Question
Units of rate constant of first and zero order reactions in terms of molarity $$M$$ unit are respectively
A.
$${\sec ^{ - 1}},M{\sec ^{ - 1}}$$
B.
$${\sec ^{ - 1}},M$$
C.
$$M{\sec ^{ - 1}},{\sec ^{ - 1}}$$
D.
$$M,{\sec ^{ - 1}}$$
Answer :
$${\sec ^{ - 1}},M{\sec ^{ - 1}}$$
Solution :
$$\eqalign{
& {\text{For}}\,{\text{zero}}\,{\text{order}}\,{\text{reaction,}} \cr
& = k{\left[ A \right]^{0\,}}\,i.e.\,rate = k \cr
& {\text{hence}}\,{\text{unit}}\,{\text{of}}\,k = M.{\sec ^{ - 1}} \cr
& {\text{For}}\,{\text{the}}\,{\text{fast}}\,{\text{order}}\,{\text{reaction,}} \cr
& {\text{rate}} = k\left[ A \right] \cr
& k = \frac{{M.{{\sec }^{ - 1}}}}{M} \cr
& = {\sec ^{ - 1}} \cr} $$