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Consider the reaction, 2A + B → products. When concentration of B alone was doubled, the half-life did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is
- s⁻¹
- L mol⁻¹ s⁻¹
- no unit
- mol L⁻¹ s⁻¹
Correct answer: L mol⁻¹ s⁻¹
Solution
Half-life independent of [B] means first order in B; doubling [A] doubling rate means first order in A. Overall second order, so k has units L mol^-1 s^-1 (index 1).
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