Two days in a row I'm asking Reddit for homework help. But it's Physics, so I guess it was expected. So I have this problem and I'm not sure where to quite start:
The heat of vaporization of ethyl alcohol is about 200 cal/g. If 2 kg of this fluid were allowed to vaporize in a refrigerator, show that 5 kg of ice would be formed from 0°C water.
So I initially came to the conclusion that I'd have to use Q = mL because it includes heat of vaporization, and Q = mcAt because it has specific heat, but no way I plug these numbers into either equation gets me to 5kg. A sort of similar question exists:
A 50-g chunk of 80°C iron is dropped into a cavity in a very large block of ice at 0°C. Show that 5.5 g of ice will melt. (The specific heat capacity of iron is 0.11 cal/g/°C.)
So I assumed you'd use the same set up and plug the numbers in like this:
(mL)H2 O = (mcAt)Ethyl
(5kg)(80kcal/kg)H2 O = (2kg)(200kcal/kg)(change in T)Ethyl
(450cal)H2 O = (400kcal)(change in T)Ethyl
But this doesn't exactly come out to 5kg. Any idea where I'm going wrong?
Submitted December 13, 2014 at 08:24AM by Astroyeti http://ift.tt/1qGM7qM HomeworkHelp
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