Calculate the energy needed to melt 70 grams of 0°C ice and then heat it to 45°C.

Question

The answer must be in CALORIES

Answer 1

I will explain how to solve this, but YOU do the calculations.  Look up the latent heat of fusion of water (l_f) and the specific heat of water (c) in appropriate units.  Your physics, chemistry, or thermodynamics book should have an appendix with these values.  The solution consists of 2 heat transfers.

 

m = mass of ice = mass of water (given)

 

First heat transfer:  Melt ice at a constant temperature of 0°C

 

Q₁ = ml_f

 

Second heat transfer:

 

Heat liquid water from T_i = 0°C to T_f = 45°C

 

Q₂ = mc(T_f - T_i)

 

The total heat transfer required is

 

Q = Q₁ + Q₂ = ml_f + mc(T_f - T_i)

 

Just plug in the numbers, and be careful with the units.