Latent heat of vaporization?

Question

How much more heat is needed to boil 5.0 kg of water than is needed to melt it? The latent heat of vaporization for water is 2260 kJ/kg, and the latent heat of fusion is 333 kJ/kg. 

Answer 1

To boil 5 kg of water:

 

Q_boil = (5 kg)(2260 kJ/kg) = 11300 kJ

 

 

To melt 5 kg of water:

 

Q_melt = (5 kg)(333 kJ/kg) = 1665 kJ

 

 

Q_boil - Q_melt = (11300 - 1665) kJ = 9635 kJ

 

So it takes 9635 kJ more to boil 5 kg of water than to melt it.