Relative formula mass (Mr) is the total relative mass of a molecule. It is the Ar of each atom in a molecule added together. (e.g. CO2 would be 1 x 12, because there is one carbon, plus 2 x 16, because there are two oxygens, adding to a Mr of 44)
Mr can be used to calculate the mass of a substance that can be obtained from a chemical reaction, or how much of a substance is necessary to neutralise another substance.
This formula triangle is useful in calculating masses:
When the Mr of a substance is equal to the number of grams there are of it, that is one mole. A mole is 6.022 x 10^23 particles. This is called Avagadro's number, or Avagadro's constant.
A mole of gas at room temperature and pressure always takes up 24 dm^3, or 24000 cm^3.
This formula triangle is useful in calculating masses:
When the Mr of a substance is equal to the number of grams there are of it, that is one mole. A mole is 6.022 x 10^23 particles. This is called Avagadro's number, or Avagadro's constant.
A mole of gas at room temperature and pressure always takes up 24 dm^3, or 24000 cm^3.
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