Which law explains that a gas's volume is directly proportional to its absolute temperature when pressure is held constant?

The law that explains the relationship between a gas's volume and its absolute temperature when pressure is held constant is Charles' Law. This fundamental principle in thermodynamics states that as the temperature of a gas increases, its volume also increases, provided that the pressure remains unchanged. This relationship can be represented mathematically by the equation ( V \propto T ), where ( V ) is the volume and ( T ) is the absolute temperature measured in Kelvin.

Charles' Law illustrates the kinetic theory of gases, which posits that the particles in a gas move more rapidly as temperature rises, leading to an increase in volume. This is particularly important in applications involving gas storage and management in air conditioning and refrigeration systems, where controlling temperature and volume is crucial for efficiency and performance.

In contrast, Avogadro's Law relates to the volume of gas with the amount of gas under constant temperature and pressure, Boyle's Law describes the inverse relationship between pressure and volume at constant temperature, and Dalton's Law pertains to the behavior of mixtures of gases and their partial pressures. Each of these laws addresses different aspects of gas behavior, but only Charles' Law directly addresses the relationship between volume and temperature at constant pressure.