Question

A solution of palmitic acid (Molar mass $=256g/mol$) in benzene contains $4.24g$ acid $perlitre$. When this solution is dropped on the water surface, benzene evaporates and palmitic acid forms a monomolecular film of the solid type. If we wish to cover an area of $500c{m}^2$ with a monolayer, what volume of solution should be used? The area occupied by one palmitic acid molecule may be taken to be $21\times {10}^{-20}{m}^2$.

Answer 1

V litre volume of solution taken.
$W(4.24\times V)g$
Number of atoms $=\frac{W}{Atomicmass}\times Avogadr{o}^{\prime }snumber$
$=\frac{4.24V}{256}\times 6.023\times {10}^{23}$
Area $=500\times {10}^{-4}{m}^2=[\frac{4.24V}{256}\times 6.023\times {10}^{23}]\times 21\times {10}^{-20}$
$V=0.0000239liter=0.0239c{m}^3$]