Question

What are the units of rate constant for the first order reaction?

Answer 1

Let $R$ be the rate of reaction.

For first order reaction,

$R=K{\left[A\right]}^1$

$\Rightarrow K=R{\left[A\right]}^{-1}$

Whereas, $K$ and $\left[A\right]$ are rate constant and initial concentration of reactant respectively.

Therefore,

Unit of rate constant $={\left(mol{L}^{-1}\right)}^{1-n}{sec}^{-1}$

For first order reaction,

$n=1$

Unit of rate constant $={sec}^{-1}$

Hence the unit of rate constant for first order reaction is ${sec}^{-1}$.