Determine whether each of the following changes will increase, decrease, or not affect the rate with which gas molecules collide with the walls of their container: (a) increasing the volume of the container, (b) increasing the temperature, (c) increasing the molar mass of the gas.

When the volume of the container increases, the gas molecules will have more space to move around. This means they are less likely to collide with the walls of the container. Therefore, increasing the volume of the container will decrease the rate with which gas molecules collide with the container walls.

As the temperature of the gas increases, the average kinetic energy of the gas molecules increases as well. According to the Kinetic Molecular Theory, gas molecules move faster at higher temperatures. Faster gas molecules will collide more frequently and with greater force. Thus, increasing the temperature of the gas will increase the rate of collisions between gas molecules and the container walls.

Now let's consider increasing the molar mass of the gas. The relationship is less straightforward, but we can use the ideal gas law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature, to analyze. Given the same pressure, volume, and temperature, increasing the molar mass means having more massive gas molecules in the container. When the gas molecules are more massive, they will have higher momentum and kinetic energy at the same temperature. However, at the same temperature, massive gas molecules will move more slowly than lighter gas molecules, since the kinetic energy is inversely proportional to the mass. Therefore, the more massive gas molecules will collide with the container walls less frequently but with greater force. The overall rate with which gas molecules collide with the walls will not be significantly affected, as the decrease in collision frequency is offset by the increase in the force of collisions. So, increasing the molar mass of the gas will not affect the rate of collisions with the container walls.