Question

Which of the following processes is not responsible for the presence of electric charge on the sol particles?
A. Electron capture by the sol particles
B. Adsorption of ionic species from solution
C. Formation of Helmholtz electrical double layer
D. Absorption of ionic species from solution

Answer 1

Hint: Here, you need to think about the reactions that take place in the solution when two reactants react with each other like electron transfer or formation of compounds.

Complete step by step answer:
Absorption of ionic species from solution is not responsible for the presence of electric charge on the sol particles. Charge on the sol particles is due to three reasons which are electron capture by the sol particles, adsorption of ionic species from solution and due to formation of Helmholtz electric double layer.
This is because colloidal particles absorb preferentially positive or negative ions present in the dispersion medium. Also, when two or more ions are present in the dispersion medium the selective adsorption of ions common to the colloidal particles takes place resulting in the formation of positively charged and negatively charged particles in the colloidal solution. Therefore, no absorption of ionic species takes place from the solution.

Therefore, the correct answer is option D.

Additional Information:
Double layers a structure that appears on the surface of an object when it is exposed to a fluid. The object might be a solid particle, a gas bubble, a liquid droplet or a porous body. Helmholtz was the first person to realize that charged electrodes immersed in electrolyte solutions repel the co-ions of the charge while attracting counter ions to their surfaces.

Note:/b>
Here we noted that absorption of ionic species is not a reason for electric charge on the sol particles. Charged surfaces are often useful in creating surfaces that will not adsorb certain molecules which are used in paints. Polymers are used in such cases as they contain ionizable groups, which provide a surface charge when submerged in an aqueous solution.