posted by Anonymous .
2 KClO3 ----> 2 KCl + 3 O2
Suppose the "inert" material in the mixture was not really inert, but that is reacted with oxygen from the atmosphere when heat was applied. Would the apparent mass of oxygen liberated be larger or smaller than it should be?
Then, suppose that some sample material was lost by spilling during heating. Would the experimentally determined percentage KClO3 be larger or smaller than the true value?
If the inert material soaked up some of the liberated oxygen, wouldn't you think less free O2 would be liberated?
If you spill some of the sample the mass O2 liberated will be less so the percent will be less.