The Mole and Chemical Composition:
Conversions
If you are given a mass IN GRAMS and you are to convert to
number of ATOMS or PARTICLES:
Draw your “T-CharT” anD follow This proCess:
Mass (GRAMS)
1 Mole
Molar Mass of
the compound
(GRAMS)
The molar mass is the mass of ONE
mole. It lets us make the connection
between grams and moles!!
6.022 x 1023 atoms / ions
compounds / PARTICLES
1 Mole
Avogadro’s number is how many of
ANYTHING is in ONE mole of
something. How many THINGS or
PARTICLES are in one mole!
Each step you are CANCELLING OUT the units!
Write and REWRITE your units over and over again.
THE UNITS DO THE MATH FOR YOU!!

You can always cut off the end steps, but never cut out a middle step! You must
ALWAYS go through moles to get from grams to atoms.

If you are given a vale in MOLES and need to go to ATOMS, than you may cut off
the first step because there is no need of using grams! You must use Avogadro’s
number as a conversion factor between moles and atoms (1 mole = 6.022x1023
atoms).

The MOLAR MASS is the mass of 1 mole! This enables us to go from MASS (grams)
to number of MOLES!!


Just like there are 12 in. in one foot, there are 31.9988 g in one mole of oxygen gas (O2)
The molar mass is just adding up the masses from the Periodic Table.
o Examples: NH3  You would add up the mass of ONE nitrogen
(14.0067g/mol) and add in the mass of THREE hydrogens (1.00795g/mol) to get
the molar mass of Ammonia (NH3) = 17.03055g/mol!! 
The Mole and Chemical Composition:
Conversions
Going from GRAMS to MOLES:
Convert 10.58 grams of Al(OH)3 to moles of Al(OH)3
10.58 g Al(OH)3
1 mol Al(OH)3
78.00205 g Al(OH)3
= 0.1391 mol Al(OH)3
Going from MOLES to GRAMS:
Convert 0.895 moles of H2 to grams of H2
0.895 mol H2
2.0159 g H2
1 mol H2
= 1.80 g H2
Going from MOLES to PARTICLES (or atoms):
Convert 1.58 moles of Fe2(SO4)3 to atoms of Iron (III) Sulfate
6.022x1023 atoms Fe2(SO4)3
1 mol Fe2(SO4)3
1.85 mol Fe2(SO4)3
= 1.11x1024 atoms Fe2(SO4)3
Going from PARTICLES (or atoms) to MOLES:
Convert 4.08x1023 atoms of MgCl2 to moles of magnesium chloride
4.08x1023 atoms MgCl2
1 mol MgCl2
6.022x1023 atoms MgCl2
= 0.678 mol MgCl2
Going from GRAMS to PARTICLES (or atoms):
Convert 45.89 grams of sulfur dioxide to atoms of sulfur dioxide
45.89 g SO2
1 mol SO2
64.0648 g SO2
6.022x1023 atoms SO2
1 mol SO2
= 4.314x1023
atoms SO2
Going from PARTICLES (or atoms) to GRAMS:
Convert 8.59x1023 atoms of bromine gas to grams of bromine gas
8.590x1023 atoms Br2
1 mol Br2
6.022x1023 atoms Br2
159.80 g Br2 = 227.9 g Br2
1 mol Br2