The ammonia evolved from 0.21 g of an organic compound by Kjeldahl method neutralised 15 ml of N/20 sulphuric acid solution. Calculate the percentage of nitrogen.

Explanation

`"weight of organic compound = 0.21 g"`
`"Normality of acid "=(N)/(20)`
Volume of standard acid
neutralised by ammonia = 15 ml
1000 ml of 1N ammonia contains = 14 g of nitrogen
15 ml of ammonia of normality
`(N)/(20)" conains nitrogen "=(14xx15xx1)/(1000xx20)`
0.21 g of compound contains nitrogen
`=(14xx15)/(1000xx20)`
100 g of compound contains nitrogen
`=(14xx15xx100)/(1000xx20xx0.21)=5g`
`therefore" Percentage of nitrogen = 5"`