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# Thermal energy watch

1. I am working on thermal energy for A2 physics at the moment and I have got stuck on the following question:

A 7.0 kg block of iron is heated to 750 degrees celcius. It is placed in an insulated tub containing 2.0 kg of water at 20 degrees celcius. Assuming all the water is brought to the boil rapidly, calculate the mass of water which boils off.

Specific heat capacity of water=4200Jkg^-1K^-1
Specific heat capacity of iron=220Jkg^-1K^-1
Specific latent heat of vaporisation of water=2260KJ kg^-1

Would anyone be able to help?

2. Is this degree level or A level?

The simple answer would be to calculate the energy of iron (750-99.9)*7*Cv, then put that energy into the water, and any left over from heating water to 99.9 degrees will go into vaporising it.

If that's a degree question, the answer would be much more involved.
3. Heat given by hot iron= Heat gained by water + Latent heat of vaporisation
4. (Original post by Lelyke)
Heat given by hot iron= Heat gained by water + Latent heat of vaporisation
Thanks for your reply, we appreciate the fact you want to help, but could you please not post full solutions to problems.
The idea is to help people do the problem themselves.
Just the first part would have been sufficient.

http://www.thestudentroom.co.uk/wiki...ring_questions

Thanks
5. Sorry new to the forum. I'll bear that in mind next time.

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Updated: March 8, 2013
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