Unit 2-Kinetics

Question 1

What is meant by the order of a reaction?

Answer 1

The number of species/molecules/ particles/ions/ moles of reactant(s) involved in the rate determining step/slowest step

Question 2

How is the order of reaction determined?

Answer 2

The order of a reaction can only be determined from experimental data.

Question 3

What is meant by a reaction being zero/first/second order with respect to a particular reactant?

Answer 3

Doubling concentration has no effect on the rate (zero)
Doubling concentration doubles the rate (first)
Doubling concentration quadruples rate (second)

Question 4

What would be the overall order of reaction for these rate equations?

1. rate = k [A]^{<span>0</span>}
2. rate = k [A]¹
3. rate = k [A]²
4. rate = k [A]¹ [B]¹
5. rate = k [A]² [B]⁰
6. rate = k [A]² [B]¹ [C]¹

Answer 4

1. 0
2. 1
3. 2
4. 2
5. 2
6. 4

Question 5

What rate equation does this data fit?

Answer 5

Rate = k [X][Y]

Question 6

What would be the rate equation?

Answer 6

Rate = k [H₂O₂][I^-]

or

Rate = k [H₂O₂][I^-][H⁺]⁰

Question 7

If the rate equation is = k [H₂O₂][I^-], calculate the rate constant.

Answer 7

k = rate/[H₂O₂][I^-]

Substitute any of the experimental data

k = 9.2x10^-6 / (0.02x0.02)

0.023 mol^-1 l s^-1

Question 8

What are the units of k for a zero-order reaction if the rate is in mol l^-1 s^-1 and concentration is mol l^-1?

Answer 8

rate = k [A]⁰

k = rate / [A]⁰

k = mol l^-1 s^-1

Question 9

What are the units of k for a first-order reaction if the rate is in mol l^-1 s^-1 and concentration is mol l^-1?

Answer 9

rate = k [A]¹

k = rate / [A]¹

k = mol l^-1 s^-1 / mol l^-1

k = s^-1

Question 10

What are the units of k for a second-order reaction if the rate is in mol l^-1 s^-1 and concentration is mol l^-1?

Answer 10

rate = k [A]²

k = rate / [A]²

k = mol l^-1 s^-1 / (mol l^-1)²

k = mol l^-1 s^-1 / mol² l^-2

k = mol l^-1 s^-1 / mol² l^-2

k = mol^-1 l s^-1

Question 11

What are the units of k for a third-order reaction if the rate is in mol l^-1 s^-1 and concentration is mol l^-1?

Answer 11

rate = k [A]³

k = rate / [A]³

k = mol l^-1 s^-1 / (mol l^-1)³

k = mol l^-1 s^-1 / mol³ l^-3

k = mol^-2 l² s^-1