南邮材料化学答案第四章习题答案.docVIP

材料化学热力学 Chapter 4 Chemical Thermodynamics of Materials 1. Cs熔体的标准吉布斯自由能（单位为J）与温度T（单位为K）的关系为 ΔGom, Cs=2100-6.95T, 求Cs的熔点。Relationship between the standard Gibbs free energy (in units of J) of Cs melt and temperature T (K) is shown as ΔGom, Cs=2100-6.95T, please determine the melting point of Cs. 解：根据热力学定律，当ΔG0时，反应可以自发进行，因此ΔG＝0时对应的平衡反应（即Cs由固相转变为液相的反应）的温度即为Cs的熔点。由ΔGom, Cs=2100-6.95T＝0，可得T＝302K，所以Cs的熔点为302K。 Answer: According to the laws of thermodynamics, when ΔG 0, the reaction can be spontaneous. Therefore, ΔG = 0 corresponding to the equilibrium reaction of Cs change from solid phase into liquid phase, the temperature corresponding to the melting point of Cs. From ΔGom, Cs=2100-6.95T＝0, we can get T＝302K, so the melting point of Cs is 302K. 通过埃灵罕姆图解释为何碳在高温下可以用作金属氧化物的还原剂。According to the Ellingham diagram, please explain why the carbon can be used as a reductant of the metal oxides at high temperature. 答：根据埃灵罕姆图，ΔGo-T曲线越在下方，氧化物的ΔGo负值越大，其稳定性就越高。所以在给定的温度下，位于下方的ΔGo-T曲线所对应的元素可使位于上方曲线的金属氧化物还原。由埃灵罕姆图还可知，CO生成线的斜率为负，随着温度升高，ΔGo越负，CO稳定性越高。而金属氧化物的生成线的斜率都为正，随着温度升高，ΔGo越正，氧化物稳定性越低。所以，碳在高温下可以用作金属氧化物的还原剂。According to the Ellingham diagrams, the lower the site of ΔGo-T curve, the bigger the negative value of ΔGo, the more stable the metal oxide. So, at a given temperature, the element of the below ΔGo-T curve can reduce the metal oxide of the above ΔGo-T curve. We can see that the slope of CO formation line is negative, and with the increase of temperature, ΔGo becomes more negative, indicates that CO is more stable. However, the slopes of metal oxides formation line are all positive, with the increase of temperature, ΔGo becomes more positive, indicates that metal oxide is more unstable. Therefore, the carbon can be used as a reductant of the metal oxides at high temperature. 3.（a）对任何反应，请说明ΔG和ΔGo为0的意义；（b）对于“如果反应的ΔGo是正值，则反应不会如反应式所写的那样向右进行”的说法，谈谈你的观点。(a) for any reaction, please indicate the significance of ΔG和ΔGo; (b) For “if ΔGo of a reaction is positive, the reaction will not go