Question

A reaction is experimentally found to follow the rate law, Rate = kA2 where k = 0.355 M^-1min^-1. Starting with Ao = 1.55 M, how many seconds will it take for At = 0.150M

A.6.58 s
B.395 s
C.6.02 s
D.17.0 s
E.1.02 x 103 s

Answer 1

The answer is A. 6.58 s.

To solve this problem, we can use the integrated rate law for a second-order reaction with constant concentration of one reactant:

t = (1 / (k * Ao)) * (1 / At - 1 / Ao)

Given:

k = 0.355 M^-1min^-1

Ao = 1.55 M

At = 0.150 M

Plugging in the values:

t = (1 / (0.355 M^-1min^-1 * 1.55 M)) * (1 / 0.150 M - 1 / 1.55 M)

t ≈ 6.58 seconds

Therefore, the answer is A. 6.58 s.

The other options are incorrect:

• B. 395 s is too high.
• C. 6.02 s is slightly inaccurate due to rounding.
• D. 17.0 s is too high.
• E. 1.02 x 10^3 s is significantly too high.