As the temperature of a gas increases, what generally happens to its density?

When the temperature of a gas increases, its density generally decreases. This phenomenon occurs due to the behavior of gas molecules. As temperature rises, gas molecules gain kinetic energy and move more vigorously. This increased activity causes the molecules to spread apart, resulting in an expansion of the gas.

Density is defined as mass per unit volume. While the mass of the gas remains constant when the temperature increases, the volume of the gas increases because the molecules are less densely packed. Consequently, as the volume increases and the mass remains the same, the overall density of the gas decreases.

In contrast, gases that are cooled would experience a decrease in volume and an increase in density, as the molecules move closer together and occupy less space. This understanding is rooted in the principles of gas laws, particularly Charles's Law, which establishes the relationship between temperature and volume at constant pressure.