Question

A compound X on heating With excess Sulphuric Acid at 443 K gives an unsaturated compound Y X also react with Na to evolve a colourless gas Z.Identify X Y andZ

Answer 1

1. When an Alkanol Eg. Ethanol is heated with excess concentrated sulphuric acid, the Sulphuric acid acts as a dehydrating agent thus removing the water molecules from the Alkanol to form an unsaturated compound of the respective Alkanol. And in this case the compound is Ethene.

2. When Ethanol reacts with group one metals Eg. Sodium , the hydrogen in the hydroxyl branch is displaced to form a metal ethoxide and hydrogen gas. In this case the compound formed is Sodium Ethoxide.

The identities of xyz are thus :

X - Ethanol

Y- Ethene

Z - Hydrogen

Answer 2

The names of the compounds are as follows.

X - Ethanol

Y - Ethene

Z - Hydrogen

Given:

X heated with $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ at 443 K gives a compound called Y which is unsaturated.

To find:

X, Y and Z

Solution:

X on heating with excess $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ at 443 K produces a compound called Y which is an unsaturated one.

An unsaturated compound means it have double bond between carbon atoms.

$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OH } \stackrel { \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } , 443 \mathrm { K } } { \longrightarrow } \mathrm { CH } _ { 2 } = \mathrm { CH } _ { 2 } + \mathrm { H } _ { 2 } \mathrm { O }$

Here,

$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OH } \quad denotes \quad X$

$\mathrm { CH } _ { 2 } = \mathrm { CH } _ { 2 } \quad denotes \quad Y$

In the above reaction concentrated $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ removes an water molecule from ethanol to form ethene.

Ethanol get reacted with sodium to evolve hydrogen gas (Z). The chemical reaction is as follows.

$2 \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OH } + \mathrm { Na } \rightarrow \mathrm { C } _ { 2 } \mathrm { H } _ { 5 } \mathrm { ONa } + \mathrm { H } _ { 2 }$

Here,

$2 \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OH } \quad denotes \quad X$

$\mathrm { H } _ { 2 } \quad denotes \quad Z$

Therefore, X, Y, and Z are ethanol, ethene, and hydrogen respectively.