Moles are a unit to define the amount of a substance.
One mole of every atom contains 6.02 x 1023atoms. One mole of carbon is 6.02 x 1023atoms, one mole of hydrogen is 6.02 x 1023原子,等等。数量6.02 x 1023is known as Avogadro's number.
Even though every substance has the same amount of atoms (6.02 x 1023atoms), they have different weight. Therefore, the number of grams in a mole is different from substance to substance. For example: one mole of carbon atoms has a mass of 12 g, while one mole of magnesium has a mass of 24 g.
Moles allows us to calculate the masses of different substance that are involved in reactions.
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