Question

State with reasons whether all solutions obey the equation of van't Hoff for osmotic pressure.​

Answer 1

The equation of Van't Hoff for osmotic pressure.

Explanation:

Osmotic Pressure is defined as the minimum external pressure required to prevent or stop osmosis.

In other words, it is the pressure exerted by solute particles on the semi-permeable membrane to prevent the flow of solvent molecules.

It is represented by π.

Osmotic pressure is directly proportional to Molar concentration of solution and Temperature.

π=iCRT

i is the Van't Hoff Factor.

R is Universal Gas Constant

T is temperature

C is concentration of solution in terms of molarity.

1. Non-electrolytes when added to reaction mixtures, neither associate nor dissociate. Thus, Van't Hoff factor(i) is one.

Example: urea, glucose.

2. Electrolytes that dissociate in the solution have Van't Hoff factor greater than one.

Example: Sodium chloride, Magnesium sulphate.

3. Electrolytes that associate in the reaction mixture have Van't Hoff factor less than one.

Example: weak organic acids.

Van't Hoff equation for osmotic pressure is only applicable for dilute solutions.

They cannot be applied on concentrated solutions.

Solute must be non-volatile in nature.