<P> The pressure dependence of the rate constant is associated with the activation volume . For the reaction proceeding through an activation - state complex: </P> <Dl> <Dd> A + B ⇌ A ⋯ B → P </Dd> </Dl> <Dd> A + B ⇌ A ⋯ B → P </Dd> <P> the activation volume, ΔV, is: </P>

For gaseous reaction the unit of rate of reaction is