WATER PROPERTIES

Water has unique properties

• It is made of molecules.• Each molecule is made up of one atom of

oxygen and two atoms of hydrogen.

The main properties

• Density and dilation. The density of the ice is lower than the density of the water. Ice floats on water.

• A powerful solvent. It can dissolve many solvents.– Can water dissolve grease, oil?– Can water dissolve gases such as oxygen and

carbon dioxide?

• It has a high specific heat. Water does not get hot or cold easily. – Water is an ideal substance to absorb and

accumulate heat.– Water moderates the Earth´s climate.

• Cohesion• Adhesion• Surface tension• Capillarity

Adhesion and cohesion• Cohesion: Water is attracted to water.

• The water drop is composed of water molecules that like to stick together

Adhesion: Water is attracted to other substances

• Water drops on pine needles, showing the effects of gravity, adhesion, and cohesion on water.

Cohesion is seen in the actual water drop—the water molecules stick to each other, forming a drop.Property of gravity, which is causing the water drops to roll along the pine needle. Property of adhesion is holding them, at least for now, to the pine needle.

• Cohesion makes a water drop a drop– The drop seems to have a "skin" holding it – It turns out that this surface tension is the result of the tendency of water molecules to attract one another. 

Capillarity action

• Capillary action seen as water climbs to different levels in glass tubes of different diameters.

• The movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension.

• Plants and trees couldn't survive without capillary action (adhesion and cohesion forces)

Surface tension

• Floating paper clip made of steel The high surface tension helps the paper clip - with much higher density - float on the water.

• the cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension.

• Walking on water: Small insects such as the water strider (pondskater) can walk on water because their weight is not enough to penetrate the surface.

• Don't touch the tent!: Common tent materials are somewhat rainproof 

• But if you touch the tent material with your finger, you break the surface tension and the rain will drip through.