Verified answer

There are three calculations required:

1) change gaseous water to liquid (uses heat of vaporization)

2) cool water from 100 C to 0 C (uses specific heat of liquid water)

3) change liquid water to solid (uses heat of fusion)

Take a look at problem #6 here:

http://www.chemteam.info/Thermochem/Thermochem-Exa...

It goes from 0 to 100, which is just the reverse of your problem. Notice how I get kJ for the answers in steps 1 and 3, but get J (which I change to kJ) in step 2.

its mass*latent heat capacity of water * change in temp

=25.4*latent heat*100

find latent heat capacity for yourself

and find the answer