Thermodynamic and Kinetic Control · 热力学控制与动力学控制
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| metastable/ˌmetəˈsteɪbl/ | 亚稳态 | yà wěn tài |
Allowed but not always happening
- Diamond should slowly turn to graphite -- yet it never seems to.
- The reaction is favourable, but unimaginably slow.
- Being allowed is one thing; happening in time is another.
- Two different questions govern every reaction.
被允许却不总在发生
- 金刚石本应慢慢变成石墨——可它似乎从不这样。
- 反应是有利的,但慢得难以想象。
- 被允许是一回事;在有限时间内发生是另一回事。
- 两个不同的问题支配着每一个反应。
Whether versus how fast
- Thermodynamics ($\Delta G$) asks whether a reaction can happen.
- Kinetics (activation energy) asks how fast it goes.
- A reaction needs a good answer to both to matter in practice.
是否对比多快
- 热力学($\Delta G$)问一个反应是否能发生。
- 动力学(活化能)问它进行得多快。
- 一个反应要在实践中有意义,两方面都要有好答案。
Which quantity tells you whether a reaction is thermodynamically favourable? · 哪个量告诉你反应是否在热力学上有利？
$\Delta G$ decides favourability; activation energy decides speed. · $\Delta G$ 决定倾向性；活化能决定速度。
To be useful in practice, a reaction should be both favourable and fast enough. · 为了在实践中有用，反应应当既有利又足够快。
Both thermodynamics and kinetics must cooperate. · 热力学和动力学必须协同作用。
Favourable yet frozen
- A reaction with $\Delta G < 0$ but a huge activation energy is stuck.
- It is favourable, yet effectively never happens.
- Such a trapped state is called metastable 亚稳态.
有利却被冻住
- $\Delta G < 0$ 但活化能巨大的反应被卡住。
- 它有利,却实际上从不发生。
- 这样被困的状态称为亚稳态。
A reaction with $\Delta G < 0$ can still be far too slow to observe. · 具有 $\Delta G < 0$ 的反应可能仍然慢到无法被观察到。
A large activation energy makes a favourable reaction slow. · 较大的活化能使一个有利的反应变得缓慢。
A favourable but kinetically trapped state is called ____. · 一个有利但被动力学捕获的状态被称为 ____。
Metastable means favourable yet effectively frozen. · 亚稳态意味着有利但在实际上被冻结了。
Kinetics can be helped
- A catalyst lowers the activation energy, unlocking a slow reaction.
- It changes the kinetics, not the thermodynamics.
- $\Delta G$ stays the same, but now the reaction actually proceeds.
动力学可以被帮助
- 催化剂降低活化能,解锁一个缓慢的反应。
- 它改变动力学,而不是热力学。
- $\Delta G$ 保持不变,但现在反应真的进行了。
Thermodynamics or kinetics? · 热力学还是动力学？
Sort each idea by whether it is set by free energy or by rate. · 根据每项是由自由能决定还是由速率决定进行分类。
A catalyst changes a reaction's... · 催化剂改变反应的...
Catalysts lower the barrier but leave $\Delta G$ unchanged. · 催化剂降低能垒但保持 $\Delta G$ 不变。
Diamond turning to graphite has $\Delta G < 0$. Why does it not happen?
- The activation energy is enormous.
- Kinetics traps it, so diamond is metastable.
金刚石变成石墨的 $\Delta G < 0$。为什么它不发生?
- 活化能极其巨大。
- 动力学把它困住,所以金刚石是亚稳态。
Diamond persists even though converting to graphite is favourable because it is... · 钻石虽然转化为石墨是有利的，但它仍能持久存在，因为它是...
A huge activation energy traps diamond in a metastable state. · 巨大的活化能将钻石锁定在亚稳态中。
Thermodynamic favourability ($\Delta G < 0$) does not guarantee a reaction is observable -- a big activation energy can make it immeasurably slow. A catalyst changes speed (kinetics), not $\Delta G$ (thermodynamics). And "metastable" means favourable but kinetically trapped.
热力学有利性($\Delta G < 0$)不保证反应可观察到——巨大的活化能能让它慢得无法测量。催化剂改变速度(动力学),而不是 $\Delta G$(热力学)。而且"亚稳态"意味着有利但被动力学困住。
Thermodynamics ($\Delta G$) says whether a reaction can happen; kinetics (activation energy) says how fast. A favourable reaction can be frozen by a huge barrier -- a metastable state like diamond. A catalyst unlocks the kinetics without changing $\Delta G$.
热力学($\Delta G$)说一个反应是否能发生;动力学(活化能)说它多快。一个有利的反应可能被巨大的壁垒冻住——像金刚石这样的亚稳态。催化剂解锁动力学而不改变 $\Delta G$。