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Organic Chemistry – Some Basic Principles and Techniques

Long Answer Type

271. An organic compound contains 69% carbon and 4.8% hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when 0.20g of this substance is subjected to complete combustion.

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272.

How is nitrogen estimated in a given organic compound by Duma's method?

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273.

In a Duma's nitrogen estimation method, 0.3 g of an organic compound gave 50 mL of nitrogen collected at 300K and 715 mm pressure. Calculate the percentage of nitrogen in the compound. (Aqueous tension of water at 300 K is 15 mm).

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274.

How is nitrogen estimated in a given organic compound by Kjeldahl’s method?

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Short Answer Type

275. During nitrogen estimation present in an organic compound by Kjeldahl’s method, the ammonia evolved from 0.5g of the compound in Kjeldahl’s estimation of nitrogen neutralised 10 mL of 1M H₂SO₄. Find the percentage of nitrogen in the compound.

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Long Answer Type

276. A sample of 0.50 g of an organic compound was treated according to Kjeldahl’s method. The ammonia evolved was abosrbed in 50 mL of 0.5 MH₂SO₄. The residual acid required 60 mL of 0.5 solution of NaOH for neutralisation. Find the percentage composition of nitrogen in the compound.

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277.
Discuss a suitable method for the estimation of halogens.

Carius method for the estimation of halogens: A known mass of the organic compound containing halogens is heated with an excess of fuming nitric acid and silver nitrate in a sealed tube called Carius tube. Cabron, hydrogen and sulphur (if present) are oxidised to CO₂, H₂O and H₂SO₄respectively whereas halogen forms a precipitate of silver halide. The precipitate is separated, washed with distilled water, dried and weighed. The percentage of halogens is then calculated. Calculations:

Let the mass of the compound taken = Wg Let the mass of halide (AgX) formed = ag

Atomic mass of halogen = x

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Short Answer Type

278. 0.3780 of an organic chloro compound gave 0.5740 g of silver chloride in Carius estimation. Calculate the percentage of chlorine present in the compound.

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