloon rises to a region where the pressure is $$0.500\ atm$$ and the temperature is $$250\ K$$, what is the new volume of the balloon?

Accepted Answer

$$6.00\ L$$

Question 7

Which of the following best describes Avogadro's Law?

Accepted Answer

At constant temperature and pressure, equal volumes of all gases contain the same number of molecules.

Question 8

A $$2.00\ g$$ sample of hydrogen gas ($$H_2) is $$collected at $$27^\circ C$$ and $$1.00\ atm. $$What is the volume of the gas? ($$R = 0.0821\ L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$, M$$_{$$H_2$$} = 2.02\ g/mol$$)

Accepted Answer

$$24.3\ L$$

Question 9

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

Accepted Answer

Gas particles exert attractive and repulsive forces on each other.

Question 10

A mixture contains $$80\%$$ nitrogen and $$20\%$$ oxygen by mole. If the total pressure is $$1.00\ atm$$, what is the partial pressure of oxygen?

Accepted Answer

$$0.20\ atm$$

Question 11

A $$1.00\ L$$ flask contains $$0.040\ mol of$$ $$O_2 at$$ $$27^\circ C. $$What is the pressure in the flask? ($$R = 0.0821\ L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$)

Accepted Answer

$$0.98\ atm$$

Question 12

Which of the following best explains why atmospheric pressure decreases with altitude?

Accepted Answer

There are fewer air molecules above a given surface as altitude increases, so the weight of the air (and thus the pressure) decreases.

Question 13

A sample of $$CO_2$$ gas has a density of $$1.96\ g/L at $$STP. What is the molar mass of $$CO_2$$? ($$R = 0.0821\ L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$, T = 273$$\ K$$, P = 1.00$$\ atm$$)

Accepted Answer

$$44.0\ g/mol$$

Question 14

Which of the following is a correct rearrangement of the ideal gas law to solve for the density ($$d) of a $$gas?

Accepted Answer

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

Question 15

A $$0.500\ L$$ sample of hydrogen gas is collected over water at $$25^\circ C$$ and a total pressure of $$755\ torr. $$The vapor pressure of water at $$25^\circ C is$$ $$24\ torr. $$What is the pressure of the dry hydrogen gas in $$atm$$?

Accepted Answer

$$0.961\ atm$$

Question 16

According to Graham's law, which gas will effuse faster: $$H_2$$ ($$M = 2.0\ g/mol) or$$ $$O_2$$ ($$M = 32.0\ g/mol$$)?

Accepted Answer

$$H_2$$ will effuse 4 times faster than $$O_2.$$

Question 17

A $$10.0\ g$$ sample of an unknown gas occupies $$5.00\ L at$$ $$27^\circ C$$ and $$2.00\ atm. $$What is the molar mass of the gas? ($$R = 0.0821\ L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$)

Accepted Answer

$$49.2\ g/mol$$

Question 18

Which of the following real-world scenarios best illustrates Dalton's Law of Partial Pressures?

Accepted Answer

The total pressure in a scuba tank is the sum of the partial pressures of oxygen, nitrogen, and other gases.

Question 19

Which of the following best explains why a helium balloon rises in air?

Accepted Answer

Helium is less dense than air, so the buoyant force pushes the balloon upward.

Gas Pressure, Gas Laws, and the Kinetic Molecular Theory

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