Q14 of 33 Page 225

Organic compound ‘A’ of molecular formula C2H4O2 gives brisk effervescence with sodium bicarbonate solution. Sodium salt of A on treatment with soda lime gives a hydrocarbon ‘B’ of molecular mass 16. It belongs to the first member of the alkane family. What are ‘A’ and ‘B’ and how will you prepare ‘A’ from ethanol?

It is given that organic compound gives brisk effervescence with sodium bicarbonate solution.


i. As we know that when ethanoic acid reacts with sodium bicarbonate, it gives brisk effervescence of carbon dioxide.


Hence, the organic compound “A” must be ethanoic acid


(CH3COOH)


The reaction of ethanoic acid with a carbonate (Na2CO3) is:



ii. When sodium salt of ethanoic acid is heated with soda lime, methane (alkane) gas is formed.



Methane (B) formed belongs to the first member of the alkane family


iii. Preparation of ethanoic acid (A) from ethanol:


Ethanol undergoes oxidation with KMnO4 to form a carboxylic acid, i.e., ethanoic acid (A)


The reaction takes place is given below:



Thus, A is ethanoic acid and B is methane.


More from this chapter

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10

Write a balanced equation using the correct symbols for these chemical reactions:

i) Action of hydrogen on ethene in the presence of nickel catalyst.


ii) Combustion of methane evolving carbondioxide and water.


iii) Dehydrogenation of ethanol.


iv) Decarboxylation of Sodium salt of ethanoic acid.


 11

Look at the picture and identify what happens. Support your answer with equations.

i) How is B formed from A?



ii) What happens when acetic acid is treated with carbonate salt. Name the gas produced. What happens when this gas is treated with lime water?



iii) What happens when acetic acid is treated with ethanol in the presence of concentrated H2SO4? Give the equation.



 12

Organic compounds ‘A’ and ‘B’ are the isomers with the molecular formula C2H6O.

Compound ‘A’ produces hydrogen gas with sodium metal, whereas compound ‘B’ does not. Compound ‘A’ reacts with acetic acid in the presence of concentrated H2SO4 bto form compound ‘C’ with a fruity flavour. What are the isomers ‘A’, ‘B’ and the compound ‘C’?


 13

Organic compound ‘A’ of molecular formula C2H6O liberates hydrogen gas with sodium metal. ‘A’ gives ‘B’ of formula C4H10O, when it reacts with concentrated H2SO4 at 413K. At 443K with concentrated H2SO4 ‘A’ gives compound ‘C’ of formula C2H4. This compound ‘C’ decolourises bromine water. What are ‘A’, ‘B’ and ‘C’?