Delta H for H2

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Leah Thomas 2E
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

Delta H for H2

Postby Leah Thomas 2E » Fri Jan 12, 2018 6:54 pm

In problem 8.57 it states that the delta H for H2 is -286 kJ/mol but I though Professor Lavelle mentioned that at hydrogen's most stable form, delta H is equal to zero. Someone please explain.

Sophie Krylova 2J
Posts: 59
Joined: Fri Sep 29, 2017 7:06 am

Re: Delta H for H2

Postby Sophie Krylova 2J » Fri Jan 12, 2018 7:02 pm

For H2 enthalpy of formation is zero, because it already is the most elementary form. In the problem, however, it's talking about hear of combustion, which is different -- Hydrogen does release heat.

Yixin Angela Wang 2H
Posts: 51
Joined: Thu Jul 27, 2017 3:00 am

Re: Delta H for H2

Postby Yixin Angela Wang 2H » Fri Jan 12, 2018 7:13 pm

enthalpy of formation is related to the formation of the compound at hand. H2 making H2 doesn't require any extra heat because hydrogen just prefers to stay in H2 form naturally without any other factors influencing it.


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