Question

Suppose you have taken a dilute solution of oleic acid in such a way that its concentration becomes $0.01\,cm ^{3}$ of oleic acid per $cm ^{3}$ of the solution. Then you make a thin film of this solution (monomolecular thickness) of area $4\,cm ^{2}$ by considering 100 spherical drops of radius $\left(\frac{3}{40 \pi}\right)^{\frac{1}{3}} \times 10^{-3}\,cm .$ Then the thickness of oleic acid layer will be $x \times 10^{-14}\,m$. Where $x$ is ________.

Answer 1

$4 t _{ T }=100 \times \frac{4}{3} \pi r ^{3}$
$=100 \times \frac{4 \pi}{3} \times \frac{3}{40 \pi} \times 10^{-9}=10^{-8} cm ^{3}$
$t _{ T }=25 \times 10^{-10} cm$
$=25 \times 10^{-12} m$
$t _{0}=0.01 t _{ T }=25 \times 10^{-14} m$
$=25$