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  • General

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  • 浓度效应

    A beaker containing pink phenolphthalein solution, indicating low hydrogen ion concentration.

    Phenolphthalein is one of those chemicals that has one structure in a high environment and another structure in a low acid environment. If the hydrogen is high, the is colorless, but turns red if the hydrogen ion concentration is low. By adding hydrogen ions to the solution or removing them through a , we can vary the color of the dye.
    ::苯硫他林是一种化学物质,在高空环境中有一个结构,而在低酸环境中又有一个结构。如果氢高,则无色,但如果氢离子浓度低,则会变成红色。通过在溶液中添加氢离子或通过a去除,我们可以改变染料的颜色。

    Effect of Concentration
    ::浓度效应

    A change in concentration of one of the substances in an equilibrium system typically involves either the addition or the removal of one of the reactants or products. Consider the Haber-Bosch process for the industrial production of ammonia from nitrogen and hydrogen .
    ::平衡系统中一种物质的浓度变化通常涉及增加或去除一种反应剂或产品,考虑用Haber-Bosch工艺从氮和氢的工业生产氨(Haber-Bosch)。

    N 2 ( g ) + 3 H 2 ( g ) ⇄ 2 NH 3 ( g )

    ::N2(g)+3H2(g)2NH3(g)

    If the concentration of one substance in a system is increased, the system will respond by favoring the reaction that removes that substance. When more N 2 is added, the forward reaction will be favored because the forward reaction uses up N 2 and converts it to NH 3 . The forward reaction speeds up temporarily as a result of the addition of a reactant. The position of equilibrium shifts as more NH 3 is produced. The concentration of NH 3 increases, while the concentrations of N 2 and H 2 decrease. After some time passes, equilibrium is reestablished with new concentrations of all three substances. As can be seen in  Figure , if more N 2 is added, a new equilibrium is achieved by the system. The new concentration of NH 3 is higher because of the favoring of the forward reaction. The new concentration of the H 2 is lower. The concentration of N 2 is higher than in the original equilibrium, but went down slightly following the addition of the N 2 that disturbed the original equilibrium. By responding in this way, the value of the equilibrium constant for the reaction, K e q , does not change as a result of the stress to the system.
    ::如果一种物质在系统中的浓度增加,系统将作出反应,支持清除该物质的反应。如果添加了更多的N2,则前方反应将有利于前方反应,因为前方反应使用N2并将其转换为NH3。由于添加反应器,前方反应会暂时加速。随着产生更多的NH3, 平衡变化的位置会随着更多的NH3而增加。NH3的浓度会增加,而N2和H2的浓度会减少。经过一段时间后,平衡会与所有三种物质的新浓度重新建立。从图中可以看出,如果添加了更多的N2,则系统将实现新的平衡。NH3的新浓度会由于偏好前方反应而提高。H2的新浓度会降低。N2的浓度比最初的平衡要高,但随着影响原平衡的N2的添加而略有下降。通过这种方式,反应的平衡常值Keq不会因系统的压力而改变。

    Graph illustrating equilibrium shifts in concentrations of N2, H2, and NH3 in the Haber process.

    The Haber-Bosch process is an equilibrium between reactant N 2 and H 2 and product NH 3 .
    ::Haber-Bosch过程是反应剂N2和H2与产品NH3之间的平衡。

    If more NH 3 were added, the reverse reaction would be favored. This “favoring” of a reaction means temporarily speeding up the reaction in that direction until equilibrium is reestablished. Recall that once equilibrium is reestablished, the rates of the forward and reverse reactions are again equal. The addition of NH 3 would result in increased formation of the reactants, N 2 and H 2 .
    ::如果加上更多的NH3,则反向反应会比较好。 这种反应的“有利”意味着在恢复平衡之前暂时加速该方向的反应。 回顾一旦恢复平衡,前向和反向反应的速率将再次相等。 增加NH3将导致反应者N2和H2的形成增加。

    An equilibrium can also be disrupted by the removal of one of the substances. If the concentration of a substance is decreased, the system will respond by favoring the reaction that replaces that substance. In the industrial Haber-Bosch process, NH 3 is removed from the equilibrium system as the reaction proceeds. As a result, the forward reaction is favored so that more NH 3 will be produced. The concentrations of N 2 and H 2 decrease. Continued removal of NH 3 will eventually force the reaction to go to completion until all of the reactants are used up. If either N 2 or H 2 were removed from the equilibrium system, the reverse reaction would be favored and the concentration of NH 3 would decrease.
    ::如果物质浓度下降,该系统的反应将有利于替代该物质的反应。在工业型Haber-Bosch过程中,随着反应的不断推进,NH3从平衡系统中删除。因此,前方反应将有利于产生更多的NH3。N2和H2的浓度下降。继续清除NH3将最终迫使该反应完成,直到所有反应剂使用为止。如果N2或H2被从平衡系统移除,则反向反应将有利,NH3的浓度将下降。

    The effect of changes in concentration on an equilibrium system according to Le Châtelier’s Principle is summarized in  Table .
    ::根据Le Châteier原则,集中度变化对平衡系统的影响摘要见表。

    Stress Response
    addition of reactant forward reaction favored
    addition of product reverse reaction favored
    removal of reactant reverse reaction favored
    removal of product forward reaction favored

     

     

    Summary
    ::摘要

    • The effects of concentration changes on an equilibrium are described.
      ::介绍了浓度变化对平衡的影响。

    Review
    ::回顾

    1. In the Haber process, what happens if you add more hydrogen gas?
      ::在哈伯过程中,如果你增加更多的氢气会怎么样?
    2. You miscalculate and add too little nitrogen gas. Which way will the equilibrium shift?
      ::你误算并添加了太小的氮气。 平衡会如何改变?
    3. A mislabeled tank pumps in extra ammonia. What happens to the equilibrium?
      ::额外的氨水中贴错标签的油泵 平衡会怎么样?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

     

     

     

     

     

    1. What is stress in an equilibrium reactant?
      ::平衡反应器的压力是什么?
    2. What happens if more reactants are added?
      ::如果增加更多的反应器会怎么样?
    3. What happens if you remove product?
      ::如果你删除产品会怎么样?