Fertiliser Dot Point (1 Viewer)

[Lord Ac]

Can anyone help me answer these two dot-points:

3/3.5
Identify, plan, select equitment and perfprm first-hand investigations to measure the sulfate content of lawn fertiliser and explain the chemistry invovled.

3/3.6
Analyse information to evaluate the reliability of the results of the above investigation and to propose solutions to the problems encountered in the procedure.

Thanks,

Ac

 

[Huy]

http://www.boredofstudies.org/community/showthread.php?s=&threadid=8070&highlight=sulfate+content

that's for the second dot point, i answered the same dot point a while ago.

for the first, its in my old book somewhere.
but if i can remember, it was about 2-3 A4 pgs
(its 11pm on a sunday night, i'd type it out if i could)

 

[ND]

I kinda remember the first part, but i don't remember quantities.

- Dissolve x grams of furtiliser in x mls water.
- Add x mls HCl.
- Add x mls barium chloride
- Wash, then filter out precipitate (which will be barium sulphate)
- Add (was it silver nitrate?) to filtrate, if precipitation occurs, keep washing.
- Dry out precipitate and weight.
- Perform calculations to determine amount of sulphate present, and go from there.

This is all from memory (and i haven't memorised it yet), so im not certain it's all correct.

 

[jims]

yeh that sounds about right.
quantities dont really matter so long as you wiegh it all.

use say 1g of fertiliser in 25ml of water n 25ml of HCl.

u should heat the fertiliser solution n BaCl (50ml) n slowly pour the BaCl into the fertiliser solution while stirring continously to avoid sudden saturation and the formation of small precipitates.

use a sintered glass funnel to filter.

acetone to wash.

 

[Constip8edSkunk]

on the reliability issue, BaSO4 have extremely small particle size making it difficult to filtrate in school laboratory conditions...

 

[jims]

is that accuracy or reliability? i can never remember

 

[Constip8edSkunk]

both i think... coz the process isnt consistent... different attempts may get u different results, esp as school equip like filter suction device etc rnt standardised