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Question

Chemistry Question on Chemical Kinetics

In the simple reaction 2A+BA2B2A + B\to A_2B, if the concentration of A is doubled and of B is halved, then the rate of reaction will

A

increase by two times

B

decrease by two times

C

increase by four times

D

remains the same

Answer

increase by two times

Explanation

Solution

Reaction: 2A+BA2B2 A+B \longrightarrow A_{2} B Rate =C[A]2[B];C=C[A]^{2}[B] ; C \rightarrow rate constant let conc. of AA be a0&a_{0} \& that of BB be b0b_{0} \Rightarrow Rate =ca02b0=k=c a_{0}^{2} b_{0}=k (say) AumAu^m to question, is concenctration of aa is doubled & bb is halved [A]=2a0&[B]=b0/2.\Rightarrow[A]=2 a_{0} \&[B]=b_{0} / 2 . \Rightarrow Rate =c(2a0)2(b0/2)=c\left(2 a_{0}\right)^{2}\left(b_{0 / 2}\right) =2a02b0c=2k.=2 a_{0}{ }^{2} b_{0} c=2 k . \Rightarrow on doing the following changes as said in question, rate of reaction doubles.