A compound ' X ' on heating with excess ...

CBSE Class 10 Science 2018 Solved Paper

Question : 3 of 27

Marks: +1, -0

A compound '

X

' on heating with excess conc. sulphuric acid at

443\,\mathrm{K}

gives an unsaturated compound '

Y

'. '

X

' also reacts with sodium metal to evolve a colourless gas '

Z

'. Identify '

X

', '

Y

' and '

Z

'. Write the equation of the chemical reaction of formation of '

Y

' and also write the role of sulphuric acid in the reaction.

Solution:

\text{Compound X} \xrightarrow[\text{excess.conc. Heating at 443 K}]{\mathrm{H}_2\mathrm{SO}_4} \text{Unsaturated compound } Y

\underset{\text{Ethanol}}{\mathrm{CH}_3-\mathrm{CH}_2\mathrm{OH}} \quad \text{Conc. H}_2\mathrm{SO}_4 / 443\ \mathrm{K} \quad \underset{\text{Ethene}}{\mathrm{CH}_2=\mathrm{CH}_2} + \underset{\text{water}}{\mathrm{H}_2\mathrm{O}}

X = \mathrm{CH}_3\mathrm{CH}_2\mathrm{OH} \text{ (ethanol) }

Y = \mathrm{CH}_2=\mathrm{CH}_2 \text{ (ethene) }

\mathrm{CH}_3\mathrm{CH}_2\mathrm{OH} + \mathrm{Na} \rightarrow \mathrm{CH}_3\mathrm{CH}_2\mathrm{ONa} + \mathrm{H}_2

Z =

Hydrogen gas.

Here, concentrated sulphuric acid acts as a dehydrating agent, it removes water molecule from ethanol.

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