大学化学(第二版)部分习题参考答案

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1、第一章部分习题参考答案=0-2×(-16.45)=32.90(kJ·mol-1)[P33:6题]解题思路解:查附录4中有关数据如下：2NH3(g)=N2(g)+3H2(g)ΔfHmө(298.15K)/(kJ·mol-1)-46.1100Smө(298.15K)/(J·mol-1·K-1)192.45191.50130.684ΔfGmө(298.15K)/(kJ·mol-1)-16.4500△rGmө(298.15K)=∑vi△fGmө(生成物)-∑vi△fGmө(反应物)解:(1)T=298.15KΔrGmө(T

2、)≈ΔrHmө(298.15K)-T·ΔrSmө(298.15K)=92.22-398.15×198.65×10-3=13.13（kJ·mol-1）根据:ΔrGmө(T)≈ΔrHmө(298.15K)–T•ΔrSmө(298.15K)计算.(2)T=398.15K△rSmө(298.15K)＝∑viSmө(生成物)-∑viSmө(反应物)＝[191.50+(3×130.684)]-(2×192.45）=198.65(J·mol-1·K-1)△rHmө(298.15K)＝∑vi△fHmө(生成物)-∑vi△fHmө(

3、反应物)＝0–2×(-46.11）=92.22(kJ·mol-1)2NH3(g)=N2(g)+3H2(g)(3)T=300℃=300+273.15K=573.15K根据ΔrGm(T)=ΔrGmө(T)+2.303RTlgQ计算.ΔrGmө(T)=ΔrHmө(298.15K)-T·ΔrSmө(298.15K)=92.22-573.15×198.65×10-3=-21.63(kJ·mol-1)Q===100(PNH3/Pө)2(PN2/Pө)1·(PH2/Pө)3(1000/100)1·(1000/100)3(1000

4、/100)2ΔrGm(T)=ΔrGmө(T)+2.303RTlgQ=-21.63+2.303×8.314×10-3×573.15×lg(100)=0.318(kJ·mol-1)p(O2)=101.325Kpa×21％=21.28KpaP(O2)Pө1P(O2)/Pө21.28Kpa100Kpa解：查表可知：Sn(s)+O2(g)=SnO2(s)ΔfGmө(298.15K)/(kJ·mol-1)00-519.7[P33:3题]解题思路Q====4.699当T=298.15K时，ΔrGmө(T)=△rGmө(298.1

5、5K)△rGmө(298.15K)=∑vi△fGmө(生成物)-∑vi△fGmө(反应物)=(-519.7)-0=-519.7(kJ·mol-1)(1)根据ΔrGm(T)=ΔrGmө(T)+2.303RTlgQ计算.∴P(O2)＜10-89.04Kpa2.303RT-ΔrGmө(T)1P(O2)/PөP(O2)PөlgQ＞=91.04,则:Q＞1091.04即:ΔrGm(T)=ΔrGmө(T)+2.303RTlgQ＞0,非自发。ΔrGmө(T)+2.303RTlgQ＞0,(2)使Sn在常温空气中不被氧化,应使反应非

6、自发.Q==＞1091.04∴常温空气中使Sn不被氧化所需O2最高压力应低于10-89.04Kpa．=△rGmө(298.15K)+2.303×8.314×10-3×298.15×lg(4.699)=-515.86(kJ·mol-1)＜0,向正方向自发进行.∴金属锡制件在常温的空气中能被氧化。ΔrGm(T)=ΔrGmө(T)+2.303RTlgQSn(s)+O2(g)=SnO2(s)[P34:8题]设汽车内燃机内温度因燃料燃烧反应达到1300℃，试计算该反应:N2(g)+O2(g)=2NO(g)在1300℃时的标准

7、摩尔吉布斯函数变和标准平衡常数Kө。解:查表知:N2(g)+O2(g)=2NO(g)ΔfHmө(298.15K)/(kJ•mol-1)0090.25Smө(298.15K)/(J•mol-1•K-1)191.50205.14210.76△rHmө(298.15K)＝∑vi△fHmө(生成物)-∑vi△fHmө(反应物）＝2×90.25＝180.50kJ•mol-1△rSmө(298.15K)＝∑viSmө(生成物)-∑viSmө(反应物）＝2×210.76–(191.5+205.14)＝24.88J•k-1•mol

8、-1ΔrGmө(T)=ΔrHmө(T)-T·ΔrSmө(T)lgKө=2.303RT-ΔrGmө(T)lgKө=-△rGmө/2.303RT=-（141.36）/（2.303×8.314×10-3×1573.15）=-4.69T=1300℃=1300+273.15=1573.15KΔrGmө(T)≈△rHmө(298.15K)–T•△rSmө(298.15K