The Mole (mol)

In the English language there are many words that represent an exact number:

dozen       =12

century    =100

decade     =10

score        =20

couple      =2

Baker’s dozen    =13

trio           =3

fortnight  =14

week        =7

2bits        = 25

In Chemical language we have the

mol =  6.02 x 10 ²³

also known as Avogadro’s Number

Amadeos Avogadro calculated the number of atoms in a convenient mass of element.

He called it the Molar Mass.

It is the same as the Atomic Mass on the Periodic Table.

So …  for Carbon (12.0 )  means 12.0 g contain

one mol or 6.02 x 10 ²³ atoms of Carbon.

     …. for Oxygen (16.0) means 16.0 g contain

one mol or 6.02 x 10 ²³  atoms of Oxygen

   . for Hydrogen (1.0)  means 1.0 g  contain

one mol or 6.02 x 10 ²³  atoms of Hydrogen

   or the molar mass of Carbon is 12.0 g/mol,

Oxygen 16.0 g/mol,  

Hydrogen 1.0 g/mol

What is the molar mass (mol mass) of a compound/

= the sum of the mol mass of each element in the compound

1.  Must be able to count atoms in a formula

     (NH₄)₂SO₄ = 2N, 8H, 1S,4O

2.  Multiply each by their atomic mol mass  and add up for the total mol mass

Molecular Mole (mol) mass =

2x(14.0) + 8x(1.0) + 1x(32.1) + 4x(16.0) = 132.1 g/mol

PRACTICE SHEET 1 (D9,D10)