MindMap Gallery Potentiometric method and double indicator electrode amperometric titration method
Potentiometric method is an analytical method that uses the electromotive force of a primary battery to determine the content of the analyte. It is divided into direct potentiometric method and potentiometric titration method. The electrode consists of a reference electrode and an indicator electrode inserted into the test solution. Commonly used reference electrodes are saturated calomel electrodes (SCE) or silver-silver chloride electrodes. There are four types of indicating electrodes: metal-metal ion electrodes (type 1 electrodes), metal-metal refractory electrodes (type 2 electrodes), non-metal electrodes (type zero electrodes) and ion selective electrodes (membrane electrodes).
Edited at 2023-03-19 14:39:52One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
Potentiometric method and double indicator electrode amperometric titration method
liquid junction potential
When two electrolyte solutions with different compositions or different concentrations come into contact to form an interface (i.e., there is a liquid junction battery), the two electrolytes are separated by an ion-permeable separator or salt bridge. Due to the different ion diffusion rates, ion formation occurs on both sides of the interface. The potential difference is called the liquid junction potential, or liquid junction potential for short.
The function of the salt bridge is
Separate the positive and negative electrolyte solutions to prevent them from mixing with each other
communication circuit
Eliminate or reduce liquid junction potential
Maintain charge balance during the reaction to make the reaction proceed smoothly
Stable electrode potential
potentiometric method
reference electrode
Saturated calomel electrode
Electrode composition: Hg,Hg2Cl2(s)|KCl(sat.)
Electrode reaction: Hg2Cl2 2e⇌2Hg 2Cl-
Simple structure, stable potential, easy to use, commonly used
Double salt bridge saturated calomel electrode
In SCE, KCI reacts chemically with the ions in the test solution. As a result, it not only reduces the accuracy of the measurement, but also blocks the salt bridge channel, making the measurement impossible.
The ion to be measured is CI- or K. Penetration of KCI into the test solution in SCE will cause errors.
When the test solution contains I, CN-, Hg and S2- plasma, the potential of the SCE will change (drift) slowly and orderly over time, and in severe cases, the function of the SCE electrode may even be destroyed.
When the residual liquid junction potential between SCE and the test solution is large and unstable, it is often used in non-aqueous titrations.
When the temperature of the test solution is high or low, the double salt bridge saturated calomel electrode can maintain a certain temperature gradient and reduce the temperature hysteresis effect of SCE.
Silver-silver chloride electrical grade
Electrode composition: Ag,AgCl|KCl(a)
Electrode reaction: AgCl e⇌Ag Cl-
When Cl- activity and temperature are constant, the electrode potential of SSE is a constant value.
Indicating electrode
metal-based electrode
Metal-metal ion electrode
Type 1 electrode
It consists of a solution in which a metal that can undergo a redox reaction is inserted into the metal rot, referred to as a metal electrode.
The electrode potential of this type of electrode is related to the activity (concentration) of the corresponding metal ion.
Metal-metal refractory salt electrode
It consists of coating a metal with a refractory salt of the same metal on the surface and inserting an anionic solution of a refractory salt of the metal.
The electrode potential of this type of electrode can reflect the activity (concentration) of poorly soluble salt anions
This type of electrode can also be used to measure the Ksp of some poorly soluble salts
Metal-metal refractory oxide electrode
Mercury-EDTA electrode
Type III electrode
Metallic mercury (or mercury wire) is composed of a solution containing a small amount of Hg2-EDTA complex and the measured metal ion Mn
The stability constant K(MY) of the M n complex with EDTA is smaller than K(HgY)
erotic metal electrode
Category Zero Electrode
It is composed of an inert metal (Pt or Au) inserted into an ionic solution of two different oxidation states of the same element.
Ion selective electrode
ISE is a type of electrochemical sensor made of a membrane that is sensitive to the ions to be measured. It is also called a membrane electrode. The electrode produces a selective response to the ions to be measured in the solution.
composite electrode
It is an electrode form that combines the indicating electrode and the reference electrode during production.
direct potentiometry
Hydrogen ion activity measurement
pH glass electrode
Measurement precautions
Use within the pH range
The temperature of the standard buffer solution is consistent with that of the test solution
Glass electrodes need to be hydrated
Other ion activity (concentration) determination
Ion selective electrode
basic electrode
crystal electrode
Homogeneous membrane electrode
Heterogeneous membrane electrode
Amorphous electrode
rigid matrix electrode
flow carrier electrode
Positively charged carrier
negatively charged carrier
neutral carrier
Sensitizing electrode
gas sensing electrode
enzyme electrode
Common ion selective electrodes
Chlorine electrode
rigid matrix electrode
calcium electrode
Ammonia gas sensing electrode
Quantitative and qualitative
Effect of ionic strength
Effect of solution acidity
two measurement method
potentiometric titration
Principle: Based on the titration reaction, near the stoichiometric point, the potential sudden change will be large.
Use the E-V curve method, its first-level derivatives and second-level derivatives methods
Double indicator electrode amperometric titration method
Also known as permanent stop titration method
Quick and easy, the end point judgment is intuitive and accurate, and the instrument used is simple
electrochemical cell
Primary battery: chemical energy → electrical energy
Primary cell symbol: (-)Zn|ZnSo4(1mol/L)||CuSo4(1mol/L)|Cu( )
Electrolytic cell: electrical energy → chemical energy
Electrolytic cell and primary battery are reverse reactions of each other
When no current is consumed, E=E( )-E(-)
Potentiometric electrochemical analysis
potentiometric method
direct potentiometry
potentiometric titration
Voltammetry
Polarography
stripping voltammetry
Amperometric titration
conductivity method
direct conductivity method
conductometric titration
electrolysis
electrogravimetric method
coulomb method
Coulomb titration