Using Kjeldahl's method over 1 g of a soil sample, the ammonia evolved could neutralize 25 ml of 1 MH 2 SO 4 . Then, the percentage of nitrogen present in the sample is

Step-by-step solution

H 2 SO 4   +   2 NH 3 → NH 4 2 SO 4 25ml of one molar sulphuric acid = 25 mmol By applying the mole-mole analysis, mole of ammonia consumed= 50 mmol . Hence, the acid used for the ammonia adsorption = 50 - 25 = 25 mmol Normality of sulphuric acid = 2 N Mass of sample W = 1 g So, % N = 1 . 4 × N × V W = 1 . 4 × 2 × 25 1 = 70 % Hence, the percentage of nitrogen present in the sample is 70 % .