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Old Dec 7th 2016, 02:37 PM   #1
Kaydeebee
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Calculating PV work done at atmospheric pressure?

I need some help figuring out this problem. This is the original problem: How much PV work is done in kilojoules for the reaction of 3.74 mol of H2 with 1.87 mol of O2 at atmospheric pressure if the volume change is −23.9L?

And we are given this reaction: The reaction between hydrogen and oxygen to yield water vapor has ΔH∘=−484kJ:
2H2(g)+O2(g)→2H2O(g)ΔH∘=−484kJ

This is what I did. I calculated ΔH for 1.87 mol of O2 which came out to be -905.08 kJ. Then, I put this equation together: ΔH=ΔE-PΔV and I got -902.68 kJ, which was not the right answer. What am I doing wrong here?
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energy, enthalpy change, pressure, thermodynamics, volume



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