Question

For the reaction

A + 2 B + C → 3 D + 2 F

the following experimental data were obtained.

Experiment	[A] (M)	[B] (M)	[C] (M)	Rate (M/min)
1	0.10	0.10	0.10	2.0 x 10-5
2	0.10	0.10	0.30	6.0 x 10-5
3	0.20	0.10	0.10	8.0 x 10-5
4	0.10	0.40	0.10	2.0 x 10-5

Part #1:

Which represents the correct rate law?

  A) Rate = k [A]0[B]2[C]

B) Rate = k [A]2[B]0[C]

C) Rate = k [A]1[B]2[C]1

D) Rate = k [A]0[B]2[C]1

E) Rate = k [A]1[B]2[C]0

Part #2:

Which represents the correct units of the rate constant k for this reaction?

  A) 1/s

B) M/s

C) M4/s

D) 1/M2s

Part #3:

What is the value of the rate constant k for this reaction?

Answer 1

initial rates

rate1 / rate2 = ([A1][A2])^a([B1][B2])^b([C1][C2])^c

for C

2/ 6=1*([0.1/0.3)^c

C = 1

for A

rate1 / rate2 = ([A1][A2])^a

for C

2/ 8=1*([0.1/0.2)^a

1/4 = 1/2^a

A = 2

For B

rate1 / rate2 = ([A1][A2])^a

for B

2/2=1*(.1/.4)^b

b = 0

therefore

order:

rate = k*[A]^2[B]^0[C]^1

k must have units of

rate = mol/V-s

k = rate /([M/s]^2 * [M/s])

k = M/s / (M^3/s^2) = M^2 s

3)

k =

0.10

0.10

0.10

2.0 x 10-5

2*10^-5 = k*(0.1^2)(0)(0.1)

k = (2*10^-5 )/(0.1^3) = 0.02