The Extraordinary Properties of Water

Water is the ONLY compound that commonly exists in all 3 phases (solid, liquid, gas) on Earth. There would be no life on Earth without water.

A large number of substances will dissolve in water. Dissolve - A solid becoming incorporated into a liquid so as to form a solution

SOLVENT- the substance that does the dissolving. (liquid) SOLUTE- the substance that is dissolved. (solid) SOLUTION- a homogeneous mixture of a solvent and a solute

Water is the universal solvent. Most things will dissolve in water So water solutions can contain and deliver most type of essential materials to living cells

In fact, ‘water’ is very rarely pure H 2 O Pure H 2 O never occurs in nature Water’ almost always contains many types of dissolved substances like: Salt Bromine Nitrates Calcium Magnesium Sulfates Iron Sodium Potassium

Water A water molecule (H 2 O), is made up of three atoms --- one oxygen and two hydrogen. H H O

Water is a Polar molecule What is a ‘polar’ molecule? Polar molecule - a molecule that has more electrons at one side than the other. This means that one end has more negative charges than the other!

Water is Polar In each water molecule, the oxygen atom attracts more than its "fair share" of electrons The oxygen end “acts” negative The hydrogen end “acts” positive Causes the water to be POLAR

However, keep in mind that the complete water molecule is neutral (equal number of e- and p+) It’s just that the electrons are not evenly distributed!

So, what’s the big deal? Remember that opposite charges attract……like magnets

The negative oxygen end of one water molecule is attracted to the positive hydrogen end of another water molecule to form a HYDROGEN BOND

Hydrogen Bonds Formed between a negative side of one polar molecule and a positive side of another polar molecule Hydrogen Bond

Hydrogen Bonds So hydrogen bonds do not create molecules, they are simply connections between molecules Hydrogen Bond

One hydrogen bond is weak, but many hydrogen bonds are strong

The hydrogen bonds between all of the water molecules cause water to have special properties

What are the Properties of Water?

Cohesion Properties of Water

Cohesion Adhesion

Properties of Water Cohesion Adhesion High Specific Heat

Properties of Water Cohesion Adhesion High Specific Heat High Heat of Vaporization

Properties of Water Cohesion Adhesion High Specific Heat High Heat of Vaporization Less Dense as a Solid

Cohesion Attraction of water to itself Results in water droplets and surface tension

Cohesion Surface tension - water produces a surface film on water that allows light substances to lay on top of water

Cohesion … Helps insects walk across water

Adhesion Attraction between two different substances. Water will make hydrogen bonds with other surfaces (not itself) such as glass, soil, plant tissues, and cotton.

Adhesion Causes Capillary Action Which gives water the ability to “climb” structures like straws and paper towels

Capillary action – also the cause of the transpiration process which plants and trees remove water from the soil and up into the leaves.

Adhesion Also Causes Water to … Hold onto plant leaves Attach to a silken spider web

Water to water Water to something else

High Specific Heat Amount of heat needed to raise or lower 1g of a substance 1° C. Water resists a change in temperature, both for heating and cooling. Water can absorb or release large amounts of heat energy with little change in actual temperature.

As a result, lakes and oceans stabilize air and land temperatures. Large bodies of water can affect the climate.

High Heat of Vaporization Amount of energy needed to convert 1g of a substance from a liquid to a gas In order for water to evaporate, hydrogen bonds must be broken. As water evaporates, it removes a lot of heat with it (cooling effect)..

Sweating The skin

Water is Less Dense as a Solid Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

Water is Less Dense as a Solid Which is ice and which is water?

Water is Less Dense as a Solid WaterIce

For most substances, solids are more dense than liquids. But the special properties of water make it less dense as a solid - ice floats on water!

All of these properties allow water to be huge factor in living things maintaining Homeostasis HOW?

Homeostasis Water is important to homeostasis because: a. Makes a good insulator b. Resists temperature change c. Universal solvent d. Coolant

Water is the Universal solvent because MOST things dissolve in water……but not ALL things Water is only a solvent for substances that are also polar (have an unequal electrical charge)

If a substance has an even distribution of electrical charge and is NON polar then it will NOT dissolve in water.

Polar things mix/dissolve with Polar things Nonpolar things mix/dissolve in Nonpolar things And nonpolar does NOT mix with water!

how to describe a non polar substance that does not mix with water (water afraid) Hydrophobic how to describe a polar substance that will mix with water (water loving) Hydrophilic

Hydrophobic Hydrophilic