chem home work problem?

Question

kilojoules given off when 12g of steam condenses at 100 C and the liquid cools to 0 C.....i cant seem to calcualte this right because when i do im getting huge numbers.

Answer 1

Did you change the temperature to kelvin?

Answer 2

You should be getting huge numbers. That's the point of this homework lesson. I don't know from kJ, but consider: Let's condense the steam to liquid water. In my memory, that's 512cal/g.

12gH2O x 512cal/gH2O = 6144cal

Now we cool the water to 0C. That's 100degC and 1cal/g-degC

12gH2O x 1cal/g-C x 100C = 1200cal

6144cal + 1200cal = 7344cal

The numbers are indeed huge for water, because whether you're boiling it, condensing it, freezing it, or melting it, the latent heats of vaporization and fusion of water are awesome!