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  • 化学风化

    A dog sitting on rocky terrain under a clear blue sky at South Mountain Park.
     

    Why is the rock different colors on the surface and in the interior?
    ::为什么岩石表面和内部的颜色不同?

    This   is at South  Mountain  Park, near Phoenix, Arizona in the southwestern United States. The  climate  is often hot and arid. What colors are the rock in this photo? What color is the surface of the rock? What color is the interior? Why do you think there are differences in color between the surface and the interior of this rock? How is chemical weathering altering the  landscape ?
    ::这是在美国西南部亚利桑那州亚利桑那州菲尼克斯附近的南山公园。气候往往是炎热和干旱的。 这张照片中的岩石是什么颜色? 岩石表面是什么颜色? 岩石表面是什么颜色? 内地是什么颜色? 为什么你认为这块岩石表面和内地的颜色不同? 化学天气如何改变地貌?

    Chemical Weathering
    ::化学天气预报

    Chemical weathering  is different than  . The   in the rock change their chemical makeup. They become a different type of mineral or even a different type of rock. Chemical weathering works through chemical reactions that change the rock.
    ::化学天气与化学天气不同。岩石中的化学构成会改变。它们会变成一种不同的矿物质,甚至会变成另一种类型的岩石。化学天气通过改变岩石的化学反应来改变岩石。

    No Longer Stable
    ::无更长的稳定

    Most minerals form deep within Earth's  crust . At these depths, temperatures and pressures are much higher than at the surface. Minerals that were  stable  deeper in the crust are not stable under surface conditions. That’s why chemical weathering happens. Minerals that formed at higher   and pressure change into minerals that are stable at the surface.
    ::大部分矿物质在地壳深处形成。在这些深度上,温度和压力比地表高得多。 在地表条件下,地壳中稳定的矿物质在地表条件下不稳定。这就是化学风化发生的原因。在较高和压力下形成的矿物变成了在地表上稳定的矿物。

    Agents of Chemical Weathering
    ::化学气象监测剂

    There are many agents of chemical weathering. Remember that  water  was a main agent of mechanical weathering. Well, water is also an agent of chemical weathering. That makes it a double agent! Carbon dioxide and oxygen are also agents of chemical weathering. Each of these is discussed below.
    ::有很多化学气化剂。 记住水是机械气化的主要剂。 水也是化学气化的一种剂。 这使它成为一种双重剂。 二氧化碳和氧气也是化学气化的剂。 下面将讨论其中的每一种。

    Water
    ::水 水

    Water is an amazing  molecule . It has a very simple chemical formula, H 2 O. It is made of just two hydrogen atoms bonded to one oxygen  atom . Water is remarkable in terms of all the things it can do. Lots of things dissolve easily in water. Some types of rock can even completely dissolve in water ( Figure   )! Other minerals change by adding water into their structure.  Hydrolysis  is the name of the chemical reaction between a compound and water.
    ::水是一个惊人的分子。 它有一个非常简单的化学公式, 即H2O。 它由两个氢原子组成, 与一个氧原子连接在一起。 水在它所能做的一切方面都是了不起的。 许多东西很容易溶于水中。 某些类型的岩石甚至可以在水中完全溶解( 图 ) ! 其他矿物质通过在结构中添加水而变化。 水解是化合物和水之间的化学反应的名称 。

    Close-up of weathered rock in Walnut Canyon, demonstrating effects of chemical weathering.
     
    Weathered rock in Walnut Canyon near Flagstaff, Arizona.

    Carbon Dioxide
    ::二氧化二氧化碳

    Carbon dioxide (CO 2 ) combines with water as raindrops fall through the air. This makes a weak acid, called carbonic acid. This happens so often that carbonic acid is a common, weak acid found in nature. This acid works to dissolve rock. It eats away at sculptures and monuments. While this is normal, more acids are made when we add pollutants to the air. Any time we burn any  fossil fuel , it adds nitrous  oxide  to the air. When we burn  coal , rich in sulfur, it adds sulfur dioxide to the air. As nitrous oxide and sulfur dioxide react with water, they form nitric acid and sulfuric acid. These are the two main components of  . Acid rain accelerates chemical weathering.
    ::二氧化碳(CO2)与水结合, 雨滴从空气中落下。 这使得酸变得微弱, 叫做碳酸。 这经常发生, 以至于碳酸在自然界中是一种常见的、 微弱的酸。 这种酸可以溶解岩石。 这种酸在雕塑和纪念物中吞噬。 虽然这是正常的, 但当我们把污染物添加到空气中时, 酸就会增加更多的酸。 只要我们燃烧任何化石燃料, 就会增加一氧化二氮。 当我们燃烧煤炭, 富含硫磺, 就会增加二氧化硫到空气中。 随着一氧化二氮和二氧化硫与水发生反应, 它们会形成硝酸和硫酸。 这些是酸雨的两个主要组成部分。 酸雨会加速化学天气。

    Oxygen
    ::氧

    Oxygen strongly reacts with  elements  at the Earth’s surface. This process is called  oxidation . You are probably most familiar with the rust that forms when iron reacts with oxygen. Many minerals are rich in iron. Red rocks are full of iron oxides ( Figure   ). As iron changes into iron oxide, the iron oxides can also make red color in soils.
    ::氧气在地球表面与元素发生强烈反应。 这个过程被称为氧化。 您可能最熟悉铁与氧发生反应时形成的锈。 许多矿物质富含铁。 红岩充满了氧化铁(图 ) 。 随着铁变成氧化铁,氧化铁也可以在土壤中产生红色。

    Brown horse grazing in a grassy area with red rock formations in the background.
     
    The red rocks of Monument Valley are due to the oxidation of iron in the rock.

    Plants and Animals
    ::植物和动物

    Plants and animals also cause chemical weathering. As plant roots take in  nutrients , they remove elements from the minerals. This causes a chemical change in the rock.
    ::植物和动物还造成化学气候变暖,植物根植于养分中,从矿物中去除元素,导致岩石化学变化。

    Mechanical Weathering and Chemical Weathering
    ::机械气象学和化学气象学

    Mechanical weathering increases the rate of chemical weathering. As rock breaks into smaller pieces, the surface area of the pieces increases. With more surfaces exposed, there are more places for chemical weathering to occur ( Figure   ). Let’s say you wanted to make some hot chocolate on a cold  day . It would be hard to get a big chunk of chocolate to dissolve in your milk or hot water. Maybe you could make hot chocolate from some smaller pieces like chocolate chips, but it is much easier to add a powder to your milk. This is because the smaller the pieces are, the more surface area they have. Smaller pieces dissolve more easily.
    ::机械天气提高了化学风化的速度。 当岩石破碎成小块时, 碎片的表面面积会增加。 随着更多的表面暴露, 化学风化会发生更多地方( 图 ) 。 可以说你想在寒冷的一天做一些热巧克力。 很难让一大块巧克力溶解在牛奶或热水中。 也许你可以从巧克力片等小块中做热巧克力,但是在牛奶中添加粉末要容易得多。 这是因为碎块越小,其表面面积就越大。 小块更容易溶解。

    How rock breaking increases overall surface area for weathering.
     
    Mechanical weathering may increase the rate of chemical weathering.

    Summary
    ::摘要

    • Chemical weathering changes the composition of a mineral to break it down.
      ::化学风化改变了矿物的构成 以将其分解
    • Water chemically weathers rock in hydrolysis.
      ::水化学天气以水解方式岩石。
    • Carbon dioxide chemically weathers rock by creating acids.
      ::产生酸 产生二氧化碳的化学性质 以化学方式对岩石进行风化
    • Oxygen chemically weathers rock by combining with a metal.
      ::与金属结合,以化学方式对岩石进行氧气天气。

    Review
    ::回顾

    1. What is hydrolysis?
      ::什么是水解?
    1. How does carbon dioxide lead to chemical weathering?
      ::二氧化碳如何导致化学风化?
    1. How does mechanical weathering increase the effectiveness of chemical weathering processes?
      ::机械风化如何提高化学品风化过程的有效性?
    1. How do plants contribute to chemical weathering?
      ::工厂如何促进化学品风化?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

     

     

    1. What is chemical weathering?
      ::什么是化学风化?
    1. What are the three ways chemical weathering occurs?
      ::化学风化的三种方式是什么?
    1. What is oxidation? What does it produced?
      ::什么是氧化?它产生什么?
    1. What is carbonation? What does it create?
      ::什么是碳化?它创造了什么?
    1. What is hydration? What does it do?
      ::水分化是什么?
    1. In what type of environment is chemical weathering most likely to occur?
      ::在哪种环境中最有可能发生化学品风化?