Simple heat problems:

Simple heat problems are those where one thing undergoes a single change (a change in temperature or a change in phase). To solve such a problem we simply decide what formula to use (q=mcΔT for temperature changes and q=mΔH for phase changes), determine what we know and what we don’t and then solve for the missing piece.

Here are some fully worked out examples:

We can see that this problem involves a change in temperature so the correct formula is

 

Now what do we know?

q  
m 150.0 g water
c 1.000 cal/g oC (known)
ΔT 47-24 = 23oC

As the table shows, the only thing we don’t know is heat, and (not surprisingly) that’s what the question asks us to find.

We can therefore just substitute into the formula and solve:

Math imageThermo problem 1

Now we can try another problem

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