物理化学求熵变在隔离容器中,把25g50摄氏度的乙醇倒入70g10摄氏度的乙醇中,Cpm+111.5,求熵变原题如下Calculate the change in entropy when 25g ofethanol at 50℃ is poured into 70g ethanol at 10℃ in an insulated vessel,g

物理化学求熵变在隔离容器中,把25g50摄氏度的乙醇倒入70g10摄氏度的乙醇中,Cpm+111.5,求熵变原题如下Calculate the change in entropy when 25g ofethanol at 50℃ is poured into 70g ethanol at 10℃ in an insulated vessel,g
物理化学求熵变
在隔离容器中,把25g50摄氏度的乙醇倒入70g10摄氏度的乙醇中,Cpm+111.5,求熵变
原题如下
Calculate the change in entropy when 25g ofethanol at 50℃ is poured into 70g ethanol at 10℃ in an insulated vessel,given that Cp,m=111.5J*K-1*mol-1
答案是0.2 可是我算了好久都不对,求帮忙

物理化学求熵变在隔离容器中,把25g50摄氏度的乙醇倒入70g10摄氏度的乙醇中,Cpm+111.5,求熵变原题如下Calculate the change in entropy when 25g ofethanol at 50℃ is poured into 70g ethanol at 10℃ in an insulated vessel,g

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=323K   

n2=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