ka and pka

ka and pka

1. kc = [Products]/[Reactants]

2. kc[H2O) = ka

   • Acid dissociation constant

3. ka = [H+][A-]/[HA]

4. As ka increases, strength increases

5. As pka decreases, strength increases

6. HCl - monobasic acid

7. H2SO4 - dibasic

8. H3PO4 - tribasic

9. pH = -log10[H+]

10. kw = [OH-][H+]

    • [H+] = sqrt kw

11. ka = [H+][A-]/[HA]

    • H+ = sqtr ka[HA]

12. A buffer is a solution that maintains an almost constant pH when small amounts of acid or base are added to it

    • Buffer consists of a roughly 50:50 mix of a weak acid and one of its salts
    • Making a buffer
      • Take a known amount of acid and a known amount of salt and mix them together
      • Take a known amount of a weak acid and "half neutralise" it with a strong base
    • In a buffer [HA] and [A-] concentrations are high
    • Adding a base
      • [HA] decreases
      • [A-] increases
    • Adding an acid
      • [HA] increases
      • [A-] decreases

13. Buffers: pka + log10[A-]/[HA] = pH