When water is heated, how does the pressure change within a confined space?

When water is heated in a confined space, the pressure increases. This phenomenon can be attributed to the behavior of molecules when temperature rises. As water is heated, its molecules gain energy, which causes them to move faster and collide more frequently with the walls of the container. The increase in the frequency and force of these collisions results in an increase in pressure within the confined space.

This concept is grounded in the ideal gas law, which states that for a fixed volume, any increase in temperature will result in an increase in pressure. In liquids, while they are generally considered incompressible, the principles regarding the relationship between temperature, pressure, and volume still apply, especially in terms of the steam and gas phases that may develop as water reaches boiling point. Therefore, the understanding of thermodynamics supports the conclusion that heating confined water raises internal pressure due to increased kinetic energy of its molecules.