Question

how much potassium chlorate would dissolve kin 200g water at 20°C

Answer 1

The molar mass of potassium chlorite is (39.10)+ 35.45+(16×3) = 122.55 g/mol

The molar mass of water is 16+(1×2) = 18g/mol

the reaction between water and potassium chlorite is

KClO3 + H2O ——› H2+ KClO4

Basically, 122.55 grams of potassium chlorate dissolved in 18 grams of water is the same as 1 gram of potassium chlorite dissolved in 18/122.55 grams of water. Or, we can say that 18 grams of water are required to dissolve 122.55 grams of potassium chlorate and 1 gram of water is required to dissolve 122.5/18 grams of potassium chlorate

so 200 grams of water is required to dissolve (200×122.5)/18 gm of potassium chlorite = 1361.1 gm at 20°C

Answer 2

@ AJ L. I don't believe anything you wrote. First there is no reaction between KClO3 and H2O that comes close to what you wrote. Second, it is not a stoichiometric problem. Third KClO3 is potassium chlorATE and not chlorITE. Potassium chlorite would be KClO2.

@Immmm-- You need to look up and tell us what the solubility of KClO3 is per 100 g H2O or per 100 mL H2O. I expect that is in your question or your notes/text book.