When pressure is constant, how does temperature relate to volume for a gas?

When pressure is held constant, temperature and volume of a gas are directly related, which means that as one increases, the other also increases. This relationship is established by Charles's Law, which states that the volume of a gas is directly proportional to its absolute temperature, measured in Kelvin, provided that the pressure remains constant.

To illustrate this concept, consider heating a volume of gas in a rigid container. If the temperature rises, the kinetic energy of the gas molecules increases, leading to greater molecular movement. In a flexible container, like a balloon, this increased molecular movement causes the gas molecules to push outward, resulting in an increase in volume. Conversely, if the temperature decreases, the volume of the gas will also decrease, reflecting this direct relationship.

Thus, the correct understanding of gas behavior under constant pressure confirms that temperature and volume are directly related.