How do I calculate the final temperature when dropping ice into water?

[dan greig]

I have a question about droping ice into water and working out the final temp.
ice is -10 and water is 20 degrees c, I know that from -10 to 0 I can use,

Q = m.c.delta theta

but does this give me the final answer or do i need to use, Q = m.l, after 0.

I think this because this equation is used when no change in temp occurs, also after 0 do i go back to original equation?

thanks, Dan

 

[Hootenanny]

Not only will the ice be warming up, but the water will also be cooling down; this needs to be factored in also.

 

[dan greig]

i realize that from -10 to 0
the heat lost by the water = the heat gained by the ice

but what i don't quite get is that after that how do come to a final figure?

I have been given the latent heat of ice so this makes me think it needs to be involved not just using,

Q=mc delta T

meaning (T - 30) and (30 - T)

As in -10 to 20 celsius.