AqA EXAMPRO
A-LEVEL CHEMISTRY Name:
Practice Paper 3 Maximum marks: 90 Time allowed: 2 hours
These questions are from past papers covering topics and skills based on the advance
information to help you prepare for the exams this summer.
Answer all questions in the spaces provided.
You will need the Periodic Table/Data Booklet
1 A 5.00 g sample of potassium chloride was added to 50.0 g of water initially at 20.0 °C.
The mixture was stirred and as the potassium chloride dissolved, the temperature of
the solution decreased.
(a) Describe the steps you would take to determine an accurate minimum
temperature that is not influenced by heat from the surroundings.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
(4)
Page 1
,(b) The temperature of the water decreased to 14.6 °C.
Calculate a value, in kJ mol−1, for the enthalpy of solution of potassium chloride.
You should assume that only the 50.0 g of water changes in temperature and that
the specific heat capacity of water is 4.18 J K−1 g−1.
Give your answer to the appropriate number of significant figures.
Enthalpy of solution = _______________ kJ mol−1
(4)
(c) The enthalpy of solution of calcium chloride is −82.9 kJ mol−1.
The enthalpies of hydration for calcium ions and chloride ions are −1650 and
−364 kJ mol−1, respectively.
Use these values to calculate a value for the lattice enthalpy of dissociation of
calcium chloride.
Lattice enthalpy of dissociation = _______________ kJ mol−1
(2)
(d) How would magnesium chloride differ? Explain why
.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
(2)
(Total 12 marks)
Page 2
, 2 (a) The concentration of iron(III) ions in a dilute solution can be determined by visible
spectrometry. The absorption of light by a number of solutions of iron(III) sulfate,
Fe2(SO4)3(aq), was measured. The results are shown in the table below.
Concentration of Absorbance / %
Fe2(SO4)3(aq) / mol dm–3
0.020 2.2
0.040 4.7
0.060 7.0
0.080 9.4
0.100 11.8
(i) Use these results to plot a graph of percentage absorbance (y-axis) against
concentration of iron(III) sulfate solution on the grid below.
Draw a straight line of best fit.
(2)
Page 3
A-LEVEL CHEMISTRY Name:
Practice Paper 3 Maximum marks: 90 Time allowed: 2 hours
These questions are from past papers covering topics and skills based on the advance
information to help you prepare for the exams this summer.
Answer all questions in the spaces provided.
You will need the Periodic Table/Data Booklet
1 A 5.00 g sample of potassium chloride was added to 50.0 g of water initially at 20.0 °C.
The mixture was stirred and as the potassium chloride dissolved, the temperature of
the solution decreased.
(a) Describe the steps you would take to determine an accurate minimum
temperature that is not influenced by heat from the surroundings.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
(4)
Page 1
,(b) The temperature of the water decreased to 14.6 °C.
Calculate a value, in kJ mol−1, for the enthalpy of solution of potassium chloride.
You should assume that only the 50.0 g of water changes in temperature and that
the specific heat capacity of water is 4.18 J K−1 g−1.
Give your answer to the appropriate number of significant figures.
Enthalpy of solution = _______________ kJ mol−1
(4)
(c) The enthalpy of solution of calcium chloride is −82.9 kJ mol−1.
The enthalpies of hydration for calcium ions and chloride ions are −1650 and
−364 kJ mol−1, respectively.
Use these values to calculate a value for the lattice enthalpy of dissociation of
calcium chloride.
Lattice enthalpy of dissociation = _______________ kJ mol−1
(2)
(d) How would magnesium chloride differ? Explain why
.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
(2)
(Total 12 marks)
Page 2
, 2 (a) The concentration of iron(III) ions in a dilute solution can be determined by visible
spectrometry. The absorption of light by a number of solutions of iron(III) sulfate,
Fe2(SO4)3(aq), was measured. The results are shown in the table below.
Concentration of Absorbance / %
Fe2(SO4)3(aq) / mol dm–3
0.020 2.2
0.040 4.7
0.060 7.0
0.080 9.4
0.100 11.8
(i) Use these results to plot a graph of percentage absorbance (y-axis) against
concentration of iron(III) sulfate solution on the grid below.
Draw a straight line of best fit.
(2)
Page 3
