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The reaction between 1-chloro-1-phenylethane and hydroxide ions to produce 1-phenylethanol is:

\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHClCH}_{3}+\mathrm{OH}^{-} \rightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{3}+\mathrm{Cl}^{-}

1-chloro-1-phenylethane
1-phenylethanol
The rate of this reaction can be studied by measuring the amount of hydroxide ions that remain in solution at a given time. The reaction can effectively be stopped if the solution is diluted with an ice-cold solvent.

Describe a suitable method for studying the rate of this reaction at a temperature of $40^{\circ} \mathrm{C}$ , given the following.
- a solution of $0.10 \mathrm{~mol} \mathrm{dm}^{-3}$ 1-chloro-1-phenylethane, labelled A
- a solution of $0.10 \mathrm{~mol} \mathrm{dm}^{-3}$ sodium hydroxide, labelled B
- $0.10 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$
- volumetric glassware
- ice-cold solvent
- stopclock
- access to standard laboratory equipment and chemicals

Any of the three methods possible. Any 4 of the 5 points for each method available for maximum 4 marks.

Method 1

1 Ensure both solutions (A and B) at $40^{\circ} \mathrm{C}$ before mixing

2 mix known volumes of A and B and start the clock

3 at known time take out a sample / X and add it to ice-cold solvent

4 titrate against HCl

5 repeat at time at known time intervals

Method 2

1 Ensure both solutions (A and B) at $40^{\circ} \mathrm{C}$ before mixing

2 mix known volumes of A and B and start the clock

3 at known time pour into ice-cold solvent or pour ice-cold solvent in

4 titrate against HCl

5 repeat with different concentrations of either A or B, or repeat using different times

Method 3

1 Ensure both solutions (A and B) at $40^{\circ} \mathrm{C}$ before mixing

2 mix known volumes of A and B and start the clock and add pH meter

3 at a known time . . . .

4 ... . record the pH

5 repeat pH readings at known time intervals

CAIE A-Level Chemistry A2 P5.2 Planning Methods and Apparatus Topic Practice

Question 1