电化学分析-1

3) 发生电极反应或电极上发生电子转移

实验证明：金属的电极电位大小与金属本身的活泼性，金属离子在溶液中浓度，以及温度等因素有关。

-(g)

增强吸附氢气的能力并提高反

、[H+]=1mol.L-1 (严格

)

)

标准电极电位正负值的确定：

若电子由SHE流向待测标准电极,则为正,若电子从待测标准电极流向SHE,则为负。

3. 电化学池中的电流

电化学池的导通

金属电极之间——电子导电

溶液中——离子导电

电极表面——发生氧化或还原反应（界面上的电子传输）

在电极上发生的氧化还原反应产生的电流称为

而电极的双电层的作用类似于一个电容器，在改变电外电路中的电子在到达电极表面后，或者参加氧化还

电化学极化：

电化学极化

重要概念：电极电位、阳极、阴极、电重要过程：电极表面的氧化还原过程、重要公式：能斯特方程、法拉第定律

The potential of indicator electrode—responds to the

Reference electrode—has

Despite its importance as the fundamental reference electrode against which we measure all other potentials, the SHE is rarely used because it is difficult to prepare

Membrane Indicator electrodes Properties

H

near surface

Na

in interior

Ca

)(ln 'aq a nF

RT E E E E E I PB PB d M ±′=++=Nernst equation

E PB =RT z I

F ln k I a I (aq)a I (org)

PB =RT z I F ln k I a'I (aq)a'I (org)Usually ionic compound

Single crystal

Crushed powder, melted and formed

Sometimes doped (Li+) to increase conductivity

Operation similar to glass membrane

Based on potential that develops

Response towards

Gas Sensing Probes

Simple electrochemical cell

with two reference electrodes

Immobilized enzyme bound to gas permeable membrane Catalytic enzyme reaction produces small gaseous

gas sensing probe measures change in gas concentration

samples or ultramicro samples

Sensitivity: best for smaller n or z componments