Question

An organic compound was used with sodium metal and extracted with distilled water. On adding freshly prepared $FeS{O}_4$ solution followed by the addition of $FeC{l}_3$ and dil. $HCl$ produced greenish blue solution. 0.30g of the organic compound after kjeldahlisation evolved a gas (X) which was passed on 100 ml of 0.1 M $H_{2}S{O}_4$. The excess of acid required 20 ml of 0.5 M $NaOH$ for neutralisation.
Dil. $HCl$ is added to the solution in the above test to:

• A. make the solution acidic
• B. to dissolve $FeS{O}_4$
• C. to dissolve $Fe(OH{)}_2$
• D. to change $FeS{O}_4$ to $FeC{l}_2$

Answer 1

Answer: (B)

to dissolve $FeS{O}_4$

$m=0\cdot 3g$
$M=0\cdot 1M$
$V=\cdot 100ml$
$v_1=20ml$
$m.eqofacid=2\times 0\cdot 1\times 100=20$
$m.eqofBase=1\times 0\cdot 5\times 20=10$
excess of acid used to neutralize
$N{h}_3=20-10=10mg$
% $N_2=\frac{1\cdot 2\times 10meq}{0\cdot 3}=46\cdot 67$ %
Dil $HCl$ is added to dissolve $FeS{O}_4$
%$N_2=46\cdot 67$