Chem Ch 16

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Chem Ch 16
2010-05-04 19:46:50
Chemistry Chang

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  1. common ion
    • two solutes dissoved in a solvent that contain the same ion (example NaF and HF)
    • HF (aq) + H2O (l) <-> F- (aq) + H3O (aq)
    • NaF (s) --> Na+ (aq) + F- (aq)
  2. common ion effect
    the shift in equilibrium caused by the addition of a compound having a common ion
  3. Henderson-Hasselbalch equation
    • pH = pKa + log [conjugate base] / [acid]
    • the assumption that x << [HA]0 is used
    • remember p just means -log
    • can be used for acid or base, just DON'T MODIFY (use Ka)
  4. buffer solution
    • a solution that resists changes in pH
    • consists of a weak acid or a weak base and its salt
  5. indicator
    • a substance which changes color with pH
    • usually it is a weak organic acid
    • it has two distinctly different colors from its ionized form and its nonionized form
  6. end point
    the point when the indicator changes color
  7. strong acid/strong base titrations
    • HCl (aq) +NaOH (aq) --> NaCl (aq) +H2O (l)
    • H3O+ (aq) + OH- (aq) --> H2O (l)
    • use ICF table and moles
    • what remains on F line will be used to calculate pH
  8. weak acid/strong base titrations
    • CH3COOH & NaOH
    • CH3COOH (aq) + OH- (aq) --> CH3COO- (aq) + H2O (l)
    • CH3COO- + H2O <-> CH3COOH + OH-
    • will be a buffer zone around pH 3-6
    • equivalence point about pH 9
  9. strong acid/weak base titrations
    • HCl & NH3
    • H3O+ (aq) + NH3 (aq) --> NH4+ (aq) + H2O (l)
    • Once the NH4+ is formed it will undergo equilibrium with water
  10. solubility product and reaction quotient
    • Unsaturated = Ksp > Q
    • Saturated = Ksp = Q
    • Supersaturated = Ksp< < Q
    • typically, the smaller the Ksp the less soluble the salt -if they have the SAME ratios -
    • the smaller the K the more it will want to precipitate
  11. molar solubility
    (s) - the number of moles of solute in one liter of a saturated solution (mol/L)
  12. solubility
    the number of grams of solute in one liter of a saturated solution (g/L)
  13. the common ion effect and solubility
    the addition of a common ion to an insoluble salt will always decrease the solubility of the salt
  14. pH and solubility
    if an anion is the conjugate base of a weak acid, solubility increases with decreasing pH (i.e. added an acid)