Unformatted text preview: Counting Atoms
Mg burns in air (O2) to
produce white
magnesium oxide, MgO. Counting Atoms Particles in a Mole
Avogadro’s Number • Chemistry is a quantitative
science—we need a “counting unit.” Amedeo Avogadro
17761856 • The MOLE
The MOLE
• 1 mole is the amount of substance that
contains as many particles (atoms,
12
molecules) as there are in 12.0 g of 12C.
molecules) 6.0221367 x 1023 How can we figure out how
much oxide is produced
from a given mass of Mg? PROBLEM: How many moles
PROBLEM: How many moles
are represented by 0.200 g of
are represented by 0.200 g of
Mg? How many atoms?
Mg? How many atoms? Molar Mass
12
1 mol of 12C
= 12.00 g of C
= 6.022 x 1023 atoms
of C
12
12.00 g of 12C is its
12.00
MOLAR MASS Taking into account all
of the isotopes of C,
the molar mass of C is
12.011 g/mol Mg has a molar mass of 24.3050 g/mol.
0.200 g • 1 mol
= 8 .23 x 10 3 mol
24.31 g How many atoms in this piece of Mg?
8.23 x 10 3 m ol • 6.022 x 10 23 atoms
1 mol = 4.95 x 10 21 atoms Mg Page 1 There is Avogadro’s number of
There is Avogadro’s number of
particles in a mole of any substance.
particles in a mole of any substance. ...
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 Spring '08
 Staff
 Chemistry, Atom, Mole, atoms, Avogadro constant

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