Question

Identify the reaction order from each of the following rate constants.
A).$k=2.3\times {10}^{-5}Lmo{l}^{-1}{s}^{-1}$.

B).$k=3\times {10}^{-4}{s}^{-1}$

Answer 1

Solution :A
Order of reaction

Order of a chemical reaction can be
defined as the sum of power of
concentration of reactants in the rate law
expression.

Order of reaction
The units of the rate constants for zero,
first, second, and $n^{th}$ order reactions are
tabulated below-

$$\begin{array}{cc}\text{Reaction}& \text{Units of Rate constant}\\ \text{Order}& \\ 0& M.s^{-1}\left(or\right)mol.L^{-1}.s^{-1}\\ 1& s^{-1}\\ 2& M^{-1}.s^{-1}\left(or\right)L^{-1+n}.mo{l}^{1-n}\\ & .s^{-1}\\ n& M^{1-n}.s^{-1}or{L}^{-1+n}\\ & .mo{l}^{1-n}.s^{-1}\end{array}$$
The unit of second order rate constant is
$Lmo{l}^{-1}{s}^{-1}$.
Therefore, $k=2.3\times {10}^{-5}Lmo{l}^{-1}{s}^{-1}$
represents a second order reaction.

Final answer: Second order reaction

Solution:B

Order of reaction

Order of a chemical reaction can be
defined as the sum of power of
concentration of reactants in the rate law
expression

Order of reaction

The units of the rate constants for zero,
first, second, and $n^{th}$ order reactions are
tabulated below-

$$\begin{array}{cc}\text{Reaction}& \text{Units of Rate constant}\\ \text{Order}& \\ 0& M.s^{-1}\left(or\right)mol.L^{-1}.s^{-1}\\ 1& s^{-1}\\ 2& M^{-1}.s^{-1}\left(or\right)L^{-1+n}.mo{l}^{1-n}\\ & .s^{-1}\\ n& M^{1-n}.s^{-1}or{L}^{-1+n}\\ & .mo{l}^{1-n}.s^{-1}\end{array}$$
The unit of a order reate constant is $s^{-1}$.

Therefore, $k=3\times {10}^4{s}^{-1}$ represents a
first order reation.

Fianl answer: First order reaction