Thermochemistry help!

Question

how much energy is required to vaporize a 115.0g ice cube that is initially at a temperature of -11.0 C?

Answer 1

You need to calculate 4 different heat transfers and then add them to get the total heat transfer.

 

m = 115.0 g

 

(1)

 

You will heat ice from -11.0°C to the freezing point of water at 0°C.  Look up the specific heat of ice.  Call it c₁.  

 

ΔT₁ = [0 - (-11.0)]°C

 

Q₁ = mc₁ΔT₁

 

(2)

 

You will melt ice at a constant temperature of 0°C.  Look up the latent heat of fusion of water, l_f.

 

Q₂ = ml_f

 

(3)

 

You will heat liquid water from 0°C to the boiling point of water at 100°C.  Look up the specific heat of liquid water.  Call it c₃.

 

ΔT₃ = (100 - 0)°C

 

Q₃ = mc₃ΔT₃

 

(4)

 

You will vaporize the water at a constant temperature of 100°C.  Look up the latent heat of vaporization of water, l_v.

 

Q₄ = ml_v

 

The total heat transfer required is

 

Q = Q₁ + Q₂ + Q₃ + Q₄

 

Plug in the numbers, and be careful with units.