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  • General

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  • 化学反应中的能源

    Slow Burn
    ::慢烧慢

    These old iron chains give off a small amount of heat as they rust. The rusting of iron is a chemical process. It occurs when iron and oxygen go through a chemical reaction similar to burning, or combustion. Obviously, the chemical reaction that occurs when something burns gives off energy . You can feel the heat, and you may be able to see the light of flames. The rusting of iron is a much slower process, but it still gives off energy. It's just that it releases energy so slowly that you can't detect a change in temperature.
    ::这些旧铁链生锈时会释放少量的热量。 铁的生锈是一种化学过程。 当铁和氧经过类似于燃烧或燃烧的化学反应时, 就会发生。 显然, 当某物燃烧时产生的化学反应会释放出能量。 你可以感觉到热量, 你可以看到火焰的光。 铁的生锈过程会慢得多, 但是它会释放出能量。 只是它释放出能量的速度太慢, 你无法察觉温度的变化。

    The Role of Energy in Chemical Reactions
    ::能源在化学反应中的作用

    Matter rusting or burning are common examples of chemical changes. Chemical changes involve chemical reactions, in which some substances, called reactants , change at the molecular level to form new substances, which are called products. All chemical reactions involve energy, but not all chemical reactions release energy, like rusting and burning . In some chemical reactions, energy is absorbed rather than released.
    ::化学变化涉及化学反应,在化学反应中,某些物质,称为反应剂,在分子一级变化形成新的物质,即所谓的产品。所有化学反应都涉及能源,但并非所有化学反应释放能量,如生锈和燃烧。在某些化学反应中,能量被吸收而不是释放。

    Exothermic Reactions
    ::异热反应

    A chemical reaction that releases energy is called an exothermic reaction . This type of reaction can be represented with this  general chemical equation :
    ::释放能量的化学反应称为异温反应。

    Reactants → Products + Heat
    ::反应剂 + 产品+热

    Another example of an exothermic reaction is  chlorine combining with sodium to form table salt. The decomposition of organic matter also releases energy because of exothermic reactions. Sometimes on a chilly morning, you can see steam rising from a compost pile because of these chemical reactions (see photo ).
    ::一种异热反应的另一个例子是氯与钠结合形成食盐。 有机物的分解也因为过热反应而释放出能量。 有时在寒冷的清晨,你可以看到堆肥堆的蒸汽因这些化学反应而上升(见照片 ) 。

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    This compost pile is steaming because it is much warmer than the chilly air around it. The heat comes from all the exothermic chemical reactions taking place inside the compost as it decomposes.
    ::堆肥堆积在蒸汽中,因为它比周围的寒冷空气更温暖。 热来自堆肥腐烂时在堆肥中发生的所有异热化学反应。

    Exothermic chemical reactions also take place in the of living things. In a chemical process called , which is  similar to combustion, the sugar glucose is "burned" to provide cells with energy.
    ::活物中也发生异热化学反应。 在一种称为“燃烧”的化学工艺中,甘蔗糖“燃烧”为细胞提供能量。

    Endothermic Reactions
    ::内热反应

    A chemical reaction that absorbs energy is called an endothermic reaction . This type of reaction can also be represented by a general chemical equation:
    ::吸收能量的化学反应称为内温反应。这种反应也可以用一般化学方程式表示:

    Reactants + Heat → Products
    ::活性剂 +热 + 热 + 产品

    Did you ever use a chemical cold pack like the one in the picture ? The pack cools down because of an endothermic reaction. When a tube inside the pack is broken, it releases a chemical that reacts with inside the pack. This reaction absorbs heat energy and quickly cools down the contents of the pack.
    ::你曾经使用过像照片中那样的化学冷却包吗?包会因为内温反应而冷却下来。当包内的一个管破裂时,它释放出一种与包内反应的化学物质。这种反应吸收了热能,并很快冷却了包内的内容。

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    This pack gets cold because of an endothermic reaction.
    ::这群人因为内热反应而变冷

    Many other chemical processes involve endothermic reactions. Most cooking and baking, for example, involves the use of energy to produce chemical reactions. You can't bake a cake or cook an egg without adding heat energy.
    ::许多其他化学过程都涉及通热反应。例如,大多数烹饪和烘烤都涉及利用能源产生化学反应。你不能在不增加热能的情况下烤蛋糕或煮鸡蛋。

    Arguably, the most important endothermic reactions occur during . When plants produce sugar by photosynthesis, they take in light energy to power the necessary endothermic reactions. The sugar they produce provides plants and virtually all other living things with glucose for cellular respiration.
    ::可以说,最重要的内温反应发生在当植物用光合作用制糖时。当植物用光合作用制糖时,它们会吸收光能来驱动必要的内温反应。它们生产的糖能提供植物和几乎所有其他生物的甘糖,用于细胞呼吸。

    Activation Energy
    ::能源

    All chemical reactions require  energy to get started. Even reactions that release energy need a boost of energy in order to begin. The energy needed to start a chemical reaction is called activation energy . Activation energy is like the push a child needs to start going down a playground slide. The push gives the child enough energy to start moving, but once she starts, she keeps moving without being pushed again. Activation energy is illustrated in the graph .
    ::所有化学反应都需要能量才能启动。即使是释放能量的响应也需要能量来启动。启动化学反应所需的能量也称为激活能量。激活能量就像一个孩子需要从游乐场滑动的推力。推力让孩子有足够的能量开始运动,但一旦她开始,她就会不停地移动,不再被推动。振动能量在图表中显示。

    Activation Energy. Activation energy provides the “push” needed to start a chemical reaction. Is the chemical reaction in this figure an exothermic or endothermic reaction?
    ::激活能源。 激活能源提供了启动化学反应所需的“推进 ” 。 这个数字中的化学反应是异热反应还是局部热反应?

    Why do all chemical reactions need energy to get started? In order for reactions to begin, reactant molecules must bump into each other, so they must be moving — and movement requires energy. When reactant molecules bump together, they may repel each other because of intermolecular forces pushing them apart. Energy is also required to overcome these forces so the molecules can come together and react.
    ::为什么所有化学反应都需要能量才能启动?为了开始反应,反应分子必须相互碰撞,因此它们必须移动,而移动需要能量。 当反应分子聚集在一起时,它们可能会因为分子的间歇力而互相排斥。 还需要能量来克服这些力量,以便分子能够聚集起来作出反应。

    Summary
    ::摘要

    • All chemical reactions involve energy. Exothermic reactions release energy. Endothermic reactions absorb energy.
      ::所有化学反应都与能量有关 异热反应释放能量 异热反应吸收能量
    • All chemical reactions need activation energy to begin. Activation energy provides the "push" needed to get the reaction started.
      ::所有化学反应都需要启动能量才能启动。 激活能量提供了启动反应所需的“ 推进 ” 。

    Review
    ::回顾

    1. Compare  endothermic and exothermic chemical reactions. Give an example of a process that involves each type of reaction.
    ::1. 比较异温和异温化学反应:举一个例子说明每种反应都涉及的过程。

    2. Define activation energy.
    ::2. 界定激活能量。

    3. Explain why all chemical reactions require activation energy.
    ::3. 解释为什么所有化学反应都需要激活能量。

    4. Heat is a form of ____________ .
    ::4. 热量是一种形式________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

    5. In which type of reaction is heat added to the reactants?
    ::5. 反应者在何种反应中增加热量?

    6. In which type of reaction is heat produced?
    ::6. 产生何种热能反应?

    a. If there was no energy added to an endothermic reaction, would that reaction occur? Why or why not?
    :sada) 如果除热反应没有增加能量,这种反应会发生吗?为什么或为什么没有?

    b. If there was no energy added to an exothermic reaction, would that reaction occur? Why or why not?
    ::b. 如果非热反应没有增加能量,这种反应会发生吗?为什么或为什么没有?

     

    7. Explain why a chemical cold pack feels cold when activated.
    ::7. 解释为什么化学冷却包在激活时感到冷。

     

    8. Explain why cellular respiration and photosynthesis are “opposites” of each other.
    ::8. 解释为什么细胞呼吸和光合作用是彼此的 " 反对者 " 。

     

    9. Explain how the sun gives our cells energy indirectly.
    ::9. 解释太阳如何间接地给我们的细胞能量。

    Explore More
    ::探索更多

    Watch the video below to learn more about activation energy.
    ::观看下面的视频,以了解更多关于激活能量的知识。

     

    The video below explains  an experiment you can try at home that  demonstrates an exothermic reaction.
    ::下面的影片解释一个实验, 你可以在家里尝试, 展示一种异热反应。