The reaction 2A + 2B → 2C + D is first order in A and zeroth order in B. When [A]=0.03M and [B]=0.05M, the initial rate of the reaction is 7E-5 M/s. What is the value of the rate constant (k)?

Question

Answer choices:

1.4E-3 s-1

4.6E-2 s-1

2.3E-3 s-1

7.5E-5 s-1

None of the above

Answer 1

Since the reaction is 1st order in A and zero order in B, we can write the rate equation as...

Rate = k[A] (we do not include B, as the rate is independent of the concentration of B)

7x10^-5 M/s = k(0.03 M)

k = 7x10^-5 M/s / 0.03 M

k = 2.3x10^-3 s^-1