Molar Mass and Mole Calculations

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Molar mass is the mass in grams of one mole
of particles (atoms, ions, molecules, formula
units).
Equal to the numerical value of the average
atomic mass (get from periodic table)
1 mole of C atoms
=
12.0 g
1 mole of Mg atoms
=
24.3 g
1 mole of Cu atoms
=
63.5 g
So, Molar Mass is the atomic mass
expressed in units grams/mole (g/mol)
Chlorine has an atomic
mass of 35.453 amu.
So what is its molar
mass?
35.453 grams per mole
The number is the same, just
change the unit.
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How do we find the molar mass of a
compound?
 Find the molar mass of each element
in the compound
 Determine how many of each
element are in the compound.
 Multiply the number of each element
by its molar mass.
 Add these mumbers.
Aluminum
Bromide
AlBr3
In one mole of Aluminum
Bromide, there is 1 mole of
aluminum atoms and 3 moles of
bromine atoms.
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To find the molar mass of AlBr3, we do the
following:
1 mol Al x 26.9815 g/mol Al = 26.9815 g Al
3 mol Br x 79.904 g/mol Br = 239.712 g Br
26.9815 g Al + 239.712 g Br = 266.6935 g AlBr3 per
mole or 266.6935 g/mol AlBr3
Where,
n is the # of moles (mol)
m is the mass (g)
M is the molar mass (g/mol)

What is the mass of 4.72 x 1023 formula units of
chromium (III) iodide?

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