Question

For a reaction: aA → Products, [A]o -4.3 M, and the first two half-lives are 56 and 28 minutes, respectively. Calculate k (without units). Show Work!
A. 7.7 x 10^-2
B. 4.2 x 10^-3
C. 3.8 x 10^-2
D. 8.3 x 10^-3
E. None of these​

Answer 1

Answer:

C.$3.8\times 10^{-2}$

Explanation:

We are given that

Initial concentration, $[A]_o=4.3 M$

First half life, $t_{\frac{1}{2}}=56$minutes

Second half life, $t'_{\frac{1}{2}}=28$minutes

We have to find K.

The given reaction is zero order reaction.

We know that for zero order reaction

$t_{\frac{1}{2}}=\frac{[A]_o}{2k}$

Using the formula

$56=\frac{4.3}{2k}$

$k=\frac{4.3}{2\times 56}$

$k=3.8\times 10^{-2}$

Hence, option C is correct.