1. Unit 7: The Mole

2. Measuring Matter
What are three methods for measuring the amount of something?
You often measure the amount of something by one of three different methods—by count, by mass, and by volume.
We use all 3 in chemistry.

3. Converting from Count to Mass
Converting Number of Donuts to a Dozen:
1 dozen = 12 donuts

4. What is a Mole?
1 mole of any substance = 6.02  1023 particles (Avogadro’s number of particles) 602,000,000,000,000,000,000,000 - Particles can be atoms, molecules, or formula units.

5. What is a Mole?

6. Molar Mass v. Atomic Mass
Mass of 1 atom Mass of 1 mole = mass of 6.02 x 1023 atoms Atomic Mass (amu) Molar Mass (g/mol) 1 atom of Carbon 1 mole of Carbon 12.0 amu 12.0 g

7. The Definition of the Mole
Avogadro defined the mole:
One mole, 6.02  1023 particles,
is exactly 12.0 g of Carbon-12
The carbon-12 isotope is used as the standard for both amu and the mole.

8. Molar Mass of a Compound
The molar mass is the sum of the atomic mass of each element in the compound.
MgCl2 # atoms atomic mass total mass Mg Cl
Molar Mass: mole MgCl2 = 95.3 g

9. Practice Calculate the molar mass of the following: KOH
HCl
H2SO4
C2H6
(39.1x1) + (16.0x1) + (1.0x1) = 56.1 g/mol
(1.0x1) + (35.5x1) = 36.5 g/mol
(1.0x2) + (32.1x1) + (16.0x4) = 98.1 g/mol
(12.0x2) + (1.0x6) = 30.0 g/mol

10. Mole Conversions 1 mole = 6.02  1023 particles 1 mole = _______ g
*particles could be molecules, ions, atoms, formula units
1 mole = _______ g
*1 mole equals the molar mass of the atom or compound
1 mole = 22.4 L
* for gases only at STP (Standard Temperature (0˚C and Standard Pressure (1 atm))

11. MOLE CONVERSIONS How many moles is 350 g CO?
Molar Mass: 1 mole = (12.0x1) + (16.0x1) = 28.0 g
= 12.5 moles CO
350 g CO
1 mol CO
28.0 g CO
What is the volume of 0.05 mol Ne at STP?
= 1.12 L Ne
0.05 mol Ne
22.4 L
1 mol

12. Multiplying and Dividing Scientific Notation:
Multiplying exponents:
Multiply coefficients and add exponents:
(1x106) x (1x105) = 1x1011
Dividing exponents:
Divide coefficients and subtract exponents:
(1x108) ÷ (1x1016) = 1x10-8

13. Using your calculator for Scientific Notation:
To enter a number in scientific notation on your calculator use the EE or x10y or EXP button.
Example: 6.02 x 1023
enter 6.02 EE 23
[or 6.02 x10y 23]

14. Using your calculator:
Practice:
Example: (1.2 x 103) x (6.02 x 1023)
enter
1.2 EE 3 x 6.02 EE 23 =
[1.2 x10y 3 x 6.02 x10y 23 =]
= 7.2 x 1026
CHECK exponents: = 26

15. Using your calculator:
Practice:
Example: (4.9 x 109) x (6.02 x 1023)
enter
4.9 EE 9 x 6.02 EE 23 =
[4.9 x10y 9 x 6.02 x10y 23 =]
= 2.9 x 1033
CHECK exponents: = 32

16. Using your calculator:
Practice:
Example: (1.20 x 1024) ÷ (6.02 x 1023)
enter
1.20 EE 24 ÷ 6.02 EE 23 =
[1.20 x10y 24 ÷ 6.02 x10y 23 =]
= 1.99 x 100 = 1.99
CHECK exponents: = 1

17. Using your calculator:
Practice:
Example: (3.7 x 1063) ÷ (6.02 x 1023)
enter
3.7 EE 63 ÷ 6.02 EE 23 =
[3.7 x10y 63 ÷ 6.02 x10y 23 =]
= 6.2 x 1039
CHECK exponents: = 40

18. Mole Conversions How many moles is 2.17 x 1023 particles?
1 mole =6.02  1023 particles
= 0.36 x 100 = 0.36 moles
2.17 x 1023 particles
1 mole
6.02 x particles

19. Mole Conversions How many particles is 15 moles?
1 mole =6.02  1023 particles
= 9.03 x 1024 particles
15 moles
6.02 x particles
1 mole

20. Mole Conversions Convert 14 g N2 to number of molecules:
Identify the conversion factors:
1 mole = _______________ g
1 mole = 6.02 x molecules
= 3.01 x molecules N2
(14.0x2) = 28.0
14 g N2
1 mole
6.02 x 1023 molecules
28.0 g N2

21. Mole Conversions Convert 9.4x1025 molecules of H2 to grams:
First identify the conversion factors:
1 mole = ______________________ g
1 mole = 6.02 x molecules
2. Draw a 2-step “T” chart:
= 312 g H2
(1.0g x 2) = 2.0
9.4x1025 molecules
1 mole
2.0 g H2
6.02 x molecules

22. Mole Conversions 1 mole = 6.02  1023 particles 1 mole = _______ g
*particles could be molecules, ions, atoms, formula units
1 mole = _______ g
*1 mole equals the molar mass of the atom or compound
1 mole = 22.4 L
* for gases only at STP (Standard Temperature (0˚C and Standard Pressure (1 atm))

23. atoms, ions, molecules, formula units
MOLE CONVERSIONS
Molar Mass (g)
Volume in Liters
Particles:
atoms, ions, molecules, formula units
Mass in grams
particles = = 1 =