# Mole

Mole is the number of a substance which contains Avogadro’s number (NA) of particle’s. The numbers can also be refer to as Avogadro’s constant. The symbols is given as L, the value is very large, can be approximated to 26.2 x 10²³.

Avogadro’s number is equal to the number of carbon atoms in 12g of carbon (isotope carbon-12).

The particle can be of different types; atoms, molecules, and ions, and is necessary to say which type is being put into consideration.

For example it could be confusing to say 1 mole of hydrogen, if you said so, some people may mean you said 1 mole of hydrogen atom (H), why other may view it that you said 1 mole of hydrogen molecules (H2), or 1 mole of hydrogen ions (H+). So it is advisable to used the symbols of the element for example 1 mole H, 1 mole H2, or 1mole H+.

Carbon; have relative atomic mass of 12, and mass of 1 mole of atoms, (1 g-atom) 12g.

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Oxygen; have relative atomic mass of 16, and mass of 1 mole of atoms, (1 g-atom) 16g.

Hydrogen; have relative atomic mass of 1, and mass of 1 mole of atoms, (1 g-atom) 1g.

NB: the mass of 1 mole of atoms is numerically the same as the relative atomic mass of the element.

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On the post we going to solve 2 example.

1. Calculate the mass of 0.2 mole of carbon atoms?

Solutions

Relative atomic mass of carbon = 12

Therefore; mass of 1 mole of carbon atoms (1 g-atom) = 12g

Now, mass of 0.2 mole of carbon atoms = 12 x 0.2 = 2.4g.

2. Calculate the number of moles of ion atoms in 168g of ion?

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Solution

Relative atomic mass of ion = 56

56g = mass of 1 mole of ion atoms (1 g-atom)

168g = mass of 168/56 moles of ion atoms = 3moles. 