Question

Explain with examples what is meant by a 'mole' of a substance

Answer 1

I've got two definitions... Choose the one that better suits you...

• Metric (SI) unit of amount (not mass or weight) of a substance. One mole is defined as the amount of substance containing as many elementary entities (atoms, molecules, ions, electrons, radicals, etc.) as there are atoms in 12 grams of carbon-12 (6.023 x 1023). The mass of one mole of a substance equals its relative molecular mass expressed in grams. Also spelled as mol. Also called gram-molecular weight.

• It provides a specific measure of the number of atoms or molecules in a bulk sample of matter. A mole is defined as the amount of substance containing the same number of discrete entities (such as atoms, molecules, and ions) as the number of atoms in a sample of pure 12C weighing exactly 12 g.

Answer 2

Mole = Given weight of substance in gm/atomic mass

Ex :- 2 g H2O

Moleculer mass = 18
Given Weight = 2
Mole = 2/18
= 1/9
= 0.1 mole