What mass of oxygen would be produced upon thermal decomposition of 25 g of potassium chlorate (kclo3) ? the molecular weight (mw) of potassium chlorate is 122.5 g/mol?

The formula for potassium chlorate is: 2KClO₃ → 2KCl + 3O₂

If moles = mass : molar mass

then moles of KClO₃ = 25 g : [ (39 * 1) + (35.5 * 1) + (16 * 3) ] g/mol

= 25 g : (122.5 g) g/mol

= 0.2041 mol

Now the mole ratio of KClO₃ : O₂ is 2 : 3

∴ if moles of KClO₃ = 0.2041 mol

then moles of O₂ = (0.2041 mol : 2) * 3

= 0.3061 mol

Now since mass = moles * molar mass

∴ the mass of oxygen produced = 0.3061 mol * (16 * 2) g/mol

= 9.796 g

∴ the grams of oxygen gas produced when 25 grams of potassium chlorate is decomposed is ~ 9.80 g.