assignment 8

# assignment 8 - R as a function of v R , one for T=0.5 T c ,...

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Thermal Physics PHYS 253 Assignment 8, due 19 November (2010) in class 1) If p, v and T are pressure, molar volume and temperature of a gas and p c , v c and T c are the critical pressure, critical molar volume, and critical temperature, then the reduced pressure p R , the reduced molar volume v R , reduced temperature T R are defined as: ݌ ݌ ݌ , ݒ ݒ ݒ , ܶ ܶ ܶ . a) Show that, in terms of reduced quantities, the van der Waals equation becomes: ቀ݌ ቁቀݒ ቁ ൌ ܶ When the van der Waals equation is in this form, the material constants a and b do not appear explicitly. Thus, all gases that obey the van der Waals equation may be considered in the same state when the values of p R , v R , and T R are the same (i.e. each gas is measured in units of its particular values of p c , v c and T c ). This is the principle of corresponding states , which is a principle of universal similarity first established by van der Waals. bሻ Plot three curves for of p
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Unformatted text preview: R as a function of v R , one for T=0.5 T c , one for T= T c , and one for T=2 T c . What happens physically when the equation indicates three allowed values for v R for a single p R and T? 2) Using the Dieterici equation of state, , show that 4 , 2, 4 and compare the value of with the values in the following table. What do you conclude? Substance: Water 4.36 Ammonia 4.13 Carbon dioxide 3.64 Oxygen 3.49 Nitrogen 3.44 Helium 3.34 Hydrogen 3.26 Van der Waals gas 2.67 Ideal gas 1.00 3a) What happens when helium gas is compressed isothermally above the critical temperature? 3b) If water vapor is compressed isothermally above the critical temperature, will ice I form? Is it possible that ice VII will form?...
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## This note was uploaded on 12/15/2010 for the course PHYS 253 taught by Professor Petergrutter during the Fall '10 term at McGill.

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