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Question
Write four key points about order of reaction.
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Solution
- The order of a chemical reaction is experimentally determined.
- The order can be integer or fractional. Look at the reaction,
\[\ce{CH3CHO_{(g)} -> CH_{4(g)} + CO_{(g)}}\]
The rate law for the reaction was found to be rate = k[CH3CHO]3/2.
Here, the order of the reaction is 3/2. - The order of the reaction can be zero for:
\[\ce{NO_{2(g)} + CO_{(g)} -> NO_{(g)} + CO_{2(g)}}\]
The rate expression for this is: rate = k[NO2]2.
This shows that the order of reaction with respect to NO2 is 2 and with CO is zero or the rate is independent of the concentration of CO. The overall order of the reaction is 2 - Only a few reactions of third-order are known. Reactions with orders higher than three are scanty.
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