piggy 7 asked in 科學化學 · 1 decade ago

邀請中港台的高考化學精英解題

有關化學平衡和熱焓

題目如下:

http://ask.koubei.com/question/1409071703075.html

請先詳閱網址上的題目,再作回答.

並詳細列式, 因當中涉及不少單位運算及成分換算

謝謝喔

Update:

在NH4HS(s) = NH3(g) + H2S(g)

的氣體分子mole 是 1 : 1: 1

為何K1 和 K2要用2次方?

K1 = (0.22 atm)2 K2 = (0.64 atm)2

3 Answers

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  • 1 decade ago
    Favorite Answer

    (a)

    NH4HS(s) = NH3(g) + H2S(g)

    This is an heterogeneous equilibrium. The concentration/pressure of NH4HS solid should NOT be considered in the equilibrium expression.

    KP' = PNH3•PH2S

    For the decomposition of NH4­HS(s), equal amount of NH­3 and H2S is formed.

    Hence, PNH3 = PH2S.

    At 10oC:

    T1 = (273 + 10) K = 283 K .. and .. K1 = (0.22 atm)2 = 0.0484 atm2

    At 25oC:

    T2 = (273 + 25) K = 298 K .. and .. K2 = (0.64 atm)2 = 0.4096 atm2

    ln(K1/K2) = -(ΔH/R)(1/T1 - 1/T2)

    ln(0.0484/0.4096) = -(ΔH/8.314)(1/283 - 1/298)

    ΔH = +99830 J mol-1 = +99.83 kJ mol-1

    (b)

    (i)

    H2(g) + CO2 = CO(g) + H2O(g)

    (ii)

    KP = PCO•PH2O/PH2•PCO2

    For Experiment 1:

    KP = (70)(46)/(23)(140) = 1

    For Experiment 2:

    KP = (80)(48)/(32)(120) = 1

    For Experiment 3:

    KP = (50)(80)/(40)(100) = 1

    Average KP = (1 + 1 + 1)/3 = 1

    KC = KP = 1

    2009-07-19 19:02:06 補充:

    第一題下半部更正如下:

    At 10°C: T1= 283 K

    P(NH3) + P(H2S) = 0.22 atm

    Hence, P(NH3) = P(H2S) = 0.11 atm

    K1 = P(NH3)•P(H2S) = (0.11)^2 atm^2 = 0.0121 atm^2

    At 25°C: T2= 298 K

    P(NH3) + P(H2S) = 0.64 atm

    Hence, P(NH3) = P(H2S) = 0.32 atm

    K2 = P(NH3)•P(H2S) = (0.32)^2 atm^2 = 0.1024 atm^2

    2009-07-19 19:02:25 補充:

    ln(K1/K2) = -(ΔH/R)(1/T1 - 1/T2)

    ln(0.0121/0.1024) = -(ΔH/8.314)(1/283 - 1/298)

    ΔH = +99830 J mol^1 = +99.83 kJ mol^1

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  • 1 decade ago

    老爺子解釋的很詳盡

    板大,注意一下K的定義,不難明白為什麼是平方

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  • 1 decade ago

    在NH4HS(s) = NH3(g) + H2S(g)

    的氣體分子mole 是 1 : 1: 1

    為何K1 和 K2要用2次方?

    K1 = (0.22 atm)2 K2 = (0.64 atm)2

    • Commenter avatarLogin to reply the answers
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