10.2. Mass, Volume, and the Mole http://www.ck12.org
FIGURE 10.11
The mole road map shows the conversion
factors needed to interconvert between
mass, number of particles, and volume of
a gas at STP.- molar mass of Ne = 20.18 g/mol
- 1 mol = 22.4 L
Unknown
- sample volume =? L
This problem can be solved by converting grams→moles→gas volume.
Step 2: Calculate.
79 .3 g Ne× 201 mol Ne. 18 g Ne×^221 mol Ne.^4 L Ne= 88 .0 L NeStep 3: Think about your result.
The given mass of neon is equal to about 4 moles, resulting in a volume that is about 4 times larger than molar
volume.
Lesson Summary
- The molar mass of a substance is used to convert grams to moles and moles to grams. Mass can be converted
to the number of representative particles and vice-versa by using a two-step process. - Avogadro’s hypothesis states that equal volumes of all gases at the same temperature and pressure contain the
same number of particles. The volume of 1 mole of any gas is called its molar volume and is equal to 22.4 L at
standard temperature and pressure. Molar volume allows conversions to be made between moles and volume
of gases at STP. - Gas density can be calculated from the molar mass and molar volume.
- The mole road map outlines various possible conversions between mass, number of representative particles,
and gas volume.