AS & A Level CHEMISTRY9701/34 Paper 3 Advanced Practical Skills 2 May/June 2023 Authentic Marking Scheme

Cambridge International AS & A Level
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CHEMISTRY 9701/34
Paper 3 Advanced Practical Skills 2 May/June 2023

2 hours

You must answer on the question paper.

You will need: The materials and apparatus listed in the confidential instructions

INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● You may use a calculator.
● You should show all your working and use appropriate units.


INFORMATION Session
● The total mark for this paper is 40.
● The number of marks for each question or part question is shown in
brackets [ ]. Laboratory
● The Periodic Table is printed in the question paper.
● Important values, constants and standards are printed in the
question paper.
● Notes for use in qualitative analysis are provided in the
question paper. For Examiner’s Use

1

2

3

Total

This document has 12 pages.


DC (KN/JG) 310986/3
© UCLES 2023 [Turn over

, 2

Quantitative analysis

Read through the whole method before starting any practical work. Where appropriate, prepare a table
for your results in the space provided.

Show the precision of the apparatus you used in the data you record.

Show your working and appropriate significant figures in the final answer to each step of your
calculations.

1 You will investigate the enthalpy change of neutralisation, ∆Hneut, between aqueous sodium
hydroxide of known concentration and a dilute organic acid. You will use your results to suggest
the identity of the organic acid. The acid is a halogenocarboxylic acid containing one halogen
atom, X, per molecule.

NaOH(aq) + CH3CHXCOOH(aq) CH3CHXCOONa(aq) + H2O(l)

FB 1 is 1.90 mol dm−3 sodium hydroxide, NaOH.
FB 2 is a solution containing 312.5 g dm−3 of the organic acid CH3CHXCOOH.

(a) Method

● Support the cup in the 250 cm3 beaker.
● Pipette 25.0 cm3 of FB 1 into the cup.
● Place the thermometer into FB 1. Record the temperature of FB 1 in Table 1.1. This is
the temperature when the volume of FB 2 is 0.00 cm3.

● Fill the burette with FB 2.
● Run 5.00 cm3 of FB 2 into the cup containing FB 1. I
● Stir the mixture. Record the highest temperature observed.
● Run further 5.00 cm3 portions of FB 2 into the same cup. II
● On each addition of FB 2 stir the contents of the cup. Record the highest III
temperature after each addition.

Results

Table 1.1

total volume of
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00
FB 2 added / cm3
temperature
/ ºC
[3]

(b) (i) Plot a graph of temperature (y-axis) against volume of FB 2 added (x-axis) on the grid.
Select a scale on the y-axis to include a temperature of 2 ºC above your maximum
thermometer reading. Label any points you consider to be anomalous.

Draw two lines of best fit, the first for the increase in temperature and the second for
after the maximum temperature has been reached. Extrapolate the two lines so they
intersect. This intersection corresponds to the volume of FB 2 required to form a neutral
solution.



© UCLES 2023 9701/34/M/J/23

, 3




I

II

III

IV

[4]




(ii) Use your graph to determine the volume of FB 2 required to neutralise 25.0 cm3 of FB 1.


25.0 cm3 of FB 1 required .................................... cm3 of FB 2. [1]




© UCLES 2023 9701/34/M/J/23 [Turn over