Question

On the basis of Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride?

Answer 1

Minimum quantity of an electrolyte required to cause precipitation of a sol is called its coagulating value. Greater the charge on flocculating ion and smaller is the amount of electrolyte required for precipitation, higher is the coagulating power of coagulating ion. This is known as Hardy-Schulze rule.

Hence, Higher the charge on ions, the smaller is the amount of electrolyte required for precipitation.

Phosphate ion has $-3$ charge while chloride ion carries only $-1$ charge.

So, the coagulating power of phosphate is higher than chloride.