The physical properties of ionic substances
2 marks · HardExplain, in terms of the forces present, why ionic compounds such as sodium chloride have high boiling points.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Also accept: Strong electrostatic forces between ions must be overcome, requiring a large amount of energy.; There are strong attractions between oppositely charged ions in the lattice so a lot of energy is needed to separate them.
Common mistakes: Forgetting to mention oppositely charged ions.; Vague statements about strong bonds without reference to forces.
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Identifies strong electrostatic forces of attraction between oppositely charged ions.
A1 · 1 mark · States that a large amount of energy is needed to overcome these forces (linked to boiling point).
Worked solution
Ionic compounds have high boiling points because there are strong electrostatic forces of attraction between oppositely charged ions in the giant lattice structure.
A large amount of energy must be supplied to overcome these forces, so the boiling point is high.