Sulphate content in Fertilizer prac (1 Viewer)

[golgo13]

Hi, guys
Just putting it out there because I am one of the unlucky few that has been told that this assessed prac that the teacher refuses to explain much on, I was wondering if there's any tips that you guys might have or some experiences you want to share when doing this prac

Thanks

 

[x jiim]

this prac is a bitch. try not to tear the filter paper. this is the write up from my notes-

Weigh two filter papers. Grind some fertiliser into a fine powder using a mortar and pestle. Weigh out approx 1g, place in a beaker and dissolve in about 250mL 0.1M HCl. Stir to dissolve as much solid as possible, then filter off insoluble material. Heat to near boiling and add BaCl2 solution with continuous stirring until no more precipitate forms. Continue heating for 30min then allow to cool to room temp- precipitate should settle to the bottom. Pour the mixture through two filter papers and a funnel. Leave the filter papers to dry and weigh daily until weight is constant. Calculate moles of BaSO4 and thus weight of SO4 and sulfate content of fertiliser.

 

[snakeinthegrass]

Also, which type of filter paper should you use to filter the barium sulfate? I either have the choice of qualitative filter paper or ashless filter paper. And does ashless filter paper decompose with heat?

 

[golgo13]

Thanks for the reply forgot to ask what can possibly be in the fertilizer that can skew the result, being taunted by the teacher that something in all our classes pac we are doing wrong

 

[Aquawhite]

You are likely to be assessed on your method, variables or errors/things that could be improved on. For the HSC exam it is important to know what things have to be measured perfectly and allowed to react completely, and which steps must occur in excess (e.g. the titration in excess to ensure all of the ions precipitate).

Good luck. Read over some notes that are provided by other members in the resources page for specifics.