Question

The coagulating power of electrolytes having ions $Na^+, Al^{3+}$ and $Ba^{2+}$ for arsenic sulphide sol increases in the order

• A. $Al^{3+} < Ba^{2+} < Na^+$
• B. $Na^+ < Ba^{2+} < Al^{3+}$
• C. $Ba^{2+} < Na^{2+} < Al^{3+}$
• D. $Al^{3+} < Na^+ < Ba^{2+}$

Answer 1

Answer: (B)

According to Hardy Schulze rule, greater the charge on oppositely charged ion, greater is its coagulating power. Since arsenic sulphide is a negatively charged sol, thus, the order of coagulating power is $Na^+ < Ba^{2+} < Al^{3+}$