# Homework Help: Heat required to convert ice at certain temp. To water at certain temp

1. Nov 5, 2013

### astru025

1. The problem statement, all variables and given/known data

How much heat is required to convert 200 g of ice at -9°C to water at 9°C?

2. Relevant equations

I tried the equation Q= cmT. So I took 200 g x 1 cal/gram x 18 degrees. This was incorrect though.

3. The attempt at a solution
Attempt shown above. Any help would be nice! My textbook is very light on equations and such so I really don't know where to begin..

2. Nov 5, 2013

### nasu

You need some extra heat in order to melt the ice. See heat of fusion or latent heat.

3. Nov 5, 2013

### SteamKing

Staff Emeritus
You've got 3 things to consider:

1. You've got to warm the ice up to its melting point
2. You've got a phase change, where the solid ice turns to liquid water.
3. You've got to heat the liquid water up to the final temperature.

If your book is so light on equations that it doesn't cover the basics, throw it away and get a decent text. And let your instructor know that the text isn't adequate for the task.

4. Nov 9, 2013

### astru025

Why use heat of fusion though because I am changing the temperature? Isn't heat of fusion just for if the temperature is constant?

5. Nov 9, 2013

### Yanick

What happens to temperature of a system during a phase change?

6. Nov 9, 2013

### SteamKing

Staff Emeritus
Astru: here are basic notes on heat physics: http://www2.cose.isu.edu/~hackmart/Thermodynamics_2.pdf [Broken]

They explain basic terms and show how to work out simple problems.

Last edited by a moderator: May 6, 2017