Subject:- Applied Chemistry 2.

Topic:- Fuels.

Difficulty:- Medium

By Kjeldahl’s method 1.5 gm. Of a sample was analyzed. The ammonia evolved was absorbed in 50 ml of 0.1 N $H_2SO_4$.After absorption the excess $H_2SO_4$ required 35 ml of 0.1 N NaOH for neutralization. Calculate the % of nitrogen.

Solution: Given: Weight of coal sample = 1.5 gm

NaOH consumed = 35 ml

Normality of H2SO4 and NaOH = 0.1N

Quantity of H2SO4 used = 50ml

Amount of H2SO4 used = (50-35) =15ml

N% = Volume of acid consumed x Normality of acid
x1.4/weight of coal sample

=15x0.1x1.4/1.5

N% = 1.4%

Answer: N% = 1.4%