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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: zibb3r on February 12, 2011, 09:24:16 pm

Title: Gravimetric analysis SAC???
Post by: zibb3r on February 12, 2011, 09:24:16 pm

Hi guys,

I just had my SAC yesterday, and I need to do 1 question.  The SAC is on pg. 50 of the heinemann workbook titled "gravimetric determination of sulfur as sulfate in fertiliser".  Anyway the question I have trouble with is:  Use the molar masses of barium and sulfate to calculate the mass of sulfate ions in the solution".  Any idea how to do this??? 
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Thanks :smitten:

Title: Re: Gravimetric analysis SAC???
Post by: vea on February 12, 2011, 09:44:52 pm

Haha chill out with the emoticons. xD

You can use the number of moles of barium sulfate to calculate the mass of sulfate ions in the solution since:

BaSO4---->Ba2+ + SO4 2-

Basically, the mole ratio for barium sulfate and sulfate ions is 1:1 and from there you can just use stoich to calculate the mass of sulfate ions.

Title: Re: Gravimetric analysis SAC???
Post by: zibb3r on February 12, 2011, 09:56:06 pm

lol, will do :uglystupid2:

So lets say that n(BaSO₄)=0.0327 mol, how would i go from here???

Thanks

Title: Re: Gravimetric analysis SAC???
Post by: vea on February 12, 2011, 10:03:01 pm

BaSO4---->Ba2+ + SO4 2-

So the mole ratio for BaSO4 and SO4 2- is 1:1.

n(SO4 2-)=n(BaSO4)=0.0327mol

m(SO4 2-)= no. of mole X molar mass
=0.0327 X (32.07+64.00)
=3.141g (4 significant figures)

Is this correct?

Title: Re: Gravimetric analysis SAC???
Post by: zibb3r on February 12, 2011, 11:03:03 pm

looks great!!!!  can any1 clarify the procedure just to be sure?????

Title: Re: Gravimetric analysis SAC???
Post by: luken93 on February 13, 2011, 12:16:07 am

Quote from: zibb3r on February 12, 2011, 11:03:03 pm

looks great!!!!  can any1 clarify the procedure just to be sure?????

Yes it is indeed correct