Lesson2  Chemical Equilibrium and Kinetics
化学平衡和动力学
    A1  A major objective of chemist is to understand chemical reactions, to know whether under a given set of conditions two substances will react when mixed, to determine whether a given reaction will be exothermic or endothermic, and to predict the extent to which a given reaction will proceed before equilibrium is established.
化学家的一个主要目标是理解化学反应，知道在一组给定的条件下两种物质混合时能否发生反应；确定一个给定的反应是放热还是吸热；预测一个给定的反应在平衡前进行的程度。
2 An equilibrium state, produced as a consequence of two opposing reactions occurring simultaneously, is a state in which there is no net change as long as there is no change in conditions.
平衡状态是由两个对立反应同时发生产生的结果，在平衡状态下，只要条件不发生改变，这个状态就不会有净变化。
3  In this lesson it will be shown how one predict the equilibrium state of chemical systems from thermodynamic data, and conversely how the experimental measurements on equilibrium states provide useful thermodynamic data.
在这节课中，将会展示如何根据热力学数据来预测化学体系的平衡状态，以及相反地，平衡状态下的实验测量值如何提供有用的热力学数据。
4  Thermodynamics alone cannot explain the rate at which equilibrium is established, nor does it provide details of the mechanism by which equilibrium is established.
仅凭热力学无法解释平衡建立的速度，也不能提供平衡建立的详细的机理。
5  Such explanations can be developed from considerations of the quantum theory of molecular structure and from statistical mechanics. 
从分子结构的量子理论和统计力学的角度考虑可以使这样的解释得到发展。
    B1 To appreciate fully the nature of the chemical equilibrium state, it is necessary first to have some acquaintance with the factors which influence reaction rates.
要充分理解化学平衡状态的本质，首先需要对影响反应速率的因素有一定的了解。
2  The factors which influence the rates of a chemical reaction are temperature, concentrations of reactants(or partial pressures of gaseous reactants), and presence of a catalyst.
影响化学反应速率的因素有温度、反应物浓度（气体反应物的分压）和催化剂。
3  In general, for a given reaction the higher the temperature, the faster the reaction will occur.
通常，对于一个给定的反应，温度越高，反应发生的越快。
4  The concentrations of reactants or partial pressure of gaseous reactants will affect the rate of reaction, an increase in concentration or partial pressure increases the rate of most reactions.
反应物浓度或气体反应物的分压将影响反应的速率，对于大部分反应来说，增大浓度或分压，反应速率增大。
5  Substances which accelerate a chemical reaction but which themselves are not used up in the reaction are called catalysts.
可以加快反应速率但本身不参加反应的物质称为催化剂。
  C1 Dynamic Equilibrium  动态平衡
2  In many cases, direct reactions between two substances appear to cease before all of either starting material is exhausted.
许多情况下，两种物质间的直接反应在任意一种原始物料耗尽之前就会停止。
3  Moreover, the products of chemical reactions themselves often react to produce the starting materials.
而且，化学反应自身的产物能够发生反应生成原始物料。
4  For example, nitrogen and hydrogen combine at 500 ℃ in the presence of a catalyst to produce ammonia:  N2+3H2=2NH3
例如，在催化剂存在下，氮和氢在500℃能够反应生成氨：
5  At the same temperature and in the presence of the same catalyst, pure ammonia decomposes into nitrogen and hydrogen:  2NH3=3H2+ N2
在相同温度和相同催化剂存在的条件下，纯净的氨气能够分解生成氮气和氢气：
6  For convenience, these two opposing reactions are denoted in one equation by use of a double arrow:             
为了方便起见，这两个对立的反应能够用双箭头表示在一个方程式中：
7  The reaction proceeding toward the right is called the forward reaction; the other is called the reverse reaction.
向右进行的反应称为正反应，另外一个称为逆反应。
  D1 If either ammonia or a mixture of nitrogen and hydrogen is subjected to the above condition, a mixture of all the three gases will result.
如果将气氨或氮气和氢气的混合物放在上述条件下，将会产生三种气体的混合物。
2  The rate of reaction between the materials which were introduced into the reaction vessel will decrease after the reaction starts;
如果将原料放入反应器中，在反应开始后，反应速率将会降低；
3  because their concentrations are decreasing, conversely, after the start of the reaction the material being produced will react faster, since there will be more of it.
因为它们的浓度在减小，相反，在反应开始后，产物之间的反应将会加快，由于它们的浓度在增加。
react to啥意思4  Thus the faster forward reaction becomes slower, and the slower reverse reaction speeds up.
因此，较快的正反应会变慢，较慢的逆反应会变快。
5  Ultimately the time comes when the rates of the forward and reverse reactions become e
qual, and there will be no further net change.
最后，正反应和逆反应速率相等，且不再有进一步净变化的时刻终于到来。
6  This situation is called equilibrium.
这种状态叫做平衡。
7  Equilibrium is a dynamic state because both reactions are still proceeding; but since the two opposing reactions are proceeding at equal rates, no net change is observed.

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