Chemical Properties of water Chapter 6

Remember  Cornell Notes! Con/def/quesNts/Ans

Observations Beaker 1 before: Beaker 1 before: –Write observation Beaker 1 after: Beaker 1 after: –Write observation Why??? Why???

Water Cycle Draw out the water cycle: Draw out the water cycle: –Include the following: Condensation Condensation Evaporation Evaporation Precipitation Precipitation Transpiration Transpiration Uptake Uptake Percolation Percolation p. 6-4

Polarity What is the empirical formula for water What is the empirical formula for water –H2O–H2O–H2O–H2O Structural formula? Structural formula? – O H-O bond called Covalent Bond H-O bond called Covalent Bond –Atoms sharing electrons –Very stable molecules Lopsided: Lopsided: –O atom attracts the shared electrons to its large nucleus –Hydrogen positives towards outside –Like a magnet! Such positive and negative charged ends is called polarity and are found in polar molecules Such positive and negative charged ends is called polarity and are found in polar molecules HH

Polarity con’t Hydrogen bonds: Hydrogen bonds: –Definition –Picture (6-7 figure) Dipolar molecules Dipolar molecules –Definition –Picture (6-6)

Effects of Hydrogen bonding 1. Liquid Water: Bonds hold molecules together  more energy needed to form gas.Bonds hold molecules together  more energy needed to form gas. Draw picture (not in book!)Draw picture (not in book!) 2. Cohesion/Adhesion: Water molecules stick together (cohesion – sticking together) Gives more organized structure then most liquids Also sticks to other surfaces (adhesion – sticking to different) Draw picture (not in book!) Essential to the properties of water.

Effects of Hydrogen Bonding Con’t 3. Viscosity: Fluid (g or l) resisting flowFluid (g or l) resisting flow Changes by temperatureChanges by temperature Example: oil in cool vs. hot panExample: oil in cool vs. hot pan Water: more viscosityWater: more viscosity Cools: viscosity rises more than other liquids  H bonds resist heat moving molecules Cools: viscosity rises more than other liquids  H bonds resist heat moving molecules Important?: Important?: cool waters, high viscosity, drifting aquatic animals use less energy to keep from sinkingcool waters, high viscosity, drifting aquatic animals use less energy to keep from sinking Swimming animals use more energy moving through itSwimming animals use more energy moving through it Draw Picture!Draw Picture!

Effects con’t 4. Surface Tension: water’s resistance to objects attempting to penetrate its surfacewater’s resistance to objects attempting to penetrate its surface Cohesion at surface allows for surface tensionCohesion at surface allows for surface tension Large organisms: not much affectLarge organisms: not much affect Small organisms: huge affect  Jesus Lizard, boatman (water striders), planktonSmall organisms: huge affect  Jesus Lizard, boatman (water striders), plankton Current study: air-ocean interaction at surface. How does surface tension affect gas exchange? Ocean’s can absorb CO 2  surface tension affects in some way  help with climate change?Current study: air-ocean interaction at surface. How does surface tension affect gas exchange? Ocean’s can absorb CO 2  surface tension affects in some way  help with climate change? Pollution that affects:Pollution that affects: Detergents/soaps: reduce hydrogen bonding, surface tension down. How affect Jesus Lizard? Detergents/soaps: reduce hydrogen bonding, surface tension down. How affect Jesus Lizard? Draw picture!Draw picture!

Effects Con’t 5. Floating Ice Most substances cool  solid  sink or heat  gas  floatMost substances cool  solid  sink or heat  gas  float Water is different! It does become more dense as cool and less dense as heat but stops at a certain pointWater is different! It does become more dense as cool and less dense as heat but stops at a certain point Hydrogen bonds cool  crystal structure  more space than liquid water. Thus, more volume than liquid water and less dense, so floats on topHydrogen bonds cool  crystal structure  more space than liquid water. Thus, more volume than liquid water and less dense, so floats on top Important?Important? Insulates water below  retain heat  remain liquid below Insulates water below  retain heat  remain liquid below Think: More solid water, cooler climate! Thus, no life Think: More solid water, cooler climate! Thus, no life Draw Picture!Draw Picture!

You are doing the notes for rest of chapter 6!!! I will assign a section to you, you need to make the notes! I will assign a section to you, you need to make the notes! Format, colors, drawings, videos, websites, interaction???? Format, colors, drawings, videos, websites, interaction????