Course: 20.3 自发和非自发反应

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自发和非自发反应
Watch that nitro!
::小心那个硝化甘油!

Nitroglycerin is tricky stuff. An active ingredient in dynamite (where it is stabilized), “raw” nitroglycerin is very unstable. Physical shock will cause the material to explode. The reaction is shown below:
::硝化甘油是棘手的东西。炸药中的一种活性成分(在稳定的情况下)、“草”硝化甘油非常不稳定。

$\begin{aligned} 4 C_{3} H_{5} (O N O_{2})_{3} \to 12 {CO}_{2} + 10 H_{2} O + 6 N_{2} + O_{2} \end{aligned}$
$\begin{align*}4\text{C}_3\text{H}_5(ONO_2)_3\rightarrow 12\text{CO}_2+10\text{H}_2\text{O}+6\text{N}_2+\text{O}_2\end{align*}$
::4C3H5(ONO2)312CO2+10H2O+6N2+O2

The explosion of nitroglycerin releases large volumes of and is very exothermic .
::硝化甘油的爆炸释放了大量的释放物并且非常的过热

Spontaneous Reactions
::自自反应反应

Reactions are favorable when they result in a decrease in and an increase in entropy of the system . When both of these conditions are met, the reaction occurs naturally. A spontaneous reaction is a reaction that favors the formation of products at the conditions under which the reaction is occurring. A roaring bonfire is an example of a spontaneous reaction, since it is exothermic (there is a decrease in the energy of the system as energy is released to the surroundings as heat). The products of a fire are composed partly of gases such as carbon dioxide and water vapor . The entropy of the system increases during a . The combination of energy decrease and entropy increase dictates that combustion reactions are spontaneous reactions.
::当这些条件都得到满足时,反应自然发生。自发反应是一种反应,有利于在反应发生时形成产品。燃烧的营火是自发反应的一个例子,因为它是发热的(当能量释放到周围作为热能时,系统能量会减少)。火灾的产物部分由二氧化碳和水蒸气等气体组成。系统增生时,系统增生。能量减少和增生的结合要求燃烧反应是自发反应。

Bonfire.
::点火了 Bonfire.

A non-spontaneous reaction is a reaction that does not favor the formation of products at the given set of conditions. In order for a reaction to be non-spontaneous, it must be endothermic , accompanied by a decrease in entropy, or both. Our atmosphere is composed primarily of a of nitrogen and oxygen gases. One could write an equation showing these gases undergoing a to form nitrogen monoxide.
::非自发反应是一种不利于在给定条件下形成产品的反应。要使反应非自发性,它必须是终端热,伴之以酶的减少,或两者兼有。我们的大气层主要由氮气和氧气组成。人们可以写一个方程式来显示这些气体正在形成一氧化氮。

$\begin{aligned} N_{2} (g) + O_{2} (g) \to 2 NO (g) \end{aligned}$
$\begin{align*}\text{N}_2(g)+\text{O}_2(g)\rightarrow 2\text{NO}(g)\end{align*}$
::N2(g) +O2(g) 2NO(g)

Fortunately, this reaction is non-spontaneous at normal temperatures and pressures. It is a highly with a slightly positive entropy change $\begin{align*}(\Delta \text{S})\end{align*}$ . Nitrogen monoxide is capable of being produced at very high temperatures and has been observed to form as a result of lightning strikes.
::幸运的是,这种反应在正常温度和压力下是非自发的,它具有一种高度的微小正反导。一氧化氮能够在极高的温度下产生,并且由于闪电袭击而观察到形成。

One must be careful not to confuse the term spontaneous with the notion that a reaction occurs rapidly. A spontaneous reaction is one in which product formation is favored, even if the reaction is extremely slow. A piece of paper will not suddenly burst into flames, although its combustion is a spontaneous reaction. What is missing is the required to get the reaction started. If the paper were to be heated to a high enough temperature , it would begin to burn, at which point the reaction would proceed spontaneously until completion.
::人们必须小心,不要将自发一词与反应迅速发生的概念混淆起来。自发反应是有利于产品形成的一种反应,即使反应极其缓慢。一块纸不会突然燃起,尽管其燃烧是自发反应。缺少的是启动反应所需的条件。如果纸张被加热到足够高的温度,它就会开始燃烧,到那时反应会自发进行直到完成。

In a , one reaction direction may be favored over the other. Carbonic is present in carbonated beverages. It decomposes spontaneously to carbon dioxide and water according to the following reaction.
::一种反应方向可能优于另一种反应方向。碳化物存在于碳化饮料中。根据以下反应,碳化物自发分解为二氧化碳和水。

$\begin{aligned} H_{2} {CO}_{3} (a q) ⇄ {CO}_{2} (g) + H_{2} O (l) \end{aligned}$
$\begin{align*}\text{H}_2\text{CO}_3(aq)\rightleftarrows \text{CO}_2(g)+\text{H}_2\text{O}(l)\end{align*}$
::H2CO3(aq) CO2(g) +H2O(l)

If you were to start with pure carbonic acid in water and allow the system to come to equilibrium, more than 99% of the carbonic acid would be converted into carbon dioxide and water. The forward reaction is spontaneous because the products of the forward reaction are favored at equilibrium. In the reverse reaction, carbon dioxide and water are the reactants and carbonic acid is the product. When carbon dioxide is bubbled into water, less than 1% is converted to carbonic acid when the reaction reaches equilibrium. The reverse reaction, as written above, is not spontaneous.
::如果您从水中的纯碳酸开始,并允许系统达到平衡,超过99%的碳酸将被转化成二氧化碳和水。前方反应是自发的,因为前方反应的产物在平衡时得到偏好。在反向反应中,二氧化碳和水是反应物,碳酸是产品。当二氧化碳泡入水时,当反应达到平衡时,不到1%的碳酸会被转化成碳酸。如上所述,反向反应不是自发的。

Watch this video to learn about Spontaneous and Non-spontaneous Chemical Reactions:
::观看这段影片以了解自发和非自发的化学反应:

More about Spontaneous and Non-spontaneous Chemical Reactions:
::更多关于自发和非自发的化学反应:

Summary
::摘要

Spontaneous and non-spontaneous reactions are defined.
::定义了自发和非自发的反应。

Examples of both types of reactions are given.
::列举了两种反应的例子。

Review
::回顾

Why is a combustion reaction spontaneous?
::为什么燃烧反应是自发的?

Is NO formation spontaneous at room temperature?
::室温没有自发形成吗?

How do we know that the equilibrium between carbonic acid and CO ₂ goes strongly to the right?
::我们如何知道碳酸和二氧化碳之间的平衡对右边的影响很大?

Section outline

General

自发和非自发反应

Watch that nitro! ::小心那个硝化甘油!

Spontaneous Reactions ::自自反应反应

Summary ::摘要

Review ::回顾

Watch that nitro!
::小心那个硝化甘油!

Spontaneous Reactions
::自自反应反应

Summary
::摘要

Review
::回顾