Who would calculate the comparative temperature and comparative pressure of a mixed gas?

Xiu’s edition of \"Thermodynamics of Chemical Engineering\" on pages 20–21 introduces the mixing rules. You’ll understand if you check it.

It’s in any book on chemical engineering thermodynamics; this book is easy to find on forums.

Principle of corresponding states: Different substances are in a corresponding state if they have the same contrast pressure Pr (the ratio of pressure P to critical pressure Pc) and contrast temperature Tr (the ratio of temperature T to critical temperature Tc); under such conditions, their various physical properties exhibit simple corresponding relationships. Comparison temperature: Pr = P/Pc. Comparison temperature: Tr = T/Tc. Methods for determining the comparison temperature Tc’ and comparison pressure Pc’ of a mixed gas. Tc’ = (Tc1X1 + Tc2X2 + …… + TcnXn) / 100
Pc’ = (Pc1X1 + Pc2X2 + …… + PcnXn) / 100
Where: Tc1, Tc2, Tcn – the critical temperatures of each component in the mixed gas, in K ； Pc1 Pc2 Pcn —— Critical pressures of various components in the mixed gas, kgf/cm2 ； X1 X2 Xn —— the volume percentages of various components in the mixed gas, % Last edited by zhangyong6404 on 2009-4-13 09:11]

Tc’ = (Tc1X1 + Tc2X2 + …… + TcnXn) / 100
Pc’ = (Pc1X1 + Pc2X2 + …… + PcnXn) / 100
Why is 100 used for division, and not n? !

Refer to http://www.sensorok.com/tech/llgce.htm