Question

The substance $A$ when dissolved in solvent $B$ shows the molecular mass corresponding to $A_3$. What is the Van't Hoffs factor?

Answer 1

Van't Hoff Factor:

• The Van't Hoff factor provides knowledge on how solutes influence the colligative aspects of solutions.
• It is illustrated by the letter 'i.'
• The Van't Hoff factor is depicted as when a substance dissolves, the mass ratio of particle concentration to substance concentration.
• As an example, Van't Hoff factor is ideally $3$ for ${\mathrm{CaCl}}_2$, since it segregates into one ${\mathrm{Ca}}^{2+}$ ion and two ${\mathrm{Cl}}^{-}$ ions.
• Regardless, some of these ions form associations in the solution, reducing the overall amount of particles in the solution.
• The reaction to a given problem can be written as,

$\underset{1-\mathrm{\alpha }}{3\mathrm{A}}\to \underset{\mathrm{\alpha }/3}{{\mathrm{A}}_3}$

$\mathrm{i}=1-\mathrm{\alpha }=\mathrm{\alpha }/3\left(\mathrm{\alpha }=100\%\right)$

$$\begin{gathered} 1-1+\frac{1}{3} \\ =\frac{1}{3} \end{gathered}$$

Hence the Van't Hoff Factor will be $\frac{1}{3}$.