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  • 化学特性和化学反应

    A black bicycle leaning against a door, showcasing potential rust areas.

    Have you ever left your bicycle out in the rain?
    ::你有没有把自行车忘在雨里过?

    It’s not a good idea because the bicycle can soon begin to rust. You start to get a reddish-orange build-up of a rough deposit on the metal . It may start with the chain, but can spread to other parts of the bicycle, especially if there are scratches that create a bare metal surface. The formation of rust is a chemical process that takes place when iron is exposed to water and oxygen. It is estimated that damage due to rust costs U.S. businesses, military, and government over 276 billion dollars a year - a very expensive chemical process.
    ::这不是一个好主意,因为自行车很快会开始生锈。 你开始在金属上堆积粗金刚石。 它可能从链条开始,但可以扩散到自行车的其他部分,特别是如果有刮痕形成一个赤裸的金属表面。 生锈的形成是一个化学过程,当铁接触水和氧时就会发生。 据估计,由于生锈造成的破坏每年花费超过7,600亿美元的美国企业、军方和政府 — — 一个非常昂贵的化学过程。

    Chemical Properties
    ::化学化学属性

    A chemical property describes the ability of a substance to undergo a specific . A chemical property of iron is that it is capable of combining with oxygen to form iron oxide, the chemical name of rust. The more general term for rusting and other similar processes is . Other terms that are commonly used in descriptions of chemical changes are burn, rot, explode, decompose, and ferment.  Chemical properties are very useful in identifying substances. However, unlike , chemical properties can only be observed as the substance is in the process of being changed into a different substance.
    ::一种化学属性描述一种物质具有某种特定的能力。铁的化学属性是,它能够与氧气结合形成氧化铁,即生锈的化学名称。生锈和其他类似工艺的更一般的术语是 。在描述化学变化时通常使用的其他术语是燃烧、腐烂、爆炸、分解和发酵。化学属性在识别物质方面非常有用。但是,与化学特性不同的是,化学特性只有在该物质正在改变为另一种物质时才能观察到。

    Chemical Change
    ::化学化学变化

    A chemical change is also called a . A chemical reaction is a process that occurs when one or more substances are changed into one or more new substances. Zinc (Zn) is a silver gray that can be ground into a powder. If zinc is mixed at room temperature with powdered sulfur (S), a bright yellow element, the result will simply be a of zinc and sulfur. No chemical reaction occurs. However, if energy is provided to the mixture in the form of , the zinc will chemically react with the sulfur to form the zinc sulfide (ZnS).  The figure below shows the substances involved in this reaction.
    ::化学反应是指一种或多种物质变成一种或多种新物质的过程。锌(Zn)是一种银灰色,可以是粉状的灰色。如果锌在室温中与粉状硫(S)混合,则其结果只是锌和硫,不发生化学反应。但是,如果以...的形式向混合物提供能量,锌将与硫化物进行化学反应,形成锌硫化锌(ZnS)。下图显示了这种反应所涉及的物质。

    Zinc, sulfur, and zinc sulfide compound samples in individual sections.

    Zinc and sulfur are two elements that undergo a chemical reaction when heated to from the compound zinc sulfide.
    ::锌和硫是从硫化锌化合物加热到硫化锌化合物时发生化学反应的两个元素。

    A lkaline are highly reactive with water.  Watch the video to see what happens when different alkaline metals are exposed to water.
    ::Alkaline对水反应性很强。 观看视频看看不同碱性金属接触水时会发生什么。

     

     

    Summary
    ::摘要

    • A chemical property describes the ability of a substance to undergo a specific chemical change.
      ::化学属性描述物质进行特定化学变化的能力。
    • A chemical reaction is a process that occurs when one or more substances are changed into one or more new substances.
      ::化学反应是指一种或多种物质被改变为一种或多种新物质时发生的过程。

    Review
    ::回顾

    1. What is a chemical property?
      ::什么是化学财产?
    2. What is a chemical reaction?
      ::什么是化学反应?
    3. When can we observe a chemical property?
      ::我们什么时候能观察化学物质?
    4. Is freezing water a chemical property?
      ::冻结水是化学财产吗?