For `2A + B + underset((excess))(C ) rarr` Products, calculate:
(a) Rate expresison, uisng rate law.
(b) Units of rate and rate constant.
(c ) Effect on rate, if the concentration of `A` is doubled and that of `B` is tripled.

Explanation

(a) Rate `= k[A]^(2)[B]^(1)[C]^(0)` (Since `C` is in excess)
(b) Unit of rate `= mol L^(-1)` time
Unit of rate constant for third order `= L^(2) mol^(-2) time^(-1)`
(c ) Let initial concentration of `A, B`, and `C` be `a, b`, and `c`, respectively.
`:. r_(1) = k(a)^(2)(b)^(1)(c )^(0)` ...(i)
Now , `[A] = 2a, [B] = 3b`
`:. r_(2) = K(2a)^(2)(3b)^(1)( c)^(0)` ...(ii)
By Eqs. (i) and (ii), `(r_(1))/(r_(2)) = (1)/(12) :. r_(2) = 12r_(1)`