体系为不可逆的等压过程,设平衡温度为T根据能量守恒:25g÷46g/mol ×Cpm×(323K-T)=70g÷46g/mol ×Cpm×(T-283K)解得 T=293.5K
n1=25g/46g/mol=0.543mol T1=323Kn2=70g/46g/moL=1.522mol T2=283K T=293.5K ⊿S1=0.543mol×111.5J*K-1*mol-1×ln293.5/323K=-5.8J/K⊿S2=1.522mol×111.5J*K-1*mol-1×ln293.5/283K=+6.2J/K⊿S=0.4J/K