Acids and Bases and Equilbirium

  1. Secondary Standard
    • Concentration can only be accurately found by titration.
    • E.g. HCL, NAOH
  2. Primary Standard
    Accurately known concentration

    Must be:

    • In pure form consistant with chemical formula
    • Stable upon exposure to air
    • High molar mass

    e.g. oxalic acid
  3. What reacts?
    Salt from weak base and weak acid
    Both react, depends on Kb>Ka, or Ka>Kb
  4. What reacts?
    Salt from weak base and strong acid
    • Cation of weak base reacts
    • pH<7
    • Acidic
  5. What reacts?
    Salt from strong base and weak acid
    • Anion of weak base reacts (hydrolyses)
    • pH>7
    • Basic
  6. Hydrolysis
    • Forming of an acid/base by water molecules and an ion
    • Ions of strong acids/bases do not hydrolyse
  7. What reacts?
    Salt from a strong acid and a strong base
    • no hydrolyses
    • pH=7
    • Neutral
  8. Basic Ions
    Anions that are conjugate bases of weak acids are basic

    • F-, CO32- PO43- CH3COO
    • Organics
  9. Acidic Ions
    Cations that are conjugate acids of weak bases are acidic

    NH4Al3+ Mg2+

    Transition metals
  10. Spectator Ions
    Anions: Cl- BrIClO4SO42-

    Cations: LiNaKRbSr2+ Ba2+
  11. Autoionisation of water
    • In any sample of water, some H2O molecules change into H+(aq) and OH-(aq) ions.
    • They have the same concentration as they form at the same rater
    • Water is neutral
    • [H+]=1x10-7
    • [OH-]=1x10-7
  12. A strong base has a _____ conjugate acid
  13. Conjugate pairs
    Acid + Conjugate base (donates H+)

    Base + Conjugate acid (accepts H+)
  14. Bronsted-Lowry Theory
    Acid donates a proton H+

    Base accepts a proton H+
  15. Arrhenius Theory
    Acids produce hydrogen ions

    Bases produce hydroxide ions
  16. Le Chatelier:

    Reaction that absorbs heat is favoured

    Rise in temp = favours endo

    Decrease in temp = favours exo
  17. Le Chatelier:

    Increase in pressure = Shift in the direction with the fewest moles of gas
  18. Le Chatelier:

    Substance added: Shift to remove it

    Substance removed: Shift to produce it
  19. Reaction Quotient 
    Tells us if the reaction is at equilibrium

    • Q=K: equilibrium
    • Q>K: Too much product
    • Q<K: Too much reactants
  20. Equilibrium Constant
    Tells us how much product can be made before equilibrium is reached


    • K>1 = forward rxn favoured
    • K<1 = reverse rxn favoured
Card Set
Acids and Bases and Equilbirium
Module 2