Question

How can a solution of potassium phosphate be distinguished chemically from potassium sulphate solution?

Answer 1

The chemical formula of potassium phosphate is ${{K}_{3}}P{{O}_{4}}$ and the chemical or molecular formula of potassium sulphate is ${{K}_{2}}S{{O}_{4}}$ . By using ammonium molybdate chemical we can easily differentiate the chemicals potassium phosphate from potassium sulphate.

Complete answer:
- In the question it is asked how we can easily differentiate chemically potassium phosphate from potassium sulphate.
- The chemical formula of ammonium molybdate is ${{(N{{H}_{4}})}_{2}}Mo{{O}_{4}}$ .
- By using ammonium molybdate we can easily differentiate potassium phosphate easily from potassium sulphate.
- The potassium sulphate does not react with ammonium molybdate.
- But the chemical potassium phosphate will react with ammonium molybdate and forms ammonium molybdate in the form of yellow color precipitate.
- The chemical reaction of to represent the chemical reaction of potassium phosphate with ammonium molybdate is as follows.
${{\text{K}}_{\text{3}}}\text{P}{{\text{O}}_{\text{4}}}\text{+}\underset{\text{Ammonium molybdate}}{\mathop{{{\text{(N}{{\text{H}}_{\text{4}}}\text{)}}_{\text{2}}}\text{Mo}{{\text{O}}_{\text{4}}}}}\,\text{+21HN}{{\text{O}}_{\text{3}}}\to \underset{\text{Ammonium phosphomolybdate}}{\mathop{{{\text{(N}{{\text{H}}_{\text{4}}}\text{)}}_{\text{3}}}\text{P}{{\text{O}}_{\text{4}}}\text{.12Mo}{{\text{O}}_{\text{3}}}}}\,+21N{{H}_{4}}N{{O}_{3}}+12{{H}_{2}}O$
- The chemical formula of ammonium phosphomolybdate is ${{\text{(N}{{\text{H}}_{\text{4}}}\text{)}}_{\text{3}}}\text{P}{{\text{O}}_{\text{4}}}\text{.12Mo}{{\text{O}}_{\text{3}}}$ .
- In the above chemical reaction one mole of potassium phosphate reacts with one mole of ammonium molybdate in the presence of 21 moles of nitric acid and forms an yellow precipitate of one mole of ammonium phosphomolybdate.

Note:
It is one of the ways to distinguish different chemicals by taking the help of other chemicals. Potassium sulphate and potassium phosphate both the chemicals have the same cationic part of potassium but the anionic parts are different. The anionic part in potassium phosphate is phosphate and the anionic part in potassium sulphate is sulphate.