页数：51页文件大小：3.49 MB来源： Atkins’PhysChem物理化学ppt课件
本课件继续化学平衡：给出标准平衡常数与反应商的关系，讨论压力、温度对平衡组成的影响与勒夏特列原理；后半部分进入电化学，介绍电池的构成、半反应与电极的书写规则。
Chemical Equilibrium Chapter 9
Spontaneous chemical reactions The response of equilibria to the conditions Ho
Spontaneous chemical reactions 9.1 The Gibbs energy minimum (a) The reaction Gibbs energy A B d ξ A B dnA = - d ξ dnB = d ξ ξ: the ext
(a) The reaction Gibbs energy Spontaneous μ A > μ B Δ r G < 0 d G = μ A dnA + μ BdnB = - μ A d ξ + μ B d ξ =
(b) Exergonic and endergonic reactions Reverse spontaneous Δ r G > 0 endergonic reactions At equilibrium Δ r G = 0 Sp
9.2 The description of equilibrium Δ r G = Δ r G + RTlnpB / p A = Δ r G + RTlnQQ = p B / p A Δ r G = G B,
(b) The general case of a reaction μ J = μ J + RTlnaJ For a reaction: a A + bB cC + dDdG = Σ μ JdnJ = (Σ ν J
(b) The general case of a reaction For a reaction: a A + bB cC + dD
(b) The general case of a reaction For a reaction: H 2 O (g) H 2 (g) + ½ O 2 (g) Δ G = 118.08 k J mol - 1 at 23
(b) The general case of a reaction O 2 H 2 H 2 O 00 n Initial amount ½ α n α n - α n Change to reach eqm ½ α n α
(b) The general case of a reaction For a reaction: H 2 O (g) H 2 (g) + ½ O 2 (g) About 2 % of water has decompo
(c) The relation between equilibrium constants For a reaction: A + B C + D
(c) The relation between equilibrium constants The composition of gases mixture can be written as： p J、c J、yJThenK can be wri
(c) The relation between equilibrium constants When Σ ν J = 0, K = K p = K c = Ky = K n
(d) Equilibria in biological systems As we saw before that the biological standard state is pH = 7, for a reaction:
The response of equilibria to the conditions Equilibria respond to change in pressure, temperature, and concentrations of reactants and products. The equilibrium constant is not affected by the presence of a catalyst or an e
9.3 how equilibria respond to pressure The eqm constant K depends on Δ r G Δ r G is defined at a single, standard pressure. The value of Δ r G and K
9.3 how equilibria respond to pressure In a reaction vessel, the pressure can be increased by injecting an inert gas into it. If the gases are perfect: The partial pressure unchanged The molar concentrati
9.3 how equilibria respond to pressure K is a constant at given temperature. If Σ v J > 0, p Ky , the composition shift leftward If Σ v J < 0, p Ky ,
9.3 how equilibria respond to pressure Le Chatelier’ s principle: A system ateqm, when subjected to a disturbance, responds in away that tends t
9.4 The response of equilibria to temperature According to Le Chatelier’ s principle For exothermic, increase temp favors th
9.4 The response of equilibria to temperature (a) The van’ t H off equation
9.4 The response of equilibria to temperature (a) The van’ t H off equation For exothermic reaction, Δ r H < 0, T , K F
(b) The value of K at different temperature
9.5 The response of equilibria to pH (a) Acid - base equilibria in water
(b) The pH of acids and bases For a small extent of hydrogen transfer, a J [J]
(c) Acids - bases titration s Add strong base M OH to a weak acid H A To calculate the pH at any stage of th
(c) Acids - bases titration s Then we have the Henderson - Has selbalch equation In general, for S is the mo
(c) Acids - bases titration s At the stoichiometric point (equivalence point) [A -] S, [H A] [OH -]
(c) Acids - bases titration s
(d) The ‘exact’ form of the pH curve Titration curve of a weak acid and strong base for different values of pKa
(e) Using equilibria to stabilize pH: buffers The slow variation of the pH in the vicinity of S = A’, when the molar concent
(e) Using equilibria to stabilize pH: buffers The physical basis of buffer action is that the existence of an abundant suppl
(e) Using equilibria to stabilize pH: buffers Ex: Estimate the pH of an aqueous buffer solution that contains 0.200 molL - 1
(f) Using equilibria to detect changes in pH: indicators The rapid change of pH near the stoichiometric point in a titration is the bas
(f) Using equilibria to detect changes in pH: indicators When pH < pKIn, in acid form and color When pH > pKIn, in basic form and color
Equilibrium Electrochemistry Chapter 10
Thermodynamic functions of ions in solution Electrochemical cell Half - reactions and electrodes Thermodynamic functions of formation I on activities Varieties of cell Standard potentials Applications of standard potential The electrochemical series The meas
To take into account activity coefficients, for they differ from 1 on
1. the presence of strong interactions between ions in solution. Even
10.1 Thermodynamic functions of formation (a) Standard functions of formation of ions The Δ f H and Δ f G of
(a) Standard functions of formation of ions The Δ f H and Δ f G of for other ions can be calculated in relativ
(a) Standard functions of formation of ions Consider: ½ H 2 (g) + ½ Cl 2 (g) H + (a q) + Cl - (a q) Δ r G = -
(b) Contributions to the Gibbs energy of formation Thermodynamic cycles ½ H 2 (g) + ½ Cl 2 (g) H + (a q) + Cl - (a q)
(b) Contributions to the Gibbs energy of formation Thermodynamic cycles ½ H 2 (g) + ½ I 2 (s) H + (a q) + I - (a q)
(b) Contributions to the Gibbs energy of formation Thermodynamic cycles ½ H 2 (g) + ½ X 2 H + (a q) + X - (a q) The sum
(b) Contributions to the Gibbs energy of formation Gibbs energies of solvation, Δ solvG , can be estimated from Max Born
(b) Contributions to the Gibbs energy of formation Example: Estimate the value of Δ solvG (Br -, a q) - Δ solvG (Cl -
(b) Contributions to the Gibbs energy of formation Example: Estimate the value of Δ solvG (Br -, a q) - Δ solvG (Cl -
(c) Standard entropies of ions in solution The partial molar entropy of the solute can be measured. However, The
Exercises (a) 9.7, 9.11, 9.12, 9.20, 9.25 Discussion: problems 9.11 Homework
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