Edexcel A Level Chemistry

Topic Questions

5.3 Energetics II: Born-Haber

1a1 mark

This question is about dissolving different compounds.

Which of these compounds is the most soluble in water?

  A barium sulfate
  B calcium sulfate
  C magnesium sulfate
  D strontium sulfate
1b1 mark

What is the value, in kJ mol−1, for the standard enthalpy change of solution of magnesium chloride?

q4b-9cho-al-1-nov-2020-qp-edexcel-a-level-chem

Lattice energy MgCl2 (s) = −2526 kJmol−1
Hydration enthalpy of Cl (g) = − 381 kJmol−1
Hydration enthalpy of Mg2+ (g) = −1921 kJmol−1

  A +157
  B −157
  C +224
  D −224

1c6 marks

The solubility of two compounds in different solvents was investigated.
A summary of the findings is shown.

Compound Soluble in water Soluble in hexane
2-methylpentane straight x
potassium bromide x


Explain the findings of the investigation by considering the interactions between the compounds and each of the solvents.

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2a5 marks

This question is about ions and ionic compounds.

The first three ionisation energies of calcium are shown in the table.

  First ionisation Second ionisation  Third ionisation
Ionisation energy / kJ mol−1 590 1145 4912
Orbital      

i)
Complete the table by identifying the specific orbital from which each electron is removed.

(2)

ii)
Write the equation for the third ionisation energy of calcium.
Include state symbols.

(1)

iii)

Explain why the difference between the second and third ionisation energies of calcium is much larger than the difference between the first and second ionisation energies.

(2)

2b
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1 mark

The diagram, which is not drawn to scale, shows the Born-Haber cycle for lithium fluoride. The energy changes are given in kJ mol−1.

q8b-9cho-al-1-june-2018-qp-edexcel-a-level-chem

What is the value for Y, in kJ mol−1?

  A −273
  B −343
  C −432
  D −889
2c6 marks

The table shows the theoretical and experimental lattice energy values of two compounds.

Compound Theoretical lattice energy
/ kJ mol−1
Experimental lattice energy
/ kJ mol−1
lithium chloride, LiCl −845 −848
magnesium iodide, MgI2 −1944 −2327

Comment on the theoretical and experimental lattice energy values, giving the reasons for any differences and similarities.

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3a5 marks

This question is about lattice energies.

The table shows the theoretical and experimental lattice energy values of two compounds.

Compound Theoretical lattice energy
/ kJ mol–1
Experimental lattice energy / 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)

ii)
Explain why there is a significant difference in the lattice energy values for magnesium iodide.

(4)

3b
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5 marks

Data for the Born-Haber cycle for copper(II) oxide are given in the table.

Label Energy change Value / kJmol–1
A standard enthalpy change of atomisation of copper +338
B standard enthalpy change of atomisation of oxygen +249
C sum of first and second ionisation energies of copper +2704
D first electron affinity of oxygen –141
E second electron affinity of oxygen +798
F standard enthalpy change of formation of copper(II) oxide –157


i)

Complete the diagram of the Born-Haber cycle for copper(II) oxide.

Include labels of enthalpy changes with arrows indicating the direction of change, and the respective species with state symbols.

(4)

q9bi-9cho-al-1-oct-2021-edexcel-a-level-chem

ii)
Calculate the lattice energy of copper(II) oxide.

(1)

3c
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2 marks

A different energy cycle can be used to calculate lattice energy.

q9c-9cho-al-1-oct-2021-edexcel-a-level-chem

Enthalpy change Value / kJmol–1
enthalpy change of solution of CaBr2 –73
enthalpy change of hydration of Ca2+ –1577
enthalpy change of hydration of Br –336

Calculate the lattice energy of calcium bromide.

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