Fixed volume of 0.1 M benzoic acid solution is added into 0.2 M sodium benzoate solution and formed a 300 m…

Fixed volume of 0.1 M benzoic acid solution is added into 0.2 M sodium benzoate solution and formed a 300 ml, resultant acidic buffer solution. If pH of this buffer solution is 4.5 then find added volume of benzoic acid –
Given: pK a benzoicacid=4.2
  1. 100 ml
  2. 150 ml
  3. 200 ml
  4. None of these

Solution

pH=pKa+logsaltacid
4.5=4.2+logsaltacid
0.3=logsaltacid
saltacid=2
0.2×300-v0.1×v=2
v=150 ml

Asked in: JEE-TOPICTESTS-CHEMISTRY

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