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water and aqueous systems

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water and aqueous systems

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    1. WATER and AQUEOUS SYSTEMS CHAPTER 17

    3. WATER PROPERTIES THE WATER MOLECULE POLAR O-H BONDS FORMS 105° ANGLE 2 ELECTRON PAIRS

    4. WATER PROPERTIES NORMAL POLAR MOLECULES ATTRACTED TO EACH OTHER BY DIPOLE INTERACTIONS BUT… IN WATER MOLECULES, THE HYDROGEN BOND IS THE DRIVING FORCE

    5. WATER PROPERTIES HYDROGEN BONDING

    6. WATER PROPERTIES HYDROGEN BOND HIGH SURFACE TENSION HIGH SPECIFIC HEAT HIGH BOILING POINT HIGH HEAT OF VAPORIZATION

    7. SURFACE TENSION WATER SURFACE ACTS LIKE A SKIN AT SURFACE HYDROGEN BONDING IS MINIMAL, SO MOLECULES ARE DRAWN INTO WATER TIGHTLY INWARD FORCE THAT MINIMIZES SURFACE AREA

    8. SURFACE PROPERTIES TO MAKE WATER WETTER… USE A SURFACTANT SURFACE ACTIVE AGENT REDUCES SURFACE TENSION BY INTERFERING WITH HYDROGEN BONDING AT SURFACE

    9. SURFACE PROPERTIES LOW VAPOR PRESSURE HYDROGEN BONDING HOLDS DOWN WATER MOLECULES FROM EVAPORATING

    10. HEAT CAPACITY

    11. EVAPORATION 2.26 kJ TO BOIL 1 GRAM WATER AT 100 °C. LARGE AMOUNT OF ENERGY TO BREAK HYDROGEN BONDS

    12. ICE HYDROGEN BONDING CAUSES OPEN HONEYCOMB NETWORK OF MOLECULES ALLOWS ICE TO FLOAT 0.334kJ TO MELT 1 GRAM ICE AT 0OC

    13. ICE

    14. AQUEOUS SOLUTIONS SOLUTION HOMOGENEOUS STABLE MIXTURE SOLVENT DISSOLVING MEDIUM SOLUTE DISSOLVED PARTICLES

    15. SOLVATION SOLVATION OCCURS WHEN A SOLUTE DISSOLVES IF A SOLUTE CANNOT BE SOLVATED, IT IS INSOLUBLE CRYSTAL ATTRACTIONS STRONGER THAN WATER ATTRACTIONS “LIKE DISSOLVES LIKE”

    16. SOLVATIONWATER AND ETHANOL

    17. ELECTROLYTES & NON-ELECTROLYTES ELECTROLYTES CONDUCT ELECRTIC CURRENT MOLTEN OR SOLUTION STATE IONIC COMPOUNDS NON-ELECTROLYTES DO NOT CARRY A CURRENT MOLECULAR COMPOUNDS 1 2 3 4 5 6

    18. ELECTROLYTES & NON-ELECTROLYTES WEAK ELECTROLYTES PARTIALLY IONIZED IN WATER MERCURIC CHLORIDE STRONG ELECTROLYTES FULLY IONIZE IN WATER SODIUM CHLORIDE, SULFURIC ACID

    19. HETEROGENEOUS AQUEOUS SYSTEMS Suspensions Particles settle on standing Particles =100 nanometers (nm) diameter Baby synthetic antibiotics in liquid Colloids Do not settle on standing Particles between 1 nm and 100 nm in size Emulsions Colloidal dispersions of liquids in liquids Salad dressings

    20. HETEROGENEOUS AQUEOUS SYSTEMS Colloidal Blood

    22. HETEROGENEOUS AQUEOUS SYSTEMS Tyndall Effect Colloids scatter light in all directions Also seen with suspensions Never seen with solutions – Particles are too small. Brownian Motion Random movement of colloidal particles.

    23. HETEROGENEOUS AQUEOUS SYSTEMS Tyndall Effect

    25. Water of Hydration Water can co-crystallize with some compounds. Hydrate is crystalline material containing water. Fixed number of water molecules per molecule of compound. Can be driven of by heating

    27. Water of Hydration EFFLORESCE If hydrate vapor pressure higher than water in air Will lose water to the surroundings HYGROSCOPIC If hydrate vapor pressure lower than water in air Will gain water from the surroundings

    28. Water of Hydration DESSICANTS Hygroscopic materials as drying agents DELIQUESCENT Materials absorb TOO much water They become wet

    29. THE END

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