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Water Properties Lab. Water is Polar Covalent. Uneven sharing of e-. Nonpolar Oxygen (even sharing of e-). Hydrogen Bonds. Weak bonds between like molecules. p. 3 Cohesion. Attraction of water to water Makes a drop Polar ends and H-bonds attract. What forms a drop?.
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Water is Polar Covalent Uneven sharing of e- Nonpolar Oxygen (even sharing of e-)
Hydrogen Bonds • Weak bonds between like molecules
p. 3 Cohesion • Attraction of water to water • Makes a drop Polar ends and H-bonds attract
What forms a drop? • Cohesion causes water to form drops • surface tension causes them to be nearly spherical • adhesion keeps the drops in place.
Surface Tension • Water attracts itself and pulls in to form a “film” on its surface to form a drop.
Adhesion • Attraction of water to an unlike substance • (like glass) • Note the drop is flatter than on wax paper
p. 4 Water Drop Shapes • Rounder the drop, the stronger the H-bonds in the drop of water. • Round drop on wax paper (not strong adhesion to water). • As adhesion to glass is stronger + pulls the water, it makes a flatter drop.
p. 4 -#6 top Water on wax paper • Plain wax paper Soapy wax paper You can break surface tension with soap.
Polar coheres to Polar not Nonpolar • Water (Polar) has no adhesion to the wax (nonpolar) paper. It would roll right off. • Water has more adhesion to a glass plate.
p. 6 Climbing Property of Water • CHROMATOGRAPHY:Colors are separated by densities. Less dense colors go to the top. • Black is composed of all the colors. • Capillary action -cohesion (water to water) + adhesion (water to paper) • Polar water + polar ink (dissolves) Paper has pores, open spaces
Capillarity – water climbs up small spaces • The small spaces (pores of the paper) provide adhesion to the water. • The water makes a column by cohesion to itself. (water to water because they are polar)
p. 8 #6 Oil is hydrophobic • Oil and water do not mix. • H-bonding is only in polar Oil is on top Non-polar polar nonpolar Water is on bottom Polar polar
#5 Likes dissolve likesPolar dissolves polar, but not nonpolar • Cell membrane is also amphipathic (polar + nonpolar) Inside the cell membrane
p. 9 # 6Food coloring dissolves in water. • Water is polar +H-bonds • Food coloring is polar. • Makes a solution(water surrounds the dye) • Oil is nonpolar (no charge). • And no H- bonds. Polar molecules dissolve polar molecules.
Dissolving • A solute surrounds the molecules of a solvent to make a solution
Stirring oil and water • The oil will go back to being separate from the water.
Interpret #6 Getting rid of oil on water HowStuffWorks "How do you clean up an oil spill?“ (pick a video) • Detergent breaks up the oil into very small droplets. Burn Off Booms Hi-pressure water
Slick Sack • Absorbent pad Hand washing
Oil Spills Problems • a. dead sea life • b. human life ills • c. cost of clean-up
p. 9 Interpret 5 Amphipathic(bipolar) • molecules have (hydrophobic) nonpolar end and to attract oil structure, but also have a region that is polar (hydrophilic) attracts water to wash it away. Like detergent.
Soap is a surfactant • That reduces the surface tension • Breaks the cohesion of water molecules