2. Atoms, Molecules and Moles   Previous PageNext Page
     Measuring Moles; The Gas Laws

There is an easier way of measuring moles when one is dealing with gases. To a very good first approximation, the molecules of any gas are independently moving particles, having mass but negligible volume, and with negligible interactions except at the instant of collision. To the extent that this is so, all gas molecules are alike except for mass.

At the same pressure and temperature, equal volumes of any gases will contain equal numbers of moles and of molecules. This is known as Avogadro's principle, after the man who first proposed it in 1811.

It means that we do not have to weigh gases that are to enter into a reaction, we only have to bring them to a common temperature and pressure and measure volumes.

Apparatus and scientists associated with the chemistry in the following pages; Robert Boyle and Jacques Charles.

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