4C.11

[morgan 1I]

The question asks how much heat is needed to convert 80g of ice at 0 degrees C into liquid water at 20 degrees C. I thought that I had to heat the ice to 20 degrees to melt it, then change the solid to liquid. However, the answer key says that I had to have melted the ice at 0 degrees celsius, and then raise the temperature of the liquid. This caused me to use the Csp value of solid water not liquid, but how is it possible that you can melt ice whilst keeping it at the same temperature?

[505968276]

Hi, I totally get how this is confusing but I think to set up the second equation you have to have both sides of the equation in the same state so first you have to see how much energy it takes to make ice at zero degrees to water at zero degrees. The reason you can "heat" up ice without changing the temperature is because it takes energy to break the H20 bonds that make ice solid, so even though you are adding energy its not making it hotter, its just making it liquid.