Question

Which of the salt-solution is most effective for coagulation of arsenious sulphide?

• A. $BaC{l}_2$
• B. $AlC{l}_3$
• C. $N{a}_{3}P{O}_4$
• D. $NaCl$

Answer 1

The correct option is B $AlC{l}_3$

Arsenious sulphide sol is a negative colloid, $A{s}_2{S}_3$. $(S{)}^{2-}$ .So, it will be coag u lated by the cation of an electrolyte. According to the Hardy-Schulze rule, the higher the charge of the ion, the more effective it is in bringing about coagulation. Here, the cations available are $A{l}^{3+}$ (from $AlC{l}_3$ ), $B{a}^{2+}$ (from $BaC{l}_2$ ) and $N{a}^{+}$ (from $N{a}_{3}P{O}_4$ and $NaCl$). So, their power to coagulate $A{s}_2{S}_3$. $(S^{2-}$) will follow the order as $A{l}^{3+}>B{a}^{2+}>N{a}^{+}$.