How do you calculate percentage (by mass)?

Suppose that 0.267 g of a mixture containing an unknown sulfate is dissolved in 50 mL of water. The solution is then acidified with 6M HCl, heated, and an excess of aqueous BaCl2 is slowly added to the mixture resulting in the formation of a white precipitate.



Assuming that 0.358 g of the precipitate is recovered, calculate the percent by mass of SO42- in the unknown salt.How do you calculate percentage (by mass)?
OK that looks pretty straight forward.



First you know that BaSO4 will precipitate out of the solution. (refer to your solubility rules)



You obtained 0.358 g of BaSO4 so the amount of SO4 in the solution is (Molar Mass of SO4/ Molar mass of BaSO4) x 0.358 g



Once you've calculated the amount of SO4 present in grams simply divide that by the 0.267 g of the unknown mixture and multiply by 100 and you're done.How do you calculate percentage (by mass)?
actual yield/theoridical yield then multiply by 100.. so your actual yield is 0.358g and your theoridical yield is something you find my balancing the reaction and comparing ratios of moles of each of the reactants compared to the actual (products0 given )