A 315 g sample of water is heated until it has completely melted. How much heat energy was used?

1 Answer
Jun 2, 2016

Answer:

We need the latent heat of fusion of ice.

Explanation:

We want the energy involved in the phase transition:

#H_2O(s) + Delta rarr H_2O(l)#

This site lists the latent of fusion of water as #334*kJ*kg^-1#. You have been given a mass of ice to start. We assume that the water and ice (i.e. the product and the reactant) remain at #0# #""^@C#.

And thus your calculation:

#334*kJ*kg^-1xx0.315*kg# #=# #??kJ#

How would energy exchange if we measured the reverse transition, liquid water to ice?