3.  Calculate the pH of salt of weak acids.  Calculate the pH of salt of weak bases.  Define buffer, buffer ratio, and buffer capacity.  Calculate the pH of weak acid and weak base buffers.

5.  e.g. NaOAc (sodium acetate)  It is completely ionizes  It is a Bronsted base  It is hydrolyzes in water OAc - + H 2 O  HOAc + OH - K b = [HOAc] [OH - ]\ [OAc - ]

6. A - + H 2 O  HA + OH - salt weak acid K b = K w \ K a = [HA] [OH - ] \ [A - ]

7. Calculated as weak bases K b = K w \ K a = [x] [x] \ C A -

8.  e.g. NH4Cl (ammonium chloride)  It is completely ionizes  It is a Bronsted acid  It is hydrolyzes in water NH 4 + + H 2 O  NH 4 OH + H + K a = [NH 4 OH] [H + ] \ [NH 4 + ]

9. BH + + H 2 O  B + H 3 O + salt weak base K a = K w \ K b = [B] [H 3 O + ] \ [BH + ]

10. Calculated as weak acids K a = K w \ K b = [x] [x] \ C BH +

13.  A solution that resists change in pH when a small amount of an acid or base is added or when the solution is diluted  It consists of a weak acid and its conjugate base or a weak base and its conjugate acid  A mixture of a weak acid and its salt or a weak base and its salt

14. HA  H + + A - pH = pK a + log [A - ] / [HA] (Henderson-Hasselbalch equation)

15.  Calculate the pH of a buffer solution containing 0.1M acetic acid and 0.1M sodium acetate (K a = 1.75 x 10 -5 ).

16. BH +  B + H + pH = pK a + log [B] / [BH + ] pH = (pKw – pKb) + log [B] / [BH + ] pOH = pKb + log [BH + ]/ [B]

17.  Calculate the pH of a solution containing 0.07M NH 3 and 0.08M NH 4 Cl (pK b = 4.76)

18. The ratio of salt / acid [salt] / [acid] = 1 pH = pK a By changing the buffer ratio, buffers of different pH values can be prepared

19.  It is the number of moles /liter of strong acid or base needed to change the pH of buffer solution ß = dC acid or base /dpH  The buffering capacity is maximum at: pH = pK a pOH = pK b  It is satisfactory over a pH range of pK a ± 1  The larger it is, the more resistant the solution to pH change

21.  pH Calculation of salts of weak acids and bases.  Buffer Definition, buffer ratio, and buffer capacity.  pH Calculation of weak acid and weak base buffers.