6.1 Day 6 Prelab

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Questions

Consider the following hypothetical reaction between the species \(A_{(aq)}\) and \(B_{(aq)}\) to yield \(AB_{2(aq)}\):

\[ A_{(aq)} + 2 B_{(aq)} \longrightarrow AB_{2(aq)} \nonumber \]

Using the isolation method, it is found that the rate law is second order in \(A_{(aq)}\), first-order in \(B_{(aq)}\),and third-order overall. When 30.00 mL of 0.600 M \(A_{(aq)}\) is combined with 20.00 mL of 0.500 M \(B_{(aq)}\) at 25.0 °C, the initial rate of reaction is found to be 1.94 x 10-6 M/s. When 20.00 mL of 0.600 M \(A_{(aq)}\) is combined with 30.00 mL of 0.500 M \(B_{(aq)}\)at 50.0 °C, the initial rate of reaction is found to be 6.52 x 10-6 M/s. As always, assume that all aqueous solution volumes are additive and that ionic strength was constant.

(a) Determine the rate constant of this reaction (in units of M and s) at each temperature (25.0 °C & 50.0 °C) and also determine the activation energy of this reaction (in kcal per mole of \(A_{(aq)}\)). Show all work.

(b) Clearly state any assumptions that had to be made in order to successfully carry out any of the computations in (a).

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5.35 / 5.35U Introduction to Experimental Chemistry
Fall 2012

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