Results for sulfate content in fertiliser practical (1 Viewer)

[.ben]

Does anyone have the results for the sulfate fertiliser experiment. Also can you tell me how to calculate the percentage. Btw we didn't do the titration method using EDTA etc.

 

[tristambrown]

the results are going to vary too much to use someone elses depending of fertiliser type, brand, batch etc...

we used MgSO4 so our results will be huge compared to someone who tested a broad spectrum fertiliser

 

[markus123456789]

Does anyone have the results for the sulfate fertiliser experiment. Also can you tell me how to calculate the percentage. Btw we didn't do the titration method using EDTA etc.

Hey, i think the results are irrelevant for this experiements, because in the exam they will likely give you a sample and ask you to find the contend in that.. but anywho.. heres the calculations you can use

Ammonium sulfate if the main constitunet in most lawn fertilisers.

Ba + SO4 ---> Baso4 but the {n of moles Baso4= n moles so4}

convert mass of Baso4 to moles.... n= m/M

as 1:1 ratio

convert moles of sulfate to grams m= nM

express this as a % of total weight.. ie... .0005/1.5 x 100


I think thats about it...

 

[Forbidden.]

Let's say you used 1.00 grams of ground and accurately weighedfertiliser.
Then after grounding you dissolve with HCl, precipitate it with BaCl₂ then filter it out and finally you have 1.8 grams.

The formulas involed to find the percentage of sulfate in a sample of fertiliser is:

m(SO₄^2-) = m(BaSO₄) x M(SO₄^2-) / M(BaSO₄)

% m(SO₄^2-) = m(SO₄^2-) x 100 / m(fertiliser)

In words:

(mass of sulfate precipitate) = (mass of barium sulfate precipitate) x (molecular weight of sulfate) / (molecular weight of barium suflate)

(percentage mass of suflate precipitate) = (mass of sulfate) x 100 / (mass of fertiliser)

Answer:

m(SO₄^2-) = 1.8 x 96.06 / 233.37 = 0.74
% mass SO₄^2- = 0.74 x 100 / 1.00 = 74.1%

The question was modified from a previous HSC but you should NOT get a value this high because of the poor reliability as asked in a subsequent question.
Acid should be used to help dissolve the fertiliser and the precipitate should be filtered several times.