1. Molar Mass (M)
Topic 1.2

2. Mass relative atomic mass (Ar)
all masses on the periodic table are compared to CARBON- 12
no units are necessary since it is just a comparison to carbon- 12
from this we get the average atomic mass that you would find for an element on the periodic table

3. relative molecular mass (Mr)
simply comparing a given molecule to carbon
CO2 is 44. C60 is 720, O2 is 16(2) = 32
atomic or molecular mass
this is simply the mass of one atom or molecule using a very small unit of measurement called a.m.u.
therefore CO2 is 44 a.m.u.
molar mass (M)
this is how many grams you would have in a mole of a substance
therefore CO2 is 44 g/mol

4. molar mass continued…
simply change the relative atomic mass from the periodic table for the element/molecule/ compound to grams
oxygen’s atomic mass is amu
therefore 1 mole of oxygen has a molar mass is g/mol
sugar’s (C6H12O6) atomic mass is amu
carbon: (6) = 72.00
hydrogen: 1.00(12) = 12.00
oxygen: (6) = 96.00
therefore 1 mole of sugar has a molar mass of g/mol

5. Calculate the Molar Mass of Na3PO4.
Atom #
Atomic Mass
Total Na 3 X =
69.0 P 1 X
31.0 O 4 X
64.0
164.0
Therefore the molar mass is g mol-1

6. Give the molar mass (mass of one mole):
Fe → g/mol
C2H6 → g/mol
Fe(OH)2 → g/mol
C12H22O11 → g/mol
CuSO4 · 5 H2O → 238 g/mol

7. Converting Moles to Grams and Grams to Moles
conversion factor will be:
1 mole
molar mass OR
molar mass__

9. Number of moles to mass(g)
Find the mass (in grams) of 1.93 moles of MgO?
1.93 mol MgO x g MgO
mol MgO
= g MgO
Mass(g) to moles
Find the number of moles in 23.5 g of MgO?
23.5 g MgO x mole MgO
g MgO
= mol MgO

10. Number of grams to moles to particles
Find the number of particles in 13.9 g of MgO?
13.9 g MgO x 1 mole MgO_ x _6.02 X 1023 particles MgO
g MgO mole MgO
1 mole MgO_ x _6.02 X 1023 particles MgO
40.3 g MgO mole MgO
6.02 X 1023 particles MgO
40.3 g MgO molar mass (g)
= X 1023 particles of MgO
here it is again combining two conversion factors
same thing but be careful if you do this!

11. What is the mass of 2.55 × 1023 atoms of lead?
2.55 × 1023 atoms Pb ×
1 mol Pb
6.02×1023 atoms Pb
207.2 g Pb
1 mole Pb ×
= 87.8 g Pb

12. How many atoms in 22 grams of copper?

13. The Mole Road Map “Stuff” Mass Mole Volume Stuff: Atoms Molecules
6.022 x 1023
mole
mole g
Stuff:
Atoms
Molecules
Particles
Electrons
Ions
Formula Units
Mole g
mole
mole .
6.022 x 1023
22.7 L
mole
mole .
22.7 L
For Gases only:
@ STP
(Standard Temp & Pressure)
(0 oC (273 K) & 1 atm)
Volume