Trying to beat the heat of summer, a physics grad student went to the local toy store and purchased a child's plastic swimming pool. Upon returning home, he filled it with 156 liters of water at 26°C. Realizing that the water would probably not be cool enough, he threw ice cubes from his refrigerator, each of mass 30 g, into the pool. (The ice cubes were originally at 0°C.) He continued to add ice cubes until the temperature stabilized at 17°C. He then got in the pool.
The density of water is 1000 kg/m3, the specific heat of water is 1.0 cal/g °C, the specific heat of ice is 0.5 cal/g °C, and the latent heat of fusion of water is 80 cal/g.
How many ice cubes did he add to the pool to get the temperature to 17°C? (Consider the pool and ice cubes an isolated system.)
Qwater/Qice=# of ice cubes
The Attempt at a Solution
Qwater=156000g(1.0 cal/g*degree Celsius)(17-26)=-1404000cal
QIce=30g(.5 cal/g*degree Celsius)(17-0)=255cal
now do i neglect the negative in Qwater? so then i would get 1404000cal/255cal=5505.88cubs but is not the correct answer
I don't understand what i have to do with the latent heat of H2O fusion(80cal/g)