Question

The coagulating power of an electrolyte for arsenious sulphide decreases in the order:

• A. $Na ^{+}> Al ^{3+}> Ba ^{2+}$
• B. $P O_{4}^{3-}>S O_{4}^{2-}>C l^{-}$
• C. $Cl > SO _{4}^{2-}> PO _{4}^{3-}$
• D. $A l^{3+}>B a^{2+}>N a^{+}$

Answer 1

Answer: (D)

According to Hardy Schuiz rule, the coagulating power of electrolyte increases with charge on ion.
$\because A_{s}{ }_{2} S_{3}$ is negatively charged colloid and so it will be coagulated by cations.
$\therefore $ Correct order of coagulating power for $As _{2} S _{3}$ is
$A l^{3+}>B a^{2+}>N a^{+}$