The saturation vapor pressure of a substance refers to the pressure at which the substance is in equilibrium with its vapor phase at a given temperature. As the temperature decreases, the saturation vapor pressure also decreases.
The effect of temperature decrement on saturation vapor pressure can be understood through the behavior of molecules in the substance. When the temperature decreases, the average kinetic energy of the molecules decreases as well. As a result, the molecules have less energy to overcome the intermolecular forces holding them in the liquid phase, leading to a decrease in the number of molecules transitioning into the vapor phase. This reduction in the rate of vaporization corresponds to a decrease in the saturation vapor pressure.
The relationship between temperature and saturation vapor pressure is typically described by empirical equations, such as the Clausius-Clapeyron equation or Antoine equation, which provide mathematical models for calculating the saturation vapor pressure at different temperatures for specific substances. These equations take into account the molecular properties of the substance and provide a quantitative description of how the saturation vapor pressure changes with temperature.