精華區beta NTU-Exam 關於我們 聯絡資訊
黃良平91下期中 2003. 4.29 1.A particular gas is enclosed in a cylinder with a moveable piston. It is observed thatr if the walls are adiabatic, a quasi-static increase in volume results ina decrease in pressure according to the equation: (P^2)(V^5)=constant (Q=0) Find the quasi-static work done on the system, if the system evolves along the adiabat. Initially Pi=10^5 Pa, Vi=9 dm^3. In the final state Pf=3*10^5 Pa. 2.Consider a system whose Energy(U) is given by the function U=4S^2 + 3V i.e. a function U(S,V) Obtain an expression for A(T,V), the Helmholtz free energy. 3.Assuming that dry air contains 79% N2 and 21% O2 by volume, calculate the density(in grams/liter) of moist air at 25度C and 1atm pressure when the relative humidity is 60%. The vapor pressure of water at 25度C is 23.76mmHg. 4.For a gas which obeys the equation of state V(bar)=RT/P + b + cP show that the activity coefficient γ(bar)=exp(2bP + c(P^2))/2RT 5.a.Show clearly that (δU/δV)T = T(δP/δT)V - P b.Show that (δU/δV)T = 0 for an ideal gas c.Evaluate (δU/δV)T (in J/L) for one mole of Xe at 298K and 1atm assuming it follows the eqiation of state (V-nb)P = nRT where b has the value 0.051L/mol and is a constant. 6.For a gas following V(bar) = RT/P + (b - a/RT) What is the inversion temperature for the Joule-Thomson effect? What is the sign of ΔT below the inversion temperature? 7.According to Debye equation the heat capacity of a solid is proportional to the temperature cubed at low temperatures: Cp(T) = const*T^3 Show that the entropy at a temperature T' is given by S(T') = Cp(T')/3 When the Debye equation holds. 8.Derive the expression for (δH(bar)/δP)T for a gas following the virial equation P*V(bar) = RT + B(T)P