Properties of Water

Hydrogen Bonding in H2O H-bonding is especially strong in water because the O—H bond is very polar there are 2 lone pairs on the O atom Accounts for many of water’s unique properties.

Less Dense as a Solid Ice has open lattice-like structure. Ice density is < liquid. And so solid floats on water. Snow flake: www.snowcrystals.com

Less Dense as a Solid Ice has open lattice-like structure. Ice density is < liquid and so solid floats on water. PLAY MOVIE One of the VERY few substances where solid is LESS DENSE than the liquid.

High Specific Heat H bonds lead to abnormally high specific heat capacity of water (4.184 J/g•K) This is the reason water is used to put out fires, it is the reason lakes/oceans control climate, and is the reason thunderstorms release huge energy.

Abnormally High Boiling Point H bonds leads to abnormally high boiling point of water. PLAY MOVIE See Screen 13.7

High Surface Tension Molecules at surface behave differently than those in the interior. Molecules at surface experience net INWARD force of attraction. This leads to SURFACE TENSION — the energy req’d to break the surface.

Surface Tension SURFACE TENSION also leads to spherical liquid droplets.

Liquids concave meniscus ADHESIVE FORCES between water and glass H 2 Intermolec. forces also lead to CAPILLARY action and to the existence of a concave meniscus for a water column. concave meniscus ADHESIVE FORCES between water and glass H 2 O in glass tube COHESIVE FORCES between water molecules

Universal Solvent When an ionic or polar compound enters water, it is surrounded by water molecules. The relatively small size of water molecules typically allows many water molecules to surround one molecule of solute. Many substances dissolve in water and it is commonly referred to as the universal solvent.

5 properties of water Unexpectedly high boiling point High specific heat Density of solid High surface tension Universal solvent