章节大纲

  • A climber ascends a glacier using ice tools, showcasing the challenges of ice climbing.

    The man in this photo is climbing a glacier. Ice climbing is a dangerous sport that should be attempted only by highly experienced climbers. For one thing, ice is very slippery, which makes it harder than rock to grip. Clinging to the slippery vertical surface takes strength, training, and the right equipment.
    ::这张照片中的人正在攀登冰川。 攀冰是一个危险的运动,只有经验丰富的登山者才能尝试。 首先,冰非常滑,这比岩石更难抓住。 向滑滑的垂直表面靠拢需要力量、训练和合适的设备。

    From Liquid to Solid
    ::从液体到固体

    You don’t have to be an ice climber to enjoy ice. Skating and fishing are two other sports that are also done on ice. What is ice? It’s simply water in the state. The process in which water or any other changes to a solid is called freezing . Freezing occurs when a liquid cools to a point at which its particles no longer have enough to overcome the force of attraction between them. Instead, the particles remain in fixed positions, crowded closely together, as shown in the Figure .
    ::你不必成为冰山登冰者才能享受冰块。 滑冰和钓鱼是另外两种运动,也是在冰上进行的。 冰是什么? 冰只是州里的水。 水或其他任何固体变化的过程被称为冰冻。 当液体冷却到其颗粒不再足以克服它们之间吸引力的地步时,就会出现冻结。 相反,微粒留在固定的位置上,紧紧地聚集在一起,如图所示。

    The arrangement of particles in solid, liquid, and gas states.

    Freezing Point
    ::冻结点

    The at which a substance freezes is known as its freezing point. Freezing point is a physical property of matter. The freezing point of pure water is 0°C. Below this temperature, water exists as ice. Above this temperature, it exists as liquid water or water vapor. Many other substances have much lower or higher freezing points than water. You can see some examples in the Table . The freezing point of pure water is included in the table for comparison.
    ::冻结点是物质的物理属性。纯净水的冻结点为0°C。在此温度下,水作为冰存在。在此温度下,水作为液态水或水蒸气存在。许多其他物质比水的冷点低或高得多。请参见表格中的一些例子。表内列出了纯净水的冷点,以便进行比较。

    Substance Freezing Point (°C)
    Helium -272
    Oxygen -222
    Nitrogen -210
    Pure Water 0
    Lead 328
    Iron 1535
    Carbon 3500

    Q: What trend do you see in this table?
    ::问题:你在本表中看到什么趋势?

    A: Substances in the table with freezing points lower than water are . Substances in the table with freezing points higher than water are solids.
    ::A: 冰点低于水的表中物质为.冰点高于水的表中物质为固体。

    Q: Sodium is a solid at room temperature. Given this information, what can you infer about its freezing point?
    ::Q: 钠在室温下是固态的。 根据这些信息, 你能推断出它的冷点是什么?

    A: You can infer that the freezing point of sodium must be higher than room temperature, which is about 20°C. The freezing point of sodium is actually 98°C.
    ::A:可以推断钠的冷点必须高于房间温度,即大约20°C。 钠的冷点实际上是98°C。

    Summary
    ::摘要

    • Freezing is the process in which a liquid changes to a solid. It occurs when a liquid cools to a point at which its particles no longer have enough energy to overcome the force of attraction between them.
      ::冻结是液态改变固体的过程,当液体冷却到其颗粒不再有足够的能量来克服它们之间的吸引力时,就会发生。
    • The freezing point of a substance is the temperature at which it freezes. The freezing point of pure water is 0°C.
      ::物质的冷点是其冻结的温度,纯水的冷点为0°C。

    Review
    ::回顾

    1. Define freezing.
      ::定义冻结。
    2. What happens to the particles of matter when it changes from a liquid to a solid?
      ::当物质粒子从液体变成固体时会怎样?
    3. What is the freezing point of a substance? What is the freezing point of water?
      ::物质的冷点是什么?水的冷点是什么?
    4. Adding antifreeze to water lowers its freezing point. Based on this statement, what can you infer about the freezing point of antifreeze?
      ::添加防冻剂到水中会降低它的冷点。 根据这个声明,你对防冻剂的冷点有什么推论?

    Resources
    ::资源