MindMap Gallery potentiometric analysis
Instrumental analysis and potentiometric analysis are methods that use the electrical and electrochemical properties of substances to analyze. It usually makes the sample solution to be analyzed form a chemical battery (electrolytic cell or primary cell), and then based on certain physical quantities of the composed battery (such as the electromotive force between the two electrodes, the current or charge through the electrolytic cell, the electrolyte resistance, etc.) and its chemical quantity.
Edited at 2023-05-21 22:03:27One 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 analysis
Overview
definition
A method of analysis using the electrical and electrochemical properties of substances. It usually makes the sample solution to be analyzed form a chemical battery (electrolytic cell or primary cell), and then based on certain physical quantities of the composed battery (such as the electromotive force between the two electrodes, the current or charge through the electrolytic cell, the electrolyte resistance, etc.) and its chemical quantity.
Classification
conductivity analysis
potentiometric analysis
electrolytic analysis
capacitance analysis method
Polarographic and voltammetric analysis
Coulomb analysis
Principle of potentiometric analysis
Electrode potential requirements of the reference electrode: known and constant, easy to make and long life
The electrode potential of the indicating electrode changes with the activity of the ion to be measured
The composition and structure of ISE
Key: Choose a membrane that responds selectively to only specific ions in solution
Ion selective electrode
Composition and structure of pH-ISE
Internal reference electrode: Ag-AgCl electrode
Filling liquid: usually 0.1 mole HCl solution per liter
Glass film: 30-100 microns
Glass membrane electrode principle
It must be soaked in an aqueous solution for 24 hours before use. The sodium ions on the surface exchange with the hydrogen ions in the water to form a "hydration layer"
membrane potential
diffusion potential
Diffusion between different ions within the membrane phase/different ions of the same concentration (free diffusion, no selective compulsion); assuming that the hydration layers on both sides of the glass membrane are completely symmetrical, the diffusion potentials generated on both sides are equal in size and opposite in direction.
Dornan potential (boundary potential)
Selective permeability membranes or ion exchange membranes prevent at least one ion from diffusing from one liquid phase to another or exchanging with ions in the solution, resulting in uneven charge distribution between the two phase interfaces - electric double layer potential difference
type
rigid matrix electrode
Crystal membrane electrode (fluorine electrode)
Internal reference solution; 0.1mol/L NaCl and 0.1mol/L NaF mixed solution (fluoride ions are used to control the potential of the inner surface of the membrane, and chloride ions are used to fix the potential of the reference electrode)
It has high selectivity and needs to be used between pH 5-6. When the pH is high, the hydroxide ions in the solution exchange with the fluoride ions in the lanthanum fluoride crystal membrane. When the pH is low, HF or HF2- is generated.
Various types of ion selective electrodes
Potentiometric method
Electrode potential of membrane electrode
Electrode selectivity coefficient Kij
If the measured ion is i, the charge is ni; the interfering ion is j, the charge is nj
Usually Kij<<1, the smaller the Kij value, the higher the selectivity of the electrode.
potentiometric titration
Method for determining the end point of potentiometric titration
Method for measuring ion activity (concentration)
direct potentiometry
standard curve method
standard addition method