Question

What are Lyophilic and Lyophobic solutions? Give one example of each.

Answer 1

Hint: Colloids are the dissolved state of substances that either do not pass, or pass very slowly through a parchment paper. If colloids have strong affinity between particles of dispersed phase and dispersion medium, they are called as Lyophilic solutions. And the phase in which no attraction between dispersion medium is called as a Lyophobic solution.

Complete answer:
Solution, in chemistry, a homogenous mixture of two or more substances in relative quantities that can be continuously varied up to what's called the solubility limit. The word solution is generally used for the liquid state of matter, but gas and solid solutions are possible.
Dispersed phase: It is the component present in a small proportion.
Dispersed medium: It is the component present in excess.
For example, silver in water; silver is dispersion phase and water is dispersed medium.
Based on the physical state of the dispersed medium and dispersed phase is classified into two types. Solution is an important concept in colloids. In solution, the dispersion phase is solid and the dispersion medium is liquid. Depending upon the nature of attraction they divide into two parts:
A) Lyophilic solutions
B) Lyophobic solutions
> Lyophilic solution means ‘liquid-loving’ or ‘solvent attraction’. This means that there is a strong attraction between the dispersed phase and dispersion medium, i.e. dispersion phase has great affinity for the dispersion medium that results in the extensiveness of the colloidal particles. In these solutions, dispersion phase cannot easily precipitate so due to this solutions are stable in nature. These solutions are reversible in nature. Additional stabilizers are not required during their preparation. If water is used as a dispersion medium, Lyophilic solutions are called hydrolysis solutions.
Example: Starch, gum, etc.
Starch: it forms a Lyophilic solution when water is used as the dispersion medium. The formation of solution is accelerated by heating. It is quite stable and it is not affected by any electrolytic impurity.
> Lyophobic means ‘liquid-hating’. That means in these solutions there is little or no interaction between the dispersed phase and the dispersion medium i.e. dispersed phase has little affinity for dispersed medium. These solutions are easily precipitated by the addition of small amounts of electrolyte, by heating. They need stabilizing agents for their preparation.
Example: solution of metals and their insoluble compounds like sulphides and oxides.
Ferric hydroxide solution: it forms a Lyophilic solution on treatment with water. It is prepared by the hydrolysis of ferric chloride with boiling distilled water. The reaction is:
\[FeC{l_3} + 3{H_2}O \to Fe{(OH)_3} + 3HCl\]

Note: Preparation of Lyophilic solution is easy, they form directly and particles are not detectable by ultra microscope, but Lyophobic solution cannot form directly and the particles are easily detectable under ultra microscope.