Question

Ferric hydroxide sol is positively charged colloid. The coagulating power of $\mathrm { NO } _ { 3 } ^ { - } , \mathrm { SO } _ { 4 } ^ { 2 - }$ and ions would be in the order.

• A. $\mathrm { NO } _ { 3 } ^ { - } > \mathrm { SO } _ { 4 } ^ { 2 - } > \mathrm { PO } _ { 4 } ^ { 3 - }$
• B. $\mathrm { SO } _ { 4 } ^ { 2 - } > \mathrm { NO } _ { 3 } ^ { - } > \mathrm { PO } _ { 4 } ^ { 3 - }$
• C. $\mathrm { PO } _ { 4 } ^ { 3 - } > \mathrm { SO } _ { 4 } ^ { 2 - } > \mathrm { NO } _ { 3 } ^ { - }$
• D. $\mathrm { NO } _ { 3 } ^ { - } = \mathrm { SO } _ { 4 } ^ { 2 - } = \mathrm { PO } _ { 4 } ^ { 3 - }$

Answer 1

Answer: (C)

$\mathrm { PO } _ { 4 } ^ { 3 - } > \mathrm { SO } _ { 4 } ^ { 2 - } > \mathrm { NO } _ { 3 } ^ { - }$

Answer 2

Sol According to Hardy schulze rule the ions having opposite charge to sol particle cause coagulation and greater the valency of oppositely charged ion more is the coagulating power $\left( \mathrm { PO } _ { 4 } ^ { 3 - } > \mathrm { SO } _ { 4 } ^ { 2 - } > \mathrm { NO } _ { 3 } ^ { - } \right.$).