# Latent Heat

1. Jan 23, 2008

### tornzaer

1. The problem statement, all variables and given/known data
What is the energy released as water changes temperature from 20C to -10C?

2. Relevant equations
mct+lfm+mct

3. The attempt at a solution
My physics exam is day after tomorrow, however, I have no clue about this question. I was away for a week during these lessons. Can someone please walk me through the question so I can understand.

Thank you very much.

2. Jan 23, 2008

### rock.freak667

Assuming no heat losses. All the energy released goes into reducing the temperature from 20C to 0C and changing the water's phase and then lowering the temperature of the ice from 0C to -10C

3. Jan 23, 2008

### tornzaer

Well yes, but how would I set up the equation?

4. Jan 23, 2008

### rock.freak667

$$Energy=m_w c_w \Delta \theta_w + m_w l_f +m_ic_i \Delta \theta_i$$

i=ice,w=water.

5. Jan 23, 2008

### tornzaer

Can you please plug in the digits? I am confused about the temperatures.

6. Jan 23, 2008

### rock.freak667

for the change in temperature of the water it is (20-0)C and for ice it is (0-(-10))=10C.