Question

The charge on As₂S₃ sol is due to the adsorption of ______.

Options

• H⁺

• OH⁻

• O²⁻

• S²⁻

Answer 1

The charge on As₂S₃ sol is due to the adsorption of S²⁻.

Explanation:

Arsenic sulfide (As₂S₃) sol is a negatively charged colloid. When prepared (e.g., by the reaction of As₂S₃ with H₂S), the colloidal particles preferentially adsorb the common ions available in the dispersion medium, which are the sulfide ions (S²⁻). This selective adsorption of S²⁻ ions on the surface of the colloidal particles gives them a net negative charge, which is crucial for the stability of the sol due to electrostatic repulsion between the particles.