Properties and Uses of Water

Chemistry Chapter 15

Hydrides

A compound in which hydrogen is

bonded to another element. HF, HCl and HI are

hydrides of group 17 elements

Surface Tension

The resistance of a liquid to increase its surface area.

Latent Heat

The heat energy required to change the state of a substance at a constant temperature.

Latent Heat of Fusion

The energy required to change a fxed amount of solid to liquid at its melting temperature. The latent heat of fusion of water is 6.0 kJ mol−1, meaning 6.0 kJ of energy is needed to change 1 mole of water from a solid to a liquid at 0°C.

Latent Heat of Vaporisation

The energy required to change a fxed amount of liquid to a gas at its boiling temperature. The latent heat of vaporisation of water is 44.0 kJ mol−1, meaning 44.0 kJ is needed to change 1 mole of water from a liquid to a gas at 100°C.

What physical properties make water unique?

-High B.P./M.P.

-High surface tension

-Lower solid density than liquid form

What allows a water moleule to form up to four hydrogen bonds with other molecules?

Two lone pairs of electrons

What is the overall direction of force experienced by a water molecule at the surface of a glass of water?

Down

What type of bonding is responsible for water’s

relatively high latent heat values?

Hydrogen bonding

Solute

A substance that dissolves in a solvent, e.g. sugar is the solute when it dissolves in water.

Solvent

A substance, usually a liquid, that is able to dissolve a solute to form a solution. Water is a very good solvent.

Dissolution

The process of dissolving a solute in a solvent to form a solution.

Hydrated

An ion surrounded by water molecules. Hydrated ions can be found in aqueous solutions or crystalline solids.

Ion-dipole force

The attraction that forms between dissociated ions and polar water.