Estimation of nitrogen: There are two methods for the estimation of nitrogen (i) Dumas method and (ii) Kjedahl's method. i. Dumas method: A known mass of compound is heated with copper oxide (CuO) in an atomsphere of CO_(2), which gives free nitrogen along with CO_(2) and H_(2)O C_(x)H_(y)N_(z) + (2x + y//2) CuO rarr xCO_(2) + y//2 (H_(2)O) + z//2 (N_(2)) + (2x + y//2) CU The gaseous mixture is passed over a heated copper gauze which converts traces of nitrogen oxides formed to N_(2). The gaeous mixture is collected over an aqueous solution of KOH which absorbs CO_(2), and nitrogen is callected in the upper part of the graduated tube. ii. Kjeldahl's method: A known mass of organic compound (0.5 gm) is mixed with K_(2)SO_(4) (10 gm) and CuSO_(4). (1.0 gm) or a drop of mercury (Hg) and conc. H_(2)SO_(4) (25ml), and heated in Kjeldahl's flask. CuSO_(4) or Hg acts as a catalyst, while K_(2)SO_(4) raises the boiling point of H_(2)SO_(4). The nitrogen in the organic compound is quantitatively converted to ammonium sulphate. The resulting mixture is then distilled with excess of NaOH solution and the NH_(3) evolved is passed into a known but excess volume of standard HCl or H_(2)SO_(4). The acid left unused is estimated by titration with some standard alkali. The amount of acid used against NH_(3) can be thus be known and from this the percentage of nitrogen is calculated. (a) C + H + S underset(H_(2)SO_(4))overset("conc.")rarr CO_(2) + H_(2)O + SO_(2) (b) N underset(H_(2)SO_(4))overset("conc.")rarr (NH_(4))_(2)SO_(4) (c) (NH_(4))_(2) SO_(4) + 2NaOH rarr Na_(2)SO_(4) + 2NH_(3) + 2H_(2)O (d) 2NH_(3) + H_(2)SO_(4) rarr (NH_(4))_(2) SO_(4) (iii) This method is not applicable to compounds containing N in intro and azo groups, and N present in the ring (e.g., pyridine) as N of these compounds does not change to (NH_(4))_(2)SO_(4) (ammonium sulphate) under these reaction conditions 0.50 gm of an organic compound was treated according to Kjeldahl's method. The ammonia evolved was absorbed in 50ml of 0,5M H_(2)SO_(4). The residual acid required 60 ml of M/2 NaOH solution. Find the percentage of nitrogen in the compound