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Grade 12Physical Chemistry

What is meant by positive sol and negative sol?

Profile image of M Aditya
11 Years agoGrade 12
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1 Answer

Profile image of Avinash
11 Years ago
One of the most important properties of colloidal solutions is that colloidal particles posses a definite type of electrical charge. In a particular colloidal solution, all the colloidal particles carry the same type of charge, while the dispersion medium has an equal but opposite charge. Thus, the charge on colloidal particles is balanced by that of the dispersion medium and the colloidal solution as a whole is electrically neutral. For example, in a ferric hydroxide sol, the colloidal ferric hydroxide particles are positively charged, while the dispersion medium carries an equal and opposite negative charge.

The stability of a colloidal solution is mainly due to the presence a particular type of charge on all the colloidal present in it. Due to the presence of similar and equal charges, the colloidal particles repel one another and are thus unable to combine together to form larger particles. This keeps them dispersed in the medium and the colloidal remains stable. This is why sol particles do not settle down even on standing for a long time.

Based on the nature of charge, the colloidal sols may be classified as positively charged and negatively charged sols.