Water H H O

Water Basics + + Polar: part of a molecule is slightly positive, while another part is slightly negative Oxygen “hogs” electrons from hydrogen 8 protons: 10 electrons Negative charge Hydrogen 1 proton: 0 electrons Positive charge Creates hydrogen bonds where one water sticks to another 1 1 1 1 1 2 6 1 5 2 3 4 -

Red = Oxygen (negative) White = Hydrogen (positive) - - - - - - - - - + + + + + + + + + + + + + + + + + + - - - - - - - - + + + + + + + + + + + + + + + + + + - - - - - - - - - + + + + + + + + + + + + + + + + + +

Water Properties High specific heat: Resists temp changes Much energy needed to break water bonds Helps to maintain a constant body temp Cohesion: polar water molecules attracted to other polar water molecules Adhesion: polar water sticks to other molecules 7ml 6.8ml Why can this insect walk on water? It is not heavy enough to break the bonds that hold the water molecules together.

Solutions Solution: mixture where 1 substance dissolves in another 2 parts to a solution 1) Solute: substance that dissolves Atoms, ions, molecules 2) Solvent: substance in which the solute is dissolved Usually water Solution S U G A R K O O L A I D

Solutions Solution: mixture where 1 substance dissolves in another 2 parts to a solution 1) Solute: substance that dissolves Atoms, ions, molecules 2) Solvent: substance in which the solute is dissolved Usually water Ex: Human blood Solvent: Plasma (watery part of blood) Solutes: Carbs, proteins, sugars, etc…

pH Scale pH scale measures the amount of H+ ions in a solution Acid Base More H+ Few H+ neutral Few OH- More OH- Lemons Soft drink Milk Blood Baking soda Ammonia pH scale measures the amount of H+ ions in a solution 1 minute: Discuss with your neighbor: Which base has the most H+ ions? Which substance has the fewest H+ ions? Which is the strongest acid? blood Ammonia Lemons

pH Scale pH scale measures the amount of H+ ions Some molecules release H+ ions when dissolved H+ ions accumulate (acids) Acidic solution Substance A H+ H+ H+ H+ H+ H+ H+ H+ H+

pH Scale pH scale measures the amount of H+ ions Some molecules release H+ ions when dissolved H+ ions accumulate (acids) Some molecules release OH- ions when dissolved OH- ions accumulate (bases) Basic (alkaline) solution OH- OH- OH- Substance B OH- OH- OH- OH- OH- OH-

pH Scale pH scale measures the amount of H+ ions Some molecules release H+ ions when dissolved H+ ions accumulate (acids) Some molecules release OH- ions when dissolved OH- ions accumulate (bases) pH balance vital to life Ex: Blood pH (7.4): Proteins break down outside normal pH

Blood pH Normally: Balance of H+ and OH- ions in blood (7.4 pH) Alcohol abuse: Excess alcohol lowers blood pH (H+ ions accumulate) Kidney removes excess H+ Can lead to kidney damage

Review 1) Vocabulary: Polar, Adhesion, Cohesion, High Specific Heat, Solution, Solute, Solvent, pH 2) Name 4 basic features of water. 3) Which water property explains that one atom is positively charged, while another is negatively charged? 4) How does cohension and adhesion differ? 5) Which is a stronger acid? Substance A with a pH of 5 or substance B with a pH of 3? 6) Which has more H+ ions? Substance A with a pH of 5 or substance B with a pH of 3? 7) Which has more OH- ions? Substance A with a pH of 5 or substance B with a pH of 3? 8) How does a solute differ from a solvent? 9) What is the solute and solvent of blood?