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The catalyst used in Kjeldahl's method f...

The catalyst used in Kjeldahl's method for the estimation of nitrogen is:

A

Sodium

B

Magnesium

C

Mercury

D

copper

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Verified by Experts

The correct Answer is:
C
Catalyst used in Kjeldahl's method for the estimation of nitrogen is mercury.
`:.` option (3) is correct.
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A sample of 1.0 gm of organic compound was treated with NaOH and NH_(3) evolved was absorbed in 70ml 0.5M H_(2)SO_(4) . The residual acid required 65 ml of 0.5MNaOH solution of neutraization in Kjeldahl's method. What is the percentage of nitrogen in organic 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 0.50 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)

RESONANCE ENGLISH-STRUCTURAL IDENTIFICATION & PRACTICAL ORGANIC CHEMISTRY-Section -B
  1. In Kjeldahl's method, nitrogen present is estimated as

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  2. Molecular mass of a volatile substance is determined by :

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  3. The catalyst used in Kjeldahl's method for the estimation of nitrogen ...

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  4. 6 g of the organic compound on heating with NaOH gave NH(3) which is n...

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  5. The desiccants used for absorbing water during Liebig's method for est...

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  6. 0.16 g of dibasic acid required 25 ml of decinormal NaOH solution for ...

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  7. 0.28 g of nitrogenous compound was subjected to Kjeldahl's process to ...

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  8. The equivalent wieght of an acid is equal to

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  9. 0.30 gm of an organic compound gave 50 ml of nitrogen collected at 300...

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  10. Liebig test is used ot estimate

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  11. Copper wire test is called

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  12. During estimation of nitrogen present in an organic compound by Kjelda...

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  13. In Carius method of estimation of halogen, 0.15 g of an organic compou...

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  14. In sulphur estimation, 0.157 g of an organic compound gave 0.4813 g of...

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  15. An organic compound having molecular mass 60 is found to contain C = 2...

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  16. A gaseous hydrocarbon has 85% carbon and vapour density of 28. The pos...

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  17. Two element X ( at . Mass = 75) and Y(at .mass =16) combine to given ...

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  18. Quantitive measurements of nitrogen in an organic compounds is done by...

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