Question

0.35 g of an organic substance was Kjeldahlised and the ammonia obtained was passed into 100 ml of N/5 H2SO4. The excess acid required 154 ml of N/10 NaOH for neutralisation. Calculate the percentage of nitrogen in the compound

Answer 1

Volume of N/5 H2SO4 solution taken = 100 mL

The volume of N/5 H2SO4 neutralised by N/10

NaOH can be obtained as follows :

= 77 mL

Therefore,

Volume of N/5 H2SO4 used for

neutralising ammonia = (100 - 77) mL

= 23 mL

Then,

Percentage of nitrogen in the sample

= 1.4 x Normality volume of acid

Percentage of nitrogen in the sample

= 1.4 x 1/5 x 23 / 0.23 = 18.4