Question

What mass of potassium chlorate should be used in order to collect 100 mL of water? Consider the stoichiometry of the reaction and assume the volume of water is roughly the same as the volume of oxygen evolved. Assume the oxygen will be collected at room temperature and pressure (use estimates).

Answer 1

the balanced equation is-

So, from the balanced equation, it can be seen from 2 moles of KClO₃ , 3 moles of O₂ is being produced.

now, the molar volume of O₂S.T.P , is 22.4 L = 22400 mL

So, the volume of 3 moles of O₂ = (3*22400) mL = 67200 mL

as per question, it is to be assumed that the volume of O₂ equal to the volume of H₂O .

67200 mL of H₂O will be produced = 2 moles of KClO₃

100 mL of H₂O will be produced from = (2*100/67200) = 2.98*10^-3 moles of KClO₃

molar mass of KClO₃ = 122.55 g/mol

So, 2.98*10^-3 moles of KClO₃ = (122.55*2.98*10^-3) = 0.365 g of KClO₃