1. The Mass of a Mole of an Element
Atomic mass of element (mass of 1 atom) expressed in amu

2. The Mass of a Mole of an Element
Atomic mass of element (mass of 1 atom) expressed in amu
atomic masses - relative masses based on mass of C-12 (12.0 amu)
1 amu is 1/12 mass of C-12 atom

3. Molar Mass…. All contain 6.02 x 1023 atoms
= mass of 1 mol of element in grams (periodic table)
12.01 grams C has same # particles as 1.01 g H & g Fe
12.01 g C = 1 mol C
1.01 g H = 1 mol H
55.85 g Fe = 1 mol Fe
All contain 6.02 x 1023 atoms

4. What about compounds?
1 mol of H2O molecules has 2 mol of H atoms & 1 mol of O atoms (think of a compound as a molar ratio)
To find mass of 1 mol of a cmpd:
determine # moles of elements present
Multiply # times their mass (from periodic table)
add up for total mass

5. Calculating Molar Mass
Calculate molar mass of magnesium carbonate, MgCO3.
84.3 g
24.3 g g x (16.00 g) =
So, 84.3 g = molar mass for MgCO3

6. Practice problems Page 296
The decomposition of hydrogen peroxide (H2O2) provides sufficient energy to launch a rocket. What is the molar mass of hydrogen peroxide?

7. Independently do questions 7 and 8 on page 296.