Question

a) arrange the following ions according to the increasing order of efficiency of coagulation. Cl-, PO4 3-,SO4 2- b) Give the name of the rule relatedto above arrangement

Answer 1

Answer(a) : The increasing order of efficiency of coagulation will be:

$Cl^-<SO_4^{2-}<PO_4^{3-}$

Answer(b): Hardy Schulze rule

Explanation:

According to Hardy Schulze rule:

• If the charge carried by the coagulating ion is opposite to the charge of colloidal particles it will result in coagulation.
• More the charge on active ion , more will be the efficiency in coagulation. For example : phosphate ion having a valency of -3 will coagulate the positively charged colloid solution more efficiently than that of the sulfate ions with valency of -2.Similarly sulfate ion having a valency of -2 will coagulate the positively charged colloid solution more efficiency than that of the chloride ions with valency of -1.