Chemistry
posted by PleaseHelp .
The decomposition of potassium chlorite yields oxygen gas and potassium chloride. If the yield is 95%, how many grams of KClO3 are needed to produce10.0 L of O2?

Here is a worked example using KClO3 to produce oxygen. This problem requires that you work it "backwards" that is, Convert 10 L O2 to moles (moles = L/22.4), then divide by 0.95 to see how much MORE you need to produce to account for the 95% yield, then use the steps outlined in the example.
http://www.jiskha.com/science/chemistry/stoichiometry.html