Some Basic Concepts of Chemistry - Result Question 40 — JEE PYQ Chapterwise

44. An organic compound $X$ on analysis gives 24.24 per cent carbon and 4.04 per cent hydrogen. Further, sodium extract of 1.0 g of $X$ gives 2.90 g of silver chloride with acidified silver nitrate solution. The compound $X$ may be represented by two isomeric structures $Y$ and $Z . Y$ on treatment with aqueous potassium hydroxide solution gives a dihydroxy compound while $Z$ on similar treatment gives ethanal. Find out the molecular formula of $X$ and gives the structure of $Y$ and $Z$.

(1989,5 M)

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Solution:

44. Mass of chlorine in $1.0 \mathrm{~g} X=\frac{35.5}{143.5} \times 2.9=0.717 \mathrm{~g}$

Now, the empirical formula can be derived as :

	C	H	Cl
% wt :	24.24	4.04	71.72
Mole :	2	4	2
Simple ratio :	1	2	1

$\Rightarrow$ Empirical formula $=\mathrm{CH}_2 \mathrm{Cl}$.

Because $X$ can be represented by two formula of which one gives a dihydroxy compound with KOH indicates that $X$ has two chlorine atoms per molecule.

On treatment with KOH , I will give ethane-1, 2-diol, hence it is $Y . Z$ on treatment with KOH will give ethanal as