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CH. 2-2 IN CLASS NOTES

CH. 2-2 IN CLASS NOTES. PROPERTIES OF WATER. Interest Grabber. Section 2-2. Water, Water Everywhere.

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CH. 2-2 IN CLASS NOTES

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  1. CH. 2-2 IN CLASS NOTES PROPERTIES OF WATER

  2. Interest Grabber Section 2-2 Water, Water Everywhere • If you have ever seen a photograph of Earth from space, you know that much of the planet is covered by water. Water makes life on Earth possible. If life as we know it exists on some other planet, water must be present to support that life. Go to Section:

  3. 1. THE WATER MOLECULEH2O • NEUTRAL-10 P & 10E • BENT SHAPE P. 40

  4. 2. WATER IS A POLAR MOLECULE • O-SLIGHT NEG. CHARGE • H-SLIGHT POS. CHARGE • MOLECULES IN WHICH THE CHARGES ARE UNEVENLY DISTRIBUTED • LIKE A MAGNET W/ POLES • ---=_____ & += BETWEEN_____

  5. 3. HYDROGEN BONDS-------- • NOT AS STRONG AS IONIC OR COVALENT(STRONGEST) • POLAR MOLECULES ATTRACT EACH OTHER—BECAUSE PARTIAL + / -

  6. 4. PROPERTIES OF WATER • A. SINGLE MOLECULE MAY HAVE 4 H-BONDS AT THE SAME TIME • B. COHESION-ATTRACTION BETWEEN MOLECULES OF THE SAME SUBSTANCE • EX. WATER BEADS

  7. C. ADHESION • ATTRACTION BETWEEN MOLECULES OF DIFFERENT SUBSTANCES • EX: READING A GRAD. CYL.; CAPILLARY ACTION IN PLANTS • ADHESION BETWEEN WATER & GLASS IS STRONGER THAN WATER VS. WATER

  8. D. MIXTURE • 2 OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXED • EX: SALT/PEP. STIRRED • EARTH’S ATMOSPHERE

  9. E. 2 TYPES OF MIXTURES WITH WATER • 1. SOLUTIONS-all the compounds are evenly distributed throughout • solute-substance dissolved (salt) b. solvent-substance in which the solute is dissolved (water)

  10. Figure 2-9 NaCI Solution Section 2-2 Cl- Cl- Na+ Na+ Water Water Go to Section:

  11. Figure 2-9 NaCI Solution Section 2-2 Cl- Cl- Na+ Na+ Water Water Go to Section:

  12. 2. SUSPENSIONS • Water & nondissolved material; when some materials do not dissolve • Ex. Blood & components

  13. DOUBLE ARROW MEANS….. • THE REACTION CAN OCCUR IN BOTH DIRECTIONS • ARROW MEANS “FORMS” OR “PRODUCES”

  14. CHEMICAL EQUATION • H2O H+ + OH— • REACTANTS PRODUCTS • BEFORE AFTER

  15. pH Scale Section 2-2 Oven cleaner Bleach Ammonia solution Increasingly Basic Soap Sea water Human blood Neutral Pure water Milk Normal rainfall Acid rain Increasingly Acidic Tomato juice Lemon juice Stomach acid Go to Section:

  16. 1. What is pH used for? • To determine acids, bases and neutral substances

  17. 2. What does the pH value 7 mean? • There is an equal number of H+ ions and OH- ions. Example: pure water; neutral

  18. 3. Substances with a pH value above 7 are considered bases. • Under 7 are considered acids

  19. 4. What is the purpose for using a known base, a known acid, and distilled water? • The control part of the lab. To make sure the pH paper is working properly.

  20. 5. ACIDS, BASES AND pH • A water molecule can react to form ions. • H2O H+ + OH— • Water forms hydrogen +hydroxide ion ion

  21. 6. pH Scale= Potential or Power of Hydrogen • Indicates the concentration of H+ ions in a solution • Ranges from 0-14 • pH 7= H+ and OH- are equal------pure water=7 NEUTRAL

  22. 7. Acidic-any compound that forms H+ ions in solution • pH below 7, more H+ ions than OH- ions • The lower the pH the greater the acidity • Ex: HCl-hydrochloric acid In your stomach=______

  23. 8. Base-any compound that produces OH- ions in a solution • A.K.A= Alkaline • Lower concentrations of H+ ions than water, more OH- ions • pH value above 7 • Ex: oven cleaner=_______

  24. E. BUFFERS • WEAK ACIDS OR BASES • PREVENT SHARP CHANGES IN pH • Human body cells-pH 6.5-7.5-homeostasis

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