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Question
The value of rate constant of a pseudo first order reaction ______.
Options
depends on the concentration of reactants present in small amount.
depends on the concentration of reactants present in excess.
is independent of the concentration of reactants.
depends only on temperature.
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Solution
The value of rate constant of a pseudo first order reaction depends on the concentration of reactants present in excess.
Explanation:
Let's start with what a pseudo-first-order response is.
Although the pseudo-first-order reaction looks to be an order, it belong to another order. it's a second-order reaction because it involves two reactants.
Let's have a look at a reaction.
\[\ce{CH3Br + OH -> CH3OH + Br}\]
So, the rate law for the reaction is
Rate = \[\ce{k[OH][CH3Br]}\]
Rate = \[\ce{k[OH][CH3Br] = k(constant) [CH3Br] = K' [CH3Br]}\]
Only the concentration of \[\ce{CH3Br}\] will change during the reaction and the rate will be determined by the reaction's modifications.
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