07章 统计热力学基础.pptVIP

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * （4）定容热容 这个结论与经典的能量均分原理的结果是一致的，单原子分子只有三个平动自由度，每个自由度贡献 ，则N个粒子共有 。 * * （5）化学势 对于理想气体， ，代入 A 的表示式，得： * * （6）理想气体的状态方程 将A的表示式代入，由于其它项均与体积无关，只有平动项中有一项与V有关，代入即得理想气体状态方程。 用统计热力学的方法可以导出理想气体状态方程，这是经典热力学无法办到的。 * * 7. 双原子理想气体热力学函数的计算 根据配分函数的定义及可分离的性质，分子的全配分函数应该由5个部分组成，即： 7.1 双原子分子的全配分函数 * * 对于双原子分子，将各个配分函数的具体表示式代入，就得到： 对于多原子分子，前三项相同，而qr和qv 的形式因原子的结构不同而有所不同。 * * 7.2 计算氧分子的 在298.15 K和标准压力下，将1 molO2(g)放在体积为V的容器中，已知电子基态的 ,基态能量 ,忽略电子激发态项的贡献。O2的核间距 。忽略 和 的贡献。 * * 解： 这时，O2的全配分函数只有 ， 和 三项，分别计算如下，可以看出它们贡献的大小。 * * 将k、h等常数代入，O2的对称数 ,得： * * * * * * 利用Sackur-Tetrode公式计算，因为Nk=R, 所以： * * * * 所以 显然，平动熵的贡献最大。 =(9.13+43.73+152.0)J·mol-1·K-1 =204.8J·mol-1·K-1 * * THE END * * JAMES CLERK MAXWELL (1831-1879) British physicist,presented his first scientific paper to the Royal Society of Edihburgh at the age of 15.In chemistry he is best known for his Maxwell distribution and his contributions to the kinetic theory of gases. In physics his name is most often associated with his Maxwell equations for electromagnetic fields. * * LUDWIG BOLTZMANN (1844-1906) Austrian scientist,is best known for his work in the kinetic theory of gases and in thermodynamics and statistical mechanics. His suicide in 1906 is attributed by some to a state of depression resulting from the intense scientific war between the atomists and the energists at the turn of the century. On his tombstone is the inscription S = k ln W. * * ALBERT EINSTEIN (1879-1955) was born in Germany and educated in Switzerland;and he died in the United States.He was refused a position as assistant in the physics department in the Zurich Polytechnical institute on his graduation, and he settled for position as an examiner in the Swiss Patent Office in 1900. * * In a few short yea