The Detection Method Of Calcium Sulfate

Take about 0.2 g of the sample, accurately weigh it, add 10 ml of dilute hydrochloric acid and 100 ml of water to dissolve it, and under stirring, add 20 ml of 0.05 mole per liter disodium EDTA solution, and then add 20% hydrogen 15 ml of sodium oxide solution, ammonium violetate indicator (take 0.1g of ammonium violetate, add sodium chloride to make 20g, that is, 0.2-0.3g), continue to use 0.05 moles of ethylenediaminetetraacetic acid per liter Sodium was dropped until the solution changed from pink to purple. Every 1 ml of 0.05 mol per liter of disodium EDTA solution is equivalent to 6.307 mg of calcium sulfate, and then the purity is calculated.