ENG_sgwhk02

ENG_sgwhk02 - In the previous course Zeroth Law of...

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The Zeroth Law of thermodynamics Zeroth Law of thermodynamics If an object A is in thermal equilibrium with B and if B is in thermal equilibrium with C, then C is in thermal equilibrium with A. In the previous course

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Temperature law ( 温度定律) : 任一热力学的均相体系，在平衡态各自都存在一个 状态函数，称之为温度 T ；它具有这样的特性，对 于一切互呈热平衡的均相系其温度彼此相等。 Perfect-gas temperature scale ( 理想气体温标 ) 为测量温 度基准物质。在体积一定时，以气体的压强作为测温性质， 规定纯水的三相点为 273.16K, 温度计中的压强为 p tr , 于是， 热力学第零定律还保证我们可以用任何物质建立一种装置（温 度计），并确信当它与任何物质组成的达热平衡的体系 A B C 相接触时，得到的关于特殊状态量（温度）的读数是一致的 tr p p p . K / T lim 0 16 273 =
Celsius scale ( 摄氏温标 ) t: ° C H 2 O 的冰点 =0 ° C 沸点 =100 ° C ；刻度 1/100 Fahrenheit scale ( 华氏温标 ) τ : ° F H 2 O 的冰点 =32 ° F 沸点 =212 ° F ；刻度 1/180 Perfect-gas temperature scale ( 理想气体温标 ) (that turns out to be identical to the thermodynamic scale ( 热力学温 )) t: K (Kelvin) H 2 O 的三相点 =273.15K ；刻度 1/273.15 C 5 9 32 F 15 273 K C ° + = ° = ° / t / . / T / t τ

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1.6 Equation of state ( 物态方程 ) The equation of state is mathematical relation between macro properties for an uniform system at equilibrium In fact the real equation can be established only for the measurable macro properties the most seen equation is the equations concerning n,p,V,T -2 nd Lecture- The thermodynamic law of equilibrium is often expressed using differential equation e.g., d U = F d S - p d V The equation of state is the integral of first degree of the differential equation i.e., V = V ( T , p , n )
Equation of state of perfect gas is pV = nRT or pV m = RT Two assumptions were made in writing this equation: (1) Neglecting the dimension of particle at a given T p →∞ , V 0 ; (2) Neglecting the interaction between particles p =( n/V ) RT at given T p n/v (Molecule density) This equation is applicable to real gas at low pressure and relatively high temperature m V (Molar volum V = ) n

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Rewrite pV = nRT RT M m pV = ρ = m/V (gas density) RT M V m p 1 = or RT p M = or At given T , when p 0, is invariable m -gas ±mass M- molar mass
In experiment, plot ( ρ / p ) against p , and use the value of ( / p ) at p 0 to calculate M M =( ) p 0 RT ρ p ( / p ) p ( ) p 0 ρ p

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Equation of state of mixed perfect gas (1) Daolton theorem of partial pressure P = Σ p i At constant temperature and constant volume the total pressure of a mixed gas equals the sum of pressures of all individual gas (2) Amagat theorem of partial volume V = Σ V i At constant temperature and constant pressure the total volume of a mixed gas equals the sum of volumes of individual gas inside the mixture) At T,V the pressure of a gas inside the mixture P i = x i P ii i i nn Molar fraction x = = n Σ n At T,p the volume of a gas inside the mixture V i = x i V
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ENG_sgwhk02 - In the previous course Zeroth Law of...

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