The decomposition of hydrogen peroxide in aqueous solution is a first-order reaction: Time in min: 0, 10; Volume (V, in ml): 25.0, 20.0, where V is the number of ml of potassium permanganate required

Question

The decomposition of hydrogen peroxide in aqueous solution is a first-order reaction: Time in min: 0, 10; Volume (V, in ml): 25.0, 20.0, where V is the number of ml of potassium permanganate required to decompose a definite volume of hydrogen peroxide solution, at the given time. From the following data, the rate constant (in min^-1) of reaction is (ln 5 = 1.6, ln 2 = 0.7)

Prashant Kotian · Accepted Answer

Correct answer: B. The volume of required for titration is directly ∝ the concentration of remaining at that time: V_0 ∝ [A]_0 = 25.0 mL and V_t ∝ [A]_t = 20.0 mL at t = 10 min. For a first-order reaction: K = 1/t * ln(V_0/V_t) = 1/10 * ln(25/20) = 1/10 * ln(1.25) = 1/10 * [ln(5) - ln(4)] = 1/10 * [1.6 - 2(0.7)] = 0.02 min^-1.

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