Question about Finding Sulfur in Fertiliser Prac

[Blair1994]

Just wondering how you would propose to minimise the error of other ions reacting to form the precipitate.
Is it like because the sample is non homogenous, you could get samples from the bottom, top and middle of the fertiliser and test them. Then average them out?
Could someone please eloborate/help me explain it a little better ><

[Blair1994]

anyone?

[nacho]

Actually, during the prac, it is assumed that none of the other ions will react with the precipitating agent.
you will often get discussion questions asking you for 'assumptions you have made' in which case you would use this one

[Blair1994]

hmm then what other error can i mention for an overestimation?
other than precipitation not being fully dried

[Greatness]

hmm then what other error can i mention for an overestimation?
other than precipitation not being fully dried

-The apparatus may have been contaminated
-the precipitate may contain impurities

[Greatness]

Well the impurities may have been that contaminants in the apparatus, so maybe ensuring that the apparatus are clean. You could say that there may have been other substances in the chemical solutions that you used.

[vea]

Certain substances can actually be added to prevent other precipitates from forming.

Hydroxide and carbonate ions are present in the fertiliser. By adding HCl, the H+ ions can react with hydroxide and carbonate and prevent say barium ions from precipitating with them instead of precipitating with sulfate.