The rate law for a reaction describes how the rate of the reaction depends on the concentration of the reactants. The rate law is determined experimentally and is generally given by the expression:
Rate
=k[‌ Reactant1]m[‌ Reactant2]n[‌Reactant3]p...where
k is the rate constant and
m,n,p, etc., are the reaction orders with respect to each reactant.
For the given reaction,
CHCl3(g)+Cl2(g)⟶CCl4(g)+HCl(g),the order of reaction with respect to
CHCl3(g) is one, and the order with respect to
Cl2(g) is
‌. Therefore, the rate law can be expressed as:
‌ Rate ‌=k[CHCl3]1[Cl2]‌‌. ‌Comparing this expression to the given options, the correct rate law corresponds to:
Option A:
‌ Rate ‌=k[CHCl3][Cl2]1∕2