# Thermodynamics: heat needed to melt block of a metal

1. Jun 18, 2011

### teggenspiller

1. The problem statement, all variables and given/known data
the latent heat of fusion for this metal is 500Cal/kg. The latent heat of vaporization is 600Cal/kg and specific heat of the liquid metal is 500C/kg K. How much heat is needed to melt an 8kg block of this metal when its temperature is exactly at the melting point?

2. Relevant equations
T= kelvins
c=specific heat
Q is heat needed

Q= m*c*delta T
Q=m*Latent heat (either fusion or vapor)
3. The attempt at a solution

Q= 8 * 500Cal/kg

Will someone please sho wme how to do this>?

2. Jun 18, 2011

### danago

3. Jun 18, 2011

### teggenspiller

4. Jun 18, 2011

### teggenspiller

thats the problem. my coices are 400, 100, 200, 1600 and none of the above. and i answered none the above, but answer is 1600.

5. Jun 18, 2011

### Staff: Mentor

But the answer is clearly NOT 1600. So apparently the marker (or marking program) or the question statement is wrong.

6. Jun 18, 2011

### danago

What units are the answers given in? The only thing i can think of is that the answers are given in some unit besides Calories? Either that, or the answers are wrong.

7. Jun 18, 2011

### mukundpa

what are the units of energy, cal or cal/kg ?

8. Jun 18, 2011

ahg i see.