章节大纲

  • 常规

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  • 保护质量法

    Various metallic screws and nuts scattered on a flat surface.

    Have you ever lost a screw?
    ::你曾经失去过螺丝吗?

    The following situation happens all too often.  You have taken apart a piece of equipment to clean it up. When you put the equipment back together, somehow you have an extra screw or two.  Or you find out that a screw is missing that was a part of the original equipment.  In either case, you know something is wrong.  You expect to end up with the same amount of material that you started with, not with more or less than what you had originally.
    ::以下情况经常发生。 你拆掉了一个设备来清理它。 当你把设备重新组装起来, 你就会发现一个或两个额外的螺丝。 或者你发现一个螺丝丢失了, 这是原始设备的一部分。 无论哪种情况, 你都会知道有问题。 你期望最终得到与你最初一样多的材料, 而不是比原来少的东西。

    Law of Conservation of Mass
    ::保护质量法

    By the late 1700s, chemists accepted the definition of an as a substance that cannot be broken down into a simpler substance by ordinary chemical means.  It was also clear that elements combine with one another to form more complex substances called compounds.  The chemical and of these compounds are different than the properties of the elements from which they were formed.  There were questions about the details of these processes.
    ::到1700年代后期,化学家们接受了一种物质的定义,这种物质不能通过普通化学手段细分成一种较简单的物质,还清楚的是,各种元素相互结合形成更复杂的物质,称为化合物,化学和这些化合物的特性不同于形成这些物质的元素的特性,对这些工艺的细节有疑问。

    In the 1790s, a greater emphasis began to be placed on the quantitative analysis of .  Accurate and reproducible measurements of the masses of reacting elements and the compounds they form led to the formulation of several basic laws .  One of these is called the law of , which states that during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants .  In other words, mass cannot be created or destroyed during a chemical reaction, but is always conserved.
    ::在1790年代,人们开始更加强调量化分析。精确和可复制地测量反应元素和化合物的质量导致制定若干基本法律,其中一项法律称为化学反应法,规定在化学反应中,产品的总质量必须与反应剂的总质量相等。 换言之,在化学反应中无法制造或销毁质量,但总是得到保存。

    As an example, consider the reaction between silver nitrate and sodium chloride.  These two compounds will dissolve in water to form silver chloride and sodium nitrate.  The silver chloride does not dissolve in water, so it forms a solid that we can filter off.  When we evaporate the water, we can recover the sodium nitrate formed.  If we react 58.5 grams of sodium chloride with 169.9 grams of silver nitrate, we start with 228.4 grams of materials.  After the reaction is complete and the materials separated, we find that we have formed 143.4 grams of silver chloride and 85.0 grams of sodium nitrate, giving us a total mass of 228.4 grams for the products.  So, the total mass of reactants equals the total mass of products, a proof of the law of conservation of mass.
    ::例如,考虑一下硝酸银和氯化钠的反应。这两种化合物将在水中溶解,形成氯化银和硝酸钠。氯化银不会溶解在水中,从而形成一个我们可以过滤的固体。当我们蒸发水时,我们可以回收形成的硝酸钠。如果我们用169.9克硝酸盐对58.5克氯化钠作出反应,我们从228.4克物质开始。在反应完成和材料分离之后,我们发现我们已经形成了143.4克氯化银和85.0克硝酸钠,使我们的产品总质量达到228.4克。因此,反应剂的总质量等于产品的总质量,证明保护质量的法律。

     

    Summary 
    ::摘要

    • The law of conservation of mass states that, during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants.
      ::质量保护法规定,在化学反应期间,产品的总质量必须等于反应物的总质量。

    Review
    ::回顾

    1. The law of conservation of mass states that, during a chemical reaction, the total ______ of the products must be equal to the total ______ of the reactants.
      ::保护质量法规定,在化学反应过程中,产品总量必须等于反应器总量。
    2. Describe an example of the law of conservation of mass.
      ::说明保护质量法的例子。