移动性和扩散系数有什么区别

The移动性和扩散系数之间的关键区别is that mobility is the ability of a charged particle to move due to the effect of an电场whereas diffusion coefficient is a constant that describes the relationship between molar flux and the concentration gradient.

移动性是带电颗粒通过介质移动作为对电场的响应的能力。扩散系数是摩尔通量之间的比例常数（由于molecular diffusion) and the concentration gradient of chemical species.

内容

1.Overview and Key Difference
2.What is Mobility
3.什么是扩散系数
4.Relationship Between Mobility and Diffusion Coefficient
5.Mobility and Diffusion Coefficient in Tabular Form
6.Summary – Mobility vs Diffusion Coefficient

What is Mobility

移动性是带电颗粒通过介质移动作为对电场的响应的能力。This electric field pulls the charged particles. In this context, charged particles are mainly electrons or protons. We can separate different ions according to their mobility; when this separation is done in the gas phase, it is calledion mobility光谱法，如果它处于液态状态，我们可以称之为电泳.

When there is a charged particle in a gas or liquid state that occurs at a uniform electric field, the charged particle can be accelerated to a velocity that is called a constant drift velocity. The mathematical expression for mobility is as follows:

v_d= µE

In this equation, v_drefers to the drift velocity, µ refers to the mobility and E is the magnitude of the electric field. The unit of measurement for v_dis m/s, the unit of measurement for µ is m²/v.s，E的测量单位为v/m。因此，带电颗粒的迁移率是漂移速度与电场大小的比率。

Moreover, electrical mobility is directly proportional to the net electrical charge of the charged particle.

什么是扩散系数？

proportiona扩散系数是一个常数lity between the molar flux (due to molecular diffusion) and the concentration gradient of chemical species. It describes the driving force of diffusion. Therefore, the higher the diffusion coefficient, the faster the diffusion of substances. The unit of measurement of this parameter is m²/s.

Typically, the diffusion coefficient depends on temperature. In solids, the diffusion coefficient at different temperatures can be calculated using the Arrhenius equation. Similarly, we can use the Stokes-Einstein equation to calculate the temperature dependence of diffusion coefficient in liquids. In gases, the relationship between diffusion coefficient and temperature can be determined using the Chapman-Enskog theory.

Relationship Between Mobility and Diffusion Coefficient

Mobility and diffusion coefficient are closely related terms. Here, electrical mobility is related to the diffusion coefficient of the sample species through the following equation. It is called the Einstein relation.

µ = (q/kT)D

In this equation, µ is the mobility, q is the electrical charge, k is the Boltzmann constant, T is the temperature of the gas, and D is the diffusion coefficient. Therefore, depending on the gas temperature and the electrical charge of the charged particle, the mobility is directly proportional to the diffusion coefficient.

Difference Between Mobility and Diffusion Coefficient

迁移率和扩散系数之间的关键差异是，由于电场的效果，迁移率是带电粒子移动的能力，而扩散系数是一个常数，它描述了摩尔通量与浓度梯度之间的关系。

The following table summarizes the difference between mobility and diffusion coefficient for side by side comparison.

Summary – Mobility vs Diffusion Coefficient

Mobility and diffusion coefficient are two related chemical terms. The key difference between mobility and diffusion coefficient is that mobility is the ability of a charged particle to move due to the effect of an electrical field whereas diffusion coefficient is a constant which describe the relationship between molar flux and the concentration gradient.

Reference:

1.“”扩散系数.”概述|ScienceDirect主题.

Image Courtesy:

1.“”Motion by electrophoresis of a charged particle” By Daniele Pugliesi – File:Moto di uno ione in un elettrolita.svg (my work)(CC BY-SA 3.0)via Commons Wikimedia