 Calculate the pH of weak acids.  calculate the pH of weak bases.  Calculate the pH of salt of weak acids.  Calculate the pH of salt of weak bases.

 e.g. Acetic acid (CH 3 COOH) CH 3 COOH → CH 3 COO - + H + Ka = [CH 3 COO - ] [H + ] / [CH 3 COOH] ↓ Ka = [H + ] 2 / [CH 3 COOH]

 e.g. Ammonia (NH 3 ) NH 3 + H 2 O → NH4 + + OH - K b = [NH4 + ] [OH - ] / [NH 3 ] ↓ K b = [OH - ] 2 / [NH 3 ]

 e.g. CH 3 COONa (sodium acetate)  It is completely ionizes in water  It is a bronsted base CH 3 COO - + H 2 O  CH 3 COOH + OH -

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

Calculated as weak base K b = K w \ K a = [OH - ] 2 /[salt] ↓ Final equation ……………………………………… Example 7.9 page 232

 e.g. NH4Cl (ammonium chloride)  It is completely ionizes in water  It is a bronsted acid NH H 2 O  NH 3 + H 3 O +

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

Calculated as weak acid K a = K w \ K b = [H + ] 2 \ [salt] ↓ Final equation …………………………………. Example 7.10 page 233

 pH Calculation of weak acids and bases.  pH calculation of salts of weak acids and bases.