Water

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 1 1 1 1 1 2 6 1 5 2 3 4 -

Water Basics H+ H+ O- O- H+ O- H+ H+ O- O- H+ H+ O- O- 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 H+ O- H+ O- H+ O- Hydrogen bond H+ O- H+ O-

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

It takes a lot of energy to change water’s temperature Water Properties High specific heat: Resists temp changes Much energy needed to break water bonds It takes a lot of energy to change water’s temperature

Water Properties High specific heat: Resists temp changes Much energy needed to break water bonds Helps to maintain a constant body temp The weight of our bodies is mostly water. Our body temperature doesn’t change much even when we exercise. If our temperature changes too much, we feel sick.

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 Why can this this paper clip stay on top of water? It is not heavy enough to break the hydrogen bonds that hold the water molecules together.

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 meniscus 35 29 ml 25 25 ml 15 5

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 Crystal light… Kool-aid… Country Time Lemonade…

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… Plasma WBCs & Platelets RBCs

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 Acid Base neutral Blood 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?