A mole is an amount of stuff.
In 2g of hydrogen gas – or 1 mole – there are 600000000000000000000000 [six times ten to the twenty-three] molecules of hydrogen the same number as in 18g of water – can you see why?
Chemists don’t do big numbers – this is called the number of molecules in one mole, Avogadro’s Number.
Count Lorenzo Amadeo Avogadro
Avogadro was an Italian Count, with a doctorate in ecclesiastical law and an interest in science. In 1811, he published an article that clearly showed the difference between molecules and atoms. Bear in mind that people didn’t really know what they were talking about in terms of how chemistry worked back then. He suggested that the great English chemist John Dalton had got himself muddled up and he pointed out that “atoms” of nitrogen and oxygen are in reality “molecules” containing two atoms each. Thus two molecules of hydrogen can combine with one molecule of oxygen to produce two molecules of water.
Avogadro’s big contribution was this…
‘Equal volumes of all gases at the same temperature and pressure contain the same number of molecules.’
which is now known as Avogadro’s Principle.
One mole of gas occupies 24 dm³ at standard temperature and pressure.
Atoms and molecules are very small but a moles-worth of anything bigger is huge. For example,
An Avogadro’s number of soft drink cans would cover the surface of the earth to a depth of over 300km.
If you had Avogadro’s number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of nearly ten miles.
If we were able to count atoms at the rate of a million per second, it would take about 20 billion years to count the atoms in one mole – older than the age of the Universe.
Put another way, only about 0.000000000000000014 moles worth of people watched Barack Obama’s swearing in as the 44th president of the USA, rather more than the 45th.