The Hardy Schulze Rule is a rule in chemistry used to determine the coagulating value of a solution and thus deals with the process of coagulation in a solution. It was discovered by William Hardy and Hans Schulze.
Index
Schulze Hardy Rule Statement
The Hardy Schulze rule states that the amount of electrolyte required for the coagulation of a certain amount of a colloidal solution depends on the valency of the coagulating ion.
What is Coagulation
Coagulation is the chemical process of joining two colloidal particles which result in the formation of larger particles, that eventually settle down as precipitate or float on the surface.
This process usually takes place on the addition of electrolytes to the solution. These electrolytes can be either positive or negative, based on the electric charge of the solution. These electrolytes are often called coagulating ions or flocculating ions.
The Process of Coagulation
Upon addition of an electrolyte, into a colloidal solution, the particles of the solution attract the coagulating ions and get neutralized.
It was observed that the greater the valency of flocculating ion, the greater is its power to coagulate.
Hardy Schulze Rule Example
Let us discuss some Hardy Schulze rule example which will help understand the concept better.
Eg. 1: Among PO4-3 and Cl– which ion has more power of coagulation?
Among PO4-3 and Cl–, PO4-3 has higher coagulation power as its valency is greater than that of Cl ion.
Eg. 2: Place the following electrolytes in the order of increasing power of coagulation,
PO4-3, Cl–, [Fe(CN)6]4-.
The order of increasing power of coagulation for the above electrolytes are,
Cl– < PO4-3 < [Fe(CN)6]4-.
FAQs
The coagulation or flocculation value is the minimum amount of electrolyte required to be added to one liter of a colloidal solution so as to achieve complete flocculation or coagulation of the solution.
The rule in chemistry states, the amount of electrolyte required for the coagulation of a certain amount of a colloidal solution depends on the valency of the coagulating ion.
The power of coagulation of a colloidal solution or an electrolyte varies as follows,
The higher the charge or valency of an electrolyte, the higher is its coagulation power.
