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Chapter 20

The First Law of Thermodynamics

热力学系统
热力学系统
A thermodynamic system is a set of objects whose thermodynamic properties are of interest. The system is considered to be embedded in its surroundings or ...
在体积更改期间完成的工作
在体积更改期间完成的工作
In mechanics, work is done on an object when the force acting on it displaces the object. In thermodynamics, work done on a system can be estimated when ...
热力学状态之间的路径
热力学状态之间的路径
Consider the two thermodynamic processes involving an ideal gas that are represented by paths AC and ABC in Figure 1: In the first process for path A to ...
热和自由膨胀
热和自由膨胀
The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states—that is, on the path. ...
内能
内能
The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic ...
热力学第一定律
热力学第一定律
A change in the internal energy of a system depends on the the net heat transfer into the system and the net work done by the system. The first law of ...
热力学第一定律:解决问题
热力学第一定律:解决问题
The first law of thermodynamics states that the change in internal energy of the system is equal to the net heat transfer into the system minus the net ...
循环进程和孤立系统
循环进程和孤立系统
A thermodynamic system with zero heat exchange and work is an isolated system. For these systems, the internal energy remains constant. In the case of a ...
等温过程
等温过程
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to ...
等压和等压过程
等压和等压过程
A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or ...
理想气体的热容 I
理想气体的热容 I
Heat capacity is the ratio of heat absorbed by the substance corresponding to its temperature change. It is also called thermal capacity and the SI unit ...
理想气体的热容 II
理想气体的热容 II
For a system that undergoes a thermodynamic process at a constant volume condition, the heat absorbed is used only to increase the system's internal ...
理想气体的热容 III
理想气体的热容 III
The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents ...
理想气体的绝热过程
理想气体的绝热过程
When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, ...
绝热过程中的压力和体积
绝热过程中的压力和体积
Free expansion of a gas is an adiabatic process. However, there are few differences between free expansion and adiabatic expansion. During free expansion, ...
绝热过程中所做的功
绝热过程中所做的功
Consider the adiabatic compression of an ideal gas in the cylinder of an automobile diesel engine. The gasoline vapor is injected into the cylinder of an ...
热力学势
热力学势
Thermodynamic potentials are state functions that are extremely useful in analyzing a thermodynamic system. They have dimensions of energy. The four ...
麦克斯韦热力学关系
麦克斯韦热力学关系
Maxwell's thermodynamic relations are very useful in solving problems in thermodynamics. Each of Maxwell's relations relates a partial ...
焦耳-汤姆逊效应
焦耳-汤姆逊效应
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous ...
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