Avogadro's Number

Avagadro's Number (The Mole)

Definition

Also see: SI Units#Mole (mol)

Calculations

Formula

Where:

  • is the number of moles
  • is any quantity of anything
  • is Avogrado's number

Note: calculations should be rounded with Significant Figures

Intuition

All this is really saying is "if we have 3 moles of n then we have of N"

Example

How many moles are in atoms of ?

solution

Since has 2 sig figs, we must round to 2 sig figs

Relation to Atomic Mass Units

Moles can also be used to directly convert from Atomic Mass Units to grams

Equation

Let be the weight of the object, then

Examples

  • 1 carbon atom weighs
    1 mole of carbon atom weighs
  • 1 hydrogen atom weights
    1 mole of hydrogen atoms weighs
    1 mole of hydrogen molecules weighs
  • In a sample of , you will have of atoms
  • In a sample of , you will have of atoms