Question

The units of rate constant of a reaction when the rate of reaction is directly proportional to the concentration of one of the reactants is:

• A. mole${}^{-1}$ litre sec${}^{-1}$
• B. mole litre${}^{-1}$sec${}^{-1}$
• C. sec${}^{-1}$
• D. litre${}^2$ mole${}^{-2}$ sec${}^{-1}$

Answer 1

Answer: (C)

sec${}^{-1}$

For a first-order reaction, the rate of reaction is directly proportional to the concentration of one of the reactants.

Differential rate law, $r=k\left[A\right]$ or $k=\frac{\left[A\right]}{r}=\frac{mol/l}{mol/l.sec}$.

The rate constant, $k$, has units of $se{c}^{-1}$.