章节大纲

  • A twenty-dollar bill featuring a portrait of Andrew Jackson, representing its consistent monetary value.

    How much is twenty dollars really worth?
    ::20美元到底值多少钱?

    I agree to mow someone’s lawn for twenty dollars (it’s a fairly big yard). When they pay me, they give me a $20 bill. It doesn’t matter whether the bill is brand new or old, dirty, and wrinkled – all these bills have the same value of $20. If I want more $20 bills, I have to mow more lawns. I can’t say, “This particular bill is actually worth more than $20.” To have more money, I have to put in more work.
    ::我同意用20美元修剪某人的草坪(这是一个相当大的院子 ) 。 当他们付钱给我时,他们给了我20美元的帐单。 不管帐单是全新的还是老旧的、肮脏的和有皱纹的 — — 所有这些帐单的价值都是一样的20美元。 如果我要更多20美元的帐单,我必须再修剪更多的草坪。 我不能说 , “ 这个具体的帐单实际上价值超过20美元。 ”要拥有更多的钱,我就必须投入更多的工作。

    Extensive and Intensive Properties
    ::广泛和密集财产

    Extensive Properties
    ::宽属性属性

    Some properties of matter depend on the size of the sample, while some do not. An extensive property is a property that depends on the amount of matter in a sample. The mass of an object is a measure of the amount of matter that an object contains. A small sample of a certain type of matter will have a small mass, while a larger sample will have a greater mass. Another extensive property is volume . The volume of an object is a measure of the space that is occupied by that object.
    ::有些物质的属性取决于样本的大小,而有些则取决于样本的大小。大属性是一种取决于样本中物质数量的属性。一个对象的质量是测量一个对象所含物质数量的尺度。一个特定类型物质的小样本将具有小质量,而一个较大的样本则具有更大的质量。另一个大属性是体积。一个物体的体积是该对象所占用空间的量。

    The figure below illustrates the extensive property of volume. The pitcher and glass both contain milk. The pitcher holds approximately two quarts and the glass will hold about 8 ounces of milk. The same milk is in each container. The only difference is the amount of milk contained in the glass and in the pitcher
    ::下图显示了大容量的特性,投手和玻璃都含有牛奶,投手持有大约两夸特,玻璃将持有大约8盎司的牛奶,每个容器都有同样的牛奶,唯一的区别是玻璃和投手中装的牛奶数量。

    A hand pouring milk from a pitcher into a glass, illustrating volume as an extensive property.
    Milk pitcher and glass.

    Intensive Properties
    ::密集属性

    The electrical conductivity of a substance is a property that depends only on the type of substance. Silver, gold, and copper are excellent conductors of electricity, while glass and plastic are poor conductors. A larger or smaller piece of glass will not change this property. An intensive property is a property of matter that depends only on the type of matter in a sample and not on the amount. Other intensive properties include color, temperature , density, and .
    ::物质的导电率仅取决于物质的类型。 银、 金和铜是极好的电力导电器,而玻璃和塑料是差的导电器。 大小的玻璃不会改变这种特性。 密集的财产仅取决于样本中物质的类型,而不取决于数量。 其他密集的特性包括颜色、温度、密度和 。

    A spool of copper wire illustrating the concept of intensive properties in materials.
    Copper wire.

    The copper wire shown in the picture  above  has a certain electrical conductivity. You could cut off the small end sticking out and it would have the same conductivity as the entire long roll of wire shown here. The conductivity is a property of the copper metal itself, not of the length of the wire.
    ::上图中显示的铜线具有一定的导电性。 您可以切除小端的电流, 并且它具有与此处显示的整个长卷线相同的导电性。 导电性是铜金属本身的特性, 而不是电线的长度 。

     

     

     

    Summary
    ::摘要

    • An extensive property is a property that depends on the amount of matter in a sample.
      ::大量财产是一种取决于抽样中物质数量的财产。
    • Mass and volume are examples of extensive properties.
      ::质量和体积是广泛特性的例子。
    • An intensive property is a property of matter that depends only on the type of matter in a sample and not on the amount.
      ::集约财产是一种物质财产,仅取决于抽样中物质的类型,而不取决于数量。
    • Color, temperature, and solubility are examples of intensive properties.
      ::颜色、温度和溶解度是密集特性的例子。

    Review
    ::回顾

    1. Define extensive property.
      ::界定广泛的财产。
    2. Give two examples of extensive properties.
      ::举两个广泛特性的例子。
    3. Define intensive property.
      ::定义密集属性。
    4. Give two examples of intensive properties.
      ::举两个密集特性的例子。