Question

In the proecure, the filtrate is tested with the two test reagents, what does it mean if test tube treated with the 1 M SrCl₂ reagent shows a precipitate in the test for the limiting reactant? what does it mean if test tube is treated with the 1 M Na₃PO₄ test reagant shows a precipitate? Be sure to clearly describe the reasons of your answers.

Answer 1

In the first test tube, SrCl2 is added to give a precipitate, to know the presence of limiting reactant.   this shows the presence of either an impurity(contamination) in smaller quantity or one of the reactants being left behind unreacted.

The precipitate could due to the presence of sulphate ion which is white strontium sulphate .

The precipitate with sodium phosphate may be due tothe presence of magnesium ions, which is precipitated as magnesium ammonium phosphate in the presence of ammonium hydroxide.