## Calculating enthalpy

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vasilivv
Newbie
Posts: 1
Joined: Mon Nov 22, 2021 8:22 am

### Calculating enthalpy

Hi!
I'm going to translate a task from my native language to English, so sorry in advance if there are some mistakes and terms are off.
I got this equation - 2H2 + O2 -> 2H2O and I need to calculate the enthalpy.

In this reaction, a mixture of H2 and O2 is 180g (g is equally distributed.)
I know that I need to calculate the moles to be able to get the enthalpy, but I'm not sure how to do so. I have tried to come up with ideas, but nothing has come to my mind.
ChenBeier
Distinguished Member
Posts: 1005
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

### Re: Calculating enthalpy

You have 90 g H2 and 90 g O2 correct.
That mean you have 90/2 = 45 mol H2 and 90/32 = 2,81 mol O2
So you can only do the double what means 5,625 mol H2 bring in reaction
You will get the same amount of water, what is x 18 g/ mol = 101,25 g. The rest of 78,75 g = 39,375 mol H2 is not used.