Question

The reaction $ 2A+B+C\xrightarrow{{}}D+E $ is found to be first order in $ A $ , second in $ B $ and zero order in $ C $ . What is the effect on the rate of increasing concentration of $ A $ , $ B $ and $ C $ two times?

• A. 72 times
• B. 8 times
• C. 24 times
• D. 36 times
• E. none of the these

Answer 1

Answer: (B)

The rate law for the reaction is as: $ r=\frac{dx}{dt}=k(A){{(B)}^{2}}{{(C)}^{0}}=k(A){{(B)}^{2}} $
On increasing the concentrations of A, B and C two times.
$ r=\frac{dx}{dt}=k(2A){{(2B)}^{2}}{{(2C)}^{0}} $ $ =8k(A){{(B)}^{2}} $
Thus, the rate increases eight times.