What is the effect of increase in pressure on the boiling point of a liquid?

An increase in pressure generally leads to an increase in the boiling point of a liquid. This relationship between pressure and boiling point is described by the Clausius-Clapeyron equation. According to this principle, when the pressure on a liquid is increased, its boiling point also increases.

To understand why this happens, let's consider the basic concept of boiling. Boiling occurs when the vapor pressure of a liquid equals the external pressure (atmospheric pressure or pressure in a closed system). When the external pressure is lower than the vapor pressure of the liquid at a particular temperature, the liquid will boil and convert into a gas.

Now, when you increase the external pressure, the vapor pressure must also increase to reach the boiling point. As a result, the temperature at which the vapor pressure equals the external pressure (boiling point) must also increase.

Conversely, if you decrease the external pressure, the boiling point will decrease. This is why water boils at lower temperatures at higher altitudes (where atmospheric pressure is lower) and why pressure cookers can raise the boiling point of water, allowing food to cook at higher temperatures than under normal atmospheric pressure.

In summary, increasing pressure increases the boiling point of a liquid, while decreasing pressure lowers it.