1. Calculations with Molar Mass The Molar Mass Lesson 2

2. Molar Mass
The atomic mass of an element is the relative mass of the element. It is measured in grams and found on the periodic table.
The molar mass is the mass of one mole of particles and the unit is grams/mole.
Let’s see where to find it on the periodic table!

3. Formula Molar Mass (g/mol)1H
1.0 g/mole
4.0 g/mole He
CO more than one atom ???

4. To find the Molar Mass
Consider the molar mass of all the atoms involved:
CO2
1 ( 12.0 ) + 2 (16.0)
= 44.0 g/mole.

5. Formula Molar Mass (g/mol)1H
1.0 g/mole
4.0 g/mole He
44.0 g/mole
CO2
Fe2O3

6. To find the molar mass:
Fe2O3
2 (55.8) + 3 (16.0)
= g/moles.

7. TRY: Find the molar mass of:
Ni2(CO3)3

8. Formula Molar Mass (g/mol)1H
1.0 g/mole
4.0 g/mole He
44.0 g/mole
CO2
159.6 g/mole
Fe2O3
297.4 g/mole
Ni2(CO3)3
Al(NO3)3 .5H2O

9. Al(NO3)3 .5H2O
1 ( 27.0) + 3 (14.0) + 9 (16.0) (1.0) + 5 (16.0)
Al N O H O
303.0 g/mole

10. TRY: Find the molar mass of
Lead(II) iodate

11. Conversion factors are back!

12. The molar mass is a new conversion factor that can convert between grams and moles
Avogadro’s number is another conversion factor that can convert between moles and particles
Particles
Moles
Grams
1.00 mole =
6.02 x 1023 particles
Molar Mass
From Periodic Table
? g / mole

13. Convert 56.6 grams of C to moles.
x mole
= moles
12.0 g
Don’t forget sig figs!
3 sig figs

14. Convert 6.9 moles of PbO2 into grams
x g
= 1.7 x 103 g
1 mole

15. Two-Step Mole Calculations

16. Convert 2.00 g CH4 into molecules
grams
moles
molecules
2.00 g CH4
x mole
x x 1023 molecules
= x 1022 molecules
16.04 g
1 mole

17. Convert 9.56 x 1026 molecules Cl2 into grams.
moles
grams
9.56x1026 molec Cl2
x 1 mole
x g
= x 105 g
6.02 x 1023 molec
1 mole

18. Try: Convert 692.5 grams Na2CO3 into molecules.
g moles molecules

19. Happy Mole day to You particles moles g
Try: Convert 8.66 x 1024 particles of CaCl2 into grams
particles moles g
Happy Mole day to You

20. Homework
Pg ,9,12,19
Pg pract. prob.