when the order n of the reaction rate is determined by this formula:
rate = K * [A]^n
when we have the unit of rate M S^-1
and the unit of [A] M
So:
1- for k = 8.79 x 10^2 M S^-1 :
when the unit of K here is M S^-1
by substitution in rate formula:
M S^-1 = M S^-1 * M ^n
∴ M^n = 1
∴M^0 = 1
∴ this reaction rate is zero order reaction
2- when k = 4.46 x 10^-1 and has unit M-1 S-1:
by substitution in rate formula:
M S^-1 = M-1 S-1 * M^n
∴M^2 = M^n
∴n = 2 so this is the second order reaction
3- when K 2.35 x 10^6 and it's unit is S-1 :
So by substitution in rate formula:
M S^-1 = S^-1 * M^n
∴ M^n = M
∴ n = 1
So this is the first order reaction
4- when k = 1.88 x 10^-3 and its unit is M-2 S-1
by substitution in rate formula:
M S^-1 = M^-2 S^-1 * M^n
∴ M^n = M^3
∴ n = 3
∴ this is a third order reaction
from 1 & 2 & 3 & 4
so we can see that the correct answer is (4), K= 1.88 x 10^-3 M-2 S-1 is the highest order reaction.
