Water

● There is the same amount of water on Earth as there was when the Earth was formed. The water from your faucet could contain molecules that dinosaurs drank. ● Nearly 97% of the world’s water is salty or otherwise undrinkable. Another 2% is locked in ice caps and glaciers. That leaves just 1% for all of humanity’s needs — all its agricultural, residential, manufacturing, community, and personal needs. Water Facts

● Water regulates the Earth’s temperature. It also regulates the temperature of the human body, carries nutrients and oxygen to cells, cushions joints, protects organs and tissues, and removes wastes. ● 75% of the human brain is water and 75% of a living tree is water. ● A person can live about a month without food, but only about a week without water. ● Water expands by 9% when it freezes. Frozen water (ice) is lighter than water, which is why ice it floats in water.

Water Water is a compound Formula –H 2 O (2 Hydrogen and 1 Oxygen)

Why is water unique? Hydrogen Bonds-Polarity, High Specific heat, cohesion, adhesion

Polarity Polarity allows water to be the perfect solvent –Water can dissolve many things –No other liquid can come close to being able to dissolve as many thing as water can –Because of this, water is nearly always carrying something else along with it

Hydrogen bonds High specific heat- resists changes in temperature Cohesion- water sticks to itself causing surface tension Adhesion- water sticks to other things, meniscus, capillary action Capillarity- water travels upward through small tubes due to adhesion and cohesion

Other Special Qualities Water is the only naturally occurring compound on Earth that can be found in all three physical states When water freezes it floats –Extremely unique property –Contracts as it cools until it hits 4° C when it expands again

Why does Water Expand into Ice?

Diffusion Diffusion-The movement of particles from areas of high concentration to areas of low concentration Examples –Perfume bottle –Cookies in the oven –Kool-Aid

What diffusion looks like hill.com/sites/ /student_view0/c hapter2/ hill.com/sites/ /student_view0/c hapter2/animation__how_diffusion_works.ht ml hill.com/sites/ /student_view0/c hapter2/animation__how_diffusion_works.ht ml

Solutions Mixture- a blend of substances that is not equal throughout (heterogeneous) Solvent + Solute = Solution Solvent- Liquid capable of dissolving other substances Solute- substance being dissolved Solution- a mixture of substances that is equal throughout (homogeneous)

Mixtures

Solutions + = SolventSolutionSolute

Osmosis Osmosis-Diffusion of water molecules, usually involving a semi-permeable membrane Concentration Gradient- difference in concentration from one side of membrane to the other Equilibrium-the same everywhere Remember water always moves from areas of high water concentration to areas of low water concentration

Osmosis hill.com/sites/ /student_view 0/chapter2/animation__how_osmosis_w orks.html

The tonics of life Isotonic-Concentration of solutes is the same in solution and cell. Hypertonic-Concentration of solutes is higher in the solution. Hypotonic-Concentration of solutes is lower in the solution.