化学专业英语翻译〔修订版〕33化学反应速度.docVIP

化学专业英语 翻译（校准版） 33 化学反应速度 Introduction 介绍 In this chapter we look into how chemical reactions occur. The principal aspect we examine is the rate of a reaction, and we shall see how it. depends on the temperature and the concentrations of the species that are present. 在本章中，我们来看看化学反应是如何发生的。我们研究的主要的方面是反应速率，我们将看到温度和存在的物质的浓度是如何影响化学反应速率的。 There are two main reasons for studying the rates of reactions. The first is the practical importance of being able to predict how quickly a reaction mixture will move its equilibrium state: the rate might depend on a number of factors under our control, such as the temperature, the pressure, and the presence of a catalyst, and, depending on our aims, we may be able to make the reaction proceed at an optimum rate. For instance, in an industrial process it might be economical for the reactions to proceed very rapidly; but not so rapidly as to produce an explosion. By contrast, in a biological process it may be appropriate for a reaction to proceed only slowly, and to be switched on and off at the demand of some activity. 研究反应速率的主要原因有两个。首先是具有实际重要性的一点，也就是能够预测反应混合物何时到达它的平衡状态：化学反应速率可能取决于一些我们控制之下的因素，如温度，压力，和催化剂的存在，而且，根据我们的目的，我们也许能够使化学反应以一个最佳的速度进行。比如，在工业流程中，可能由于化学反应进行得非常迅速从而带来经济效益，但是也不能太过迅速以至于产生爆炸。相反，在一个生物进程中，化学反应可能只有进行得缓慢才是合适的，并且反应根据一些生物活动的需求进行和停止。 The second reason for studying reaction rates (which, as we shall see, is closely bound up with the first) is that the study of rates can reveal the mechanisms of reactions. The term ‘mechanism’ has two connotations in this context. The first is the analysis of a chemical reaction into a sequence of elementary steps. For example, we might discover that the reaction of hydrogen and bromine proceeds by a sequence of steps involving the fission of Br2 into two bromine atoms, the attack of one of these atoms on H2, and so on. The statement of all the elementary steps constitutes the statement of the mechanism of the reaction. The other meaning of mechanism relates to the individual ste