Chlorofluorocarbons (CFC) act as catalysts for the destructionof ozone in the up

Question

Chlorofluorocarbons (CFC) act as catalysts for the destructionof ozone in the uper atmosphere. Ultra violet light from the sunbreaks carbon-chlorine bonds in CFC's.

CF2Cl2 CF2Cl + Cl

The Cl atom reacts with ozone.

Cl + O3 ClO + O2
ClO + O Cl + O2

The direct reaction is

O3 + O 2 O2

Which of the following are true about these reactions ?

a) The direct reaction breaks down O3 at a slowerrate than the same reaction where Cl is used as a catalyst.

b) When Cl is used as a catalyst, it functions as anintermediate in the resulting two-step mechanism.

c) The presence of Cl provides a mechanism with higherEa 's than the direct reaction (in the absence ofCl)

d) E (reaction energy) is the same whether Cl is presentas a catalyst or not

e) When Cl is used as a catalyst it is a homogeneouscatalyst

Explanation / Answer

          a , b ,d , e are true Reasons : a is true beacause 'a reaction is faster inthe presence of a catalyst'                 b is true beacause Cl do not take part in the reaction .                 d is true beacause the difference in reaction energy depends onproducts and reactants only                  e is true beacause both Ci and reactants are in the same phase.            

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