13.19 阶段图图

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  阶段图图

  

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  How are rockets able to shoot up into the air?
  ::火箭如何射向空中?

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  Many rockets use a combination of kerosene and oxygen for their fuel. Oxygen can be reduced to the liquid state either by cooling or by using high pressure . Since the oxygen is in a container essentially out in the open, maintaining a temperature of -183°C (the boiling point of oxygen) is not practical. But high pressure can be used to force the oxygen into tanks and cause it to liquefy so it can then mix with the kerosene and provide a powerful ignition to move the rocket.
  ::许多火箭的燃料混合使用煤油和氧气,氧气可以通过冷却或使用高压降低到液体状态,因为氧气基本上在露天的容器中,因此维持至 - 183°C(氧气沸点)的温度是不切实际的,但高压可以用来迫使氧气进入罐体,使其液化,然后与煤油混合,提供动力点火来移动火箭。

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  Phase Diagrams
  ::阶段图图

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  The relationships among the solid, liquid, and vapor (gas) states of a substance can be shown as a function of temperature and pressure in single diagram. A phase diagram is  graph showing the conditions of temperature and pressure under which a substance exists in the solid, liquid, and phases. Examine the general phase diagram shown in  Figure . In each of the three colored regions of the diagram, the substance is in a single state (or phase). The dark lines that act as the boundary between those regions represent the conditions under which the two phases are in equilibrium.
  ::物质的固态、液态和蒸气(气)状态之间的关系可以在单一图表中显示为温度和压力的函数。一个阶段图是图表,显示一种物质存在于固体、液体和各个阶段的温度和压力状况。看看图中显示的一般阶段图。在图表的三个有色区域中,该物质处于一个单一的状态(或阶段)。作为这些区域之间的边界的暗线代表两个阶段处于平衡状态的条件。

  

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  General phase diagram, which shows the state (phase) of a substance as a function of its temperature and pressure.
  ::一般阶段图,该图显示物质的状态(阶段)与其温度和压力的函数值。

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  Find the  $\begin{array}{r}X\end{array}$ on the pressure axis and presume that the value of  $\begin{array}{r}X\end{array}$ is standard pressure of 1 atm. As one moves left to right across the red line, the temperature of the solid substance is being increased while the  pressure remains constant. When point $\begin{array}{r}A\end{array}$ is reached, the substance melts and the temperature  $\begin{array}{r}B\end{array}$ on the horizontal axis represents the normal melting point of the substance. Moving further to the right, the substance boils at point  $\begin{array}{r}Y\end{array}$ and so point  $\begin{array}{r}C\end{array}$ on the horizontal axis represents the normal boiling point of the substance. As the temperature increases at a constant pressure, the substance changes from solid to liquid to gas.
  ::在压力轴上找到 X, 并假设 X 的值是标准1 个温度。 当一个人左向右移动时, 固体物质的温度会上升, 而压力却保持不变。 当到达 A 点时, 物质熔化 和水平轴上的温度 B 代表物质的正常熔点 。 向右移动, 物质在 Y 点和 C 点处沸腾, 代表物质的正常沸腾点 。 当温度在恒定压力下上升时, 物质会从固体变成液体, 变成气体 。

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  Start right above point  $\begin{array}{r}B\end{array}$ on the temperature axis and follow the red line vertically. At very low pressure, the particles of the substance are far apart from one another and the substance is in the gas state. As the pressure is increased, the particles of the substance are forced closer and closer together. Eventually the particles are pushed so close together that attractive forces cause the substance to condense into the liquid state. Continually increasing the pressure on the liquid will eventually cause the substance to solidify. For the majority of substances, the solid state is denser than the liquid state and so putting a liquid under great pressure will cause it to turn into a solid. The line segment $\begin{array}{r}R-S\end{array}$ represents the process of , where the substance changes directly from a solid to a gas. At a sufficiently low pressure, the liquid phase does not exist. The point labeled  $\begin{array}{r}TP\end{array}$ is called the triple point . The triple point is the one condition of temperature and pressure where the solid, liquid, and vapor states of a substance can all coexist at equilibrium.
  ::在温度轴上右下B点开始, 并垂直沿着红色线。 在非常低的压力下, 物质的颗粒彼此相距甚远, 并且物质处于气体状态。 随着压力的增加, 物质的颗粒会被紧紧地推在一起。 最终, 粒子会一起推近, 导致物质凝结到液态中。 持续增加液体的压力最终会导致物质固化。 对于大多数物质来说, 固态比液体状态更稠密, 所以在巨大的压力下将液体放入液体会使其变成固体。 线段 R- S 代表物质从固体直接变化到气体的过程。 在足够低的压力下, 液相并不存在。 点标记的TP 被称为三重点。 三点是温度和压力的一个条件, 即物质的固体、 液体和蒸气状态都能在平衡中共存。

   

   

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  Science Friday: Snowflake Safari
  ::科学星期五:雪花Safari

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  Next snowstorm, grab a magnifying glass and look carefully at snowflakes. Bullet rosettes, stellar plates and capped columns are just a few of the many varieties of snow crystals. In this video by Science Friday, physicist Kenneth Libbrecht shares secrets about snowflakes.
  ::下一场雪暴,拿起放大镜,仔细看雪花。 子弹玫瑰、恒星板和圆柱只是许多雪晶种类中的少数。 在科学周五的这段影片中,物理学家肯尼斯·利布雷赫特分享了雪花的秘密。

   

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  CK-12 Simulation
  ::CK-12 模拟

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  Explore phase diagrams in action with this simulation focused on phase change: 
  ::试探阶段图,在模拟中以阶段变化为重点:

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  Summary
  ::摘要

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  • A phase diagram is a graph which the conditions of temperature and pressure under which a substance exists in the solid, liquid, and gas.
    ::相位图是指一种物质存在于固体、液体和气体中的温度和压力条件的图。
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  • The triple point is the one condition of temperature and pressure where the solid, liquid, and vapor states of a substance can all coexist at equilibrium.
    ::三点是温度和压力的一个条件,即物质的固体、液体和蒸气状态在平衡时都能共存。

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  Review
  ::回顾

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  1. What is a phase diagram?
     ::什么是阶段图?
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  2. What is the triple point?
     ::三个点是多少?
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  3. In above, what does point C represent?
     ::在上文中,C点代表什么?