Question

Derive rate constant units for third order reactions.

Answer 1

For a third order reaction,

Rate = k [A]³

or \[\ce{k = \frac{Rate}{[A]^3}}\]

= \[\ce{\frac{conc time^{-1}}{conc^3}}\]

= conc.⁻² time⁻¹

If concentration is expressed in mol L⁻¹ and time in seconds, the units will be mol⁻² L² s⁻¹.