Raoult's Law

Relates the partial vapor pressure of a component in an ideal solution to the mole fraction of that component in the liquid phase and the vapor pressure of the pure component: p_i = x_i · p_i*.

For an ideal liquid solution at a given temperature, the partial vapor pressure of component i (p_i) above the liquid equals the product of the mole fraction of i in the liquid phase (x_i) and the vapor pressure of the pure component i at that temperature (p_i*): p_i = x_i·p_i*.

Raoult’s Law states that, for an ideal liquid solution, the partial vapor pressure of each volatile component equals the mole fraction of that component in the liquid multiplied by the vapor pressure of the pure component at the same temperature (p_i = x_i·p_i^°); it describes vapor‑pressure lowering in solutions whose components interact like the pure substances.