Topic 1 Gases

1. Topic 1 Gases

2. 1.1 Ideal gases The state equation of ideal gases The pressure-volume relationship — Boyle’s law V=constant×1/P or PV=constant The temperature-Volume relationship — Charles’ law V=constant×T or V/T=constant The quantity-volume relationship — Avogadro’s law V=constant×n V∝nT/P PV=nRT R--- Avogadro constant

3. Units of pressure • 1 Pa=1 N.m-2 • 1 kPa=103 Pa • 1 MPa=106 Pa • 1 torr= 1 mmHg=133.322 Pa • 1 atm=760 torr=1.01325×105Pa • 1 bar=105 Pa=0.9869 atm =750.06 torr Micro view about pressure of gases

4. Value of R • 8.3145 J.mol-1.K-1 • 0.083145 L.bar.K-1.mol-1 • 82.058 cm3.atm.mol-1.K-1 • 0.082058 L.atm.mol-1.K-1 • 1.98722 cal.mol-1. K-1 • 62.364 L.Torr.K-1. mol-1

5. 1.2 Mixture of ideal gases • Dalton law: Amagat law:

6. 1.3 Real gasesdo not follow the ideal state equation Internal pressure: induced by interaction between molecules Volume of gas molecules Kamerling-Onnes equation: van der Waals equation: b, molecular volume

7. Numerical Example:

8. Fugacity of real gases The efficient pressure ,fugacity coefficient Determination of fugacity coefficient 1. Graphical method Measure P, Vm, T 2. Corresponding states method Compression factor, Z=pV/nRT

9. The parameters of critical states of real gases Critical temperature Tc: Above which the gas can not be liquefied by increasing the pressure Cricital pressure Pc: The minimum pressure the gas could be liquefied at Tc Cricital volume Vc: The molar volume of the gas at Tc and Pc Vc, Tc and Pc the critical parameters Critical Point Data for Methane: Pc = 46.3 bar, Tc = 190.6 K, Vc =0.099 L mol-1, Zc = 0.29.

10. A few characteristics of some actual gases :

11. van der Waals equation: The corresponding critical constants The corresponding states Corresponding temperature 对比温度 Corresponding pressure 对比压力 对比体积 Corresponding volume

12. Principle of corresponding states At critical point all gases are equally nonideal.

13. Plotting Z-π-θfigure: ……

14. PVm=ZRT Newton diagram