Question

0.16 g of dibasic acid requires 25 mL decimolar NaOH solution for complete neutralisation. The molecular mass of the acid is

• A. 256
• B. 64
• C. 32
• D. 128

Answer 1

Answer: (D)

128

Answer 2

$0. 16 \,g$ 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 $=\frac{W_{mg}}{\text{millimoles}}$ $=\frac{0.16 \times 1000}{1.25}$ $=128$