Solution of an acid & its anion (that is , it’s conjugate base) or of a base and its common cation are buffered. When we add a small amount of acid or base to any one of them, the pH of solution changes very little. pH of buffer solution can be computed as –
For acidic buffer : pH = pK a + log 
For basic buffer : pOH = pK b + log 
It is generally accepted that a solution has useful buffer capacity (pH change resisting power) provided that the value of 
for acidic buffer lies
within the range of 1 : 10 to 10 : 1 buffer capacity is
maximum when [conjugate base] = [acid]
(i) One litre of an aqueous solution contains 0.15 mole of CH 3 OOH (pK a = 4.8) and 0.15 mole of CH 3 COONa. After the addition of 0.05 mole of solid NaOH to this solution. The pH will be –
(assuming no change in volume) None of these (iii) Select correct statement When 100 ml of 0.2 M CH 3 COOH react with 200 ml of 0.1 M NaOH buffer solution is formed
Text Solution
Verified by Experts8.66
(i)
Sol. CH 3 COOH + NaOH → CH 3 COONa
0.15 – 0.05 0.05 0.15 + 0.05
pH = pK a + log 
(ii)
Sol. 8.66
(iii)
Sol. pH = pK a + log 
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