sulfate n fertiliser question (1 Viewer)

[lozabella]

we did this prac today...n have to write it up for tomoz! we didnt actually use fertiliser, instead we used MgS04.....which we dissolved in HCL n then added BaCl...the aim was to add enough BaCl so that all the SO4 would be used up. We need to verify a simple test to verify this....im a bit confused to what that would be...could you add nitric acid n then siler nitrate and put it in the sun and if it doesnt turn brown then all of the sulfate is gone? thats the test we used for the anion...or could u test for Ba by reacting something with it? n then if it reacts it means that al the Ba has reacted with the S04 n is now in excess?? argh im confussed....if n e one has a better way to do it that would b so helpful! also another question...why do u 'dissolve' the fertliser in HCL? is it because it wouldnt sepearte into ions in H20?? any help would b awesome! thanks!

 

[Jumbo Cactuar]

BaSO₄ is a white precipitate which is very insoluble.

HCl is to remove carbonate and sulfite ions which confuse the result.

You could filter the solution then add more Ba²⁺ and a white precipitate would indicate the presence of SO₄^2- ions in the filtrate.

 

[Jumbo Cactuar]

If you wanted to test the filtrate for Ba ions you could make the solution basic and then add potassium chromate and a yellow precipitate would indicate Ba.