# Gravimetric analysis of barium or sulfate

Which is a better way to obtain barium sulfate precipitate for gravimetric analysis: by adding $\ce{Ba^2+}$ ions to sulfate ion solution, or the other way round? I think it is better to precipitate sulfate ions by $\ce{BaCl2}$ solution, as this causes chloride ions to coprecipitate.

• @Marko use \ce to format chemical expressions. Plain math mode gives italicised formulae. See the "basic chem" section Nov 26 '15 at 15:32

## 1 Answer

I think $\ce{BaCl2}$ should be added later. This is because $\ce{BaCl2}$ is soluble in water, but the metal sulphate you will be given may not be soluble. So if you add $\ce{M2SO4}$ later, you may get a wrong result as you have to make sure that the whole of $\ce{BaCl2}$ is used up. On the other hand all chloride salts are soluble. So while filtering the $\ce{MCl}$ will be removed easily along with the solvent and you will get $\ce{BaSO4}$.

• I don't think so. Not all chloride salts are soluble and some sulfates are soluble enough. I want to hear an opinion from the precipitation point of view.
– Uros
Nov 26 '15 at 19:27