Name: pH of a Solution
Uploaded: 2019-07-19
Duration: 4 min 31 s
Description: This video discusses the pH scale and how it is useful to determine the behaviour of an acidic or basic solution. Does it also tell what the pH of a neutral...

Question

Name the basic radicals of Group-

III B

of qualitative analysis. What is the group reagent?

Accepted Answer

The Group- $III B$ radicals are ${Co}^{2 +}, {Ni}^{2 +}, {Mn}^{2 +}$ and ${Zn}^{2 +}$ . The group reagent is $H_{2} S$ in the presence of ${NH}_{4} OH$ .

Hydroxide ions produced by the dissociation of ammonium hydroxide ( ${NH}_{4} OH \overset{}{⇌} {NH}_{4}^{+} + {OH}^{-}$ ) combines with the hydrogen ions furnished by hydrogen sulphide ( $H_{2} S \overset{}{⇌} 2 H^{+} + S^{2 -}$ ) to form unionisable water. As a result, more $H_{2} S$ is ionised to maintain the equilibrium according to Le Chatelier's principle. Thus, the concentration of $S^{2 -}$ ions will be high in the solution and a stage will be reached when the ionic products of Group- $III B$ radicals and sulphide ions exceed the corresponding solubility products and Group- $III B$ radicals are precipitated out. Therefore, it is necessary to add excess of $III B$ before passing $H_{2} S$ for precipitation.

Name the basic radicals of Group- $III B$ of qualitative analysis. What is the group reagent?

Important Questions on Equilibria

Learn and Prepare for any exam you want !

Name the basic radicals of Group-III B of qualitative analysis. What is the group reagent?

Important Questions on Equilibria

Learn and Prepare for any exam you want !

Name the basic radicals of Group- $III B$ of qualitative analysis. What is the group reagent?