# The Mole Concept

Here is what you have to know from the Chapter 9 in Chemistry Live entitled ” The Mole Concept”. You dont need to know the reasons for them. These notes will include the keys or the tools you need to solve the problems, the problems themselves are simple maths and we might deal with them in another note. In later notes(chapter10 in Chemistry Live) we include the relationship between the mole and volumes of gases. I put in the result here but the explanation/problems come later IA.

Keys

* One mole is the amount of a substance that containes the Avagadro Constant number of particles of that substance.
* Avagadro Constant = 6 x 1023 particles
* One particle = one atom, or molecule-depending on the substance e.g a mole of water will contain 6 x 1023 H2O molecules.
* Mass of one mole of an element is its atomic number in grammes e.g. one mole of carbon will weigh 12 g because carbon is element number 12.
* Mass of one mole of a compound will be the sum of the individual atomic masses of each element in the compound in grammes. e.g. one mole of water will weigh (1H + 16o + 16o) = 33g
* At S.T.P one mole of any gas occupies 22.4 litres

Summary: 1 mole = Avagadro Ct. 6 x 1023 particles = Atomic number in grammes or sum of Atomic numbers in a molecule of the compound and @s.t.p. occupies 22.4 litres if it is a gas.