Question 1

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

Accepted Answer

Gas particles move randomly, have negligible volume, and experience only elastic collisions.

Question 2

A 60 L container holds 120 g of ethane ($$C_2H_6) at$$ $$283\ K. $$What is the pressure inside the container? (Use $$R = 8.314\ J\ $$mol^{-1}$$\ K$$^{-1}$$, molar mass C_2H_6 = 30$$\ g/mol$$)

Accepted Answer

$$P = 1.57\ bar$$

Question 3

Which equation correctly relates the density $$\rho of an $$ideal gas to its pressure $$P$$, molar mass $$M$$, and temperature $$T$$?

Accepted Answer

$$\rho = \dfrac{PM}{RT}$$

Question 4

If a balloon filled with air at $$293\ K$$ and $$1.2\ bar is $$placed in the sun and the temperature rises to $$323\ K$$, what is the percentage increase in pressure, assuming volume is constant?

Accepted Answer

10%

Question 5

Which of the following is NOT an assumption of the ideal gas law?

Accepted Answer

Gas particles interact via strong intermolecular forces.

Question 6

A mixture contains 10 g $$H_2$$, 16 g $$O_2$$, and 56 g $$N_2. $$Which component has the highest mole fraction?

Accepted Answer

$$H_2$$

Question 7

What is the partial pressure of oxygen in air at $$1.00\ atm if $$air contains 21 mol% $$O_2$$?

Accepted Answer

$$0.21\ atm$$

Question 8

Which formula expresses Dalton’s Law of Partial Pressures for a mixture of gases?

Accepted Answer

$$P_{total} = P_1$ + P_2$ + ... + P_n$$

Question 9

Which equation gives the root mean square (RMS) speed of a gas molecule?

Accepted Answer

$$v_{rms} = \sqrt{\dfrac{3RT}{M}}$$

Question 10

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

Accepted Answer

Gas particles are far apart and the volume of the particles is negligible compared to the container.

Question 11

What is the value of the universal gas constant $$R in SI $$units?

Accepted Answer

$$8.314\ J\ $$mol^{-1}$$\ K$$^{-1}$$

Question 12

Which equation relates the Boltzmann constant $$k_B to $$the gas constant $$R$$ and Avogadro’s number $$N_A$$?

Accepted Answer

$$k_B = \dfrac{R}{N_A}$$

Question 13

A gas sample is cooled at constant pressure. What happens to its volume?

Accepted Answer

Volume decreases

Question 14

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

Accepted Answer

$$PV = nRT$$

Question 15

If the number of moles and pressure of a gas are kept constant, what happens to the volume when the temperature is doubled?

Accepted Answer

Volume doubles

Question 16

Which property of gases allows them to fill any container regardless of its shape?

Accepted Answer

Random motion and negligible intermolecular forces

Question 17

What is the SI unit of pressure?

Accepted Answer

Pascal ($$Pa)$$

Question 18

Which of the following best describes the Maxwell-Boltzmann distribution?

Accepted Answer

It describes the distribution of speeds among gas molecules at a given temperature.

Question 19

A gas mixture contains $$N_2$$ and $$O_2. If $$the mole fraction of $$O_2 is$$ $$0.25$$ and the total pressure is $$800\ torr$$, what is the partial pressure of $$O_2$$?

Accepted Answer

$$400\ torr$$

Gases: Properties, Laws, and Molecular Theory

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