1. MOLAR MASS
CHAPTER 7-2

2. How to find the molar mass of an element
The molar mass of any substance is the mass (in grams) of one mole of the substance.
It is expressed as grams/mole (g/mol).
The molar mass of elements is found by looking at the average atomic mass of the element on the periodic table.

3. Sample Problems Find the molar mass of the following elements:
C = 12 g C / 1 mol C
Fe = 56 g Fe / 1 mol Fe
Ca = 40 g Ca / 1 mol Ca

4. How to find the molar mass of a compound
The molar mass of compounds, we need to find the molar mass from the chemical formula of the compound.
The molar mass of a compound can be calculated by adding the average atomic masses (in g/mol) of the atoms in the compound.
Molar mass serves as a bridge between the mass of a material and the number of moles since it is not possible to measure the number of moles directly.
How to find the molar mass of a compound

5. Sample Problem Find the molar mass of H2O O = 1 x 16 = 16 18
H = 2 x 1.0 = 2
O = 1 x 16 = 16 18
Molar mass of H2O is 18 g/mol .
It is a conversion unit and it can be written as
18 g H2O = 1 mol H2O

6. Converting grams to moles and moles to grams
molar mass of N2O3 = 76 g/mol
Molar mass is used to convert between grams and moles of substances.
Sample Problem
How many grams are in 9.45 mol of N2O3
76 g N2O mol N2O3 x = g N2O3
1 mol N2O3