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