Question

If the rate of a reaction is given as (-rA) = (frac{k_1+C_A^2}{k_2×C_A} frac{mol}{m^3 min} ), then the units of k1 and k2 respectively are ____

(a) (frac{mol^2}{m^6} ) and min

(b) min and (frac{mol^2}{m^6} )

(c) mol and min

(d) m^3 and mol

Answer 1

The correct answer is (a) (frac{mol^2}{m^6} ) and min

To explain: Two quantities of the same dimensions can only be added. As the unit of concentration is (frac{mol^2}{m^3} ) , k1 has the units (frac{mol^2}{m^6} ).

Equating the units of all known quantities on both sides, (frac{mol}{m^3 min} = frac{mol^2}{m^6} × frac{1}{k_2×(frac{mol}{m^3})}. )

Hence, k2 has the unit of min.