O3 + NO --> O2 + NO2 (all in gas state)

Question

Calculate the change in enthalpy for the reaction at room temp. using the following data

^Hf:

O3 = 143
NO = 90
NO2 = 33

So, I have 143+90--> X + 33. I don't know what the enthalpy of O2 is. I assume you simply subtract the enthalpy of products from the enthalpy of reactants. Is that correct?

Answer 1

Yes, that is right.
delta H products - delta H reactants = delta H reaction. Delta H formatin for O2 is zero. However, let me point out that in your 143+90 ==> x + 33, you have reversed that process. You should have
DHrxn = 33 -(143 + 90)

Answer 2

How many electrons in an atom can have the following designations 5px and 1p

Answer 3

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