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101-2 Physical Chemistry I 2nd Exam.
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注意事項:(a)需完整列式計算方予計分,(b)計算題答案請附單位方可計分,(c)有小題未作答者該大題不計部分分數
1. Describe the content of the first law of thermodynamics.
2. Define and compare the following terms:
(a)
(b)
(c)
(d)
(e)
Enthalpy and Internal energy
Isothermal process and Adiabatic process
Reversible expansion and expansion against a constant pressure
Enthalpy of formation and Enthalpy of combustion
State function and path function
3. A sample consisting of 1.00 mol Ar is expanded isothermally at 0°C from 22.4 dm3 to 44.8 dm3 (a)
reversibly, (b) against a constant external pressure equal to the final pressure of the gas, and (c)
freely (against zero external pressure). For the three processes calculate final pressure Pf , q, w, ΔU,
and ΔH.
Ans:
(a)
(b)
(c)
4. A sample consisting of 1.00 mol of perfect gas molecules, for which Cv,,m= 3R/2, initially at Pi =
120 kPa and Ti = 300 K, is heated reversibly to 350 K at constant volume. Calculate the final
pressure Pf, ΔH, ΔU, q, and w.
Ans:
5. A sample of argon (Ar) of mass 12.0 g that is expanded reversibly and adiabatically from 1.0 dm3
at 273.15 K to 3.0 dm3. Calculate the final temperature Tf, the final pressure Pf, ΔH, ΔU, q, and w .
Ans:
6. The constant-pressure heat capacity of a sample of a perfect gas was found to vary with
temperature according to the expression Cp/(J K−1) = 20.0 + 0.4T. Calculate q, w, ΔU, and ΔH when
the temperature is raised from 0°C to 50°C (a) at constant pressure, (b) at constant volume.
Ans:
(a)
(b)
7. A sample consisting of 1 mol of perfect gas atoms (for which CV,m=3R/2) is taken through the
cycle shown in Fig. 2.33. (a) Determine the temperature at the points 1, 2, and 3. (答案請標示於圖中)
(b) Calculate q, w, ΔU, and ΔH for each step and for the overall cycle.
Step
q
w
U
H
1→2
2→3
3→1
Overall
Figure 1
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101-2 Physical Chemistry I 2nd Exam.
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8. (a) Define reaction of formation and reaction of combustion.
(b) Write sown the combustion reaction for phenol.
Ans:
The standard enthalpy of formation of phenol (C6H5OH) is −165.0 kJ mol−1.
The standard enthalpy of formation H2O(l) is −285.83 kJ mol−1
The standard enthalpy of formation CO2(g) is −393.51 kJ mol−1
Use these data to calculate
(b) the standard enthalpy of combustion of phenol.
Ans:
(c) the standard internal energy change of combustion(ΔcU0) of phenol.
Ans
9. From the following data,
(1)
(2)
(3)
Heat capacity information
B2H6(g) Cp,m= 56.7 J/(mol K); H2(g) Cp,m= 28.824 J/(mol K); O2(g) Cp,m=29.355 J/(mol K);
C(s,graphite)=8.527 J/(mol K); C(g)=20.838 J/(mol K)
(a) Write down the formation reaction of diborane, B2H6(g) Ans:
(b) Determine
for diborane, B2H6(g), at 298 K.
Ans:
(c) Calculate
for diborane, B2H6(g), at 350 K.
Ans:
(d) Calculate fU0 for diborane, B2H6(g), at 298 K.
Ans:
10. (a) Define internal energy(T), expansion coefficient (), isothermal compressibility (T) and
Joule–Thomson coefficient (μ)
(b) Explain and derive the properties of each parameter in (a) for an ideal gas system
(c) 於標示氣體可被液化的區域,說明原因標示 inversion temperature 並說明
該溫度所呈現的性質.
(d) Prove that for ideal gas Cp,m - Cv,m = R (本題可於以下空白處作答)
Figure 2
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