Question

The coagulating power of electrolytes that have the ions $B{r}^{-},C_2{O}_4^{2-}$ & $\left[Fe\right(CN{)}_6{]}^{3-}$ for ferric hydroxide sol increases in the order:

• A. $B{r}^{-}>C_2{O}_4^{2-}>\left[Fe\right(CN{)}_6{]}^{3-}$
  
• B. $B{r}^{-}<C_2{O}_4^{2-}<\left[Fe\right(CN{)}_6{]}^{3-}$
  
• C. $B{r}^{-}<\left[Fe\right(CN{)}_6{]}^{3-}<C_2{O}_4^{2-}$
  
• D. $\left[Fe\right(CN{)}_6{]}^{3-}<B{r}^{-}<C_2{O}_4^{2-}$

Answer 1

The correct option is B $B{r}^{-}<C_2{O}_4^{2-}<\left[Fe\right(CN{)}_6{]}^{3-}$


Ferric hydroxide is a positive sol (cationic sol). Hence, its coagulation will depend on the coagulating power of the anion which is directly proportional to the valency of the anion [Hardy Schulze law].