Standard enthalpy of formation

  • #1
So when they said that to produce water vapor at standard state it releases -241 KJ/mol
and liquid water -284 KJ/mol

You can't create water vapor at standard temperature but I assume they used Hess' law
Anyway, my question is when you change from water to vapor you need 44KJ/mol

So that would be the energy required to change from 25 C liquid to 25 C vapor.
Does it change for example when you want to change it from another temperature?
 

Answers and Replies

  • #2
mjc123
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Yes. Do you know a formula for the variation of ΔH with temperature?
 

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