Calorimetry

What happens when you mix substances of differing temperature?

You get a mixture with a temperature somewhere between the two original temperatures.

How much is "between"?

That depends on the amount of substance (mass) and the nature of the substance (specific heat).

Since energy cannot be created or destroyed, the amount of heat lost by one substance must equal the amount gained by the other.  Said another way, the total energy change must be zero.  NOTE: This means that in the math, one substance's heat will be negative.

DQ_{for one substance}+DQ_{for the other}=0

You mix 2Kg of water at 80C with 4Kg of alcohol at 50C.  What is the final temperature (Tf) of the mix? (assuming no heat lost to outside environment)

C_water=4186J/KgC    C_alcohol=2430J/KgC