Question

explain the method of measuring the size of oleic acid molecule​

Answer 1

The method of measuring the size of oleic acid molecules :-

${ \large{ \purple{\underline{\underline{ \rm{Molecular \: Layer \: Method :}}}}}}$

This method is used to estimate size of molecules of liquid and it is suitable for liquid for large molecular size. For example :- Oleic Acid.

Now let's find out the size of oleic acid molecule :-

First we will make a solution by putting 1 cc of oleic acid into 400 cc of alcohol.

Concentration of solution is $\frac{1} {400}$ of oleic acid in alcohol.

We will put the solution into water ${ \rm{(H_{2}O)}}$ and will make a film. After sometime, alcohol will evaporate. We will first mark that film on tracing paper and then put it on graph paper. So from mm graph paper we will easily calculate its area.

$\purple{ \rm{Molecular \: Layer \: Method : Derivation}}$

◉ n = Number of drops to make a film

◉ V = Volume of one drop

Volume of n drops of the solution = nV cm³

Amount of oleic acid in this solution

$\blue{ \tt{ = \frac{nV}{400 A} \: {cm}^{3} }}$

A and V we have already calculated ☑

Thickness of the film,

$\blue{ \sf{t = \frac{Volume \: of \: the \: film}{Area \: of \: the \: film}}}$

$\blue{ \tt{t = \frac{nV}{400A} \: cm }}$

Assuming that the film has one molecular thickness,

➯ t = diameter of molecule of oleic acid (approx.)

The value of t is found to be ${10}^{ - 9} \: m$

$\purple{{ \green{ \underline{ \boxed{ \blue{ {10}^{ - 9} \: m \: { \small{ \sf{(approx)}}}}}}}}}$

This is the rough estimation.........

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