The avogadro’s law states that ‘equal volumes of all gases under the same condition of temperature and pressure contain the same number of molecules’. This means that 100cm3 of each of the following gases; ammonia, dinitrogen oxide, oxygen, carbondioxide and sulphur dioxide, at say 20°C and 730mmHg pressure contain the same number of molecules. By Avogadro’s law therefore, volume can be changed to mole.
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