Contents of Today S.J.T.U. Phase Transformation and Applications Review previous On Gibbs free energy Electrochemical Nomenclature Calculation of Cell voltage Direction of Reaction etc. SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 9 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 9 electrochemistry I Contents of Today Review previous On Gibbs free energy Electrochemical Nomenclature Calculation of Cell Voltage Direction of Reaction etc
饱和蒸气压 S.J.T.U. Phase Transformation and Applications 饱和蒸气压概念 将一杯纯溶液置于密闭的钟 罩内，一定时间后液面将有 液相 气相 所下降，直到罩内气体压力 达到一定数值为止。此时的 A G(A) P1 气体压力称为该液体的饱和 蒸气压，简称蒸气压。分子 B G(B) P2 运动学，蒸发与凝聚的速度 相等时，气液两相达到动态 平衡条件 平衡。 G(A,liquid )=G(gas,P1) 。 饱和蒸气压的应用 G(B,liquid)=G(gas,P2) 一凝聚态某组元的化学势 4G(A-→B,liquid)=4G(gas,P1→P2) 一化学反应气相的化学势 4G(gas,P1→P2)=P7dG ·例子 SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 9 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 9 electrochemistry I 饱和蒸气压 • 饱和蒸气压概念 – 将一杯纯溶液置于密闭的钟 罩内，一定时间后液面将有 所下降，直到罩内气体压力 达到一定数值为止。此时的 气体压力称为该液体的饱和 蒸气压，简称蒸气压。分子 运动学，蒸发与凝聚的速度 相等时，气液两相达到动态 平衡。 • 饱和蒸气压的应用 – 凝聚态某组元的化学势 – 化学反应气相的化学势 • 例子 液相 气相 A G(A) P1 B G(B) P2 G( A,liquid ) G( = gas,P1 ) G( B,liquid ) G( = gas,P2 ) 平衡条件 ΔG( A B,liquid ) G( →= → Δ gas,P1 P2 ) P2 P1 ΔG( gas,P1 P2 ) dG → = ∫
Question 6 S.J.T.U. Phase Transformation and Applications At-5 C,the vapor pressure of ice is 3.012 mmHg and that of supercooled liquid water is 3.163 mmHg.Tha latent heat of fusion of ice is 5.85 kJ/mol at-5C.Calculate AG and AS per mole for the transition from water to ice at-5°C. AG-5C 3.163 mmHg 3.012 mmHg Vapor pressure 1AG-0 △G-0 Ice Water △Gand△Sat-5C SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 9 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 9 electrochemistry I Question 6 At -5 °C, the vapor pressure of ice is 3.012 mmHg and that of supercooled liquid water is 3.163 mmHg. Tha latent heat of fusion of ice is 5.85 kJ/mol at -5 °C. Calculate ΔG and ΔS per mole for the transition from water to ice at -5°C. Ice Water ΔG and ΔS at -5 °C ΔG1 -5 °C ΔG=0 ΔG=0 Vapor pressure 3.163 mmHg 3.012 mmHg
5.1 THERMODYNAMIC ACTIVITY (2) S.J.T.U. Phase Transformation and Applications i No Units 三 Reference state:temperature,pressure and physical form Standard state:pressure and physical form Gas:pure gas at one atmosphere Condensed mater:pure liquid or solid under one atmosphere CdG,-G,-G=RTn人-RTna dG,-G,-G;=RTIn P=RTIna, Ideal gas P The fugacity of a condensed phase is equal to the fugacity of the vapor in equilibrium with it. The value of thermodynamic activity changes not only with pressure but also with composition. SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 9 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 9 electrochemistry I 5.1 THERMODYNAMIC ACTIVITY (2) o i i i f f α ≡ i i i i i G G i RT ff =−= RTGGdG ln = lnα ∫ o o o i i i i i G G i RT PP =−= RTGGdG ln = lnα ∫ o o o Ideal gas No Units Reference state: temperature, pressure and physical form Standard state: pressure and physical form Gas: pure gas at one atmosphere Condensed mater: pure liquid or solid under one atmosphere The fugacity of a condensed phase is equal to the fugacity of the vapor in equilibrium with it. The value of thermodynamic activity changes not only with pressure but also with composition
5.2 CHEMICAL EQUILIBRIUM S.J.T.U. Phase Transformation and Applications bB+cC=dD+eE Expression for a chemical reaction OWron=AG=dGD+eGE-bGB-cGc GB =G&+RTInag AG=d(Go+RT Inap)+e(Gi RT Inde)-b(GB+RT InaB)-c(Gc+RTInac) △G=△G°+RTIn J G=0 △G°=dG)+eGE-bGB-cG& Equilibrium constant d。 e J b △G°=-RTInm）)=-RTIn K SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 9 electrochemistry I
Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 9 electrochemistry I 5.2 CHEMICAL EQUILIBRIUM + = + eEdDcCbB δ rev D E B −−+=Δ= GcGbGeGdGW C )ln()ln()ln()ln( D +=Δ RTGdG α D E ++ RTGe α E B +− RTGb α B C +− RTGc α C o o o o α +Δ=Δ ln JRTGG o o o o o o D E B C −−+=Δ cGbGeGdGG c C b B e E d D J αα αα α = B BB += RTGG lnα o α KRT α JRTG mequilibriu −=Δ ln ( ) −= ln o Equilibrium constant Expression for a chemical reaction ΔG 0 =