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You and your lab partner are studying the rate of a reaction, A + B --> C. You m

ID: 1023707 • Letter: Y

Question

You and your lab partner are studying the rate of a reaction, A + B --> C. You make measurements of the initial rate under the following conditions:

Experiment [A] (M) [B] (M) Rate (M/s)

1 0.7 1.3

2 1.4 1.3

(a) Which of the following reactant concentrations could you use for experiment 3 in order to determine the rate law, assuming that the rate law is of the form, Rate = k [A]^x [B]^y? Choose all correct possibilities.

[A] = 0.7 and [B] = 2.6

[A] = 0.7 and [B] = 3.9

[A] = 1.4 and [B] = 2.6

[A] = 1.4 and [B] = 3.9

[A] = 2.8 and [B] = 1.3

[A] = 1.4 and [B] = 1.3

[A] = 2.1 and [B] = 1.3

[A] = 3.5 and [B] = 1.3

(b) For a reaction of the form, A + B + C --> Products, the following observations are made: tripling the concentration of A increases the rate by a factor of 9, doubling the concentration of B has no effect on the rate, and tripling the concentration of C increases the rate by a factor of 3. Select the correct rate law for this reaction from the choices below.

Rate = k[A][B][C]

Rate = k[A][C]

Rate = k[A]2 [C]

Rate = k[A][C]2

Rate = k[A]2 [C]2

Rate = k[A]3 [C]

Rate = k[A][C]3

(c) By what factor will the rate of the reaction described in part (b) above change if the concentrations of A, B, and C are all halved (reduced by a factor of 2)?

The rate will be the original rate multiplied by a factor of ._________

Explanation / Answer

a)

[A] = 0.7 and [B] = 2.6

[A] = 0.7 and [B] = 3.9

[A] = 1.4 and [B] = 2.6

[A] = 1.4 and [B] = 3.9

b) the correct answer is Rate = k[A]2 [C] because A has a 2rd order and C has a1 st order change.

c) the rate of the reaction described in part (b) above change if the concentrations of A, B, and C are all halved

will lead to =  Rate = k[A/2]2 [C/2]

= 1/8 k[A]3 [C]

The rate will be the original rate multiplied by a factor of 1/8