Untitled - Kelly Walsh High School

Gases 85
Don’t Forget!
Quick Tip
Don’t Forget!
Now you can use the reaction stoichiometry to convert from moles O 2 to moles
KClO 3 and then to grams KClO 3:
(0.021486 mol O 2 )a 2 mol KClO 3
3 mol O 2
ba 122.55 g KClO3 b 1.7554 1.76g KClO3 1 mol KClO3 Check to make sure that your answer is reasonable. In this case, for example, the
mass of the KClO 3 must be less than the mass of the impure mixture.
Another useful relationship is one derived from Avogadro’s law: 1 mol of any
gas occupies 22.4 L at STP (standard temperature and pressure of 0 o C (273 K)
and 1 atm). If you can find the volume at STP, you can then convert it to moles
using this relationship and then to grams, if needed.
Be sure when using any of the gas laws that you are dealing with gases, not liquids
or solids.
If the value 22.4 L/mol is used, make sure that it is applied to a gas at STP.