章节大纲

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  • 暂停适用

    Rough waves crash against a rocky shoreline during a stormy day.

    Why is the sea clear on some days, but not on others?
    ::为什么海洋在某些日子是清澈的,而在另一些日子却不是清澈的呢?

    On a calm day, the Caribbean Sea is clear and smooth.  You can see deep into the water, deep enough to see fish and underwater plant life without obstruction.  The situation changes markedly when a storm blows up.  The sand on the bottom of the sea is stirred up, the water becomes turbid, and you can’t see anything below the surface.  The sand forms a suspension in the water that slowly clears up again after the storm blows over.
    ::在一个平静的一天,加勒比海是清澈而平滑的。 你可以看到深水深处,深水深水深水,足够看鱼和水下植物的生命不受阻碍。 当暴风雨爆发时,情况发生了显著变化。 海底的沙子被卷起,水变得混乱,而海面下看不到任何东西。 沙子在水中形成悬浮,在暴风雨过后又慢慢地从水中清除出来。

    Suspensions
    ::暂停适用

    Take a glass of water and throw in a handful of sand or dirt.  Stir it and stir it and stir it. The water may become turbid , or unclear.  Have you made a solution?  Sand and dirt do not dissolve in water and though it may look homogeneous for a few moments, the sand or dirt gradually sinks to the bottom of the glass.
    ::你取一杯水,然后把一小撮沙子或泥土扔进水里,你使沙子搅拌它,然后把它搅拌起来。水或许变成混乱的,或模糊的。你已解决了吗?沙子和泥土,在水中不会溶化,即使表面看起来一模一样,沙子或泥土也会逐渐沉入玻璃底。

    A glass showing a layer of settled sand or dirt at the bottom.

    A suspension of dirt in water.
    ::水中的泥土悬浮

    A suspension is a in which some of the particles settle out of the upon standing.  The particles in a suspension are far larger than those of a solution and thus gravity is able to pull them down out of the dispersion medium (water).  The typical diameter for the dispersed particles (the sand) of a suspension is about 1000 times greater than those of a solution (less than approximately two nanometers for particles in solution, compared to greater than 1000 nanometers for particles in suspension).  Unlike in a solution, the dispersed particles can be separated from the dispersion medium by filtering.  Suspensions are heterogeneous because at least two different substances in the mixture can be identified.
    ::悬浮是悬浮中某些粒子在站立时沉淀的状态。悬浮中的粒子远大于溶液中的粒子,因此引力能够将它们从分散介质(水)中拉下来。悬浮中散粒子(沙子)的典型直径大约是溶液的1000倍(溶液中的粒子小于2纳米,悬浮中粒子小于1 000纳米)。与溶液不同的是,散粒子可以通过过滤从分散介质中分离出来。悬浮是多种多样的,因为混合物中至少有两种不同的物质可以识别出来。

    Some Typical Aqueous Suspensions
    ::某些典型的水性暂停水体

    Milk
    ::牛奶牛奶

    Milk is a complex mixture of water, , fats, , and minerals.  While the minerals and carbohydrates are water-soluble, the fats and some of the proteins do not dissolve but are held in suspension.
    ::牛奶是水、脂肪、脂肪和矿物的复杂混合体。 虽然矿物和碳水化合物是水溶的,但脂肪和一些蛋白质不会溶解,而是被悬浮着。

    Paint
    ::绘画画画画画

    Paint can either be water-based or use an organic solvent .  For our discussion, we will limit ourselves to water-based paints.  The materials will contain binders (organic polymers that help hold the paint to the surface of the material being painted).  In addition, pigments are included to provide the desired color.  Both the binders and the pigments are not water-soluble, so the paint must be stirred every time it is used.  Paint that is allowed to sit for a long period of time will slowly begin to separate as the suspension of binders and pigments settles out.
    ::油漆可以是基于水的,也可以是使用有机溶剂。 讨论时, 我们将仅限于使用基于水的油漆。 材料中将含有粘合剂( 有机聚合物, 有助于将涂料固定在涂料表面的有机聚合物 ) 。 此外, 颜料也包含着想要的颜色。 粘合剂和颜料都不是水溶解的, 因此每次涂料使用时都必须被搅拌。 允许长时间坐坐的涂料将随着粘合剂和颜料的悬浮而慢慢分离 。

     

     

    Summary
    ::摘要

    • Suspensions are heterogeneous mixtures.
      ::悬浮物是多种混合物。
    • Some of the material in a suspension will settle out on standing.
      ::暂停执行中的一些材料将就站定下来。
    • Solid material in a suspension can be removed by filtration.
      ::悬浮中的固体材料可通过过滤清除。

    Review
    ::回顾

    1. Is a suspension a heterogeneous or a homogeneous mixture?
      ::悬浮物是异质混合物还是同质混合物?
    2. How can the solid material in a suspension be separated from the liquid?
      ::如何将悬浮中的固体材料与液体分开?
    3. Which part of milk is in suspension?
      ::牛奶的哪个部分被停产了?