posted by M .
Sulfamethoxazole has the molecular formula C10H11N3O3S.
10.0 g of tablets containing sulfamethoxazole and trimethoprim were crushed and dissolved in water. A strong oxidising agent was added, which converted all the sulfur in the sulfamethoxazole into sulfate ions.
Following this, an excess of barium nitrate was added which resulted in precipitation of barium sulfate with no remaining sulfate ions in solution.
If the mass of the precipitate obtained was 2.2758 g, what is the percent by mass of sulfamethoxazole in the tablets, assuming that all of the sulfur present came from sulfamethoxazole?