Q: A 2.00 L flask contains 1.15 atm of Ar. If the gas is transferred to a 4.50 L container at constant temperature, what is the new pressure of Ar?

$$P_2$$ = \frac{$$V_1$$}{$$V_2$$} \times $$P_1$$ = \frac{2.00}{4.50} \times 1.15 = 0.511$$ atm

Q: A mixture contains 0.249 mol CH$$_4$$, 0.143 mol C$$_2H$_4$$, and 0.0688 mol C$$_4H$_{10} in a 1.5 L $$flask at 273.15 K. If the total pressure is 6.98 bar, what is the partial pressure of C$$_2H$_4$$?

$$P_{C_2H_4} = X_{C_2H_4} \times P_t = \frac{0.143}{0.461} \times 6.98 = 2.17$$ bar

Question 1

Which statement best describes Dalton's Law of Partial Pressures for a mixture of ideal gases?

Accepted Answer

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

Question 2

A 2.00 L flask contains 1.15 atm of Ar. If the gas is transferred to a 4.50 L container at constant temperature, what is the new pressure of Ar?

Accepted Answer

$$P_2$$ = \frac{$$V_1$$}{$$V_2$$} 	imes $$P_1$$ = \frac{2.00}{4.50} 	imes 1.15 = 0.511$$ atm

Question 3

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 4

A mixture contains 0.249 mol CH$$_4$$, 0.143 mol C$$_2H$_4$$, and 0.0688 mol C$$_4H$_{10} in a 1.5 L $$flask at 273.15 K. If the total pressure is 6.98 bar, what is the partial pressure of C$$_2H$_4$$?

Accepted Answer

$$P_{C_2H_4} = X_{C_2H_4} 	imes P_t = \frac{0.143}{0.461} 	imes 6.98 = 2.17$$ bar

Question 5

If the volume of a gas sample is decreased at constant temperature, what happens to the pressure and why?

Accepted Answer

Pressure increases because molecules strike the walls more often.

Question 6

Which of the following will increase the average kinetic energy of gas molecules in a container?

Accepted Answer

Increasing the temperature of the gas.

Question 7

A flask contains 10 mol of H$$_2$$ gas. If 3 mol of Ar gas is added to the flask at constant temperature and volume, what happens to the pressure of H$$_2$$?

Accepted Answer

The pressure of H$$_2$$ remains the same.

Question 8

Which equation correctly relates the partial pressure of a gas to its mole fraction and the total pressure in a mixture?

Accepted Answer

$$P_a = X_a P_t$$

Question 9

Three bulbs contain CO$$_2 (1.5 L$$, 2.13 atm), H$$_2 (1.0 L$$, 0.861 atm), and Ar (2.0 L, 1.15 atm). If all stopcocks are opened and temperature remains constant, what is the total pressure in the system?

Accepted Answer

$$P_t = 0.511 + 0.191 + 0.710 = 1.412$$ atm

Question 10

According to kinetic molecular theory, what is the effect of increasing the molar mass of a gas on the average speed of its particles at constant temperature?

Accepted Answer

The average speed decreases as molar mass increases.

Question 11

Which of the following best explains why pressure increases when temperature increases at constant volume?

Accepted Answer

Molecules strike the walls more often and with greater force.

Question 12

A mixture of gases contains 2 mol O$$_2$$ and 3 mol N$$_2 at a $$total pressure of 5 atm. What is the partial pressure of O$$_2$$?

Accepted Answer

$$P_{O_2$} = X_{O_2$} P_t = \frac{2}{5} 	imes 5 = 2$$ atm

Question 13

Which of the following statements about gas particle collisions is TRUE according to kinetic molecular theory?

Accepted Answer

Collisions between gas particles and the container walls are completely elastic.

Question 14

If you increase the pressure on a gas sample by decreasing the volume, what happens to the speed of the gas particles?

Accepted Answer

The speed of the gas particles increases.

Question 15

Which property of a gas is directly proportional to the temperature in Kelvin according to kinetic molecular theory?

Accepted Answer

Average kinetic energy of the particles.

Question 16

A mixture of gases is in a container. Which factor determines the partial pressure of each gas?

Accepted Answer

The number of moles of the gas and the total pressure.

Question 17

Which of the following is a consequence of the assumption that gas particles are far apart and have negligible volume?

Accepted Answer

Gases are highly compressible.

Question 18

In a mixture of gases, which statement is correct regarding the effect of collisions between different gas particles?

Accepted Answer

The speed of gas particles is not affected by collisions with other gas particles.

Question 19

A container holds a mixture of three gases: A, B, and C. If $$P_A = 2$$ atm, $$P_B = 3$$ atm, and $$P_C = 1$$ atm, what is the total pressure?

Accepted Answer

$$P_t = P_A + P_B + P_C = 2 + 3 + 1 = 6$$ atm

Question 20

Which of the following best describes the relationship between pressure and the frequency of molecular collisions with the container walls?

Accepted Answer

Pressure increases as the frequency of collisions increases.

Gas Mixtures, Partial Pressures, and Kinetic Molecular Theory – General Chemistry I Study Notes

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