Answer
$(a) 4.6\times10^{-2}s^{-1 } $
$(b) 1.3\times10^{-1}M^{-1}s^{-1 }$
Work Step by Step
(a) When the reaction is first order with respect to A ,
$$ Rate = k_1[A] $$
$$ k_1 = \frac{Rate}{[A]} = \frac{1.6\times10^{-2}Ms^{-1}}{0.35M}$$
$$ k_1 = 4.6\times10^{-2}s^{-1 } $$
(b) When the reaction is second order with respect to A,
$$ Rate = k_2[A]^2 $$
$$ k_2 = \frac{Rate}{[A]^2} = \frac{1.6\times10^{-2}Ms^{-1}}{(0.35M)^2}$$
$$ k_2 = 1.3\times10^{-1}M^{-1}s^{-1 } $$
