Surface Chemistry

Tyndall effect is the optical characteristics of light in which comparable particle size of colloids and bombarded light wavelength can produce this type of effect. For scattering effect of light in Tyndall effect refractive index of dispersed phase and dispersion medium should be greatly different.

$\left[Ag{\left(N{H}_3\right)}_2\right]\left[Ag{\left(CN\right)}_2\right]contains{\left[Ag{\left(N{H}_3\right)}_2\right]}^{+}and{\left[Ag{\left(CN\right)}_2\right]}^{-}$

 ln ${\left[Ag{\left(N{H}_3\right)}_2\right]}^{+},$  oxidation state of Ag = +1

$ln{\left[Ag{\left(CN\right)}_2\right]}^{-}$   , oxidation state Ag = +1

Hence; sum of oxidation state = 2

$\left(\frac{x}{m}\right)=K{P}^{1/n}$           

$\frac{10}{1}=K{\left(100\right)}^{1/n}................\left(1\right)$     

$\frac{15}{1}=K{\left(200\right)}^{1/n}................\left(2\right)$

$\frac{V}{1}=K{\left(300\right)}^{1/n}...............\left(3\right)$

Dividing (2) by (1)

$\frac{15}{10}={\left(\frac{2}{1}\right)}^{1/n}$ = (2)^1/n

$\frac{V}{10}=10^{0.279}$

$V=10*10^{0.279}=10^{1.279}=10^x$

$\therefore x=1.279=127.91*10^{-2}\approx 128*10^{-2}$

Ans. = 128

By increases in temperature absorption decreases, T₁ > T₂ means higher absorption at T₂ temperature.

In the lyophilic colloids, the colloidal particles are extremely solvated.

FeCl₃ + K₄ [Fe (CN)₆] (Potassium ferrocyanide)

excess

|

K Fe [Fe (CN)₆]

(colloidal species)

Prussian Blue coloured 

colloidal complex

Tyndall effect is more effectively shown by lyophobic colloidal solution.

During adsorption of a gas on solid surface, process is exothermic i.e. $\Delta H=-ve\left(\Delta H<0\right)$  and entropy decreased, because gas particle resides on solid surface. Hence $\Delta S<0.$

When AgNO₃ added to Kl solution, it form precipitate of Agl (s) which absorb I^- ions from Kl and colloidal particles become negatively charged.