Mole Concept

Mole, which is symbolized n, and has a unit mol is the counting unit for number of atoms, ions or molecules.  One mole is the amount of substance (either in atoms, ions or molecules) as the number of atoms in 12 g of Carbon-12.  Scientists found out that 1 mole of any substance contains 6.02 x 10²³ particles. This number is called Avogadro's Number (N), in honor of the Italian Scientist Amedeo Avogadro (1776-1856) with the unit mol^-1.  Which means there are 6.02 x 10²³ particles per mole of a substance.

Example:

1 mole of C atoms = 6.02 x 10²³ atoms
1 mole of CO₂ molecules =  6.02 x 10²³ molecules
1 mole of SO₃^-2 ions  =  6.02 x 10²³ ions

Mole is just the same as dozen, 1 dozen of eggs = 12 pcs of eggs, 1 dozen of chairs = 12 pcs of chairs.  Anything that is 1 dozen always contains 12 pcs.  One mole on the other hand,  always contains 6.02 x 10²³ particles.

Interconverting  Moles to the number of Particles

Using the Avogadro's number we can determine the number of atoms, ions or molecules of a given substance.

1.  Calculate the number of C atoms in 0.350 mol of C₆H₁₂O₆.  

Solution:

2.  How many moles of CO₂ are in 3.1 x 10²⁴ CO₂ molecules?

Solution:

3.  Aluminum is a metal with a high strength-to-mass ratio  and a high resistance to corrosion.  Calculate the number of atoms of 0.371 mol of Al.

Solution:

4.  Cobalt (Co) is a metal that is added to street to improve its resistance to corrosion.  Calculate the number of moles of 5.00 x 10²⁰ atoms of Co.

Solution:

5.  How many oxygen atoms are in a) 0.25 mol Ca(NO₃)₂, and  b) 1.50 mol of Na₂CO₃?

a.

b.