Question

As temperature increases does a compounds vapor pressure change? Does its boiling point change? Explain

Answer 1

As the temperature increases , the vapour pressure of the liquid increases. This is due to the increase in the kinetic energy of the liquid molecules.

At a higher temperature, more molecules have enough energy to escape from the liquid or solid. At a lower temperature, fewer molecules have sufficient energy to escape from the liquid or solid.

But boiling point of the liquid won't change at normal atmospheric pressure, because boiling point depends on the pressure of the surroundings.

Boiling point is the temperature at which the vapour pressure of the liquid becomes equal to the atmospheric pressure.

As the surroundings pressure is low then boiling point of a liquid is also low.

Example : A liquid at high pressure has a higher boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures. For example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude.

Because the atmospheric pressure decreases at high altitudes, hence boiling point also decreases.

At normal atmospheric pressure every liquid has a specific boiling point which is a constant.