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��OUTLINES OF PHYSICAL CHEMISTRY
��necessary to point out that the values of a and b depend on the nature of the gas under examination.
Application of the Equation. — In order the better to un- derstand these theories let us take an example, and again we shall choose Andrews's observations on carbon dioxide.
It has been found that Van der WaaWs equation con- veniently expresses the behaviour of gaseous carbon dioxide
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���so-
��if we put a = 0-00874 and b = 0-0028. At 0°C. and under one atmosphere pressure we should have :
��which gives for r the value
��At the temperature t°G. the equation will be :
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��(
��, + !<«») (, - 0«BS) = !™» x (278 + .).
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