Question

Trichloromethane on heating with silver powder gives an unsaturated hydrocarbon A.
i) Write the reaction when A is treated with water in presence of 60% H2SO4 and HgSO4
[1]
ii)What happens when A is treated with Ozone and then with Zn? [1]
iii) How can you distinguish between A and ethane? [2]
iv) What happens when A is reacted with alkaline solution of KMnO4

Answer 1

Answer:

Explanation:

$CHCl_{3} + Ag$ ⇒$C_{2} H_{2}$ (A)

An Alkyne is formed.

(a)  one molecule of water adds to alkynes  on warming with mercuric sulphate and dilute  sulphuric acid at 333 K to form carbonyl compounds.

Refer attachment for equation.

(b) Ozonolysis. Ethylene reacts with ozone to produce Acetylene ozonoid which is further hydrolysed in the presence of zinc to form glyoxal.

($CHO-CHO$)

(c) They can be distinguished by adding Bromine water.

Unsaturated hydrocarbons turn bromine water colourless, hence the test tube in which (A) was present turns from orange to colourless, which is not so with ethane.

(d) It will form two moles of $H-CHO$.

Answer 2

Trichloromethane on reaction with silver powder exchange the ions with each other to form acetylene molecules called ethylene and silver chloride,

Here ,the unsaturated hydrocarbon is ethylene.

i)The reaction of ethylene$H_{2}SO_{4}$  and $HgSO_{4}$

$CH$≡$CH+H_{2}O$---$\frac{dil H_{2}SO_{4} }{HgSO_{4} }$$H_{2}C=C-H$$\frac{Ketonisation}{}$$CH_{3} -CHO$(acetaldehyde

                                                       |

                                                      $OH$

ii) Ethylene reacts with ozone to give 2 molecules of formaldehyde.

iii) Ethane is a saturated hydrocarbon whereas ethene or ethylene is an unsaturated hydrocarbon.

Ethane has no double bonds whereas ethylene has double bonds.

iv)

When ethylene reacts with alkaline  potassium permanganate it gives ethane-1,2-diol or ethylene glycol.

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