1. Introducing the Mole
A mole is a chemistry unit used like a dozen or a gross
Groups large numbers of objects together
For example, 3 dozen eggs is 36 (3 x 12) or a gross of paperclips is 144
A mole is a much larger group
6.02 x 1024 of anything is a mole
Usually use only for atoms, ions, or molecules
So x 1024 of something is two moles, x 1024 is 3 moles, etc.

2. Moles and Mass
Remember that the number with a decimal at the bottom of the periodic table squares was the average atomic mass
Weighted average of masses of different isotopes
Mass of one atom
We’re in luck! This is also the mass of one mole of the element in grams.
This is what the mole was based around
Chemists do like to make their lives easier
Ex.: What is the mass of one mole of zinc?
Answer: g
Ex.: What is the mass of one mole of sodium?
Answer: g

3. Moles and Mass (cont.)
This means it’s easy to convert moles to mass for elements:
Multiply the number of moles by the average atomic mass to get the mass for that number of moles
# of moles × avg. atomic mass = total mass
Ex.: What is the mass of 2 moles of phosphorus?
2 moles × g per mole of P = g P

4. Moles and Mass (cont.)
We can figure out the mass of a mole of compounds, too.
Called molar mass
We’ll need the formula.
Tells us how many atoms of each element we have
Multiply the mass of each element by how many atoms of it you have.
Then add up all the numbers you get.

5. Moles and Mass (cont.)
Ex.: What is the mass of a mole of water (H2O)? 2 atoms H: 2 × = g 1 atom O: 1 × = g g = 1 mole H2O Ex.: What is the mass of a mole of H2SO4? 2 atoms H: 2 × = g 1 atom S: 1 × = g 4 atoms O: 4 × = g g = 1 mole H2SO4

6. Moles and Mass (cont.)
When you’ve found the mass of a mole of a compound, you can find the mass of multiple moles the same way as you did for elements.
Ex.: What is the mass of 3 moles of water?
3 moles × g = g water
Ex.: What is the mass of 5.2 moles of H2SO4?
5.2 moles × g = g H2SO4