Chapter 18, Problem 124A

(a)

Interpretation Introduction

Interpretation: The influence of adding more gas particles on the pressure of the contained gas is to be explained.

Concept Introduction: According to kinetic-molecular theory, gas particles travel arbitrarily and in straight lines until they collide elastically with either other gas particles or one of the container's walls. These contacts with the walls of the container determine the gas's pressure.

Answer to Problem 124A

Adding more gas particles will increase the pressure of the contained gas.

Explanation of Solution

Pressure increases favor the side with fewer particles, whereas pressure decreases favor the side with more particles. When the volume of the container remains the same, an increase in the number of gas molecules increases the pressure of the contained gas.

(b)

Interpretation Introduction

Interpretation: The influence of decreasing gas temperature on the pressure of the contained gas is to be explained.

Concept Introduction: According to kinetic-molecular theory, gas particles travel arbitrarily and in straight lines until they collide elastically with either other gas particles or one of the container's walls. These contacts with the walls of the container determine the gas's pressure.

Answer to Problem 124A

The decreasing gas temperature will decrease the pressure of the contained gas.

Explanation of Solution

When the temperature decreases, the average kinetic energy decreases, and the velocity of the gas particles when they strike the walls of the container decreases. The pressure is the force exerted by the particles per unit of area on the container. Therefore as the temperature decreases, the pressure of the contained gas must decrease.

(c)

Interpretation Introduction

Interpretation: The influence of reducing container volume on the pressure of the contained gas is to be explained.

Concept Introduction: According to kinetic-molecular theory, gas particles travel arbitrarily and in straight lines until they collide elastically with either other gas particles or one of the container's walls. These contacts with the walls of the container determine the gas's pressure.

Answer to Problem 124A

Reducing the container volume will increase the pressure of the contained gas.

Explanation of Solution

The volume of the container affects the pressure that is exerted on it. If the volume of a container is reduced, the available space for gas molecules to move around also becomes reduced. As a result, they will collide with the container's walls more often, increasing the pressure.