The rate law for a chemical reaction can be written based on the order of the reaction with respect to its reactants. For the given reaction:
2A+B⟶ product
and the information that it is first order in
A(A) and zeroth order in
B(B), the rate law is expressed as:
rate
=k[A]1[B]0Since the reaction is zeroth order in
B, the concentration of
B does not affect the rate and hence
[B]0=1. This simplifies the rate expression to:
rate =k[A]1 The rate of the reaction is given as
6×10−4moldm−3 s−1 and the concentrations of
A and
B are both
0.3M(M=mol∕dm3). Substituting the rate and the concentration of
A into the simplified rate law gives us:
6×10−4moldm−3 s−1=k(0.3M)1Solving for the rate constant
k :
k=Performing the division:
k=k=2×10−3 s−1Thus, the rate constant
k for the reaction is
2×10−3 s−1, which corresponds to Option
B.