1. The Mole

2. The Mole SI unit for “amount of substance”
Chemists use this unit because they deal with such small particles
Can be related to:
Number of particles
Mass
Volume

3. (Avogadro’s number = 6.02 x 1023)
Number of Particles
1pair = 2 particles
1 dozen = 12 particles
1 mole = x representative particles
(Avogadro’s number = 6.02 x 1023)

4. Representative Particles refer to the species present in a substance
Element
Ion
Ionic Compound
Covalent Compound
Rep. Particle
Atom
Ion
Formula Unit
Molecule

5. Representative Particle Examples
Atom: Fe, Al, K, S, Na, H, O
Ion: Na1+, Cl1-, NO31-, Mg2+
Molecule: H2O, O2, Cl2, CO2, H2, CCl4
Formula Unit: NaCl, K2SO4, AgNO3

6. Particle Calculation Examples:

7. Mass Molar mass = the mass of one mole of a substance
Gram atomic mass = mass of one mole of an atom
Gram molecular mass = mass of one mole of a molecule
Gram formula mass = mass of one mole of a formula unit

8. Will one dozen feathers have the same MASS as one dozen eggs? Explain.
What does this tell us about the MASS of one mole of different substances?

9. Different Substances Have Different Molar Masses…
If you have one mole of 2 different substances, they may each have a different mass even though the number of particles (6.02 x 1023) is the same.

11. Molar Mass Calculations

12. Converting with Molar Mass
Use molar mass to convert from grams  moles or moles  grams
1 mole = molar mass (g)

13. Volume 1 mole = 22.4 L of a gas at STP
Molar Volume – volume of 1 mole of a gas at STP
STP = standard temperature (0oC) and standard pressure (1atm)
1 mole = 22.4 L of a gas at STP

14. Mass/Volume Examples

15. Percent Composition Percent (by mass) of all elements in a compound
Can be calculated by using Molar Mass
Can be used as a conversion factor in dimensional analysis

16. Percent Composition Examples

17. Empirical Formulas
Give the lowest whole-number ratio of all elements in a compound (all of the subscripts in the formula are reduced)

18. Examples: H2O2 – true formula for hydrogen peroxide
HO – empirical formula for hydrogen peroxide
CO2 – true formula for carbon dioxide
CO2 – empirical formula for carbon dioxide

19. Calculating Empirical/True Formulas
Given the percent composition, it is possible to calculate the empirical formula and the true formula of a substance

20. Calculation Examples