Thermodynamics △H=断裂键的离解能之和一新生成键的离解能之和 H th-Br H H Br bonds being broken bonds being formed IT bond of ethene Dh=256 kJ morC-H DH=423 kJ mor, H-Br DH=366 kJ. morC-Br DH=289 kJmol dh total=622 kJmol dh total =712 kJ-mol Ah for the reaction=622 kJ mol-712 kJ mol=-90 kJ mol
Thermodynamics Δ H0 = 断裂键的离解能之和 － 新生成键的离解能之和 H H H H H B r C C H H H H H Br + bonds being broken bonds being formed π bond of ethene DH0 = 256 kJ mol-1 H B r DH0 = 366 kJ mol-1 C H C B r DH0 = 423 kJ mol-1 DH0 = 289 kJ mol-1 DH0total = 622 kJ mol-1 DH0to t al = 712 kJ mol-1 H0 for t he r eact i o n = 6 2 2 kJ m o l-1 - 712 kJ m o l-1 = - 9 0 kJ m o l-1
Thermodynamics 已知键的裂解能,焓变是可以计算的 ●但是熵变较难计算 ●如果熵变不大,气相反应可通过焓变粗略估 计反应在能量上是否有利 ●另一个困难是多数有机反应在溶液中进行, 存在溶剂化作用,增加了计算难度
Thermodynamics z 已知键的裂解能，焓变是可以计算的 z 但是熵变较难计算 z 如果熵变不大，气相反应可通过焓变粗略估 计反应在能量上是否有利 z 另一个困难是多数有机反应在溶液中进行， 存在溶剂化作用，增加了计算难度
Thermodynamics 热力学能告诉我们反应是否能进行,却不能预计反应 的速度如何?也不能告诉我们反应具体进程是怎样 an gonic reaction放能反应 an endergonic reaction吸能反应 products 5o9L △G △G oducts reactants progress of the reaction progress of the reaction Keq>1 Keg 1 △ G is negative △ G is possitive
Thermodynamics 热力学能告诉我们反应是否能进行，却不能预计反应 的速度如何？也不能告诉我们反应具体进程是怎样 re a ctan t s product s reactan t s produc t s ∆ G ∆ G progres s of the re a cti o n progre s s of the re a cti o n Free energy an exer g o nic reactio n 放能反应 a n en d e r g o nic r eactio n 吸能反应 Keq > 1 Keq < 1 ∆ G i s nega tiv e ∆ G is p ossitiv e 的？
Kinetics Questions: o How fast the reaction occurs? How about the energy barrier of the reaction? o How about the progress of the reaction?
Kinetics Questions: z How fast the reaction occurs? z How about the energy barrier of the reaction? z How about the progress of the reaction?
Kinetics Kinetics(动力学)/ is the field of chemistry that describes the rates of chemical reactions and the factors that affect those rates reaction/ rate and affecting facters, reaction progress (反应速率及影响因素,反应进程等)
Kinetics z Kinetics （动力学） is the field of chemistry that describes the rates of chemical reactions and the factors that affect those rates. z —— reaction rate and affecting facters, reaction progress (反应速率及影响因素，反应进程等)