This question is about ionic compounds.
(a) Draw dot-and-cross diagrams of the ions in magnesium hydroxide, showing the
outer shell electrons only.
Use × for magnesium electrons, ● for oxygen electrons and for each
hydrogen electron.
(2)
(b) Which definition correctly describes the enthalpy change of solution, Δ H ?
sol
(1)
Enthalpy change of solution, Δ H
sol
The enthalpy change when 1 mol of gaseous ions dissolves in
A
sufficient water to give an infinitely dilute solution.
The enthalpy change when 1 mol of an ionic substance dissolves in
B
water to give an infinitely dilute solution.
The enthalpy change when 1 mol of gaseous ions dissolves in
C
sufficient water to give a solution of concentration 1 mol dm−3 .
The enthalpy change when 1 mol of an ionic substance dissolves in
D
water to give a solution of concentration 1 mol dm−3 .
*P76895A02028*
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(c) The table shows the information needed to calculate the
standard enthalpy change of formation of magnesium fluoride.
Label Description Value / kJ mol−1
A enthalpy change of formation of magnesium fluoride
B lattice energy of magnesium fluoride −2957
C enthalpy change of atomisation of magnesium +148
D 1st ionisation energy of magnesium +738
E 2nd ionisation energy of magnesium +1451
F enthalpy change of atomisation of fluorine +79
G 1st electron affinity of fluorine −328
Question
Mathematics
Edexcel2024
2
(ii) Calculate the value of Δ H [MgF (s)].
f 2
(1)
*P76895A02228*
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(iii) The experimental and theoretical values of the lattice energy for MgF and
Question
Mathematics
Edexcel2024
Explain the differences in these values.
(4)
Experimental lattice energy Theoretical lattice energy
Compound
/ kJ mol−1 / kJ mol−1
MgF −2957 −2913 2
MgI −2327 −1944 2
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(Total for Question 8 = 12 marks)
*P71912A02228*
PMT
(b) Another silver compound is silver chloride, AgCl. Values for its lattice energy can
be found by experiment or by theoretical calculation.
Experimental lattice energy Theoretical lattice energy
Compound
/ kJ mol–1 / kJ mol–1
Silver chloride –905 –833
(i) Give two assumptions used in the model to calculate the
theoretical lattice energy.
(2)
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(ii) Explain the difference in the two values for the lattice energy of silver chloride
by considering the possible bonding models.
(3)
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(Total for Question 9 = 13 marks)
Question
Mathematics
Edexcel2023
Lattice energy of CaCl (s) –2258
Question
Mathematics
Edexcel2022
2
C Cl (aq) + 2NaBr(aq) → 2NaCl(aq) + Br (aq)
Question
Mathematics
Edexcel2022
2
D Cl (aq) + 2NaF(aq) → 2NaCl(aq) + F (aq)
Question
Mathematics
Edexcel2022
2
(c) The halogens can form halide ions during reactions.
Complete the electronic configuration of the chloride ion.
(1)
1s2
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Question
Mathematics
Edexcel2022
2HOBr(aq) + 2H+(aq) + 2e– Br (aq) + 2H O(l) Ed = +1.57 V
Question
Mathematics
Edexcel2022
2
(i) Explain why the disproportionation of bromine in water is not
thermodynamically feasible under standard conditions.
Include the overall equation for the disproportionation and its Ed value.
cell
(3)
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(ii) Bromine disproportionates in water to a small extent at 298 K.
Give a possible reason why this reaction occurs.
(1)
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Question
Mathematics
Edexcel2022
though it has fewer electrons in its molecules
• the density of ice at 0 °C is less than that of water at 0 °C.
Explain these properties.
You should include a labelled diagram to show the intermolecular forces between
two molecules of water.
(6)
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*P67093RA01532*
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PMT
(c) Use the data in the table to answer the questions.
Enthalpy change Value / kJ mol–1
Enthalpy change of hydration of K+ –322
Enthalpy change of hydration of Ca2+ –1650
Enthalpy change of solution of KCl +17.2
Lattice energy of KCl –711
(i) Name the two properties of ions that affect the value of their
enthalpy change of hydration.
(2)
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(ii) Calculate the enthalpy change of hydration for chloride ions by completing
the energy cycle, including labels, and using the data in the table.
(3)
Δ H
soln
KCl(s) + aq K+(aq) + Cl–(aq)
enthalpy change of hydration for Cl– ions kJ mol–1
..............................................................
(Total for Question 5 = 9 marks)
Question
Mathematics
Edexcel2022
3 3
Question
Mathematics
Edexcel2022
2
(c) Lead-acid batteries are used as storage cells in some cars.
The electrolyte is sulfuric acid, one electrode is lead and the other is
lead(IV) oxide, PbO .
Question
Mathematics
Edexcel2022
As the cell discharges, the lead and the lead(IV) oxide are both converted to
solid lead(II) sulfate, PbSO , and the concentration of the sulfuric acid decreases.
Question
Mathematics
Edexcel2022
7 2
(i) Write the overall equation for the reduction of dichromate(VI) ions to
chromium(III) ions by zinc in acid conditions.
State symbols are not required.
(2)
(ii) Calculate Ed for the reaction in (c)(i).
cell
(1)
(iii) Predict whether or not a further reduction of chromium(III) ions to
chromium(II) ions will occur. Justify your answer.
(1)
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Question
Mathematics
Edexcel2022
7 2
Determine, using the experimental data, the brand of nail that was analysed.
(5)
Question
Mathematics
Edexcel2022
2
B 2H (g) + 2O (g) + 4e– → 4OH – (aq)
Question
Mathematics
Edexcel2022
2
C 4OH – (aq) → 2H (g) + 2O (g) + 4e–
Question
Mathematics
Edexcel2022
2
D 2H O(l) → 4H + (aq) + O (g) + 4e–
Question
Mathematics
Edexcel2022
*P67093RA0232*
PMT
Answer ALL questions.
Some questions must be answered with a cross in a box .
If you change your mind about an answer, put a line through the box
and then mark your new answer with a cross .
Question
Mathematics
Edexcel2022
This question is about the elements in Group 2 of the Periodic Table.
(a) Magnesium powder is added to a beaker of water containing a few drops of
Universal Indicator.
The apparatus is set up as shown and allowed to stand for a few days.
test tube filled with water
water and Universal Indicator
filter funnel
magnesium powder
State two changes that will be seen after a few days.
(2)
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(b) Explain how the trend in the reactivity of the Group 2 elements is determined by
their electronic configurations.
(3)
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Question
Mathematics
Edexcel2022
2
Explain, in terms of electrons, why this is a redox reaction.
(2)
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(d) An experiment was carried out to determine the molar volume of hydrogen at
room temperature.
Question
Mathematics
Edexcel2022
2
Calculate the molar volume of hydrogen from the results of this experiment.
Include units in your answer.
(2)
(Total for Question 2 = 9 marks)
Question
Mathematics
Edexcel2022
2
B Br (aq) + 2NaF(aq) → 2NaBr(aq) + F (aq)
Question
Mathematics
Edexcel2021
*P65463A0728*
Turn over
PPMMTT
(c) A sodium atom has 11 protons whereas a potassium atom has 19 protons.
Explain why the first ionisation energy of sodium is greater than that of potassium.
(3)
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Question
Mathematics
Edexcel2021
enthalpy change of hydration of Ca2+ –1577
enthalpy change of hydration of Br– –336
Calculate the lattice energy of calcium bromide.
(2)
(Total for Question 9 = 12 marks)
Question
Mathematics
Edexcel2021
This question is about acids and buffer solutions.
(a) Ethanoic acid, CH COOH, is a monobasic acid.
Question
Mathematics
Edexcel2021
This question is about lattice energies.
(a) The table shows the theoretical and experimental lattice energy values of
two compounds.
Theoretical lattice energy Experimental lattice energy
Compound
/ kJ mol–1 / kJ mol–1
magnesium iodide –1944 –2327
barium iodide –1831 –1877
(i) State what can be deduced by the close similarity of the lattice energy values
for barium iodide.
(1)
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(ii) Explain why there is a significant difference in the lattice energy values for
magnesium iodide.
(4)
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Question
Mathematics
Edexcel2021
*P65463A02528*
Turn over
PPMMTT
(ii) Calculate the lattice energy of copper(II) oxide.
(1)
(c) A different energy cycle can be used to calculate lattice energy.
Ca2+(g) + 2Br–(g) CaBr (s)
Question
Mathematics
Edexcel2020
(s) Mg2+(aq) + 2Cl−(aq)
Lattice energy MgCl (s) = −2526 kJ mol−1
Question
Mathematics
Edexcel2019
*P58306A0228*
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PMT
Answer ALL questions.
Some questions must be answered with a cross in a box .
If you change your mind about an answer, put a line through the box
and then mark your new answer with a cross .
Question
Mathematics
Edexcel2019
This question is about some redox reactions of chlorine, bromine and iodine.
(a) An excess of aqueous potassium bromide was added to chlorine water and the
solution turned orange.
(i) Write an equation for this reaction. State symbols are not required.
(1)
(ii) Silver nitrate solution was added to the mixture in (a) and excess
dilute ammonia solution was then added to the precipitate formed.
Only some of the precipitate dissolved.
Deduce why only some of the precipitate dissolved.
(3)
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(iii) Aqueous potassium bromide was added to aqueous iodine, instead of
chlorine water. There was no reaction.
Give a reason why no reaction occurred.
(1)
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Question
Mathematics
Edexcel2019
8 2 4
(i) Give a reason why the reaction between iodide ions and peroxodisulfate ions
has a high activation energy and is therefore very slow without a catalyst.
(1)
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(ii) Explain, with the aid of two equations, how the iron(II) ions catalyse this
reaction. State symbols are not required.
(3)
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(b) The oxidation of sulfate(IV) ions to sulfate(VI) ions is catalysed by cobalt(II) ions in
acidic solution. The role of cobalt(II) ions is similar to that of iron(II) ions in (a).
Co2+
SO2– + ½O (cid:127)(cid:111) SO2–
Question
Mathematics
Edexcel2019
B H +
C Mn 2+
D MnO –
Question
Mathematics
Edexcel2019
First ionisation energy of sodium
+496 kJ mol–1
Na(g) + ½H (g)
Question
Mathematics
Edexcel2019
The expression for the ionic product of water is
K = [H+(aq)] [OH–(aq)]
w
The value of K at 310 K is 2.40 × 10–14 mol2 dm–6
w
(i) Calculate the pH of water at 310 K.
Give your answer to two decimal places.
(2)
(ii) Predict, with a reason, whether water is acidic, alkaline or neutral at 310 K.
(2)
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(iii) Predict, with a reason, the sign of the enthalpy change for the ionisation of water.
(1)
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(Total for Question 6 = 15 marks)
Question
Mathematics
Edexcel2019
Enthalpy change of atomisation Lattice energy
of sodium of sodium –804 kJ mol–1
+107 kJ mol–1
hydride
Na(s) + ½H (g)
Question
Mathematics
Edexcel2019
Enthalpy change of formation
of sodium hydride –56 kJ mol–1
NaH(s)
(i) Identify and correct the two errors in this Born-Haber cycle.
(2)
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(ii) Calculate the first electron affinity, in kJ mol–1, of hydrogen, using the values
given in the cycle.
(1)
Question
Mathematics
Edexcel2019
f
The standard entropy change of the system, (cid:168)S , for this reaction is
system
–76.5 J K–1 mol–1.
(i) Deduce the feasibility of this reaction at 298 K by calculating the free energy
change, (cid:168)G.
(2)
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(ii) Calculate the temperature at which (cid:168)G = 0.
(1)
Question
Mathematics
Edexcel2019
2 2
In an alkaline fuel cell the oxidation half-equation is
H (g) + 2OH–(aq) (cid:111) 2H O(l) + 2e– 2 2
Deduce the reduction half-equation for the alkaline fuel cell.
State symbols are not required.
(1)
(d) Lattice energies provide an indication of ionic bond strength.
Which are the lattice energies of the hydrides NaH, KH and MgH ?
Question
Mathematics
Edexcel2019
(1)
Lattice energy / kJ mol–1
Sodium hydride, NaH Potassium hydride, KH Magnesium hydride, MgH
Question
Mathematics
Edexcel2019
A –804 –711 –1018
B –804 –711 –2718
C –804 –911 –1018
D –804 –911 –2718
(Total for Question 8 = 8 marks)
Question
Mathematics
Edexcel2019
3 3
Explain how this buffer system helps to control the pH of blood when extra
carbon dioxide is present due to strenuous exercise.
(3)
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Question
Mathematics
Edexcel2019
2 3
The composition of an equilibrium mixture at 698 K and a total pressure of
Question
Mathematics
Edexcel2019
40 atm is shown in the table.
Substance SO (g) O (g) SO (g)
Question
Mathematics
Edexcel2019
2 3
Number of moles /mol 0.0160 0.0120 0.772
(i) Calculate the value of K at this temperature.
p
Include units, if appropriate.
(5)
(ii) Calculate the number of sulfur dioxide molecules present in this equilibrium mixture.
(1)