how much heat is absorbed when one kg of a liquid gets vaporised at its boiling point?
we know that
Q = mL
here
Q is the heat absorbed
m is the mass of the substance (water) = 1 kg
l is the latent heap of vaporization (of water) = 2257 KJ/kg
thus,
Q = 1 x 2257
so, we get
Q = 2257 KJ of heat absorbed