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Class 11  »  Chemistry  »  Chemical Bonding and Molecular Structure

Ionic Bond Lattice Energy Born Haber Cycle - UNSOLVED PRACTICE SET

Class 11

Chapter: Chemical Bonding and Molecular Structure | Topic: Ionic Bond Lattice Energy Born Haber Cycle

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Class 11

IONIC BOND LATTICE ENERGY BORN HABER CYCLE - UNSOLVED PRACTICE SET

Topic: Ionic Bond Lattice Energy Born Haber Cycle

Time: 40 mins | Marks: 30 | Difficulty: Medium

Multiple Choice Questions

Q1. An ionic bond is formed between:

  1. Two atoms with similar electronegativities
  2. A metal and a non-metal with large electronegativity difference
  3. Two non-metals
  4. Two noble gases

Q2. Lattice energy is defined as:

  1. The energy required to break one mole of an ionic compound into gaseous ions
  2. The energy released when one mole of an ionic compound is formed from gaseous ions
  3. The energy required to melt one mole of an ionic solid
  4. The energy released when electrons are transferred

Q3. The Born-Haber cycle is used to calculate:

  1. Bond energy of covalent bonds
  2. Lattice energy of ionic compounds
  3. Enthalpy of vaporization
  4. Ionization energy

Q4. Which factor does NOT affect lattice energy?

  1. Charge on the ions
  2. Size of the ions
  3. Colour of the compound
  4. Inter-ionic distance

Q5. The lattice energy of NaCl is more negative than that of KCl because:

  1. Na⁺ is smaller than K⁺
  2. Na⁺ is larger than K⁺
  3. Cl⁻ is different in both
  4. NaCl has covalent character

Q6. In the Born-Haber cycle for NaCl, the step involving electron gain enthalpy corresponds to:

  1. Na(g) → Na⁺(g) + e⁻
  2. Cl(g) + e⁻ → Cl⁻(g)
  3. Na(s) → Na(g)
  4. Na⁺(g) + Cl⁻(g) → NaCl(s)

Short Answer Questions

Q7. Define ionic bond. What are the essential conditions for the formation of an ionic bond? 

Q8. What is lattice energy? How does it depend on the charge and size of ions?

Q9. Write the Born-Haber cycle for the formation of NaCl(s) from its elements, naming each step.

Q10. Why is the lattice energy of MgO much higher than that of NaCl?

Q11. Your grandmother stores pickles in ceramic jars rather than metal containers. She explains that salt (NaCl) in the pickle brine would react with metal. Using the concept of ionic bonding and lattice energy, explain why NaCl dissolves easily in water but is extremely stable as a solid crystal.

Q12. Why do ionic compounds have high melting and boiling points?

Long Answer Questions

Q13. Explain the formation of an ionic bond with a suitable example. Describe the factors that influence the formation of ionic bonds. How does Fajans' rule explain the partial covalent character in some ionic compounds? Illustrate with examples.

Q14. Describe the Born-Haber cycle for the formation of an ionic compound (take MgCl₂ as an example). Identify all the enthalpy changes involved and show how lattice energy can be calculated using Hess's law. Why is the experimental determination of lattice energy difficult, making the Born-Haber cycle so valuable?

Q15. During a chemistry project, your team is asked to compare the properties of NaCl, MgO, and Al₂O₃.

(a) Arrange these compounds in order of increasing lattice energy. Explain your reasoning based on ionic charges and radii.

(b) Which compound would you expect to have the highest melting point? Why?

(c) Why does Al₂O₃ find use as a refractory material in furnace linings, while NaCl does not?

(d) A student claims that since all three are ionic compounds, they should all be equally soluble in water. Is this claim correct? Explain using the concept of lattice energy vs. hydration energy.

Numerical / Application-Based Problems

Q16. The lattice energy of NaCl is −788 kJ/mol. Given the following data for the Born-Haber cycle:

Enthalpy of sublimation of Na = 108 kJ/mol

Ionization energy of Na = 496 kJ/mol

Dissociation energy of Cl₂ = 243 kJ/mol

Electron gain enthalpy of Cl = −349 kJ/mol

(a) Calculate the enthalpy of formation of NaCl(s).

(b) Draw a schematic Born-Haber cycle showing all the steps with their values.

(c) Why is the enthalpy of formation negative despite several endothermic steps?

Q17. Compare the lattice energies of the following ionic compounds:

(a) NaF and NaI

(b) MgO and NaCl

(c) CaCl₂ and KCl

For each pair, predict which has the higher lattice energy and calculate the approximate ratio using the formula: Lattice energy ∝ (Z⁺ × Z⁻)/r₀

(Ionic radii: Na⁺ = 95 pm, K⁺ = 133 pm, Mg²⁺ = 72 pm, Ca²⁺ = 100 pm, Cl⁻ = 181 pm, F⁻ = 136 pm, I⁻ = 216 pm, O²⁻ = 140 pm)

Q18. The Born-Haber cycle for MgO involves the following steps:

Enthalpy of atomization of Mg = 148 kJ/mol

First ionization energy of Mg = 738 kJ/mol

Second ionization energy of Mg = 1450 kJ/mol

Enthalpy of atomization of O₂ = 249 kJ/mol (for ½O₂)

First electron gain enthalpy of O = −141 kJ/mol

Second electron gain enthalpy of O = +744 kJ/mol

Lattice energy of MgO = −3890 kJ/mol

(a) Calculate the enthalpy of formation of MgO(s).

(b) Why is the second electron gain enthalpy of oxygen positive, unlike the first?

(c) Compare the magnitude of the lattice energy of MgO with NaCl (−788 kJ/mol). What does this difference tell you about the relative hardness and melting points of these compounds?


Total: 30 Marks | Time: 40 mins

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