How can the boiling point of a liquid in a closed vessel be increased?

The boiling point of a liquid in a closed vessel can be increased by raising the pressure in that vessel. When pressure is applied to the liquid, it requires a higher temperature to reach the point where the vapor pressure of the liquid equals the pressure exerted on its surface. This relationship is described by the principles of thermodynamics, particularly Raoult's Law and the Clausius-Clapeyron equation.

For instance, in a pressure cooker, the increased pressure allows water to boil at temperatures higher than its standard boiling point of 100 degrees Celsius at atmospheric pressure. This increase in the boiling point enables cooking food more quickly and at higher temperatures.

Lowering the temperature, adding more liquid, or cooling the vessel would either decrease the boiling point or have no significant effect on it, making them ineffective methods for increasing the boiling point in a closed vessel.