版权所有：华东理工大学物理化学教研室 16 1). The thermodynamic definition of entropy a). Heat stimulates disorderly motion in the surroundings; work stimulates uniform motion of atoms in the surroundings, does not change the degree of disorder, and so does not change the entropy. b). A change in the extent to which energy is dispersed in a disorderly manner depends on the quantity of energy transferred as heat. 4.2 Entropy
版权所有：华东理工大学物理化学教研室 16 1). The thermodynamic definition of entropy a). Heat stimulates disorderly motion in the surroundings; work stimulates uniform motion of atoms in the surroundings, does not change the degree of disorder, and so does not change the entropy. b). A change in the extent to which energy is dispersed in a disorderly manner depends on the quantity of energy transferred as heat. 4.2 Entropy
版权所有：华东理工大学物理化学教研室 17 1). The thermodynamic definition of entropy T q S d rev d = The thermodynamic definition of entropy is based on The units of entropy: J K -1. The units of Molar entropy: J K -1 mol –1 (the same as that of R) 4.2 Entropy
版权所有：华东理工大学物理化学教研室 17 1). The thermodynamic definition of entropy T q S d rev d = The thermodynamic definition of entropy is based on The units of entropy: J K -1. The units of Molar entropy: J K -1 mol –1 (the same as that of R) 4.2 Entropy
版权所有：华东理工大学物理化学教研室 18 1). The thermodynamic definition of entropy For a measurable change between two states i and f this expression integrates to: ∫ = fi rev dTq ΔS To calculate the difference in entropy between any two states of a system, integrate the heat supplied at each stage of the path divided by the temperature at which the heat is supplied. 4.2 Entropy
版权所有：华东理工大学物理化学教研室 18 1). The thermodynamic definition of entropy For a measurable change between two states i and f this expression integrates to: ∫ = fi rev dTq ΔS To calculate the difference in entropy between any two states of a system, integrate the heat supplied at each stage of the path divided by the temperature at which the heat is supplied. 4.2 Entropy
版权所有：华东理工大学物理化学教研室 19 Example Calculate the change in entropy when 50kJ of energy is transferred reversibly and isothermally as heat to a large block of copper at (0) ℃, and (b) 70 ℃
版权所有：华东理工大学物理化学教研室 19 Example Calculate the change in entropy when 50kJ of energy is transferred reversibly and isothermally as heat to a large block of copper at (0) ℃, and (b) 70 ℃
版权所有：华东理工大学物理化学教研室 20 Example 4.1- Calculating the entropy change for the isothermal expansion of a perfect gas Answer: ∫ = = fi rev d rev Tq q T S 1 Method: Δ 2 1 3 rev 1.8 10 JK 273K 50 10 J Δ − = × × = = T q (a) S 2 1 3 rev 1.5 10 JK (70 273)K 50 10 J Δ − = × + × = = T q (b) S
版权所有：华东理工大学物理化学教研室 20 Example 4.1- Calculating the entropy change for the isothermal expansion of a perfect gas Answer: ∫ = = fi rev d rev Tq q T S 1 Method: Δ 2 1 3 rev 1.8 10 JK 273K 50 10 J Δ − = × × = = T q (a) S 2 1 3 rev 1.5 10 JK (70 273)K 50 10 J Δ − = × + × = = T q (b) S