What is the role of reduced copper gauze in the estimation of nitrogen by Duma's method ?

Describe the principle involved in the quantitative estimation of nitrogen by Kjeldahl's method.

Kjeldahl's method is used in the estimation of

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

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 0.4gm of an organic compound was treated according to Kjeldahl's method. The ammonia evolved was absorbed in 50ml of 0.5M H_(3)PO_(3) . The residual acid required 30 ml of 0.5M Ca(OH)_(2) . Find the percentage of N_(2) in the compound

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 0.002 gm of an organic compound was treated according to Kjeldahl's method. 0.2 xx 10^(-4) mol of H_(2)SO_(4) was required to neutralise NH_(3) . Calculate the percentage of N_(2)

What is the role of silica in the metallurgy of copper.

Differentiate between the principle of estimation of nitrogen in an organic compound by (i) Dumas method and (ii) Kjeldahl’s method.

In DNA and RNA, nitrogen atom is present in the ring system. Can Kjeldahl method be used for the estimation of nitrogen present in these. Give reasons.

(i) Name the method of refining to obtain silicon of high purity. (ii) What is the role of SiO_2 in the extraction of copper? (iii) What is the role of depressants in froth floatation process ?

which element is estimated by carius method?