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Topic: heat and enthalpy of phase transitions  (Read 1882 times)

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Offline ChristinaMM

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heat and enthalpy of phase transitions
« on: February 09, 2013, 03:00:26 PM »
hey everyone i have a conceptual question mostly, but here is the problem, and I will show you what i have so far.

problem: If we start with 325 g of water at 30.0 degrees celcius, how much heat must we add to convert all the liquid into vapor at 100 degrees c.
 I know that we have to do the phase transition: 325 g(1mol/18.02g)(40.7kj/mol)=734.04kJ.

would i be done there? or do i have to also do q=mc(change in temp) 325g(4.184j/gc)(100-30)=95.1kJ to heat the water and add 734.04kj+95.1kJ. please help. thanks ;D

Offline Borek

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Re: heat and enthalpy of phase transitions
« Reply #1 on: February 09, 2013, 04:05:20 PM »
You have to heat the water first.
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