# Homework Help: Including a heat for a phase change or not?

1. Jul 1, 2013

### catzmeow

Hi PF!

I just took a test for my class and there is one problem I can't get my mind off of. I'm not necessarily looking for the correct solution here, just if my thinking was correct. It went more or less like this: there is 40g of ice at 0 degrees C in 200g of water in an aluminum calorimeter. Both water and calorimeter are at 0C. There is also a bit of copper at 98C. The system's final temp is 2 C.

Was I right to include a phase change of ice to water to rise to 2C? I also included the change in heat using the specific heat of water and another step including the specific heat of ice?

Did I include too much/over think this?

Thanks!

2. Jul 1, 2013

### Andrew Mason

Do you think there will be any ice at 2C? If not, you were quite right to take into account the phase change.

AM

3. Jul 1, 2013

### catzmeow

Haha yes very true. For some reason I feel like I shouldn't have included the specific heat of water or of ice... I'm not sure. Something felt off about it but I can't put my finger on it...

4. Jul 1, 2013

### Staff: Mentor

You shouldn't have used the specific heat of ice for the portion originally ice that was heated from 0 to 2. You should have used the specific heat of water for this.

5. Jul 1, 2013

### catzmeow

Hmmm I only wish I could go back and change it!! Thank you, chestermiller, I'll have to remember this for the next test...

6. Jul 2, 2013

### CWatters

Yes, should include the heat for the phase change but it should be..

Specific Heat of the original water
+ Latent heat for the ice->water
+ Specific Heat of the ice that is now water

7. Jul 2, 2013

### catzmeow

I want to say I did do that, I can't exactly remember now. I wasn't sure if I included to many changes or not...thanks for your input!!