热力学是研究能量及其转换的科学，特别是在宏观系统中的热与功之间的相互作用。以下是一些热力学的基础知识： Thermodynamics is the study of energy and its transformations, especially the interaction between heat and work in macroscopic systems. Here are some basics of thermodynamics:
热力学定律 The laws of thermodynamics
1. **热力学第零定律**：如果两个系统分别与第三个系统达到热平衡，则这两个系统也处于热平衡。 1. **Zeroth law of thermodynamics**: If two systems are each in thermal equilibrium with a third system, then the two systems are also in thermal equilibrium.
2. **热力学第一定律**：能量守恒定律。系统内能的变化等于系统吸收的热量减去系统对外做的功。可以用方程表示为： 2. **First law of thermodynamics**: the law of conservation of energy. The change in the internal energy of a system is equal to the heat absorbed by the system minus the work done by the system. It can be expressed as an equation:
\[ \[
\Delta U = Q - W \Delta U = Q - W
\] \]
其中，\(\Delta U\) 是系统内能的变化，\(Q\) 是吸收的热量，\(W\) 是对外做的功。 Among them, \(\Delta U\) is the change in the internal energy of the system, \(Q\) is the heat absorbed, and \(W\) is the work done externally.
3. **热力学第二定律**：自然界中的所有自发过程都伴随着熵的增加。可以用方程表示为： 3. **Second Law of Thermodynamics**: All spontaneous processes in nature are accompanied by an increase in entropy. This can be expressed as an equation:
\[ \[
\Delta S_{\text{总}} \geq 0 \Delta S_{\text{total}} \geq 0
\] \]
其中，\(\Delta S_{\text{总}}\) 是总熵的变化。熵是衡量系统无序程度的物理量。 Where \(\Delta S_{\text{total}}\) is the change in total entropy. Entropy is a physical quantity that measures the degree of disorder in a system.
4. **热力学第三定律**：当温度接近绝对零度（-273.15℃或0K）时，系统的熵趋近于一个常数，通常假设为零。这意味着在绝对零度，所有的分子运动停止，系统达到最大的有序状态。 4. **The third law of thermodynamics**: As the temperature approaches absolute zero (-273.15°C or 0K), the entropy of the system approaches a constant, usually assumed to be zero. This means that at absolute zero, all molecular motion stops and the system reaches its maximum order.
重要概念 Key Concepts
- **热**：热是能量的一种形式，通常从高温物体传递到低温物体。 - **Heat**: Heat is a form of energy that is usually transferred from a hotter object to a cooler object.
- **温度**：温度是衡量物体热运动的强度，通常用摄氏度（℃）、华氏度（℉）或开尔文（K）来表示。 - **Temperature**: Temperature is a measure of the intensity of thermal motion of an object and is usually expressed in Celsius (℃), Fahrenheit (℉) or Kelvin (K).
- **功**：功是能量的一种形式，通常表示为力与距离的乘积。 - **Work**: Work is a form of energy usually expressed as the product of force and distance.
- **熵**：熵是衡量系统无序程度的物理量。自然界中所有自发过程都伴随着熵的增加。 - **Entropy**: Entropy is a physical quantity that measures the degree of disorder in a system. All spontaneous processes in nature are accompanied by an increase in entropy.
- **热力学平衡**：当系统的宏观状态参数（如温度、压力等）不随时间变化时，系统处于热力学平衡状态。 - **Thermodynamic equilibrium**: When the macroscopic state parameters of the system (such as temperature, pressure, etc.) do not change with time, the system is in thermodynamic equilibrium.
热力学过程 Thermodynamic process
- **等温过程**：温度保持不变的过程。 - **Isothermal process**: A process in which the temperature remains constant.
- **等压过程**：压力保持不变的过程。 - **Isobaric process**: A process in which the pressure remains constant.
- **等容过程**：体积保持不变的过程。 **Isochoric process**: A process in which the volume remains constant.
- **绝热过程**：系统与外界没有热交换的过程。 - **Adiabatic process**: A process in which there is no heat exchange between the system and the outside world.
热力学在工程、物理、化学等领域有着广泛的应用，是理解能量转换和物质行为的基础。 Thermodynamics has a wide range of applications in engineering, physics, chemistry and other fields, and is the basis for understanding energy conversion and material behavior.
