Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Mnesarchus on April 18, 2014, 09:59:46 PM

Title: Breaking down ozone by free radicals equations
Post by: Mnesarchus on April 18, 2014, 09:59:46 PM

Hi everyone,
  I was reading my textbook and there was a section about reactions of CFCs and nitrous oxides on ozone, which as you all know is going to break it down into oxygen. The equations given were:
Cl₂+UV light→2Cl•
Cl•+O₃→ClO•+O₂
ClO•+O•→Cl•+O₂
The overall equation is
O•+O₃→2O₂

O₃+UV light→O₂+O•
NO+O₃→NO₂+O₂
NO₂+O•→NO+O₂
The overall equation is:
2O₃→3O₂

So I was thinking, in the first case, to arrive at the overall equation you add the two equations above together and cancel out the like terms - right? If we used this method to work out the overall equation, then why is the second overall equation then different from the first? Anyway just by looking at the equation it seems in both cases to have produced two oxygen molecules...

Thanks.