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Give the preparation of alkane from carboxylic acid by the electrolysis. |
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Answer» Solution :* An aqueous solution of SODIUM or potassium salt of a carboxylic acid on electrolysis gives alkane containing even number of carbon atoms Example : Salt of Na of acetic, ETHANE is obtained by the electrolysis of sodium acetate is as follows.  In this reaction there is always a formation of even carbon product of alkane. Reaction : (a) In aqueous solution of sodium salt of acid, `CH_(3)COO^(-)` is anion and `Na^(+)` is cation in a solution. `2CH_(3)COO^(-)Na^(+) hArr 2CH_(3)COO_((aq))^(-) + 2Na_((aq))^(+)` ...(a) (B) (i) Oxidation at anode : Anion `CH_(3)COO^(-)` goes to the anode, losses its electon and doesoxidation and `CH_(3)` is formed.  (ii) `H_(3)OVERSET(.)(C)+overset(.)(C)H_(3) rarr UNDERSET("Ethane(gas)")(CH_(3)-CH_(3))uarr` (c) Reduction at cathode : Cation does not reduced at cathode but `H_(2)O` gets reduced and hydrogen `(H_(2))` is being released. (i) `H_(2)O + e^(-) rarr ""^(-)OH + overset(.)(H)` (ii) `2overset(.)(H)rarr H_(2) uarr` `2Na^(+) + 2H_(2)O + 2e^(-) rarr 2NaOH + H_(2(g))` ...(c) (d) Total reaction = (a) + (b) + (c) are as follows  Limitations : MEthane cannot be prepared by this by this method. |
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