Consider the net reaction O + O 3 --> 2O 2 The standard enthalpies of formation
ID: 1020909 • Letter: C
Question
Consider the net reaction O + O3 --> 2O2
The standard enthalpies of formation of O and O3 are 249.2 and 142.7 kJ/mol respectively. a) Calculate the reaction enthalpy. b) Why does this reaction not proceed on its own, to any appreciable extent, in the stratosphere?
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a) So, reaction enthalpy is sum of products - sum of reactants therefore it's 0-(249.2+142.7) = -391.9kJ/mol.
b) I'm not so sure about.. Maybe because there is no catalyst present? Like NO? Doesn't NO need to be present to form the oxygen free radicals which cause destruction of the ozone?
Explanation / Answer
In stratosphere this reaction takes place
O + O3 ---> 2O2
But it doesn't take place on its own
It takes place in the presence of uv light which can break the bond to form O free radical