Question

Why silica crucible is used instead sintered crucible in gravimetric analysis for barium as barium sulphate?

Answer 1

We are flying blind here given that we have no details of the experiment....

Explanation:

But I presume you perform the gravimetric determination of `BaSO_4(aq)` from say a barium salt and ADDED sulfuric acid.

`BaX_2(aq) + H_2SO_4(aq) rarr BaSO_4(s)darr + 2HX(aq)`

Now when you add the sulfuric acid to the barium salt in solution, an insoluble precipitate of barium sulfate as a white solid deposits. Now you would like to collect ALL the precipitate, and determine its mass. Now you could pour off the supernatant fluid from the flask, give the precipitate a bit of a wash, and THEN determine the mass of precipitate as barium sulfate.

Alternatively, you could pre-weigh the `"sintered glass frit"`, the term is `"heated to constant mass"`, pour the slurry of barium sulfate thru the frit, the which would retain the solid precipitate, while allowing the supernatant fluid to pass thru.

After drying the frit, and the solid precipitate collected by the frit, an accurate mass of `BaSO_4(s)` could be recorded....the which then has to be related to your starting masses.

Apologies if you are doing another experiment, but we ain't got much to go on here.