Physical 2 Section 1 - Unit 18: Kinetics

Question 1

Explain qualitatively why doubling the temperature has a much greater effect on the rate of the reaction than doubling the concentration of the reactant (3 marks)

Answer 1

• Reaction occurs when molecules have E>Ea
• Doubling T by causes many more molecules to have this E
• Whereas doubling the concentration only doubles the number with this E

Question 2

Define rate constant (1 mark)

Answer 2

• A number which allows us to equate rate and concentration
  OR
• The constant of proportionality in the rate expression

Question 3

Define order of reaction (1 mark)

Answer 3

• The sum of the powers to which the concentrations of all the species involved in the reaction are raised

Question 4

Rate determining step (1 mark)

Answer 4

Slowest step

Question 5

What is meant by the term order of reaction with respect to X (1 mark)

Answer 5

Power of concentration term in the rate equation