# Homework Help: Hot metal + water = Tf?

1. Oct 16, 2005

### Pengwuino

hot metal + water = Tf???

Yet again I find i am stumped by having no clue as to what I did in this incredibly easy problem.

Simple right?

1 = water
2 = copper

m1c1 delta T1 = -m2c2 delta T2

This simplifies to...

m1= (-m2c2 delta T2)/(c1 delta T1)

which is...

(-(110*.2*(25.6-82.4)))/((4.18*(25.6-22.3)) = 95.8533g

Computer says i'm wrong and it slapped me

I then did the lazy way and calculated the energy required to lower the copper's temperature. With that, I manually figured out how much water there was and got the exact same answer.

Where am I going wrong here?

Last edited: Oct 16, 2005
2. Oct 16, 2005

### Joel

Significant digits? I don't know...

3. Oct 16, 2005

### siddharth

Did you do your numerical calculation right? Isn't the answer 90.59 g?

4. Oct 16, 2005

### Pengwuino

I tried 3 and 4 sig. figures with +/- 1 each direction and nothings coming out correctly. God i wanna pound the writers of this textbook.