we know that titration is a method by which we can calculate the concentration of an unknown acid or base by reacting with a stoichiometric amount of acid or base there is a similar technique called gravimetric analysis this is where the analyte is not an acid or base but some substance with the capacity to precipitate or otherwise separate from solution we can then measure the mass of the precipitate or analyze some other aspect of the resulting system and compare with the initial mass of the analyte to figure out the concentration of the analyte this was one of the first techniques ever devised for quantitative chemical analysis let's try an example to put this into context say there is a solid mixture that contains some amount of magnesium sulfate and we want to know what percent by mass of this solid mixture is represented by magnesium sulfate first we find the mass of this mixture and we find that it is 0.455 grams then we dissolve this mixture in water and we add excess barium nitrate this will cause a double displacement reaction whereby water insoluble barium sulfate will precipitate and we collect this precipitate to find that it has a mass of 0.6168 grams what can we do with this information well we certainly can't do anything with mass so let's convert this precipitate mass into moles using the molar mass of barium sulfate then from there since there is one sulfate in each compound and we know that every sulfate in barium sulfate came from a formula unit of magnesium sulfate we know that whatever number of moles of barium sulfate we get that's the number of moles of magnesium sulfate that were in solution then we can use the molar mass of magnesium sulfate to convert from moles back to mass and doing the arithmetic we get 0.318 grams of magnesium sulfate that must have been in solution from there it's easy to get the mass percentage we just take the mass of magnesium sulfate and divide by the total mass of the initial solid mixture before we dissolved it and then multiply by a hundred that gives us 69.91 percent as the amount of the solid mixture that was represented by magnesium sulfate and that's how we perform gravimetric analysis