自由能和焓之间的差异

关键区别 - 免费Energyvs Enthalpy

自由的energy and enthalpy are two热力学terms used to explain the relationship between heat energy and chemical reactions that occur in a thermodynamic system. Free energy or thermodynamic free energy is the amount of work that a thermodynamic system can perform. In other words, free energy is the amount of energy that is available in that thermodynamic system to perform thermodynamic work. Enthalpy, on the other hand, is a thermodynamic quantity that represents the total energy content in a thermodynamic system. Thekey differencebetween free energy and enthalpy is that自由能提供可用的总能量来进行热力学工作，而焓可以将热力学系统的总能量转换为热力学系统。

内容

1.Overview and Key Difference
2.What is Free Energy
3.什么是焓
4.自由能与焓之间的关系
5.并排比较 - 自由能与表格形式的焓
6。概括

What is Free Energy?

自由的energy is the amount ofenergyavailable for a thermodynamic system to perform thermodynamic work. Free energy has the dimensions of energy. The value of the free energy of a thermodynamic system is determined by the present state of the system; not by its history. There are two main types of free energy often discussed in thermodynamics;Helmholtz自由能and Gibbs free energy.

Helmholtz Free Energy

Helmholtz自由能是在封闭的热力学系统中可用的能量，可在恒定温度和体积下进行热力学工作。因此，Helmholtz能量的负值表示热力学系统可以通过保持其体积常数执行的最大工作。为了保持音量恒定，某些总热力学工作是作为边界工作完成的（以保持系统的边界）。下面给出了Helmholtz能量的方程。

a = u - ts

Where A is the Helmholtz free energy, U is the internal energy, T is a temperature, which is a constant and S is theentropyof the system. Entropy is a thermodynamic quantity representing the unavailability of a system’s thermal energy for conversion into mechanical work.

吉布斯自由能：

这吉布斯自由能the energy that is available in a closed, thermodynamic system to perform thermodynamic work at constant temperature and pressure. The volume of the system can vary. Free energy is denoted by G. The equation of Gibbs free energy is given below.

G = H – TS

In the above equation, G is Gibbs free energy, H is the enthalpy of the system, Y is the temperature, which is a constant and S is the entropy of the system.

什么是焓？

系统的焓是与系统的总热含量相等的热力学量。它等于internal energy系统的压力和体积乘积。因此，它是系统的热力学特性。这equation of enthalpy在下面给出。

H = U + PV

因此，H是系统的焓，U是系统的内部能量，P是压力，V是体积。系统的焓是该系统释放热量（进行非机械工作）的能力的指示。焓用符号H表示。

Determining the enthalpy of a system allows us to indicate if a chemical reaction isexothermic or endothermic. The change in enthalpy of a system can be used to determine the heat of reactions and also to predict if a chemical reaction is spontaneous or non-spontaneous.

自由能和焓之间有什么关系？

这吉布斯自由能and enthalpy are related through the following equation.

G = H – TS

In the above equation, G is Gibbs free energy, H is the enthalpy of the system, Y is the temperature, which is a constant and S is the entropy of the system. Both G and H has the same units of measurement.

What is the Difference Between Free Energy and Enthalpy?

自由的Energy vs Enthalpy
自由的energy is the amount of energy available for a thermodynamic system to perform thermodynamic work.	系统的焓是与系统的总热含量相等的热力学量。
Concept
自由能为执行热力学工作的总能量提供。	Enthalpy gives the total energy of a system that can be converted to heat.
转换
自由能提供可以转换为系统机械工作的能量。	Enthalpy gives the energy that can be converted to non-mechanical work of the system.

概括–自由的Energyvs Enthalpy

自由的energy and enthalpy of a thermodynamic system represent energy that is available in a system. The key difference between free energy and enthalpy is that free energy gives the total energy available to perform thermodynamic work whereas enthalpy gives the total energy of a system that can be converted to heat.

Reference:

1.这Editors of Encyclopædia Britannica. “Free energy.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 5 Jan. 2012.Available here
2.Helmenstine, Anne Marie, D. “What Is Enthalpy in Chemistry and Physics?” ThoughtCo, Jan. 25, 2018.Available here
3.“ Helmholtz自由能。”Wikipedia，Wikimedia基金会，2018年2月17日。Available here
4.“Gibbs (Free) Energy.” Chemistry LibreTexts, Libretexts, 12 Jan. 2018.Available here

Image Courtesy:

1.“赫尔曼签证官n Helmholtz’ (Public Domain) viaCommons Wikimedia