In an autocatalytic reaction, where a product speeds up the reaction, the plot of reactant concentration against time typically shows

Athe fastest rate at $t = 0$ , steadily slowing afterwards
Ban initial slow period, then rapid decrease, and finally a levelling off
Ca straight line of constant slope
Da rate that is highest only at the very end

Answer: B

Initially there is little catalyst (product), so the rate is low. As product accumulates the rate rises, then falls again as the reactant is exhausted. The concentration curve is therefore S-shaped, unlike ordinary first-order decay whose rate is highest at

t = 0

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In an autocatalytic reaction, where a product speeds up the reaction, the plot of reactant concentration against time typically shows

Answer: B

More questions on Parallel, consecutive and reversible reactions, catalysis