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  1. Unusual water properties
    • high boiling points
    • melting point
    • heat of vaporization
    • surface tension
  2. Properties of water
    • high intermolecular forces
    • hydrogen bonds
    • polar
    • non-tetrahedral bond angles
    • H-bond donor and acceptor
    • potential to form four H-bonds per water
  3. In liquid water
    the molecules are held by a random three dimensional network.
  4. Water serves as an excellent solvent
    for ionic and polar substances
  5. Ionic compounds
  6. Polar compounds
    • sugars
    • simple alcohols
    • amines
    • aldehydes
    • ketones
  7. Measure the attraction forces by determining
    the dielectric constant F= e1e2/Dr^2
  8. Water forms hydrogen bonds with the functional groups of these compounds
    • hydroxyls
    • amines
    • carbonyls
  9. Water molecules “reorganize” to around the non-polar compound
    and form an H-bonded water network around the compound
  10. Hydrophobic interaction leads to a local cagelike structure known
    as “clathrate” that surrounds each solute molecule
  11. Amphipatic
    refers to molecules that possess both, a strongly polar and strongly nonpolar groups
  12. Examples of amphipathic
    Salts and fatty acids
  13. The ionic carboxylate head ( polar)
    hydrates, while the long hydrophobic tail remains insoluble
  14. Colligative properties include
    • freezing point depression
    • boiling point elevation
    • vapor pressure lowering
    • osmotic pressure effects
  15. When a solution is separated from water by a semipermeable membrane
    the water moves from a range of higher concentration (pure water) of water to a region of lower concentration (solution)
  16. Water has a small tendency
    to form ions
  17. From the ionization of water
    results a H+ and a OH- group
  18. The acid dissociation constant is given by
    Ka = [ H + ] [ A -] /[HA]
  19. We can refer to Keq as Kw for water. Kw is the
    ionization constant of water
  20. Concentration of water is constant
  21. The more acid the solution is
    the more [ H + ] and less [ OH -]
  22. The more basic the solution is
    the more [ OH -] and less [ H +]
  23. Kw=
    [ H + ][ OH -]= 1X10-14
  24. pH
    • is defined as the negative logarithm of hydrogen ion concentration
    • pH = -log([H+])
  25. pKw =
    pH + pOH = 14
  26. Electrolytes are
    substances that form ions and, therefore, cause an increase in electrical conductivity
  27. Strong electrolytes
    completely dissociate in water, to form ions
  28. Some strong electrolytes are
    salts (NaCl and K2SO4) , and strong acids (HCl)
  29. Weak electrolytes
    don’t completely dissociate in water, to form ions
  30. Some weak electrolytes are
    weak acids (HAc, H2CO3)
  31. The Henderson-Hasselbalch Equation
    • For any acid HA, the relationship between the pKa, the concentrations existing at equilibrium and the solution pH is given by
    • pH = pKa + log10 [A¯ ] /[HA]
  32. Titration
    is the analytical method used to determine the amount of acid in a solution
  33. The point at which the concentration of the conjugate acid and conjugate base remain constant is
    the pKa
  34. Buffers
    Maintenance of pH is essential to all cells, because changes in pH would be disruptive for to metabolism
  35. Buffer systems
    • intracellular pH: H2PO4 and histidine systems
    • extracellular: H2CO3(bicarbonate system)
  36. The bicarbonate buffer system is important to maintain
    the blood plasma pH
Card Set:
2013-09-29 00:05:33
Biochemistry Water

Garrett Book, Water, pH, water properties, pH formulas
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