For the first order opposed by first order reaction ; k f …

Chemistry Chemical Kinetics General Single Correct MCQ

Published by: CGP EDU Academic Team

Published on: August 13, 2026

For the first order opposed by first order reaction ;

k f = 9 × 10 –3 min –1 and k b = 2 × 10 –3 min –1

If we start with the concentration of A equal to 1 (M) what will be concentration of B in 10 3 /11 mins?

0.818 (M)

0.409 (M)

0.517(M)

0.190 (M)

Text Solution

Verified by Experts

The correct answer is:

The integrated rate equation is

ln = (k f + k b ) × t

ln = 11 × 10 –3 × = 1 = ln e

∴ = e or x eq = e x eq – x e

or x e = e x eq – x eq

or x =

or x = x eq = x eq × 0.632

1 0

(1 – x eq ) x eq

∴ = =

or 2 x eq = 9 – 9 x eq

or x eq = = 0.818

∴ x = 0.818 × 0.632

or x = 0.517 (M)

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