华东理工大学：物理化学（中英文）Physical chemistry Peter atkins (Sixth edition)

3.1 State functions 2). Changes in internal energy For a closed system of constant composition, U is a func tion of v and T. When v changes to v+ dy at constant Ty changes to U=U+au/av),dv When T changes to T+dT at constant V, U changes to U=U+aU/aT), dT U=U+au/av),dv+ou/oT) dT du=ou/ov) dv+ou/oT), dt 版权所有:华东理工大学物理化学教研

版权所有：华东理工大学物理化学教研室 11 For a closed system of constant composition, U is a func￾tion of V and T. When V changes to V + dV at constant T, U changes to U U ( U V) V T ' = +   d 2). Changes in internal energy U U ( U T) T V ' = +   d U U ( U V) V ( U T) T T V ' = +   d +   d U ( U V) V ( U T) T T V d =   d +   d When T changes to T+dT at constant V, U changes to 3.1 State functions

3.1 State functions du=auav),dv +auoT), dT au the slope of a plot of U against T at constant V. T du= dy +cut U lav, the internal pressure the same dimension as p du=idv+cdt In a closed system of constant composition, du is propor tional to dy and dt, the coefficients of proportionality being the partial derivatives 版权所有:华东理工大学物理化学教研

版权所有：华东理工大学物理化学教研室 12 , the internal pressure, the same dimension as p T T V U π         = V C T V U U V T d  d + d        = T V U         the slope of a plot of U against T at constant V. dU = πT dV +CV dT U ( U V) V ( U T) T T V d =   d +   d CV In a closed system of constant composition, dU is propor￾tional to dV and dT, the coefficients of proportionality being the partial derivatives. 3.1 State functions