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请帮我解释一下一级相变和二级相变的区别
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我在网上查到了解释，但是一大套的理论，看的头大，博学的虫子们可否帮我扫了这个盲，谢谢啦 |
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growingpains
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我给你两种解释，第一种看不懂看第二种，还不行我就没有办法了！
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mybobo(金币+1):谢谢你！
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1 物态变化也称为相变。初中物理讲的物态变化是指固、液、气三种物态间的变化，这种变化是相变中的一类，称为一级相变。它的特点是：①相变过程中，体积要发生明显的改变；②相变过程中要吸收或放出所谓的相变潜热、此外，还有另一类相变，它们没有以上两个特点，既不发生体积的突变，也不吸收或放出相变潜热，但它的某些特性，如热容量、热膨胀系数等要发生突变，这类相变称为二级相变。某些物质在温度低到一定程度时电阻会突然消失，成为超导体，就是一种二级相变。 2 自然界中可以观察到的相变主要是一级相变。二级相变主要是一些比较特殊的相变：如铁磁相变、超导相变等等。 |
2楼2006-05-25 01:47:25
qlp1026
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3楼2006-05-25 08:32:20
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Ehrenfest classification Phase transitions were labelled by the lowest derivative of the free energy that is discontinuous at the transition. First-order phase transitions exhibit a discontinuity in the first derivative of the free energy with a thermodynamic variable. The various solid/liquid/gas transitions are classified as first-order transitions because they involve a discontinuous change in density (which is the first derivative of the free energy with respect to chemical potential.) Second-order phase transitions have a discontinuity in a second derivative of the free energy. These include the ferromagnetic phase transition in materials such as iron, where the magnetization, which is the first derivative of the free energy with the applied magnetic field strength, increases continuously from zero as the temperature is lowered below the Curie temperature. The magnetic susceptibility, the second derivative of the free energy with the field, changes discontinuously. Under the Ehrenfest classication scheme, there could in principle be third, fourth, and higher-order phase transitions. |
4楼2006-05-27 06:11:49