Sillisic acid is positive sol or negativ sol
Answers
This topic belongs to surface chemistry ; at this time, in my mind, I'm thinking about two processes. Ok, colloids / colloidal solution can be produced by “peptization”– it is an adsorption phenomenon { I'm not sure which kind of adsorption it is bcz in many cases you can see physiosorption followed by chemisorption ( for this one can follow B.E.T. isotherms) }.
However, Electrophoresis is probably the best way to know what is the intrinsic charge of the colloid whether it is (+ve) or (–ve) charged. But yes no movement at isoelectric point of that colloidal solution.
What is Electrophoresis ?
The existence of the electrical charge can be shown by the process of ‘Electrophoresis’. It involves the movement of colloidal particles towards one or the other electrode when placed under the influence of an electric field. The movement of colloidal particles under the influence of an electric field is called Electrophoresis.
As soon as the colloidal particles reach the oppositely charged electrode, they gat neutralized and coagulated. Electrophoresis can be used to find out the nature of the charge that the colloidal particles carry. Colloidal particles may migrate towards either of the electrode i.e. anode or cathode depending upon the charge on the colloidal particles.
• By Coagulation: In this another process, one need to have two known charged colloidal solutions – one is positive and other is negative charged; the result would be better if they are highly chargedl, I mean greater value of Z+ or Z– ; bcz here I want to use “coagulation technique” ( so why higher charge required for better result u can understand: yeah it's “Schulze–Hardy principal” ). So, in this process, u need to take the tested colloid and treat some portion seperately with your two known colloids; now coagulation will tell u the answer. If, the tested one easily coagulates in known (+ve) charged colloid, then that tested sol must have (–ve) charge and vice–versa.
In the 2nd case I just try to use a little concept, Electrophoresis is much better one. But I wrote the later one, bcz we can use this process at our home too — we just required two known different charged colloidal solutions.