The reaction: H3C-CH2- + OH^- - H3C-CH^-- + obeys the rate law for pseudo first-order kinetics in the presence of a large excess of hydroxide ion. If 1% of nitro ethane undergoes reaction in half a m

Question

The reaction: H3C-CH2-$NO_2$ + OH^- -> H3C-CH^--$NO_2$ + $H_2O$ obeys the rate law for pseudo first-order kinetics in the presence of a large excess of hydroxide ion. If 1% of nitro ethane undergoes reaction in half a minute when the reactant concentration is 0.002 M, what is the pseudo first-order rate constant?

Prashant Kotian · Accepted Answer

Correct answer: A. For a first-order (or pseudo-first-order) reaction, the rate constant is given by: k' = 2.303/t * log(a/(a-x)). Given: t = 0.5 min, x = 1% of a. Therefore, a/(a-x) = 100/99. Substituting the values: k' = 2.303/0.5 * log(100/99) = 4.606 × 0.00436 = 0.0201 min^-1 ≈ 2 × 10^-2 min^-1.

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