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Properties of Water Notes

Properties of Water Notes. p. 46. +. +. +. +. +. -. -. -. -. -. -. -. 2 Hydrogen atoms. -. 1 Oxygen atom. 8+. 8+. 8n. -. 8n. -. -. -. H 2 O. -. -. -. -. -. -. -. -. I. Structure. 2 Hydrogen atoms + 1 Oxygen atom -> H 2 O.

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Properties of Water Notes

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  1. Properties of Water Notes p. 46

  2. + + + + + - - - - - - - 2 Hydrogen atoms - 1 Oxygen atom 8+ 8+ 8n - 8n - - - H2O - - - - - - - - I. Structure • 2 Hydrogen atoms + 1 Oxygen atom -> H2O

  3. polar – has charged areas (hydrogen side positive, oxygen side negative) Opposite ends attract – water molecules try to stick together

  4. II. Properties of Water • Capillary action – water molecules are attracted to each other & surrounding materials Examples: • Meniscus • Straws • “Wick” away moisture

  5. Cohesion – like molecules stick together (ex: raindrops) • Adhesion – unlike molecules stick together (ex: raindrops cling to a line)

  6. 2. Surface tension • Tight surface of water • Caused by polar molecules pulling on each other

  7. 3. Universal Solvent • Water dissolves many substances • Solution – mixture formed when one substance dissolves in another • Solvent – substance that does the dissolving • Solute – the substance being dissolved

  8. 4. High Specific Heat • Amount of heat needed to increase the temperature of a substance by 1oC • High because water is polar • Effects: • Water takes longer to heat up or cool down

  9. III. Changing State • States of Matter: • Solid – close molecules, rigid structure (ice) • Liquid – molecules move freely, take shape of container (water) • Gas – molecules move very freely, spread out (water vapor)

  10. Evaporation - Change from liquid to gas Gas • Condensation – Change from gas to liquid

  11. Solid • Freezing – Change from liquid to solid • Melting – Change from solid to liquid

  12. Comprehension Check

  13. 1) A water molecule is made up of a. two hydrogen atoms bonded to an oxygen atom. b. two hydrogen atoms bonded together. c. two oxygen atoms bonded to a hydrogen atom. d. two oxygen atoms bonded together.

  14. 2) Because water consists of polar molecules, a. most of it is found at the North and South Poles. b. water molecules tend to stick together. c. it falls as sleet or snow when temperatures are cold. d. it can be attracted using a magnet.

  15. 3) Tightness across the surface of water that is caused by polar molecules pulling on each other is called a. surface tension. b. capillary action. c. condensation. d. polar action.

  16. 4) Water is often called the universal solvent because a. it can cling to the fibers of paper and cloth. b. it dissolves so many substances. c. it exists in all three states on Earth. d. its frozen form floats on its liquid form.

  17. 5) Water is the only substance on Earth that a. commonly exists in all of its different states. b. freezes at very low temperatures. c. boils at very high temperatures. d. exists in the liquid state.

  18. 6) The process by which a gas changes into a liquid is called a. evaporation. b. condensation. c. melting. d. freezing.

  19. Properties Capillary action Adhesion Cohesion Surface tension Universal solvent Available Materials Dropper Water Penny Soap Salt Graduated cylinder Straw Food coloring Pepper String Paper towels Wax paper ?? (Ask if I have it) Experiment with Water Properties • Pick a water property to experiment with. Observe your property in action. • What happens normally? • Is there any way to affect what happens? • Write a paragraph about what you observed.

  20. Example Experiments with Water Properties • Follow that String (p. 49) • How many drops of water fit on the side of a penny? (p. 51) • What effect does soap have on the surface tension of water? • Can you prevent a meniscus from forming on a graduated cylinder? • How many coins can you fit into a full glass of water? • Will a pin float on top of water?

  21. References • http://learn.sdstate.edu/Deb_Pravecek/Chem106L/Chem106L/estimating_between_graduations.htm • http://www.madsci.org/posts/archives/feb98/887637827.Ch.r.html • http://www.southwest.com.au/~jfuller/liquids/hydrometers.htm • http://www.newton.dep.anl.gov/askasci/chem00/chem00060.htm • http://www.tappi.org/paperu/fun_science/towelAbsorb.htm • http://www.pbase.com/minoltaman/image/31683275 • http://www.howard.k12.md.us/res/rm/chris/Raindrop.gif • http://discover.edventures.com/functions/termlib.php?action=&termid=259&alpha=s&searchString= • http://fizyka.phys.put.poznan.pl/~pieransk/Physics%20Around%20Us/Surface%20tension.jpg • http://discover.edventures.com/images/termlib/s/specific_heat/support.gif • http://www.conwaycorp.com/water/services/experiments.html

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