The required amount of electrolyte for the coagulation of a definite quantity of colloidal solution is dependent on the valency of the coagulating ion (which is the ion that holds a charge which is opposite to the charge of the colloidal particles). This observation is often referred to as the Hardy Schulze law. Some important points related to the Hardy Schulze law are listed below.
- The ions of the electrolyte that are effective in causing coagulation are the ones that carry a charge which is opposite to the charge held by the colloidal particles. These ions can be referred to as flocculating ions or coagulating ions.
- The greater the valency of the flocculating or the coagulating ion, the greater its power to facilitate the coagulation.