Question

For the reaction, A + B → Products, the rate law is Rate = k [A]^2/3 [B]². What are the units of rate constant?

Answer 1

Given:

Rate = k [A]^2/3 [B]²

Rate has units of mol L⁻¹ s⁻¹ = concentration × time⁻¹

overall order = \[\ce{\frac{2}{3} + 2 = \frac{8}{3}}\]

Units of rate constant k = \[\ce{\frac{Rate}{[A]^{2/3} [B]^2}}\]

= \[\ce{\frac{conc. time^{-1}}{[conc.]^{8/3}}}\]

= \[\ce{[conc]^{1 − 8/3} * time^{-1}}\]

= [conc]^−5/3 . time⁻¹