Question

From information in Table 16-3, explain how you would use ${\mathbf{KMnO}}_{\mathbf{4}}$to find the content of ${\left({\mathrm{NH}}_4\right)}_{\mathbf{2}}{\mathbf{S}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{8}}$in a solid mixture with${\mathbf{\left(}{\mathbf{NH}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{2}}{\mathbf{S}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{4}}$What is the purpose of phosphoric acid in the procedure?

Short answer

The end point of phosphoric acid is the development of yellow colour in ${\mathrm{Fe}}^{3+}$

Step-by-step solution

Concept used

The answer is not given in the Drive.

How to determine the content of (NH4)S2O8x using potassium permanganate in the solid mixture with (NH4)S2O4 must be specified, as well as the function of phosphoric acid in this operation.

Given data: For ${\mathrm{S}}_2{\mathrm{O}}_8^{2-}$species, the reaction is

Given as,

${\mathrm{S}}_2{\mathrm{O}}_8^{2-}+2{\mathrm{Fe}}^{2+}+2{\mathrm{H}}^{+}\rightleftharpoons 2{\mathrm{Fe}}^{3+}2{\mathrm{HSO}}_4^{-}$

Extra standard is supplemented with peroxydisulphate.

${\mathrm{Fe}}^{2+}$having${\mathrm{H}}_3{\mathrm{PO}}_4$ Remaining${\mathrm{Fe}}^{2+}$ titrated with${\mathrm{MnO}}_4^{-}$

A weighted amount of the solid combination is added to the solution containing more standard${\mathrm{Fe}}^{2+}$ and phosphoric acid.

Each mol $\left({\mathrm{NH}}_4\right){\mathrm{S}}_2{\mathrm{O}}_8$of oxidises two mol of ${\mathrm{Fe}}^{2+}$and ${\mathrm{Fe}}^{3+}$

To compute the quantity of ${\mathrm{Fe}}^{2+}$consumed by$\left({\mathrm{NH}}_4\right){\mathrm{S}}_2{\mathrm{O}}_8$ extra${\mathrm{Fe}}^{2+}$ is titrated with normal potassium permanganate.

The end point of phosphoric acid is the development of yellow colour in${\mathrm{Fe}}^{3+}$