发布时间 : 星期六 文章HSC Chemistry使用手册Eh-pH Diagram模块中文更新完毕开始阅读
17. Eh - pH - DIAGRAMS (Pourbaix-diagrams)
Eh-pH-diagrams show the thermodynamic stability areas of different species in an aqueous solution. Stability areas are presented as a function of pH and electrochemical potential scales. Usually the upper and lower stability limits of water are also shown in the diagrams with dotted lines. Traditionally these diagrams have been taken from different handbooks12. However, in most handbooks these diagrams are available only for a limited number of temperatures, concentrations and element combinations.
Eh-pH图显示不同物种在水溶液中的热力学稳定区。稳定的地区作为一个潜在的尺度和电化学作用的pH值。通常上、水下稳定极限也与虚线图所示。传统上，这些图已从不同的handbooks12。然而，在大多数手册这些图是只有数量有限的温度，浓度和元素组合。
The Eh-pH module of HSC Chemistry allows the construction of diagrams in a highly flexible and fast way, because the user can draw the diagrams exactly at the selected temperature and concentration.
HSC化学Eh-pH模块允许在一个高度灵活和快速的方式图解，因为用户可以画出图形，在选定的温度和浓度。
The Eh-pH-module is based on STABCAL - Stability Calculations for Aqueous Systems - developed by H.H. Haung, at Montana Tech., USA9,10. Eh-pH模块是基于stabcal稳定性计算水系统由H.H.黄发达，蒙大纳科技，usa9,10。
17.1 Introduction
Eh-pH-diagrams are also known as Pourbaix Diagrams according to author of the famous Pourbaix diagram handbook12. The most simple type of these diagrams is based on a chemical system consisting of one element and water solution, for example, the
Mn-H2O-system. The system can contain several types of species, such as dissolved ions, condensed oxides, hydroxides, oxides, etc. The Eh-pH-diagram shows the stability areas of these species in the redox potential-pH-coordinates.
Eh-pH图也称作Pourbaix图根据著名的Pourbaix图handbook12作者。这些图的最简单的类型是基于化学系统组成的一个元素和水的解决方案，例如，在mn-h2o-system。该系统可以包含多种类型的物种，如溶解离子，浓缩的氧化物，氢氧化物，氧化物，等电位-pH图显示在氧化还原电位pH这些物种的稳定区域的坐标。
Usually the redox potential axis is based on the Standart Hydrogen Electrode (SHE) scale designated Eh, but other scales can also be used. The redox potential of the system represents its ability to change electrons. The system tends to remove electrons from the species when the potential is high (Eh > 0). These conditions may exist near the anode in the
electrochemical cell, but can also be generated with some oxidizing agents (Cu + H2O2 =
CuO + H2O). In reducing conditions, when potential is low (Eh < 0), the system is able to supply electrons to the species, for example, with a cathode electrode or with some reducing agents.
通常氧化还原电位轴是基于标准氢电极（她）规模划啊，但也可以使用其他表。该系统的氧化还原电位代表其改变电子的能力。系统会删除电子从物种可能是当高（EH > 0）。这些条件可能存在在电化学电池的阳极，但也可以与一些氧化剂（H2O2生成Cu +铜+ H2O =）。在还原条件下，当为低电位（Eh＜0），该系统能够提供电子的物种，例如，与阴极电极或与还原剂。
The pH of the system describes its ability to supply protons (H(+a)) to the species. In acid conditions (pH < 7) the concentration of the protons is high and in caustic conditions (pH > 7) the concentration of protons is low.
pH值的系统描述其提供质子的能力（H（+））的种类。在酸性条件下（pH＜7）质子的浓度较高，在碱性条件下（pH＞7）的质子浓度低。
Usually a large amount of different species exist simultaneously in the aqueous mixtures in fixed Eh-pH-conditions. The Pourbaix diagrams simplify this situation a lot by showing only the predominant species which content is highest in each stability areas. The lines in the diagrams represent the Eh-pH-conditions where the content of the adjacent species is the same in the equilibrium state. However, these species always exist in small amounts on both sides of these lines and may have an effect on practical applications.
通常一个大的不同物种的数量同时存在固定的Eh-pH条件水混合物。Pourbaix图简化这种情况很多只显示优势种，内容是每个稳定性最高的地区。图中的线代表Eh-pH条件下相邻物种的内容是在平衡状态下相同。然而，这些品种都存在少量的这些线的两侧，可能对实际应用的影响。
The lines in the diagrams can also be represented with chemical reaction equations. These reactions may be divided into three groups according to reaction types:
图中的线也可以用化学反应方程式。这些反应可分为三组，根据反应类型：
1. Horizontal lines. These lines represent reactions that are involved with electrons, but are independent of pH. Neither H(+a)-ions nor OH(-a)-ions participate to these reactions. 1水平线。这些线代表的反应，涉及电子，但独立的博士没有H（+）离子和OH（-）-离子参与反应。
2. Diagonal lines with either positive or negative slope. These lines represent reactions that are involved with both electrons and H(+a)-and OH(-a)-ions.
2。对角线或正或负的斜率。这些线代表的反应，涉及电子和H（+）和（-）-离子哦。 3. Vertical lines. These lines represent reactions that are involved either with H(+a)- or OH(-a)-ions, but are independent of Eh. In other words, electrons do not participate with these reactions.
3垂直线。这些线代表反应，可能与H（+）或（-）-离子哦，但独立的啊。换句话说，电子不参与这些反应。
The chemical stability area of the water is shown in the Eh-pH-diagrams with dotted lines. The upper stability limit of water is based on the potential when the oxygen generation starts on the anode. It is specified by the reaction:
水的化学稳定性区域是在虚线的Eh-pH图所示。水上稳定极限是基于势当氧代开始在阳极。它是由指定的反应： 2 H2O = O2(g) + 4 H(+a) + 4 e- 2 H2O = O2（g）+ 4 H（+）+ 4—
The lower stability limit is based on hydrogen formation on the cathode. It is specified by the reaction:
较低的稳定极限是基于阴极上氢的形成。它是由指定的反应： 2 H(+a) + 2 e- = H2(g) 2 H（+）+ 2 E = H2（g）
The construction of the diagrams with HSC Chemistry EpH module is quite a simple task. However, several aspects must be taken into account when specifying the chemical system and analyzing the calculation results, for example:
用HSC-Chemistry弗模块图的建设是一个相当简单的任务。然而，几个方面必须考虑指定化学系统分析计算结果，例如：
1. A basic knowledge of chemistry, aqueous systems and electrochemistry or hydrometallurgy is always needed in order to draw the correct conclusions. 1。一个基本的化学知识，水系统和电化学或湿法总是为了得出正确的结论。 2. The EpH module carries out the calculations using pure stoichiometric substances. In practice minerals may contain impurity elements and the composition may deviate slightly from the stoichiometric one.
2。弗模块进行计算，采用纯化学物质。在实践中可能含有的杂质元素和矿物组成可能稍微偏离化学计量。
3. There are always some errors in the basic thermochemical data of the species. This may have significant effect on the results, especially if the chemical driving force of the reaction is small. Usually small differences between Pourbaix diagrams from different sources can be explained by the slightly different basic data used.
3。总有一些物种的基本热化学数据的一些错误。这可能会对结果有显著的影响，特别是如果该反应的化学驱动力小。通常小差异Pourbaix图从不同的来源可以通过使用略有不同的基本数据的解释。
4. Sometimes data for all existing species is not available from the HSC database or from the other sources. This will distort the results if the missing species are stable in given conditions. The missing unstable species will have no effect on the results.
4。有时数据中的所有现存的物种是无法从数据库或从其他来源的造血干细胞。这会扭曲结果如果丢失的物种是在特定条件下稳定。失踪的不稳定的物种会对结果没有影响。 5. The EpH module does not take into account the non-ideal behavior of aqueous solutions. However, in many cases these ideal diagrams give a quite good idea of the possible reactions in aqueous solutions, especially if the driving force of the reactions is high. 5。弗模块没有考虑到溶液的非理想行为。然而，在许多情况下，这些理想图给出可能的反应的一个相当好的主意在水溶液中，特别是如果该反应的驱动力是高。
6. Thermochemical calculations do not take into account the speed of the reactions (kinetics). For example, the formation of the SO4(-2a) ion may be a slow reaction. In these cases metastable diagrams created by removing such species from the system may give more consistent results with the experimental laboratory results.
6。热化学计算不考虑反应的速度（动力学）。例如，在形成SO4（2A）离子可能是一个缓慢的反应。在这些情况下，亚稳态图，从系统中除去这些物种创造了可以提供更一致的结果与实验结果。
The HSC user must be very careful when drawing conclusions from Eh-pH-diagrams due to these limitations and assumptions. However, these diagrams may offer extremely valuable information when combining the results with the experimental work and with a good knowledge of aqueous chemistry. There is no universal kinetic or thermochemical theory available, which could entirely substitute traditional experimental laboratory work with pure theoretical calculation models.
HSC的用户必须非常小心，当得出结论Eh-pH图由于这些限制和假设。然而，这些图可以提供极有价值的信息时，将结果与实验工作和与水化学知识好。有没有通用的动力学、热化学理论可用，可完全替代传统的纯理论计算模型实验的实验室工作。 More information on Eh-pH-diagrams, calculation methods and applications can be found from different handbooks, for example, from the Pourbaix Atlas12.
在Eh-pH图计算方法和应用的更多信息，可以发现不同的手册，例如，从儿atlas12。