What is vapour pressure of a liquide

What liquid?

The vapor pressure of a liquid refers to the pressure exerted by its vapor molecules when they are in equilibrium with the liquid. It is a measure of the tendency of the liquid to evaporate into a gas phase.

To calculate the vapor pressure of a liquid, you can use the Clausius–Clapeyron equation, which relates the vapor pressure of a substance to its temperature:

ln(P₁/P₂) = -(ΔH_vap/R)(1/T₁ - 1/T₂)

Where:
P₁ and P₂ are the vapor pressures at temperatures T₁ and T₂, respectively.
ΔH_vap is the enthalpy of vaporization, which is the amount of heat required to vaporize one mole of the liquid.
R is the ideal gas constant.
T₁ and T₂ are the temperatures at which the vapor pressures are measured.

It's important to note that the vapor pressure of a liquid increases with temperature. As the temperature rises, the average kinetic energy of the liquid molecules increases, leading to an increased number of molecules with sufficient energy to overcome the intermolecular forces and transition into the gas phase.

Experimental data or the use of thermodynamic tables is often required to obtain accurate values of vapor pressure for specific liquids, as the enthalpy of vaporization varies among substances.