A mixture contains sand and KClO3. The sand is not affected by heating, while the KClO3 is decomposed to KCl and oxygen by heating. A 5.000 g sample, when heated until no further reaction occurred, gave off a gas which occupied a volume of 0.9605 liters at 24.2 oC and 768.0 torr pressure. What is the percent, by weight, of sand in the mixture?
A chemistry teacher told me this is how to do it:
What is the gas that is given off? Sure, it's oxygen. Use PV=nRT to determine the moles of O2 produced.
Use the equation below to determine the moles of KClO3 that decomposed from the moles of O2 actually produced.
2 KClO3 --> 2 KCl + 3 O2
Find the mass of KClO3 from the moles of KClO3 and subtract from 5.0 grams to get the mass of sand, and its percentage.
But I am still confused. Can someone please help me or break it down into lamen terms for me please!! Thank you!!