Explore BrainMass
Share

Explore BrainMass

    15 Thermodynamics Problems (Delta G, Delta S, Delta H)

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    1) From the following Ho and So values predict which of reactions I, II, and III would be spontaneous at 300ºC.

    H (kJ)
    S(J/K)

    I
    -5.0
    -15

    II
    -10.0
    +20

    III
    -5.0
    -30

    A. I
    B. II
    C. III
    D. I and II
    E. II and III

    2) From the following Ho and So values predict which of reactions I, II, and III would be spontaneous at 25ºC.

    H (kJ)
    S(J/K)

    I
    +10.5
    +30

    II
    +1.8
    -113

    III
    -126
    +84

    A. I
    B. II
    C. III
    D. I and II
    E. II and III

    3) Calculate the entropy change (J/mole.K) of the reaction. The molar entropies [S] are given in brackets after each substance.

    2 CuS(s) [66.5] + 3 O2(g) [205.1]" 2 CuO(s) [42.6] + 2 SO2(g) [248.2]

    A. -114.2
    B. -139.1
    C. +33.0
    D. +68.2
    E. +166.7

    4) Calculate the entropy change (J/mole.K) of the reaction. The molar entropies [S] are given in brackets after each substance.

    3 NO2(g) [240.1] + H2O(l) [69.9] --> 2 HNO3(aq) [146.4] + NO(g) [210.8]

    A. -286.6
    B. -212.4
    C. -156.3
    D. +47.2
    E. +156.3

    5) Given Sº = -266.3 and the listed [Sº values] calculate Sº for Fe3O4(s).

    4 Fe3O4(s) [____] + O2(g) [205.1] ---> 6 Fe2O3(s) [87.4]

    A. +111.1
    B. +122.4
    C. +134.1
    D. +146.4
    E. +159.6

    6. Given Sº = -114.3 and the listed [Sº values] calculate Sº for CCl4(g).

    CH4(g) [186.3] + 4 Cl2(g) [223.0] ---> CCl4(g) [____] + 4 HCl(g) [186.9]

    A. +150.6

    B. +175.6

    C. +216.4

    D. +195

    E. +240.5

    7. Predict which of the following reactions has a negative entropy change.

    I. 2 SO2(g) + O2(g) --> 2 SO3(g)

    II. MgO(s) + CO2(g) --> MgCO3(s)

    III. PCl5(s) --> PCl3(l) + Cl2(g)

    A. I

    B. II

    C. III

    D. I and II
    E. II and III

    8) Predict which of the following reactions has a positive entropy change.

    I. Ag+(aq) + Cl-(aq) --> AgCl(s)

    II. NH4Cl(s) --> NH3(g) + HCl(g)

    III. 2 NH3(g) --> N2(g) + 3 H2(g)

    A. I
    B. II
    C. III
    D. I and II
    E. II and III

    9) The enthalpy and entropy change of a reaction are -6.1 kJ/mole and +38.9 J/mole K respectively at 25ºC. What is the free energy change in kJ/mole?

    A. -17.7
    B. -11.6
    C. -5.5
    D. +5.5
    E. +17.7

    10) The enthalpy and entropy change of a reaction are -26.1 kJ/mole and +3.89 J/mole K respectively at 25ºC. What is the free energy change in kJ/mole?

    A. -30.3
    B. -27.3
    C. -24.9
    D. -17.3
    E. +24.9

    11) Using the listed information calculate Kp at 25ºC.

    Ag2O(s) --> 2 Ag(s) + 1/2 O2(g)

    Hºf (kJ/mole) -31.0, 0.0, 0.0

    Sº (J/K.mole) 121.3, 42.6, 205.1

    A. 2.22 x 10-3
    B. 3.41 x 10-2
    C. 2.22 x 10-2
    D. 1.09 x 10-2
    E. 4.41 x 10-1

    12) Nitrosyl chloride decomposes by the following reaction with Hº = -51.7 kJ/mole and Sº = 48.2 J/mole.K. Estimate Kp at 100ºC.

    NOCl(g) --> 1/2 N2(g) + 1/2 O2(g) + 1/2 Cl2(g)

    A. 6.21 x 107
    B. 2.48 x 108
    C. 7.45 x 108
    D. 3.25 x 109
    E. 5.67 x 109

    13) Using the listed information calculate the temperature (C) where Kp = 1.0.

    Ag2O(s) --> 2 Ag(s) + 1/2 O2(g)

    Hºf (kJ/mole) -31.0, 0.0, 0.0

    Sº (J/K.mole) 121.3, 42.6, 205.1

    A. 152
    B. 194
    C. 222
    D. 367
    E. 441

    14) Using the listed [DGºf values] calculate DG for the reaction:

    4 NH3(g) [-16.5] + 5 O2(g) [0.0] --> 4 NO(g) [+86.6] + 6 H2O(g) [-228.6]

    A. -1091.2
    B. -959.2
    C. -878.8
    D. -438.4
    E. -125.5

    15) Using the listed [[DGºf values] calculate DG for the reaction:

    4 FeS2(s) [-166.7] + 11 O2(g) [0.0] --> 2 Fe2O3(s) [-740.9] + 8 SO2(g) [-300.3]

    A. -3217.4
    B. -2464.5
    C. -1884.5
    D. -1207.9
    E. -874.5

    © BrainMass Inc. brainmass.com October 9, 2019, 8:35 pm ad1c9bdddf
    https://brainmass.com/chemistry/energetics-and-thermodynamics/15-thermodynamics-problems-delta-g-delta-s-delta-h-156063

    Solution Summary

    Fifteen thermodynamics problems (DeltaG - Gibbs Free Energy, DeltaS - Entropy, DeltaH - Enthalpy) are solved with full working and explanations. This is a great set of problems.

    $2.19