Question

2 ICl + H_2----->I₂ + 2 HCl

Experiment	[ICl]o, M	[H2]o, M	Initial Rate, M s-1
1	0.129	8.70×10-2	1.67×10-3
2	0.258	8.70×10-2	3.34×10-3
3	0.129	0.174	6.68×10-3
4	0.258	0.174	1.34×10-2

Complete the rate law for this reaction in the box below.
Use the form k[A]^m[B]ⁿ , where '1' is understood for m or n and concentrations taken to the zero power do not appear. Don't enter 1 for m or n.

Rate =

____________

From these data, the rate constant is _______M^-2s^-1.

Answer 1

1)

see experiment 1 and 2:

[ICl] doubles

[H2] is constant

rate doubles

so, order of ICl is 1

see experiment 1 and 3:

[ICl] is constant

[H2] doubles

rate becomes 4 times

so, order of H2 is 2

overall order = 1 + 2 = 3

Rate law is:

rate = k*[ICl]*[H2]^2

Answer:

rate = k[ICl][H2]^2

2)

Put values from 1st row of table in rate law

rate = k*[ICl]*[H2]^2

1.67*10^-3 = k*0.129*0.0870^2

k = 1.7104 M-2.s-1

Answer: 1.71 M-2.s-1