1 / 20

Properties of Water

Properties of Water. Chapter 2. Water (H 2 O). Most important inorganic molecule in living things. Living organisms = 75-80% H 2 O. Many biological processes require H 2 O Survive 21-24 days without food Survive 3 days without water. Three Physical States of H 2 O. Solid (ice) Liquid

jerome-parsons
Télécharger la présentation

Properties of Water

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Properties of Water Chapter 2

  2. Water (H2O) • Most important inorganic molecule in living things. • Living organisms = 75-80% H2O. • Many biological processes require H2O • Survive 21-24 days without food • Survive 3 days without water

  3. Three Physical States of H2O • Solid (ice) • Liquid • Gas (vapor)

  4. Properties of Water • Buoyancy • Polarity • Cohesion • Adhesion • Surface Tension • High Specific Heat • Forms solutions • Neutral pH

  5. Heats Slowly & Cools Slowly • High Specific Heat- a lot of heat is needed to raise the temperature of 1 gram of H2O by 1°C • H2O retains heat & cools slowly. • Ex: pool/ocean is warm in the fall. • Allows organisms to maintain relatively constant body temperatures.

  6. Polar Molecule • Atoms of different elements don’t always share e- equally. • More protons (+) in the nucleus means a stronger attraction for electrons (-).

  7. Polar Molecule • e- drawn the nucleus with more protons MORE than the others. • Charges form  polar molecules or polar regions of large molecules

  8. Cohesion- ability of H2O molecules to resist coming apart. • Keeps H2O molecules together as they move from roots to leaves. Giant Sequoia

  9. Cohesion and Surface Tension • How droplets of H2O form. • Attraction between H2O molecules  surface tension • Surface Tension- molecules in the surface layer are H-bonded to H2O molecules below them. • Prevents water’s surface from easily breaking. Water Strider Droplet Formation

  10. Adhesion • Adhesion- attraction between H2O molecules and molecules of other substances (that can form H-Bonds). • Due to polarity of H2O • Other polar substances get wet (mix with H2O) • Nonpolar molecules, like oils, do not.

  11. Adhesion and Capillary Action • Attraction of H2O to surfaces with a charge  capillary action • Capillary Action- tendency of liquids to rise in tubes of small diameter. • Explains movement of H2O from roots  leaves

  12. Forms Solutions • Many substances dissolve in H2O. • Solution- mixture in which 1+ substances are evenly distributed in another substance. • Can be mixtures of liquids, solids, or gases. • Substances transported in organisms as solutions of water. • Ex: Plasma (liquid part of blood)- made up of various ions and macromolecules, as well as gases, that are dissolved in H2O.

  13. Parts of Solutions • Solute- substance being dissolved. • Ex: Sugar • Solvent- substance in which solute is dissolved. • Ex: H2O Sugar + H2O  Sugar H2O **Sugar & H2O molecules remain unchanged and can be separated again.**

  14. Low Density Solid • Ice (solid) is LESS dense than liquid H2O.

  15. Acids and Bases • Bonds break between some water molecules as they collide. • Forms a H ion (H+) and a hydroxide ion (OH-). • Pure H2O ALWAYS has a low concentration of H+ and OH- ions • H+ ions = OH- ions

  16. Acids and Bases • Compounds that form H+ when dissolved in H2O are acids. • Adding acids to pure H2O  H+ level increases above that of pure H2O • Bases- compounds that reduce [H+] in a solution. • Many bases form OH- when dissolved in H2O. • Lower [H+] because OH- reacts with H+ to form H2O.

  17. Acids and Bases • pH scale- measures H+ concentration in a solution.

  18. Acids and Bases • Each whole # (on pH scale) represents a factor of 10. • Solution with pH 5 has 10 times more H+ than a solution with pH 6. • Note: Stomach acid pH= 2 Blood pH= 7.5

  19. Questions • Lemons have a pH of 2. Are lemons acidic or basic? • The strongest bases have a pH of ____. • Pure water is a neutral substance. What is the pH of pure water?

  20. Animations/Tutorials/Videos • Matter: http://www.teachersdomain.org/asset/lsps07_int_naturematter/ • Matter Video Review: http://www.teachersdomain.org/asset/psu06-nano_vid_matter/ • Atomic Structure: http://www.teachersdomain.org/asset/lsps07_int_theatom/ • Chemical Bonding: http://www.teachersdomain.org/asset/lsps07_int_chembonds/ • Water Video: http://www.teachersdomain.org/asset/idptv11_vid_d4ksow/ • NOVA Hunting the Elements Video: http://www.pbs.org/wgbh/nova/physics/hunting-elements.html

More Related