Asked by Dan

Change in enthalpy problem. Consider the reaction represented below. Referring to the data in the table below, calculate the standard enthalpy change for the reaction at 25 degrees C.

O3(g)+NO(g)-->O2(g)+NO2(g)

Standard enthalpy of formation in kJ/mol:

O3(g) 143
NO(g) 90
NO2(g) 33

I am sure this isn't a hard problem, but I can't really remember how to do it.
Answered by DrBob222
delta H<sub>reaction</sub> = delta H<sub>products</sub> - delta H<sub>reactants</sub>
Answered by Dan
Ok, so I have DeltaHrxn=(X+90)-(143+90). How do you calculate the enthalpy of O2 (X above) when it is not given to you. Am I even doing that right?
Answered by DrBob222
No. Re-read my answer. I said
PRODUCTS - REACTANTS.
You have one of the reactants on the product side.
DHrxn = DH products - DH reactants.
DHrxn = (O2 + NO2) - (O3 + NO)
DHrxn = (0 + 33) - (143 + 90) = ??
Answered by yea
drbob222 is correct . the answer is 200. DUh!!
Answered by Nope
It's -200. not 200
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