Work Step by Step
a. As heat is added, the average translational energy of a gas molecule increases. The speedier molecules strike the walls with greater average force, increasing the pressure. Equation 18.13 shows that the pressure is proportional to the average kinetic energy. b. As the volume decreases, the container becomes smaller. The gas molecules strike the walls more frequently, increasing the pressure. Equation 18.13 shows that the pressure increases as the volume decreases, even when the average kinetic energy stays the same.