# Notes - Molar Mass - Mr. Lawson`s Website ```Chemical
Compounds
What is a COMPOUND?
A substance composed of two or more
elements that have been chemically united.
What is a CHEMICAL FORMULA?
A way of expressing the atoms that make
up a compound
Number of Atoms in a Compound
Please collect the number of atoms in a compound
worksheet from the front of the room
Note: just do the first page, if you need extra practice
do the back!
Molecular Mass
Sum of the atomic mass of each element that makes up the
compound.
Unit = Unified atomic mass unit = One Proton OR One Neutron
• Example:
H2O
= (2 x H) + (1 x O)
= (2 x 1u) + (1 x 16u) = 18u
NOTE: WE ARE NOT INTERESTED IN MOLECULAR MASS! We can’t weigh
individual Molecules!
Molar Mass - Our second NEW Unit Converter
• The mass of one mole of a particular
Molecule!
• Expressed as either….
grams
mol
OR
mol
grams
Example:
Example:
What is the molar mass of NaCl?
• # of Na atoms =
____________
• Atomic mass of Na =
____________
• # of Cl atoms =
____________
• Atomic mass of Cl =
____________
What is the molar mass of H2O?
• # of H atoms =
____________
• Atomic mass of H =
____________
• # of O atoms =
____________
• Atomic mass of o =
____________
• Molar mass =
•
____________
Molar mass =
____________
Remember…
Molar Mass is a unit converter
• It allows us to convert from…..
grams  mols or mols  gram
• It’s units are g/mol or mol/g