How would you minimise these gravimetric analysis errors?

[man0005]

Homework Statement

-precipitate not being pure e.g. other ions (present in the precipitate increasing the weight of the precipitate)
- in an experiment where BaSO4 is used and some of it isn't dissolved in the wash due to the 'low solubility' of BaSO4 - resulting in a lower weight, decreasing the percentage by mass of the precipitate.
-impurities in the sample

Homework Equations

The Attempt at a Solution

 

[Borek]

-precipitate not being pure e.g. other ions (present in the precipitate increasing the weight of the precipitate)

Sometimes called coprecipitation.

in an experiment where BaSO4 is used and some of it isn't dissolved in the wash due to the 'low solubility' of BaSO4 - resulting in a lower weight, decreasing the percentage by mass of the precipitate.

No idea what you mean.

impurities in the sample

How is it different from the first point?

But, it is up to you to try to solve the question. So, how do you propose to minimize errors?

 

[man0005]

with the co precipitation
since I am finding the amount of sulfur in a samle of fertiliser
Since 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 you please help me elaborate on that/explain it a little better ><

 

[Borek]

Sorry, I have no idea what you are asking about.

Methodology of taking samples has nothing to do with coprecipitation.