1. Unit 2 Lesson #5 Avogadro’s Number & The Mole (p.14-16)
How Big is A Mole?

2. A. What is the Mole? 1. A counting number (like a dozen)
2. Avogadro’s number (NA)
1 mole =  1023 representative particles

3. 3. Using Dimensional Analysis to Make Conversions
a. Convert 48 eggs to dozens of eggs Conversion factor : 48 eggs X 1 dozen 1 12 eggs b. Convert 6 dozen to number of eggs 6 dozen X 12 eggs 1 1 dozen

4. 4. Molar Conversion Factors
a. # of Particles (atoms, molecules, ions, etc.) 1 mole =  particles
b. Molar mass = mass of 1 mole of a substance
1 mole = molar mass
c. Molar Volume = 22.4 Liters for any gas at STP (Standard Temperature Pressure)
*STP = T = 0o C or 273 K P = 1.0 atmosphere (atm)
1 mole = molar volume

5. Mole Relationships

6. Representative Particles & Moles
Substance
Chemical Formula
Representative Particle
Rep Particles in 1.00 mole
Carbon C
6.02 x 1023
Nitrogen gas N2
Calcium ion
Ca2+
Magnesium fluoride
MgF2

7. Representative Particles & Moles
Substance
Chemical Formula
Representative Particle
Rep Particles in 1.00 mole
Carbon C
Atom
6.02 x 1023
Nitrogen gas N2
Molecule
Calcium ion
Ca2+
Ion
Magnesium fluoride
MgF2
Formula unit

8. B. Mole to Particle Conversions
6.022  1023 NA
MOLES
NUMBER OF
PARTICLES
(particles/mol)
Particles = atoms, molecules, formula units, ions, etc
NA atoms/mol
NA molecules/mol

9. 1. How many molecules are in 2.50 moles of C12H22O11?
6.02  1023
molecules
C12H22O11
1 mol C12H22O11
2.50 mol
C12H22O11
= 1.51  1024
molecules
C12H22O11

10. 2. If you have 2.23 x 1018 atoms of sodium, how many moles is that?
2.23  1018
atoms Na
1 mole Na
6.02  1023
atoms Na
3.70 x 10-6
moles Na =

11. = 2.26  1024 formula units Ca(OH)2
3. How many formula units is 3.75 moles of calcium hydroxide?
6.02  1023
formula units
Ca(OH)2
1 mol Ca(OH)2
3.75
mol Ca(OH)2
= 2.26  1024
formula units
Ca(OH)2

12. C. Molar Mass Conversions
1. Molar Mass = The mass of one mole of an element or compound
Atomic mass (on the PT) tells the...
mass of each atom (amu)
grams per mole (g/mol)
2. Round to 2 decimal places

13. 3. Molar Mass Examples 12.01 g/mol 26.98 g/mol 65.39 g/mol a. carbon
b. aluminum
c. zinc
12.01 g/mol
26.98 g/mol
65.39 g/mol

14. 4. Molar Mass Examples H2O 2(1.01) + 16.00 = 18.02 g/mol NaCl
a. water
b. sodium chloride
H2O
2(1.01)
NaCl
= g/mol
= g/mol

15. 5. Molar Mass Examples NaHCO3 22.99 + 1.01 + 12.01 + 3(16.00)
a. sodium bicarbonate
b. sucrose
NaHCO3
(16.00)
= g/mol
C12H22O11
12(12.01) + 22(1.01) + 11(16.00)
= g/mol

16. 6. Molar Mass Examples Mg(OH)2 24.31 + 2(16.00) + 2(1.01)
a. magnesium hydroxide
b. ammonium sulfate
Mg(OH)2
(16.00) + 2(1.01)
= g/mol
(NH4)2SO4
2(14.01) + 8(1.01) (16.00)
= g/mol

17. D. Molar Mass Conversions
6.02  1023 NA
MASS IN
GRAMS
MOLES
NUMBER OF
PARTICLES
(g/mol)
(particles/mol)
Particles = atoms, molecules, formula units, ions, etc
NA atoms/mol
NA molecules/mol

18. 1. How many moles of carbon atoms are in 26 g of carbon?
26 g C
1 mol C
12.01 g C
= 2.2 mol C

19. 2. Find the mass of 2.1  1024 molecules of NaHCO3.
1 mol NaHCO3
6.02  1023
Molecules NaHCO3
84.01 g NaHCO3
1 mol NaHCO3
= 290 g NaHCO3

20. 3. How many atoms are in 22.5 grams of potassium?
6.02  1023
atoms K
1 mol K
22.5 g K
1 mol K
39.10 g K
= 3.46 x 1023 atoms K

21. E. Molar Volume ConversionsNA
Molar Mass
Molar Vol
* Molar Volume = 22.4 Liters for any gas at STP

22. What is the volume at STP of 4.00 g of CH4?
4.0g X 1 mole X L = 5.6 L
g mole

23. 2. How many grams of He are present in 8.00 L of He at STP?
8.0 L X 1 mole X grams = 1.4 g
L mole