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  • General

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  • 升华

    A snowy street scene at night with a fence and snow-covered trees.

    How did the early settlers do their laundry in the winter?
    ::早期定居者在冬天怎么洗衣服?

    Of course, they could wash the clothes inside, but where to dry them?  There were no dryers available, so the clothes had to be hung up to dry.  In the winter, you would expect that ice would form on the clothes, but that didn’t happen.  Even in weather, the water might freeze initially, but would eventually go off as a vapor – from solid ice directly to the stage.  There are still families today who have to rely on this cumbersome process to get their laundry done.
    ::当然,他们可以在里面洗衣服,但在哪里干?没有烘干机,所以衣服必须挂在干燥处。 在冬天,你预期衣服上会形成冰层,但这不会发生。 即使在天气中,水起初可能冻结,但最终会像蒸气一样消失 — — 从坚固的冰层直接到舞台。 今天仍有家庭不得不依靠这个繁琐的过程来洗衣服。

    Sublimation 
    ::升华

    Vapor Pressure of a Solid
    ::固体蒸气压

    T he of a liquid  is dependent  upon temperature .  Solids also have a vapor pressure, though it is generally much less than that of a .  A snow bank will gradually disappear even if the temperature stays below 0°C.  The snow does not melt, but instead passes directly from the solid state to the vapor state.  Sublimation is the from a solid to a gas without passing through the liquid state.
    ::液体由温度决定。 固体也有蒸气压力, 虽然通常比蒸气压力低得多。 即使温度保持在0°C以下, 积雪也会逐渐消失。 积雪不会融化, 而是直接从固体状态传到蒸气状态。 升温是指从固体到气体,而不经过液体状态。

    Examples of Sublimation
    ::升华实例

    Sublimation of Iodine
    ::碘的升华

    When iodine is heated sublimation can be readily observed. Iodine's vapor is a distinctive purple color and has a very strong scent, making it easy to detect. The video below shows the sublimation and of iodine. The beaker containing iodine is covered with a watch glass that contains ice. When the iodine is heated it sublimes. When iodine vapors cool, deposition occurs. Deposition is the change of state from a gas to a solid. 
    ::当碘被加热时,可以很容易地观察到碘的升温。碘的蒸气是一种特殊的紫色,气味非常浓,很容易检测。下面的视频显示了升温和碘。含碘的油杯被一个装有冰的手表玻璃覆盖。当碘被加热时,它就会被升温。当碘蒸气冷却时,沉积就会发生。沉积是气体的状态变化。

     

     

    Dry Ice
    ::干冰

    "Dry ice," or solid carbon dioxide, is a substance that sublimes at atmospheric pressures.  Dry ice is very cold (−78°C) and so is used as a coolant for goods such as ice cream that must remain frozen during shipment.  Because the dry ice sublimes rather than , there is no liquid mess associated with its change of state as the dry ice warms as shown in Figure .
    ::“干冰 ” 或 固碳二氧化碳 , 是一种在大气压力下被淹没的物质。 干冰非常寒冷( - 78°C ) , 因而被用作冰淇淋等货物的冷却剂,而冰淇淋在装运过程中必须保持冷冻。 由于干冰的高度而非,因此,干冰的温度随干冰的温度变化而变化,并不存在液体混杂,如图所示。

    A bowl emitting vapor, illustrating the sublimation of dry ice at room temperature.
    At room temperature, solid carbon dioxide or "dry ice" will quicky sublimate back into gaseous carbon dioxide.

    Ferrocene
    ::铁石棉

    Ferrocene (an iron-containing compound) is usually purified by sublimation. A sample of  crude ferrocene is gently heated causing it to sublime. When  the ferrocene is cooled, reddish ferrocene crystals deposited on the outside of that tube as shown i n  Figure . 
    ::Ferrocene(含铁化合物)通常是通过升温净化的,一个原油铁的样本被轻轻地加热,导致其升温。

    Reddish ferrocene crystals formed on a surface after sublimation process.
    Ferrocene purified by sublimation.

     Summary
    ::摘要

    • Sublimation is the change of state from a solid to a gas without passing through the liquid state.
      ::令人赞叹的是状态从固体变成气体而不经过液体状态。
    • Deposition is the change of state from a gas to a solid.
      ::沉积是状态的改变 从气体变成固体
    • Carbon dioxide is an example of a material that easily undergoes sublimation.
      ::二氧化碳是很容易升华的材料的例子。

    Review
    ::回顾

    1. Define sublimation.
      ::定义升华。
    2. What is another name for solid  carbon dioxide?
      ::固体二氧化碳的另一个名称是什么?
    3. How is ferrocene purified?
      ::铁是如何净化的?
    4. Name a substance which undergoes sublimation.
      ::命名为可升华的物质。