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Q.
0.16 g of dibasic acid requires 25 mL decimolar NaOH solution for complete neutralisation. The molecular mass of the acid is
Some Basic Concepts of Chemistry
Solution:
$0. 16 \,g$ of dibasic acid is neutralised by
$=25\,m\,L$ of $0.1\,M\,NaOH$
$H_{2}X+2\,NaOH=Na_{2}X+H_{2}O$
Millimoles of acid $=\frac{1}{2} \times$ millimoles of $NaOH$
$NaOH =\frac{1}{2}\times25\times0.1=1.25$
Now, millimoles $=\frac{W_{mg}}{\text{Mol.mass}}$
or Mol mass $=\frac{W_{mg}}{\text{millimoles}}$
$=\frac{0.16 \times 1000}{1.25}$
$=128$