# Need help on a simple question-phase transfer

1. Dec 9, 2005

### zhen

question:
How much energy in kilojoules is required to convert 10.0 g of ice at -108 to water vapor at 1108°C? Specific heats are 2.09 J/g K for both ice and water vapor, and 4.18 J/g K for liquid water. Heats of vaporization and fusion are 2260 and 335 J/g.

This is what I did:
10g*108C*2.09J/g K + 10g * 335J/g + 10g*100C * 4.18 J/g K + 10g * 2260 J/g + 1008C * 10g * 2.09 J/g K= 50434.4 J =50.43 kJ

This question is a multiple choice, and there is no such choice, so this answer must be wrong. Unfortunately, I really don't know what is wrong with that.

I only the total energy is equal to the heat required to change the -108c ice to 0 C; then plus the energy require to melt the ice and then so far and so on....

2. Dec 9, 2005

### vaishakh

Well, i find your answers convincing though I have not claculated exactly. yo have missed no equation.

3. Dec 9, 2005

### zhen

I don't think I missed any equation,(maybe there are, but I really can not think of one), and there is no mistake in the calculation.

4. Dec 9, 2005

### Bystander

You'll want to "check" this value. Either the problem statement included incorrect information, or you've misread something somewhere.

5. Dec 9, 2005

### zhen

i check it, there is nothing wrong.
so... i think there is something wrong in the question.
I choose the closest answer which is 30 somthing, and that is correct....