1. Water essential for life (as we know it!) any other chemical with this low of a molecular weight = GAS (but it’s a liquid at room temp!) b/c of it’s polarity, it tends to stick to itself COHESION b/c of it’s polarity, it tends to stick to other stuff ADHESION

4. Temperature b/c H 2 O molecules are so strongly attracted to each other, it requires quite a bit of heat to disrupt those bonds  H 2 O can absorb a lot of heat and the temperature doesn’t change too much converse is true as well moderates temperature on land moderates temperature in your body – sweatingfever

5. Cohesion b/c of H+ bonds, H 2 0 has a HIGH surface tension – water striders

6. Adhesion b/c of H+ bonds, H 2 0 has a HIGH surface tension – meniscus in glass containers http://www.chemistryland.com/CHM151W/04-Solutions/liquids/meniscus.jpg

7. States of Matter solid: electrons moving slowly liquid: electrons moving faster gas: electrons moving FAST!! usually when a substance solidifies, it shrinks: the atoms move more closely together NOT H 2 O: expands b/c H bonds form rigid structure holding each molecule apart

8. so? b/c of this, solid H 2 O (aka. ice) is less dense than liquid H 2 O so? floats on top of body of water (prevents them from freezing solid-insulation) pop can explodes in freezer (you’re in trouble now!)

10. Like dissolves Like polar substances dissolve in polar solvents means they get shells of hydration! Solution = solute + solution – in us, solution = H 2 O non-polar substances DO NOT dissolve in polar solvents

11. Forms shells of hydration! http://web.virginia.edu/Heidi/chapter2/chp2.htm

14. pH water is constantly moving; a certain percentage of those molecules break up – ions are formed: H + OH - – have equal amounts of each type of ion some compounds release only H + some compounds release only ions that can accept H + (negatively charged)

15. pH ACID: compound that releases H + – strong: throw it in H 2 O and it dissolves completely – weak: throw it in H 2 O, some dissolves, some doesn’t BASE: compound that accepts H + – strong: throw it in H 2 O and it dissolves completely – weak: throw it in H 2 O, some dissolves, some doesn’t p = -log of H = hydrogen

16. pH pH scale tells you number of H+ ions present pH = 0 (pure H + ) pH = 1 (10 x fewer H + ) pH = 2 (10 x fewer H + ) b/c pH = -log, you get stronger (more H + ions) as the number gets lower

18. Figure 2.14_1 Increasingly ACIDIC (Higher H  concentration) Tomato juice pH scale Battery acid Lemon juice, gastric juice Vinegar, cola NEUTRAL [H  ]  [OH  ] Rainwater Human urine Saliva Pure water

19. pH pH gets higher = fewer and fewer H + so pH of 14 = safe, right? – NO!! 7 is neutral: = number of H + and ion that can accept H + as you go up the scale, the amount of ions that can accept H + increases (becomes basic or alkaline) (10 x diff. between each #)

20. Figure 2.14_2 Oven cleaner Increasingly BASIC (Higher OH  concentration) NEUTRAL [H  ]  [OH  ] Household bleach Household ammonia Milk of magnesia Pure water Human blood, tears Seawater pH scale

21. Figure 2.14_3 Acidic solution Neutral solution Basic solution

22. Buffer: minimizes Δs in pH buffers accept H + when it is high buffers donate H + when it is low keeps pH in a stable position buffers in your blood keep you from dying when your body produces a lot of acids