AS-Level Chemistry Chapter 4 Chemical Bonding The Peculiar Properties of Water

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The Peculiar Properties of Water

1) Solid ice is less dense than liquid water

- Most solids are denser than their liquids, this is because in the solid state, the molecules are packed closer and occupies smaller volume.

- However, solid ice is less dense than liquid water.

- This is because in the solid state, the water molecules are bonded to each other through hydrogen bonding to form a giant 3-dimensional tetrahedral structure. This structure has a lot of empty spaces in between the water molecules.

- When heat is supplied, some of the hydrogen bond breaks down and the rigid structure collapses, filling up the spaces in between them, thus decreasing the volume occupied and increasing its density.

2) Solubility of substances in water

- Most covalent compounds are not soluble water while ionic compounds are. - However, some covalent compounds are soluble in water because they can form hydrogen bonds with water, some examples are ammonia and alcohols

3) High boiling point of water

- The boiling point of water is exceptionally high compared to other Group 16 hydrides

- This is because water molecules are capable of forming hydrogen bonds between themselves. This additional type of intermolecular forces increases its boiling point significantly.

4) High surface tension and viscosity

- Water has a high viscosity. This is because hydrogen bonding reduces the ability of water to slide over each other, making it more viscous.

- Water has a high surface tension. This is because hydrogen bonds also exert a significant downward force at the surface of liquid.