Question

What is the composition of Magnesia mixture ?
a.) mixture of magnesium sulphate, ammonium chloride and ammonia
b.) mixture of a solution of magnesium chloride, ammonium phosphate and ammonia
c.) mixture of a solution of magnesium chloride, ammonium chloride and ammonia
d.) mixture of a solution of magnesium chloride and ammonium chloride

Answer 1

Hint The Magnesia mixture is used to test the phosphorus. The soluble Phosphorus when react with magnesia mixture gives out precipitates of magnesium ammonium phosphate. These ppt are white in colour. The magnesium is present in the form of its sulphate ion.

Complete step by step answer :
The Magnesia mixture is a reagent which is used to analyse the phosphorus. This phosphorus analysing reagent consists of a solution of an aqueous mixture of ammonium chloride and magnesium sulphate along with ammonia.
The magnesia mixture can be easily prepared.
To prepare, one needs solid ammonium chloride which is very easily available in our chemistry lab. This solid ammonium chloride is added to aqueous magnesium chloride solution. Then, the solution is boiled for some time so that there is uniform dissolution. Then, it is cooled for some time and then in it, ammonium hydroxide is added. The ammonium hydroxide is added slowly and to the extent that a strong smell of ammonia is observed.
Then our solution of magnesia mixture is complete and ready to analyse phosphorus.

So, the correct answer is the option a.).

Note: It must be noted that the magnesia mixture is a mixture of magnesium sulphate, ammonium chloride and ammonia and it is different from the milk of magnesia. The milk of magnesia is the solution of magnesium hydroxide.