if we did not use an excess of the BaCl2 solution it would decrease the mass percentage of sulfate in the unknown sample.
The net precipitation equation would be.
Ba2+(aq) + SO42-(aq) → BaSO4(s)
If BaCl2 (Ba2+) is not taken in excess then the precipitation would not be completed as some of the sulfate ions would still be remaining in the solution. This would decrease the mass percentage of sulfate in the unknown sample.
If some tiny pieces of filter paper still remained mixed with the precipitate(BaSO4) then the mass of sulfate would increase and it gives a high mass percentage of the sulfate.
mass percentage of sulfate = (mass of sulfate/mass of sample)*100
Learn more about precipitation here brainly.com/question/14675507
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Found it http://my.ccsd.net/userdocs/documents/uGKpi9UAEwFpSIgE.pdf
Answer:
I'm a bit confused on where the question is. Perhaps re-write it in the comments? I'd love to help but this seems more like an answer than a question xD
Explanation: