Section outline

  • General

    Collapse all Expand all

  • 分离混合体

    A person holds a green pan with soil and water for gold panning.

    How did gold miners search for gold?
    ::金矿开采者如何寻找黄金?

    Beginning in the late 1840s, thousands of prospectors rushed to California to search for gold. One of the approaches taken to isolate the gold from the soil was called “panning.” Dirt would be placed in the pan and covered with water. After thorough mixing, the pan is gently swirled to remove dissolved material while the heavier gold settles to the bottom of the pan. The gold is then separated from the of soil and water.
    ::从1840年代后期开始,数千名探矿者冲到加利福尼亚寻找黄金,把黄金从土壤中分离出来的方法之一被称为“横穿” 。 泥土将放在锅里,并被水覆盖。 彻底混合后,锅被轻轻地挥动以去除溶解材料,而较重的金矿则沉入锅底,然后将黄金从土壤和水中分离出来。

    Separation of Mixtures
    ::混合体分离

    Not everyone is out searching for gold (and not many of those searchers is going to get much gold, either). In a , it is important to isolate the component(s) of interest from all the other materials so they can be further characterized. Studies of biochemical systems, environmental analysis, pharmaceutical – these and many other areas of research require reliable separation methods.
    ::并不是每个人都在寻找黄金(而且这些搜索者中也没有多少人会得到很多黄金 ) 。 在一个方面,重要的是将感兴趣的成分从所有其他材料中分离出来,这样它们才能进一步定性。 生物化学系统研究、环境分析、制药 — — 这些以及许多其他研究领域都需要可靠的分离方法。

    Here are a number of common separation techniques:
    ::以下是一些共同的分离技术:

    Chromatography
    ::色谱学

    Chromatography is the separation of a mixture by passing it in solution or suspension or as a vapor (as in chromatography) through a medium in which the components move at different rates. Thin-layer chromatography is a special type of chromatography used for separating and identifying mixtures that are or can be colored, especially pigments.
    ::色谱法是指将混合物分解成溶液或悬浮剂或通过各成分以不同速度移动的介质(如色谱法)作为蒸气(如色谱法),将混合物分解为溶液或悬浮剂或蒸发剂。

    Distillation

    ::蒸馏

    Distillation is an effective method to separate mixtures comprised of two or more pure . Distillation is a purification process where the components of a liquid mixture are vaporized and then condensed and isolated. In simple distillation, a mixture is heated and the most volatile component vaporizes at the lowest temperature . The vapor passes through a cooled tube (a condenser), where it condenses back into its liquid state. The condensate that is collected is called distillate.
    ::蒸馏是分离由两个或两个以上纯度组成的混合物的一种有效方法。蒸馏是一种净化过程,其中液态混合物的成分蒸发,然后凝固和分离。在简单蒸馏过程中,一种混合物被加热,最挥发性的成分蒸发在最低温度下。蒸汽通过冷却管(凝结器),凝结到液态中。收集的凝凝凝液称为蒸馏液。

    Distillation apparatus with components for boiling, condensing, and collecting distilled liquid.
    Distillation apparatus.

    In  Figure , we see several important pieces of equipment. There is a source, a test tube with a one-hole stopper attached to a glass elbow and rubber tubing. The rubber tubing is placed into a collection tube which is submerged in cold water. There are other more complicated assemblies for distillation that can also be used, especially to separate mixtures, which are comprised of pure liquids with boiling points that are close to one another.
    ::在图中,我们看到了几个重要的设备。有一个源,一个带有玻璃肘和橡胶管的单孔塞具的试验管;橡胶管被放在一个浸在冷水中的收集管中;还有其他一些更复杂的蒸馏组件,也可以用来分离,特别是用来分离混合物,这些混合物由纯液体组成,其沸点相互接近。

    Evaporation
    ::蒸发

    is a technique used to separate out homogenous mixtures where there is one or more dissolved solids. This method drives off the liquid components from the solid components. The process typically involves heating the mixture until no more liquid remains, Prior to using this method, the mixture should only contain one liquid component, unless it is not important to isolate the liquid components. This is because all liquid components will evaporate over time. This method is suitable to separate a soluble solid from a liquid.
    ::是一种在存在一种或多种溶解固体的情况下用来分离同质混合物的技术。这种方法将液体成分从固体成分中分离出来。这一过程通常涉及加热混合物直至不再有液体残留,在使用这种方法之前,混合物只应包含一个液体成分,除非分离液体成分不重要。这是因为所有液体成分会随着时间的流逝而蒸发。这种方法适合于将可溶解的固体从液体中分离出来。

    In many parts of the world, table salt is obtained from the evaporation of sea water. The heat for the process comes from the sun.
    ::在世界许多地方,食盐来自海水蒸发,过程的热量来自太阳。

    Evaporation ponds for salt extraction with pools of water and salt mounds around.
    Once the sea water in these evaporation ponds has evaporated, the salt can be harvested.

    Filtration
    ::过滤

    Filtration is a separation method used to separate out pure substances in mixtures comprised of particles some of which are large enough in size to be captured with a porous material. Particle size can vary considerably, given the type of mixture. For instance, stream water is a mixture that contains naturally occurring biological organisms like bacteria, viruses, and protozoans. Some water filters can filter out bacteria, the length of which is on the order of 1 micron. Other mixtures, like soil, have relatively large particle sizes, which can be filtered through something like a coffee filter.
    ::过滤是一种分离方法,用来分离由粒子组成的纯物质,其中某些颗粒体积足够大,足以用多孔材料捕获。鉴于混合物的类型,粒子体积可能有很大差异。例如,溪流水是一种混合物,含有细菌、病毒和原生动物等自然产生的生物生物有机体。有些水过滤器可以过滤细菌,其长度大约为1微米。其他混合物,如土壤,其颗粒体积相对较大,可以通过咖啡过滤器过滤。

    Filtration process showing movement of particles through a porous material.
    Filtration.

      

     

     

     

    Summary
    ::摘要

    • Mixtures can be separated using a variety of techniques.
      ::混合体可以使用多种技术进行分离。
    • Chromatography involves solvent separation on a solid medium.
      ::色谱法涉及溶剂在固体介质上分离。
    • Distillation takes advantage of differences in boiling points.
      ::蒸馏利用沸点的差异。
    • Evaporation removes a liquid from a solution to leave a solid material.
      ::蒸发将液体从溶液中除去,留下固体物质。
    • Filtration separates solids of different sizes.
      ::过滤法将不同大小的固体分开。

    Review
    ::回顾

    1. Why is it important to separate materials from a mixture?
      ::为什么必须将材料与混合物分开?
    2. What is chromatography?
      ::什么是色谱学?
    3. What is distillation
      ::什么是蒸馏
    4. What is filtration?
      ::什么是过滤?
    5. What is evaporation?
      ::什么是蒸发?
    6. What technique would you use to separate sand from water? There are two possibilities.
      ::你用什么方法把沙子和水分开?
    7. What technique would you use to separate alcohol from water?
      ::你用什么方法把酒精和水分开?