You and your lab partner are studying the rate of a reaction, A + B --> C. You m
ID: 946545 • 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:
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) [A] = 3.8 and [B] = 1.8
b)[A] = 1.9 and [B] = 2.7
c) [A] = 3.8 and [B] = 2.7
d) [A] = 5.7 and [B] = 0.9
e) [A] = 1.9 and [B] = 1.8
f) [A] = 3.8 and [B] = 0.9
g) [A] = 9.5 and [B] = 0.9
h) [A] = 7.6 and [B] = 0.9
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 3, 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.
a) Rate = k[A][B][C]
b) Rate = k[A][C]
c) Rate = k[A]2[C]
d) Rate = k[A][C]2
e) Rate = k[A]2[C]2
f) Rate = k[A]3[C]
g) 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 ____.
Experiment [A] (M) [B] (M) 1 1.9 0.9 2 3.8 0.9Explanation / Answer
At the start, B is kept constant and A is doubled so, u get realation for rate of reaction and conc of A independent of B.
So find the dependence of rate of reaction on conc of B .. U need to keep the conc of A constant. That is , it may have values like 1.9 M and 3.8 M.
If A is 1.9 M then we consider exp-1 and exp-3 similarly, if A is 3.8 M then we consider exp-2 and exp-3.
At the same time we should not keep conc of B =0.9 since the again the conc of B will be same at all time
So,the possible options are
(a) ; (b) ; (c) and (e)
(2)
rate proportional to 1 st power of conc of A from statement-1
rate is independent of conc of B from statement -2
rate is proportional to 1 st power of conc of C from statement-3
So, b) Rate = k[A][C] is correct option
(3)
Rate = k[A][C]
new rate = k x[A/2][C/2]
=1/4 k[A][C]
=0.25 x original rate
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