# Homework Help: Need help on a simple question - tempeture change

1. Dec 7, 2005

### zhen

The question is:
A 1000 g sample of lead shot, at 300°C, is dropped into 100 g of water at a temperature of 5.6°C. The specific heats of lead and water are 0.129 and 4.184 J/g°C, respectively. What is the final temperature of the mixture, in degrees Celsius?

I was doing my chemistry pratice, then I saw this question, I don't have a clue at all. It looks very similar to the high school physics, but I can not remember anything. Can you just give me some hints?

I just remember the change of Tw and Tl is the same.
but how does it relate to the heat capacity?...

I solve for the energy of the water: 100 X 4.184 X 5.6 = 2343.04 J
.......................................lead: 1000 X 0.129 X 300 = 38700 J

then what should I do?

2. Dec 7, 2005

### zhen

nevermind, i finially remember what to do....

3. Dec 7, 2005

### Astronuc

Staff Emeritus
And if the final temperature exceeds 100°C, there is a phase change of the water at 100°C, which would also have to be considered.

Heat of vaporization of water = 2.26 J/kg or 539 cal/g.

Hopefully you remembered $\Delta H$= m cp$\Delta T$

4. Dec 7, 2005

### zhen

I remembered it after I post, but I really appriciated it, thank you

Last edited: Dec 7, 2005