Rates of Reaction

Question 1

What is a rate of reaction?

Answer 1

The change in concentration of a species per unit of time

Question 2

Explain the collision theory

Answer 2

• reactants moving too slowly results in molecules bouncing (no reaction)
• reactants not facing the right way results in molecules bouncing (no reaction)
• reactants energetic & oriented correctly results in a chemical reaction

Question 3

What is activation energy and transition state?

Answer 3

• the minimum energy required to initiate a chemical reaction
  ~ Transition state = highest energy point in the reaction

Question 4

What factors affect the rates of reaction?

Answer 4

• temperature
• catalysts
• surface area
• pressure
• concentration

Question 5

REFRESH RATE EQUATIONS

Answer 5

(REFER TO LECTURE SLIDE 14)

Question 6

Explain zero-order reactions

Answer 6

• Rate is independent of the concentration of reactant. Overall reaction order = 0
  ~ for zero-order reactions the rate does not change
  (reaction depends on a catalytic bottle neck)

Question 7

Explain first-order reactions

Answer 7

• The rate is proportional to the concentration of a single reactant raised to the first power

Question 8

Explain half-life of a reaction

Answer 8

• Time taken for the concentration of a reactant to drop to half of its original value
~ for a first-order reaction, the half-life is constant

Question 9

Explain second-order reactions

Answer 9

• Has a rate law with a sum of the exponents equal to 2. Overall reaction order = 2

Question 10

Define Molecularity

Answer 10

• The number of individual molecules of the reacting species taking part in the rate determining step of a reaction

Question 11

What is a “fast reaction” (low activation energy) referred to as?

Answer 11

• Kinetically favourable