Section outline

  • A tarnished silver platter and pitcher next to orange flowers on a cloth.

    Why is the silver dark?
    ::为什么银色的黑暗?

    The platter and pitcher shown above provides an example of tarnish, a caused when silver metal reacts with hydrogen sulfide produced by some industrial processes or as a result of decaying animal or plant materials:
    ::上面所展示的盘子和投手是一个玷污的例子,它是由银金属与某些工业过程产生的硫化氢发生反应或由于动物或植物材料衰变造成的:

    2 Ag + H 2 S → Ag 2 S + H 2

    ::2Ag+H2SAg2S+H2

    The tarnish can be removed using a number of polishes, but the process also removes a small amount of silver along with the tarnish.
    ::利用一些抛光剂可以清除污点,但这一过程也清除了少量的银和污点。

    Single-Replacement Reactions
    ::单件更替反应

    A single-replacement reaction is a reaction in which one replaces a similar element in a . The general form of a single-replacement (also called single-displacement) reaction is:
    ::单置换反应是一种反应,在这种反应中,一种反应取代了一种反应中的类似要素。

    A + B C → A C + B

    ::A+BC-AC+B

    In this general reaction, element  A is a metal and replaces element B , also a metal, in the compound. When the element that is doing the replacing is a , it must replace another nonmetal in a compound, and the general equation becomes:
    ::在这种一般反应中,元素A是金属,在化合物中取代元素B也是金属。当进行替换的元素是 a 时,必须在化合物中替换另一个非金属,一般方程如下:

    Y + X Z → X Y + Z

    ::Y+XXY

    Y  is a nonmetal and replaces the nonmetal  Z in the compound with X .
    ::Y是非金属,以X取代化合物中的非金属Z。

    Metal Replacement
    ::金属更换

    Magnesium is a more reactive metal than copper. When a strip of magnesium metal is placed in an aqueous solution of copper(II) nitrate, it replaces the copper. The products of the reaction are aqueous magnesium nitrate and solid copper metal.
    ::镁是一种比铜更具反应性的金属,当一带镁金属被置于铜(II)硝酸盐的水溶液中时,它取代铜,反应的产品是水镁硝酸盐和固体铜金属。

    Mg ( s ) + Cu(NO 3 ) 2 ( a q ) → Mg(NO 3 ) 2 ( a q ) + Cu ( s )

    ::Mg(s)+Cu(NO3)(aq)+Cu(NO3)(aq)+Mg(NO3)(q)+Cu(s)

    This subcategory of single-replacement reactions is called a metal replacement reaction because it is a metal that is being replaced (magnesium).
    ::这一分类的单重置反应被称为金属重置反应,因为它是一种正在被替换的金属(镁)。

    Hydrogen Replacement
    ::氢更换

    Many react easily with acids and when they do so, one of the products of the reaction is hydrogen gas. Zinc reacts with hydrochloric to produce aqueous zinc chloride and hydrogen ( Figure  ).
    ::锌与盐氯化发生反应,生产水氯化锌和氢(图......)。

    Zn ( s ) + 2 HCl ( a q ) → ZnCl 2 ( a q ) + H 2 ( g )

    ::Zn+2HCl(aq) nCl2(aq) +H2(g)

    In a hydrogen replacement reaction, the hydrogen in the acid is replaced by an active metal.
    ::在氢置换反应中,酸中的氢被活性金属所取代。

    A test tube with bubbling gas, indicating a reaction, possibly hydrogen production.
    Zinc metal reacts with hydrochloric acid to give off hydrogen gas in a single-displacement reaction.

    Some metals are so reactive that they are capable of replacing the hydrogen in water. The products of such a reaction are the metal hydroxide and hydrogen gas. All group 1 metals undergo this type of reaction. Sodium reacts vigorously with water to produce aqueous sodium hydroxide and hydrogen (see Figure  ).
    ::有些金属反应性太强,以至于能够取代水中的氢,这种反应的产物是氢氧化金属和氢气,所有第1类金属都发生这种反应,钠与水产生氢氧化钠和氢(见图)。

    2 Na ( s ) + 2 H 2 O ( l ) → 2 NaOH ( a q ) + H 2 ( g )

    ::2Na(s)+2H2O(l)%2NaOH(aq)+H2(g)

    A vigorous reaction of sodium with water producing a spray of hydrogen gas.
    Sodium metal reacts vigorously with water, giving off hydrogen gas. A large piece of sodium will often generate so much heat that the hydrogen will ignite.

    Halogen Replacement
    ::卤素更换

    The element chlorine reacts with an aqueous solution of sodium bromide to produce aqueous sodium chloride and elemental bromine.
    ::元素氯与水溶解的溴钠发生反应,产生水溶氯化钠和元素溴。

    Cl 2 ( g ) + 2 NaBr ( a q ) → 2 NaCl ( a q ) + Br 2 ( l )

    ::Cl2(g)+2NaBr(aq)+2NaBr(aq)+2NaCl(aq)+Br2(l)

    The reactivity of the halogen group (group 17) decreases from top to bottom within the group. Fluorine is the most reactive halogen, while iodine is the least. Since chlorine is above bromine, it is more reactive than bromine and can replace it in a halogen replacement reaction.
    ::卤素组(第17组)的反作用性在组内从上到下下降。氟是最具反应性的卤素,而碘是最小的。由于氯高于溴,因此它比溴更具反应性,可以代之以卤素替代反应。

    Summary
    ::摘要

    • In a single-replacement reaction, one element takes the place of another similar element in a compound.
      ::在一次替换反应中,一个元素取代化合物中另一个类似元素。
    • Common types of single-replacement reactions include metal replacement, hydrogen replacement, and halogen replacement.

       


      ::常见的单一替换反应类型包括金属替换、氢替换和卤素替换。

    Review
    ::回顾

    1. What is a metal replacement reaction?
      ::什么是金属替代反应?
    2. Will a non-metal replace a metal?
      ::非金属将取代金属吗?
    3. What is the most reactive halogen?
      ::什么是最具反应性的卤素?
    4. What products will I get if I add potassium metal to water?
      ::如果我在水中添加钾金属,我能得到什么产品?