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  • 酸和碱基

    Danger! Battery Acid!
    ::危险 电池酸

    You probably know that car batteries contain dangerous chemicals, including  strong acids. Strong acids can hurt you if they come into contact with your skin or . Therefore, it may surprise you to learn that your life depends on acids. There are many acids inside your body, and some of them are as strong as battery acid. Acids are needed for  digestion and some forms of energy production. Genes are made of , of amino acids , and of fatty acids .
    ::你可能知道汽车电池中含有危险化学物质,包括强酸。强酸会伤害你,如果它们接触你的皮肤或。因此,你可能会惊讶地知道,你的生命依赖于酸。身体里有很多酸,有些酸和电池酸一样强。消化和某些能源生产形式需要酸。基因是由氨基酸和脂肪酸制成的。

    Water and Solutions
    ::水与解决方案委员会

    Acids (such as battery acid) are solutions. A solution is a mixture of two or more substances that has the same composition throughout. Many solutions are a mixture of and some other substance. Not all solutions are acids. Some are bases and some are neither acids nor bases. To understand acids and bases, you need to know more about pure water.
    ::酸( 如电池酸 ) 是溶液 。 溶液是由两种或两种以上物质组成的混合物, 其成分自始至终相同 。 许多溶液是同一种物质混合的, 还有一些其他物质。 不是所有溶液都是酸 。 有些是碱, 有些不是酸或碱。 要理解酸和碱, 您需要了解更多关于纯水的知识 。

    In pure water (such as distilled water), a tiny fraction of water molecules naturally breaks down to form ions . An ion is an electrically charged atom or molecule. The breakdown of water is represented by the chemical equation :
    ::在纯水(如蒸馏水)中,水分子的一小部分自然分解成形离子。离子是一种电载原子或分子。水分分解由化学方程式表示:

    2 H 2 O → H 3 O + + OH -
    ::2 H2O H3O+ + OH-

    The products of this reaction are a hydronium ion (H 3 O + ) and a hydroxide ion (OH - ). The hydroxide ion, which has a negative charge, forms when a water molecule gives up a positively charged hydrogen ion (H + ). The hydronium ion, which has a positive charge, forms when another water molecule accepts the hydrogen ion.
    ::这种反应的产物是氢离子(H3O+)和氢氧化离子(OH-),具有负电荷的氢氧化离子在水分子放弃正电氢离子(H+)时形成。氢离子具有正电荷,在水分子接受氢离子时形成。

    Acidity and pH
    ::酸性和pH值

    The concentration of hydronium ions in a solution is known as acidity. In pure water, the concentration of hydronium ions is very low; only about one in ten million water molecules naturally breaks down to form a hydronium ion. As a result, pure water is essentially neutral. Acidity is measured on a scale called pH , as shown in the figure . Pure water has a pH of 7, so the point of neutrality on the pH scale is 7.
    ::溶液中氢离子的浓度被称为酸性。在纯水中,氢离子的浓度非常低;每1,000万个水分子中只有1个自然分解,形成氢离子。因此,纯水基本上是中性的。如图所示,酸性测量尺度称为pH。纯水的pH值为7,因此pH值的中性点为7。

    lesson content

    This pH scale shows the acidity of many common substances. The lower the pH value, the more acidic a substance is.
    ::此 pH 比例表显示许多常见物质的酸度。 pH 值越低, 物质酸度越高 。

    Acids
    ::酸酸

    If a solution has a higher concentration of hydronium ions than pure water, it has a pH lower than 7. A solution with a pH lower than 7 is called an acid . As the hydronium ion concentration increases, the pH value decreases. Therefore, the more acidic a solution is, the lower its pH value is.
    ::如果溶液的氢离子浓度高于纯水,则其pH值低于7, 则pH值低于7。pH值低于7的溶液称为酸。随着氢离子浓度的增加,pH值下降。因此,酸性越大,其pH值就越低。

    Did you ever taste vinegar? Like other acids, it tastes sour. Stronger acids can be harmful to organisms . Even s tomach acid would eat through the stomach if it were not lined with a layer of mucus . Strong acids can also damage materials, even hard materials such as glass.
    ::你尝过醋吗?尝过醋吗?与其他酸一样,酸味很酸。强酸可能对生物有害。即使胃酸不与一层粘结,也会通过胃部吃。强酸也会损害物质,甚至玻璃等硬材料。

    Bases
    ::基底

    If a solution has a lower concentration of hydronium ions than pure water, it has a pH higher than 7. A solution with a pH higher than 7 is called a base . Bases, such as baking soda, have a bitter taste. Like strong acids, strong bases can harm organisms and damage materials. For example, lye can burn the skin, and bleach can remove the color from clothing.
    ::如果溶液的氢离子浓度低于纯水,则其pH值高于7.7, 其pH值高于7的溶液被称为基底。 碱基,如烘制苏打,具有苦味。 像强酸一样,强基会伤害生物和破坏物质。 比如,碱能烧伤皮肤,漂白能去除衣着的颜色。

    Acids, Bases, and Enzymes
    ::酸、碱和酶

    Many acids and bases in living things provide the pH that need. Enzymes are biological catalysts that must work effectively for to occur. Most enzymes can do their job only at a certain level of acidity.  secrete acids and bases to maintain the proper pH for enzymes to do their work.
    ::许多酸和生物物质中的基底提供所需的pH值。 酶是必须有效发挥作用才能发生的生物催化剂。 大部分酶只能在一定的酸度上工作。 秘密酸和基数可以维持适当的pH值,使酶能够工作。

    Every time you digest food , acids and bases are at work in your . Consider the enzyme pepsin , which helps break down proteins in the stomach. Pepsin needs an acidic environment to do its job. The stomach secretes a  strong acid called hydrochloric acid that allows pepsin to work. When stomach contents enter the , the acid must be neutralized, because enzymes in the small intestine need a basic environment in order to work. An organ called the pancreas secretes a base named bicarbonate into the small intestine, and this base neutralizes the acid.
    ::每次你消化食物、酸和碱在工作的时候,都会在你的胃里工作。 想想酶激素, 它能帮助胃部分解蛋白质。 Pepsin需要一种酸性的环境来做它的工作。 胃里分泌一种强酸, 叫做盐酸, 使酸能够工作。 当胃内的东西进入的时候, 酸必须中和, 因为小肠中的酶需要一个基本的环境才能工作。 一种叫做胰腺分泌的器官在小肠里有一个叫做双碳酸的基体, 而这个基体可以消除酸性。

    Feature: My Human Body
    ::特质:我的人体

    Do you ever have heartburn ? The answer is probably "yes." More than 60 million Americans have heartburn at least once a month, and more than 15 million suffer from it on a daily basis. Knowing more about heartburn may help you prevent it or know when it's time to seek medical treatment.
    ::你曾经有过心脏灼伤吗?答案可能是“是的 ” 。 超过6000万美国人每月至少有一次心脏灼伤,超过1500万美国人每天遭受心脏灼伤。 更多了解心脏灼伤可能会帮助你预防,或者知道何时该寻求医疗治疗。

    Heartburn doesn't have anything to do with the heart, but it does cause a burning sensation in the vicinity of the chest. Normally, the acid secreted into the stomach remains in the stomach where it is needed to allow pepsin to do its job of digesting proteins. A long tube called the esophagus carries food from the mouth to the stomach. A sphincter, or valve, between the esophagus and stomach opens to allow swallowed food to enter the stomach and then closes to prevent stomach contents from backflowing into the esophagus. If this sphincter is weak or relaxes inappropriately, stomach contents flow into the esophagus. Because stomach contents are usually acidic, this causes the burning sensation known as heartburn. People who are prone to heartburn and suffer from it often may be diagnosed with GERD, which stands for gastroesophageal reflux disease.
    ::心脏烧伤与心脏没有任何关系,但它确实在胸部附近引起一种燃烧的感觉。 通常, 腹部的酸性被刺入胃部, 以便让Pepsin消化蛋白质。 一个叫食道的长管将食物从嘴到腹部。 食道与胃之间的一个螺旋或阀门, 允许吞咽的食物进入胃部, 然后关闭以防止胃内的东西回流到食道中。 如果这个螺丝变弱或不适当地放松, 胃内的东西会流入食道。 因为胃内的东西通常是酸性的, 导致烧灼伤的味道。 容易心痛并因此受苦的人可能会被GERD诊断为胃外科复发病患者。

    GERD — as well as occasional heartburn — often can be improved by dietary and other lifestyle changes that decrease the amount and acidity of reflux from the stomach into the esophagus.
    ::改变饮食和其他生活方式,减少胃部回流到食道的数量和酸性,往往可以改善GERRD,以及偶尔的心痛。

    • Some foods and beverages seem to contribute to GERD, so these should be avoided. Problematic foods include  chocolate, fatty foods, peppermint, coffee, and alcoholic beverages.
      ::有些食品和饮料似乎对GERD有所贡献,因此应该避免。 问题食品包括巧克力、脂肪食品、薄荷、咖啡和酒精饮料。
    • Decreasing portion size and eating the last meal of the day at least a couple of hours before bedtime may reduce the risk of reflux occurring.
      ::床前至少两小时,即减少部分尺寸和吃一天最后一顿饭,可以降低回流风险。
    • Smoking tends to weaken the lower esophageal sphincter, so quitting the habit may help control reflux.
      ::吸烟往往会削弱下低食道螺旋藻, 所以戒掉这个习惯可能有助于控制回流。
    • GERD is often associated with being overweight. Losing weight often brings improvement.
      ::GERRD常常与超重有关,减重往往带来改善。
    • Some people are helped by sleeping with the head of the bed elevated. This allows gravity to help control the backflow of acids into the esophagus from the stomach.
      ::一些人得到帮助,与床头一起睡觉。这使得重力能够帮助控制酸从胃部回流到食道。

    If you have frequent heartburn and lifestyle changes don't help, you may need medication to control the condition.  Over-the-counter (OTC) antacids may be all that you need to control the occasional heartburn attack. OTC medications are usually bases that neutralize stomach acids. They may also create bubbles (see photo ) that help block stomach contents from entering the esophagus. For some people, OTC medications are not enough, and prescription medications are instead required for the control of GERD. These prescription medications generally work by inhibiting acid secretion in the stomach.
    ::如果你经常心脏灼伤,生活方式的改变没有帮助,你可能需要药物来控制病情。要控制偶尔的心脏病发作,可能只需要场外麻醉药。 OTC 药物通常是消化胃酸的基础。它们还可能造成泡泡(见照片),帮助阻断胃部内的东西进入食道。对有些人来说,OTC 药物不够,而GERD则需要处方药物来控制。这些处方药物通常通过抑制胃酸分泌而起作用。

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    Onboard the international space station, NASA astronaut Terry Virts demonstrates how an antacid and water create bubbles as they react. Bubbling of antacids in the stomach may help keep stomach contents from backflowing into the esophagus.
    ::在国际空间站上,美国航天局宇航员Terry Virts(NASA)展示了一种抗酸和水在反应时是如何产生泡沫的。 胃部的抗酸性喷雾可能有助于防止胃内的东西回流到食道。

    Be sure to see a doctor if you can't control your heartburn, or you have it often. Untreated GERD not only interferes with quality of life, it may also lead to more serious complications, ranging from esophageal bleeding to esophageal .
    ::若无法控制心痛或经常有,请务必看医生。 未经治疗的GERD不仅会干扰生活质量,还可能导致更严重的并发症,从食道出血到食道出血。

    Summary
    ::摘要

    • A solution is a mixture of two or more substances that has the same composition throughout. Many solutions consist of water and one or more dissolved substances.
      ::一种溶液是由两个或两个以上物质混合而成,其成分自始至终相同,许多溶液由水和一种或多种溶解物质组成。
    • Acidity is a measure of the hydronium ion concentration in a solution. Pure water has a very low concentration and a pH of 7, which is the point of neutrality on the pH scale.
      ::酸度是一种溶液中氢离子浓度的测量标准,纯水浓度非常低,pH值为7,这是pH值的中点。
    • Acids have a higher hydronium ion concentration than pure water and a pH lower than 7. Bases have a lower hydronium ion concentration than pure water and a pH higher than 7.
      ::酸的氢离子浓缩度高于纯水,pH值低于7;基底的氢离子浓缩度低于纯水,pH值高于7。
    • Many acids and bases in living things are secreted to provide the proper pH for enzymes to work properly. Enzymes are the biological catalysts (like pepsin) needed to digest protein in the stomach. Pepsin  requires an acidic environment.
      ::许多活性物质中的酸和基底被秘密保存,以便为酶正常工作提供适当的pH值。 酶是消化胃蛋白所需的生物催化剂(如pepsin ) 。 Pepsin 需要一种酸性环境。

    Review
    ::回顾

    1. What is a solution?
    ::1. 什么是解决办法?

    2. Define acidity.
    ::2. 确定酸度。

    3. Explain how acidity is measured.
    ::3. 解释如何测量酸度。

    4. Compare and contrast acids and bases.
    ::4. 比较和对比酸和碱。

    5. Hydrochloric acid is secreted by the stomach to provide an acidic environment for the enzyme pepsin. What is the pH of this acid? How strong of an acid is it compared with other acids?
    ::5. 胃中隐藏了盐酸,以便为酶丙辛提供一个酸环境。这种酸的pH值是多少?与其他酸相比,一种酸的强度是多少?

    6. True or False:  Unlike strong acids, strong bases are gentle and cannot hurt you.
    ::6. 真实或假:与强酸不同,强基温和,不能伤害你。

    7. True or False:  The lower the pH, the higher the concentration of hydronium ions.
    ::7. 真实或假:pH值越低,氢离子浓度越高。

    8. Define an ion. Identify the ions in the equation below, and explain  what makes them ions:
    ::8. 定义离子。在以下方程式中标明离子,并解释这些离子是什么:

    2 H 2 O → H 3 O +  + OH -
    ::2 H2O H3O+ + OH-

     

    9. Explain why the pancreas secretes bicarbonate into the small intestine.
    ::9. 解释为什么胰腺将碳酸双碳酸盐分解到小肠中。

     

    10. Do you think pepsin would work in the small intestine? Why or why not?
    ::10. 你觉得pepsin在小肠子里有用吗?为什么不行?

     

    11. The pH of the stomach is _________ the small intestine.
    ::11. 胃的pH值是小肠。

    a. the same as
    ::a 与

    b. not as important as the pH of
    ::b. 不如pH值或pH值重要。

    c. higher than
    ::c 高于

    d. lower than
    ::d 低于

     

    12.  You may have mixed vinegar and baking soda and noticed that they bubble and react with each other. Explain why this happens. Explain also what happens to the pH of this solution after you mix the vinegar and baking soda.
    ::12. 你可能有混合醋和烘制苏打水,注意到它们相互泡泡和反应,解释为什么会发生这种情况,并解释在把醋和烘制苏打水混合之后,这个溶液的pH会发生什么。

     

    13. Pregnancy hormones can cause the lower esophageal sphincter to relax. What effect do you think this has on pregnant women? Explain your answer.
    ::13. 妊娠荷尔蒙可以使低食道螺旋藻放松,你认为这对孕妇有什么影响?解释你的答复。

    Explore More
    ::探索更多

    Watch the video below to learn more about acids, bases, and pH.
    ::观看下面的视频, 以了解更多有关酸、碱和pH值。

     The video below discusses the importance of maintaining a stable pH  in the body.
    ::以下影片讨论了保持身体pH值稳定的重要性。