Rates

Question 1

The rate equation for a reaction is
rate = k[E]
Explain qualitatively why doubling the temperature has a much greater effect on the rate of the reaction than doubling the concentration of E.

Answer 1

Reaction occurs when molecules have E>Ea
1
Doubling T by 10 °C causes many more molecules to have this E
1
Whereas doubling [E] only doubles the number with this E

Question 2

Suggest why initial rates of reaction are used to determine these orders rather than rates of reaction at other times during the experiments.

Answer 2

(At time zero/start) the concentrations are known

Question 3

State how the initial rate is obtained from a graph of the concentration of the product against time.

Answer 3

M1 (Calculate) gradient (of tangent/curve/graph)

M2 at t=0 or at start of graph/curve

Question 4

The reaction is zero order with respect to B.

State the significance of this zero order for the mechanism of the reaction.

Answer 4

Slow step or rds involves only A
OR
B does not appear in the slow step or the rds
OR
B only appears after the slow step or the rds