A combination reaction was performed as described by the reaction:A + 2B → 2CAnalysis of the kinetics for the reaction found that the reaction progress responded to changes in reagent concentration as given in the following table: Based on the kinetic data, which of the following expressions gives the rate constant for the rate law of this reaction?

Question

A combination reaction was performed as described by the reaction:A + 2B → 2CAnalysis of the kinetics for the reaction found that the reaction progress responded to changes in reagent concentration as given in the following table:  Based on the kinetic data, which of the following expressions gives the rate constant for the rate law of this reaction?

Quizplus · Accepted Answer

11ecba2d_11c3_ec95_a3bf_6783aea5fcbb_MD0008_00 The general rate law for a reaction is given by the equation: 11ecba2d_11c3_ec96_a3bf_8fb467052de8_MD0008_00 The values of m and n, which give the reaction order, can be determined by comparing the reactant concentrations and the initial rates of given kinetic data. The rate law can then be determined, and the rate constant k can be calculated by solving for k: 11ecba2d_11c4_13a7_a3bf_59b1bfddb2bd_MD0008_00 Comparing Trial 2 to Trial 1, [A] is left unchanged but [B] is doubled and the reaction rate quadruples. This means that the rate has second-order dependence on [B] (n = 2). Comparing Trial 3 to Trial 4, [A] is tripled but [B] is left unchanged. The rate triples, indicating that the reaction rate has first-order dependence on [A] (m = 1). Therefore, the overall reaction is third-order (m + n = 3), and the rate law can be written as: 11ecba2d_11c4_13a8_a3bf_cbe98baffb5c_MD0008_00 (Choice A) This expression for k comes from the incorrect rate law, Rate = k[A][B]³, which has third-order dependence on [B] (n = 3) rather than second-order dependence (n = 2). Third-order dependence would cause the reaction rate to be eight times greater when [B] is doubled. (Choice C) This expression for k comes from the incorrect rate law, Rate = k[A]²[B], which has second-order dependence on [A] (m = 2) and first-order dependence on [B] (n = 1). This would cause the reaction rate to be four times greater when [A] is doubled and only two times greater when [B] is doubled. (Choice D) This expression for k comes from the incorrect rate law, Rate = k[A][B], which has first-order dependence on [B] (n = 1). This would cause the reaction rate only to double when [B] is doubled. Educational objective: The reaction order of each reactant in a chemical process can be determined by comparing kinetic data at different concentrations, from which the rate law can be written. The rate constant k can then be evaluated from the rate law.

A Combination Reaction Was Performed as Described by the Reaction:A