2025 AQA A-LEVEL CHEMISTRY Paper 3
Question Paper & Mark Scheme (Merged)
Friday 20 June 2025 [VERIFIED]
, 2
Do not write
outside the
Section A
box
Answer all questions in this section.
0 1 A value for enthalpy of solution can be determined from the results of a calorimetry
experiment or by the application of Hess’s law.
0 1 . 1 Give the equation, including state symbols, for the process that occurs when the
enthalpy of solution of potassium hydroxide is determined.
[1 mark]
IB/M/Jun25/7405/3
, 3
Do not write
outside the
0 1 . 2 A student does an experiment to determine a value for the enthalpy of solution of box
potassium hydroxide.
The student uses this method.
Add some distilled water to a measuring cylinder and record the volume.
Pour the water into a polystyrene cup.
Record the temperature of the water in the cup.
Add 3.00 g of solid KOH to the water in the cup.
Stir the solution and record the maximum temperature reached.
Table 1 shows the student’s results.
Table 1
Initial temperature / °C 18.1
Final temperature / °C 30.4
The student calculated the enthalpy of solution of potassium hydroxide
to be –51.3 kJ mol–1
The specific heat capacity of the solution, c = 4.18 J K–1 g–1
Assume the density of the solution = 1.00 g cm–3
Calculate the volume of water that the student added to the cup.
[5 marks]
IB/M/Jun25/7405/3
, 4
Do not write
outside the
Volume of water Units
Turn over ►
IB/M/Jun25/7405/3
Question Paper & Mark Scheme (Merged)
Friday 20 June 2025 [VERIFIED]
, 2
Do not write
outside the
Section A
box
Answer all questions in this section.
0 1 A value for enthalpy of solution can be determined from the results of a calorimetry
experiment or by the application of Hess’s law.
0 1 . 1 Give the equation, including state symbols, for the process that occurs when the
enthalpy of solution of potassium hydroxide is determined.
[1 mark]
IB/M/Jun25/7405/3
, 3
Do not write
outside the
0 1 . 2 A student does an experiment to determine a value for the enthalpy of solution of box
potassium hydroxide.
The student uses this method.
Add some distilled water to a measuring cylinder and record the volume.
Pour the water into a polystyrene cup.
Record the temperature of the water in the cup.
Add 3.00 g of solid KOH to the water in the cup.
Stir the solution and record the maximum temperature reached.
Table 1 shows the student’s results.
Table 1
Initial temperature / °C 18.1
Final temperature / °C 30.4
The student calculated the enthalpy of solution of potassium hydroxide
to be –51.3 kJ mol–1
The specific heat capacity of the solution, c = 4.18 J K–1 g–1
Assume the density of the solution = 1.00 g cm–3
Calculate the volume of water that the student added to the cup.
[5 marks]
IB/M/Jun25/7405/3
, 4
Do not write
outside the
Volume of water Units
Turn over ►
IB/M/Jun25/7405/3
