Q: A sample of gas occupies 2.50 L at 1.00 atm and 273 K. What will its volume be at 2.00 atm and 273 K?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 \times 2.50}{2.00} = 1.25\ \text{L}$$

Q: A 3.00 g sample of O$$_2$$ gas is placed in a 2.50 L container at 25$$^\circC. $$What is the pressure in the container? (Use $$R = 0.0821\ \text{L atm mol}^{-1}\text{K}^{-1})$$

$$P = \frac{nRT}{V} = \frac{0.094\times 0.0821\times 298}{2.50} = 0.92\ \text{atm}$$

Q: A mixture contains 0.50 mol O$$_2$$, 0.75 mol N$$_2$$, and 0.25 mol Ar. If the total pressure is 1.2 atm, what is the partial pressure of N$$_2$$?

$$P_{N_2$} = 1.2 \times \frac{0.75}{1.5} = 0.60\ \text{atm}$$

Q: A sample of gas has a density of 1.25 g/L at STP. What is the molar mass of the gas?

$$M = dRT/P = 1.25 \times 0.0821 \times 273 / 1.00 = 28.0\ \text{g/mol}$$

Question 1

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

Accepted Answer

Gas particles are much farther apart, so there is a lot of empty space between them.

Question 2

A sample of gas occupies 2.50 L at 1.00 atm and 273 K. What will its volume be at 2.00 atm and 273 K?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 	imes 2.50}{2.00} = 1.25\ 	ext{L}$$

Question 3

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 4

A 3.00 g sample of O$$_2$$ gas is placed in a 2.50 L container at 25$$^\circC. $$What is the pressure in the container? (Use $$R = 0.0821\ 	ext{L atm mol}^{-1}	ext{K}^{-1})$$

Accepted Answer

$$P = \frac{nRT}{V} = \frac{0.094	imes 0.0821	imes 298}{2.50} = 0.92\ 	ext{atm}$$

Question 5

Which of the following conditions would cause a real gas to deviate most from ideal behavior?

Accepted Answer

High pressure and low temperature

Question 6

A mixture contains 0.50 mol O$$_2$$, 0.75 mol N$$_2$$, and 0.25 mol Ar. If the total pressure is 1.2 atm, what is the partial pressure of N$$_2$$?

Accepted Answer

$$P_{N_2$} = 1.2 	imes \frac{0.75}{1.5} = 0.60\ 	ext{atm}$$

Question 7

Which of the following best describes the relationship between temperature and the average kinetic energy of a gas?

Accepted Answer

Average kinetic energy is directly proportional to the temperature.

Question 8

At 298 K, which of the following gases will have the highest average speed (root mean square velocity)?

Accepted Answer

H$$_2$$

Question 9

A sample of NH$$_3$$ effuses through a pinhole in 42 seconds. How long would it take the same amount of O$$_2 to $$effuse under identical conditions?

Accepted Answer

$$t_{O_2$} = t_{NH_3$} \sqrt{\frac{M_{O_2$}}{M_{NH_3$}}} = 42 \sqrt{\frac{32}{17}} = 58\ 	ext{seconds}$$

Question 10

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

Accepted Answer

$$PV = nRT$$

Question 11

A sample of gas has a density of 1.25 g/L at STP. What is the molar mass of the gas?

Accepted Answer

$$M = dRT/P = 1.25 	imes 0.0821 	imes 273 / 1.00 = 28.0\ 	ext{g/mol}$$

Question 12

Which of the following statements about Dalton's Law of Partial Pressures is correct?

Accepted Answer

The total pressure of a mixture of gases is equal to the sum of the partial pressures of each gas.

Question 13

A 2.00 L sample of N$$_2 at 1.00 $$atm and 298 K is compared to a 2.00 L sample of O$$_2 at 1.00 $$atm and 298 K. Which has the higher average kinetic energy?

Accepted Answer

Both have the same average kinetic energy.

Question 14

Which of the following best describes the effect of increasing temperature on the root mean square velocity ($$u_{rms}) of a $$gas?

Accepted Answer

$$u_{rms}$$ increases as temperature increases.

Question 15

Which of the following gases will diffuse fastest under identical conditions?

Accepted Answer

H$$_2$$

Question 16

A sample of gas has a mass of 0.311 g and a volume of 225 mL at 55$$^\circC $$and 766 mm Hg. What is the molar mass of the gas?

Accepted Answer

$$M = \frac{mRT}{PV} = \frac{0.311 	imes 0.0821 	imes 328}{1.008 	imes 0.225} = 37.1\ 	ext{g/mol}$$

Question 17

Which of the following is a correct application of Avogadro's Law?

Accepted Answer

Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

Question 18

Which of the following is the correct van der Waals equation for real gases?

Accepted Answer

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

Question 19

A 1.00 L sample of gas at 25$$^\circC $$and 1.00 atm is heated to 427$$^\circC at $$constant volume. What is the final pressure?

Accepted Answer

$$P_2$$ = $$P_1$$ \frac{$$T_2$$}{$$T_1$$} = 1.00 	imes \frac{700}{298} = 2.35\ 	ext{atm}$$

Chapter 10 Student Notes

Guida di studio - Domande di pratica

Study guide - Flashcard