Thermal Equilibrium H2O(l) & H2O (s)

[phyzicz]

Homework Statement

When you mix 0.5kg of ice which has an initial temperature of -65 celsius with 3.0kg of water which as an initial temperature 20 celsius, at what temperature do both substances come to thermal equilibrium?

Answer: 1.2 Celsius

Homework Equations

q=mc[Delta]T
[Delta]T=Q/C ; Q=heat, C=Heat capacity

The Attempt at a Solution

My Thoughts: I found out that when the ice reaches 0 celsius, the temperature of the water will go down to 14.7 celsius. I did this by using the equation q=mc[delta]T and solving for the final temp of water, which would be 14.7 when ice = 0. However, I don't know how to find the thermal equilibrium temp for this problem.

I've tried equating mc[delta]T of water + mc[delta]T of ice=0 because it is a closed system by solving for the delta T, but it didn't give me the answer.

Thanks for any help.

 

[phyzicz]

anyone?