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Untitled - Kelly Walsh High School

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Gases 85<br />

Don’t Forget!<br />

Quick Tip<br />

Don’t Forget!<br />

Now you can use the reaction stoichiometry to convert from moles O 2 to moles<br />

KClO 3 and then to grams KClO 3:<br />

(0.021486 mol O 2 )a 2 mol KClO 3<br />

3 mol O 2<br />

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<br />

mass of the KClO 3 must be less than the mass of the impure mixture.<br />

Another useful relationship is one derived from Avogadro’s law: 1 mol of any<br />

gas occupies 22.4 L at STP (standard temperature and pressure of 0 o C (273 K)<br />

and 1 atm). If you can find the volume at STP, you can then convert it to moles<br />

using this relationship and then to grams, if needed.<br />

Be sure when using any of the gas laws that you are dealing with gases, not liquids<br />

or solids.<br />

If the value 22.4 L/mol is used, make sure that it is applied to a gas at STP.

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