Moles

Moles is a unit of measure used by scientists as an alternative to grams to measure mass.

When talking about moles, always state what you are dealing with. eg. atoms, molecules, ions, formulae etc.

It is the amount of a substance that contains the same number of particles as there are of carbon atoms in 12g of carbon -12

The number of carbon atoms in 12g of carbon -12 is known as Avogadro's Constant

Avogadro's constant is 6.02 X 10²³

• Therefore a mole is the amount of substance that contains 6.02 X 10²³ molecules

1 mole....

• The idea of moles is that equal volumes of all gases, under the same conditions of temperature and pressure, all contain the same number of moles or molecules.

Molar volume

To find the number of moles of a gas, we measure the VOLUME rather than the mass.

The molar volume of a gas is the volume occupied by one mole at room temperature and atmospheric pressure

• At rtp, one mole of any gas occupies a volume of 24dm³ (24l)
• 24dm³ is also known as the molar gas volume V_m

Vocabulary:

mol: sometimes you'll see this as the short form of mole

rtp: short form of at room temperature and atmospheric pressure

Links:

Chemical Calculations

Chemistry-IGCSE

Science - IGCSE

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