Year 11 Chemistry: Chapter 4 ~ The MOLE!
4.2 The MOLE
When chemists work with elements and compounds, they cannot deal with quantities as
small as individual atoms, ions or molecules.
Example:
Shoes
2
Pair
eggs
12
Dozen
A4 paper
400
Ream
23
atoms
6 x 10
MOLE
The accepted convenint quantity for chemists when working with chemicals is the
_________ .
A mole is defined as the amount of substance that
contains the same number of specified particles, as
there are atoms in 12 g of carbon-12.
 1 atom of 12C has a relative atomic mass of _____
exactly.
 1 mol of atoms of 12C has a mass of ______
exactly.
The number
of particles in 1 mole is given the symbol NA.




1 mole
1 mole
1 mole
1 mole
of hydrogen atoms contains NA hydrogen (H) atoms.
of hydrogen molecules contains NA hydrogen (H2) molecules.
of aluminium atoms contains NA aluminium (Al) atoms.
of glucose molecules contains NA glucose (C6H12O6) molecules.
Chemists have selected exactly ___g of _______ atoms to define the mole. The number
of atoms in exactly 12 g of carbon-12 is 6.022045 x 1023.
A MOLE = 6.02 x 1023 particles = Avogadro’s constant (NA)
MOLE:
 symbol for amount of substance ____ .
 The units for amount of substance ______ .
Therefore: n(glucose) = 2 : the amount of glucose molecules in the sample is 2 moles.
Example:
Calculate number of particles
1 mole of O2 molecules contains 6.02 x 1023 O2 molecules.
number of O2 molecules in 2.5 mol of O2 is:
2.5 x 6.02 x 1023
= 15.05 x 1023
= 1.5 x 1024
Number of particles (N) = amount of substance (mol) x number of part in 1 mole (NA)
N = n x NA
Example: Calculate the amount of copper atoms (mol) represented by 3.01 x 1023 copper
atoms.
*HINT: 6.02x1023 copper atoms represents 1 mol of copper atoms.
n = N
NA
Example: Calculate the amount (in mol) of oxygen atoms in 5 mol of oxygen (O2).
Example: Calculate:
 The amount (in mol) of hydrogen atoms in 2.5 mol of water molecules (H2O).
 The number of hydrogen atoms in 2.5 mol of water molecules (H2O).
/ (6.02 x 1023 mol-1)
Pg 173
Number of
Particles
Amount of
substance (n)
x (6.02 x 1023 mol-1)
QUESTIONS: 5, 6, 7 & 8.