At what temperature in the Kelvin scale does water boil. Explain what happens when we supply heat energy to water until it changes its state? What is this heat energy called?

Water boils at 100℃. To convert Celsius to Kelvin 273 should be

added to the given temperature in Celsius.

100 + 273 = 373

Therefore, water boils at 373K in the Kelvin scale.

When we supply heat energy to water, with the increase in temperature, the kinetic energy of particles in water also increases. The particles start moving faster. At a certain temperature, a point is reached when the energy supplied by heat overcomes the intermolecular force of attraction between the particles, and the particles move randomly at a greater speed in any direction. At this stage, water starts boiling and gets converted into gas; i.e., steam.

The heat energy that is used up to change the state of matter from a liquid into a gas is called latent heat of vaporisation.