A2 Chemistry Assessment Unit 4Maximum Marks: 35 Time: 30 minutes

Q1) Aqueous sodium hydroxide reacts with 2-bromopropane to form propan-2-ol and sodium bromide. The kinetics of this reaction was studied by measuring the concentration of OH− ions as a function of time. The graph below shows the results of an experiment using a solution that contained 0.20 mol dm−3

sodium hydroxide and excess 2-bromopropane.

A) Use the graph to calculate two consecutive half-lives. State the order of the reaction.

Marks: 5

B) The reaction was repeated with the same amount of 2-bromopropane but with sodium hydroxide of concentration 0.40moldm−3. The half-life was the same as when a 0.20moldm−3

solution was used. Use this information and that from (a) to deduce the rate equation for this reaction.

Marks: 3

Q2) Consider the reaction

A + 2B C + D

The reaction was studied and the following data on initial rates was obtained. Find the rate equation of this reaction.

Marks: 2

Q3) For the specific reaction, the rate equation is rate = k [X]2[Y].

The units of rate are mol dm-3s-1. What are the units of rate constant for this reaction?

Marks: 2

Q4) a) Define:

i) Rate of reactionii) Order of reaction

Marks: 2

b) 1-bromopropane and Sodium Hydroxide react to form propan-1-ol and Sodium Bromide. The rate of this reaction was measured using different concentrations of hydroxide ions and 1-bromo propane. The results are shown in the table below:

i) Deduce the order of reaction with respect to hydroxide ions and to 1-bromopropane. Justify your answer.

Marks: 4ii) Write the rate equation for this reaction.

Marks: 1iii) Calculate the value of the rate constant.

Marks: 2iv) Write a mechanism for this reaction that is consistent with your answer to (ii).

Marks: 3

c) In terms of collision theory, explain how the rate of this exothermic reaction would alter with an increase in temperature.

Marks: 4

Q5) Calculate the standard enthalpy of formation of Fe3O4(s).

Marks: 2

Q6) Calculate the standard entropy of Fe3O4(s).

Marks: 3

Q7) Calculate the total entropy change at 273K of the above reaction.

Marks: 4