|Class 12 Chemistry Chemical Kinetics||Pseudo order reaction|
Pseudo order reaction
The reaction that appears to be an nth order reaction but belongs to some different order is called Pseudo order reaction.
For example, a pseudo first order reaction is a chemical reaction between two reactants participating in a chemical reaction and therefore should be a second order reaction. But it resembles to be a first order reaction due to the presence of reactants in negligible quantity.
Let R` + R`` --> P
Rate = k[A]1[B]1
Order of reaction = 2.
Let us consider another reaction,
CH3Br + OH−→ CH3OH+Br−
Rate law for this reaction is
Rate = k [OH−][CH3Br]
Rate = k [OH−][CH3Br] = k(constant)[CH3Br]=k′[CH3Br]
As only the concentration of CH3Br would change during the reaction, the rate would solely depend upon the changes in the CH3Br reaction.