2.2 Properties of Water KEY CONCEPT Water’s unique properties allow life to exist on Earth.

2.2 Properties of Water FYI Pour yourself a glass of water and you could be drinking some of the same molecules that passed through the lips of Julius Caesar, Joan of Arc, Martin Luther King, or Adolf Hitler. Indeed, since the human body is about 60 percent water you might even be drinking a tiny part of one of those people!

2.2 Properties of Water FYI Water is one of the most amazing things about Earth—without it, there would be no life and our planet would be a completely different place—and one of the truly amazing things about water is that it's never used up: it's just recycled over and over again, constantly moving between the plants, animals, rivers, and seas on Earth's surface and the atmosphere up above

2.2 Properties of Water Why is Water necessary to Living Things? FYI % of your body is made of H 2 O water 2/3 of the molecules in your body are H 2 O molecules Your body’s cells are filled with H 2 O

2.2 Properties of Water Why is Water necessary to Living Things? - FYI H 2 O is the medium (stuff) in which most cellular events take place. Your cells are surrounded by H 2 O H 2 O helps move nutrients (food) and other substances into and out of your cells.

2.2 Properties of Water PROPERTIES OF WATER 2.2

2.2 Properties of Water 1. H 2 O Storages Energy stores heat more slowly retains this energy longer Many organisms release heat through water evaporation. –Humans cool by sweating. –Part of the homeostasis process

2.2 Properties of Water O HH _ Water is a polar molecule. –Polar molecules have slightly charged regions. –Hydrogen bonds form between the –slightly positive hydrogen atoms and the –slightly negative oxygen atom. (a weak attraction)

2.2 Properties of Water 3. Cohesion The attraction between substances of the same kind. –Causes (surface tension) -A skin or film on the surface of water -drops

2.2 Properties of Water 4. Adhesion The attraction between different substances e.g. Capillary action -H 2 O molecules move upward through a narrow tube. -The attraction to the wall of the tube sucks the H 2 O up more strongly than gravity pulls it down.

2.2 Properties of Water Capillary Action - Adhesion Adhesion Cohesion

2.2 Properties of Water 5. Dissolves many different substances Makes solutions!

2.2 Properties of Water Solution Vocabulary –Solution: a homo geneous mixture (evenly mixed) –Solvents: dissolve other substances. (e.g. water) –Solutes: dissolve in a solvent. (e.g. sugar, salt)

2.2 Properties of Water 5. Dissolves many different substances A solution is formed when –one substance dissolves in another. solution

2.2 Properties of Water solution Ionic compounds and polar molecules dissolve best in water

2.2 Properties of Water “Like dissolves like.” –Polar solvents dissolve polar & ionic solutes. –(water & salt) –Non-polar solvents dissolve non-polar solutes. –(oil & enzymes)

2.2 Properties of Water –Non-polar molecules are “shoved” together (clump) when put in a polar solvent. (oil & water)

2.2 Properties of Water Acids & Bases

2.2 Properties of Water FYI The pH of a liquid is –the presence of Hydrogen ions. H+

2.2 Properties of Water Draw this in your notebook A number line from 0 to 14 At the number 7 write “neutral – H 2 O. 1 – 6 is an acid is a base Remember in ABC or Acid comes before Base

2.2 Properties of Water A neutral solution has a pH of 7. pure water pH 7

2.2 Properties of Water Acids release a H+ ion when it dissolves in water. –pH less than 7 more acidic stomach acid pH between 1 and 3

2.2 Properties of Water A base removes H+ ions from a solution. –low H + concentration –pH greater than 7 bile pH between 8 and 9 more basic.

2.2 Properties of Water Differences in Acids and Bases in Solutions FYI Acids Tastes Sour Turns litmus paper red Reacts with some metals to give off hydrogen gas Bases Tastes bitter Turns litmus paper blue Feels slimy or slippery to the touch.

2.2 Properties of Water Table 1. The pH Scale: Some Examples pH Value H + Concentration Relative to Pure Water Example battery acid sulfuric acid lemon juice, vinegar orange juice, soda tomato juice, acid rain 5100black coffee, bananas 610urine, milk 71pure water 80.1sea water, eggs 90.01baking soda Great Salt Lake, milk of magnesia ammonia solution soapy water bleach, oven cleaner liquid drain cleaner FYI