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 without electrons 1 proton: 0 electrons Positive charge Creates hydrogen bonds where one water sticks to another

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

Water Properties Energy needed to break H bonds High specific heat: Resists temp changes Helps to maintain a constant body temp Cohesion: polar water molecules attracted to other polar water molecules (see bug picture) Adhesion: polar water sticks to other molecules

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

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

1) Name 4 basic features of water. 2) Which water property explains that one atom is positively charged, while another is negatively charged? 3) How does cohension and adhesion differ? 4) Which is a stronger acid? Substance A with a pH of 5 or substance B with a pH of 3? 5) Which has more H+ ions? Substance A with a pH of 5 or substance B with a pH of 3? 6) Which has more OH- ions? Substance A with a pH of 5 or substance B with a pH of 3?