Melting 100 g of ice takes in 33 kJ of energy.
Boiling 100 g of water takes in 226 kJ of energy.
Which statement explains why boiling takes in much more energy than melting?
Boiling breaks covalent bonds, but melting only overcomes intermolecular forces.
Liquid water molecules are further apart than in ice, so the forces between them are stronger.
Boiling separates the molecules completely, so more intermolecular forces are overcome.
Boiling happens at a higher temperature, so the covalent bonds in water are weaker.
60 exam-style questions on OCR GCSE Chemistry 2.3 Properties of materials, covering 2.3.1 Carbon bonding and the variety of organic compounds, 2.3.2 Diamond, graphite, fullerenes and graphene, 2.3.3 Bond strength, changes of state and predicting states, 2.3.4 Bulk properties and types of bonding, and 2.3.5 Nanoparticles: scale, surface area, uses and risks. Each one has a worked solution and a mark scheme showing where the marks go.