1. The Mole: A Measurement of Matter
Chemistry
The Mole: A Measurement of Matter

2. Formula Mass
Sum of the masses of all the atoms represented in a chemical formula
Units are amu

3. Sample Find the formula mass for Calcium Hydroxide.
The formula for Calcium Hydroxide is Ca(OH)2
1 Ca x amu = amu
2 O x amu = amu
2 H x 1.01 amu = amu
74.10 amu

4. Try These Find the formula masses for the following compounds: H2O
MgCl2
Fe2(SO4)3
P2O5
18.02 amu
95.21 amu
amu
amu

5. The Mole (mol) The number of atoms to get exactly 12 g of 12C
It’s a number used to measure amount
Can be used as a conversion factor
1 mol = 6.02 x 1023 particles
Often called Avogadro’s number

6. Sample How many moles are 1.5 x 1024 atoms of He?
? mol He = 1.5x1024 atoms He
6.02x1023 atom He
1 mol He
= 2.5 mol He

7. Try These How many moles are 3.0 x 1022 molecules of water?
How many molecules of ammonia are in 1.6 mol of ammonia?
How many atoms are in 4.7 mol of Argon?
0.050 mol
9.6 x 1023 molecules
2.8 x 1024 atoms

8. Molar Mass The mass of one mole of a substance
The same quantity as atomic mass or formula mass but has g/mol as its units.
Can be used as a conversion factor

9. Try These Determine the Molar Mass of the following compounds NaCl NH3
58.44 g/mol
17.04 g/mol