The release of HEAT

[jimmyche]

Can anyone help me with the following question.

How much heat is released when a lake of surface area 8.5 km^2 freezes to a depth of 1.0m? assume the water is initially at 0 degree C. The answer is 6.2 X10^11 Kcal.

Thanks.

any help is approciated.

[PeteGt]

Look up Newton's law of cooling, it should help you to figure that one out.

[Integral]

It is really much simpler then Newtons law of cooling. Since the water is at 0C already there is no temperature change involved. You know the volumn of Ice forming (area x thickness) and you should know about the heat of fusion of Ice, this is given as some number of Kcals per mole of water, simple multiplication.

If I told you any more I would be doing the problem for you.

[PeteGt]

Since i'm a chemist, i would find out the number of mol's of water you have frozen and then use the kj/mol of fusion. Thus giving it to you. but you physics people might have an easier way :-)

Pete

[jimmyche]

got it.
thanks everyone.

is just that the supplied answer is somehow wrong which confuse me.