Another problem involving more than one step

What mass of water can be cooled from 85^oC and then frozen by removing 1850 calories? Remember that the ΔH_fus of water is 79.7 cal/g.

Again, this is a two step process. The water is first cooled and then frozen. So the heat removed is the sum of the heats required for the two processes. This leaves us with the formula

So, what do we know?

Since we are solving for mass, we'll need to do some rearranging. First separating out the mass

then isolating m

Now, we can substitute in our values and solve...

Let's do one more...