MindMap Gallery potentiometric analysis
Potentiometric analysis is a large type of analysis method that uses the electrochemical properties of substances to analyze. It has clear thinking and summarizes the relevant knowledge points about potentiometric analysis under analytical chemistry.
Edited at 2021-12-10 01:42:06Avatar 3 centers on the Sully family, showcasing the internal rift caused by the sacrifice of their eldest son, and their alliance with other tribes on Pandora against the external conflict of the Ashbringers, who adhere to the philosophy of fire and are allied with humans. It explores the grand themes of family, faith, and survival.
This article discusses the Easter eggs and homages in Zootopia 2 that you may have discovered. The main content includes: character and archetype Easter eggs, cinematic universe crossover Easter eggs, animal ecology and behavior references, symbol and metaphor Easter eggs, social satire and brand allusions, and emotional storylines and sequel foreshadowing.
[Zootopia Character Relationship Chart] The idealistic rabbit police officer Judy and the cynical fox conman Nick form a charmingly contrasting duo, rising from street hustlers to become Zootopia police officers!
Avatar 3 centers on the Sully family, showcasing the internal rift caused by the sacrifice of their eldest son, and their alliance with other tribes on Pandora against the external conflict of the Ashbringers, who adhere to the philosophy of fire and are allied with humans. It explores the grand themes of family, faith, and survival.
This article discusses the Easter eggs and homages in Zootopia 2 that you may have discovered. The main content includes: character and archetype Easter eggs, cinematic universe crossover Easter eggs, animal ecology and behavior references, symbol and metaphor Easter eggs, social satire and brand allusions, and emotional storylines and sequel foreshadowing.
[Zootopia Character Relationship Chart] The idealistic rabbit police officer Judy and the cynical fox conman Nick form a charmingly contrasting duo, rising from street hustlers to become Zootopia police officers!
potentiometric analysis
Overview
definition
Classification
direct potentiometry
The electromotive force of the primary battery and the activity of the ions to be measured
Features: Determine the equilibrium concentration of a certain ion of the element to be measured in the solution
potentiometric titration
The change in electromotive force determines the titration end point and the total concentration of the solution to be tested.
Features: Determine the total amount of the substance to be measured in the solution
Reference electrode and indicator electrode
reference electrode
Classification
Standard hydrogen electrode
Definition: At any temperature, the electrode potential of the standard hydrogen electrode is zero, which is the benchmark for measuring the electrode potential of all electrodes.
First level standard electrode
calomel electrode
Use KCl solution as internal filling liquid
Secondary standard electrode
At a certain temperature, the chloride ion activity of the solution in the electrode remains constant, and the potential of the calomel electrode remains constant.
Silver-silver chloride electrode
Immersed in a certain concentration of KCl solution
Secondary standard electrode
Indicating electrode
Classification
The first type of electrode: metal-metal ion electrode
The second type of electrode: metal-metal refractory salt electrode
The third type of electrode: metal-a variety of insoluble salt (complex) electrodes
The fourth type of electrode: inert electrode
It does not undergo electrode reaction itself, but only acts as a medium for electron transfer.
Made of chemically stable inert materials immersed in a solution containing ions of two different valence states of an element
The fifth type of electrode: ion selective electrode
membrane electrode
Ion selective electrode
Definition: It is an electrochemical sensor, the key part of which is the sensitive membrane. The sensitive membrane responds selectively to specific ions in the solution, forming a membrane potential to realize the detection of ions.
membrane potential
Diffusion potential (liquid junction potential)
When the interface concentrations between the two phases are different, the potential difference formed due to the different migration rates of free diffusion of ions
Donnan potential (interface potential)
Due to the selectivity of the membrane, only certain ions are allowed to pass through, resulting in uneven charge distribution at the two-phase interface, resulting in a potential difference.
pH glass electrode
Basic structure
Electrode cavity: glass tube
Sensitive membrane: glass membrane (bulb-shaped)
Internal reference solution: AgCl saturated buffer solution
Internal reference electrode: Ag/AgCl electrode
wiring
response mechanism
Internal reference solution | hydrated glue layer | dry glass | hydrated glue layer | liquid to be tested
Internal reference electrode | Internal reference solution | Hydration layer | Dry glass layer | Hydration layer | Test solution
Total potential E glass
Determination of pH
Battery
pH glass electrode|Test solution||Reference electrode
electromotive force
E battery = E reference - E indication
E battery=K 0.059pH
method
Test the known standard buffer solution first
Test the solution to be tested again
characteristic
asymmetric potential
Alkali difference and acid difference
Suitable for solutions with pH=1-10
>10, pH is lower than actual value
<1, pH is higher than actual value
Fluoride ion single crystal membrane electrode
Basic structure
Sensitive film: LaF3 single crystal film
Internal reference electrode: Ag/AgCl electrode
Internal reference solution: 0.1mol/L NaCl and 0.1mol/L NaF mixed solution
Response principle
E film=K 0.059pF
characteristic
Need to be used between pH5-7
High pH, exchange of hydroxide ions and fluoride ions in the solution
Low pH, fluoride ions generate hydrogen fluoride
interference
Acidity effect
Cation interference
matrix interference
Eliminate distractions
The added inert electrolyte is Total Ionic Strength Adjusted Buffer (TISAB)
Composition: Potassium nitrate NaCl-HAc Potassium citrate
Classification
crystal membrane electrode
Homogeneous membrane electrode
Single crystal membrane electrode
Polycrystalline film electrode
Heterogeneous membrane electrode
Amorphous membrane electrode
glass electrode
pH glass electrode
flow carrier electrode
Nitrate electrode
calcium electrode
neutral carrier electrode
Sensitizing electrode
gas sensing electrode
bioelectrode
Main performance parameters of ion selective electrodes
Linear range, detection limit, response slope
Potential selection coefficient
How to measure Kij
Mixed solution method (fixed interference method and fixed ion method)
Response time
Direct potentiometric measurement method
battery electromotive force
Ion selective electrode as positive electrode
For electrodes that respond to cations, take the positive sign
For electrodes that respond to anions, take the negative sign.
standard curve method
TISAB function
Maintain a large and relatively stable ionic strength to stabilize the activity coefficient
Maintain the solution within a suitable pH range to meet the requirements of the ion electrode
Mask interfering ions
One time standard addition method
advantage
Only one standard solution is needed, no standard curve is required
No need to add TISAB, the operation is simple and fast
Suitable for forming complex test solution systems
Continuous standard addition method-Glan plotting method
Factors affecting accuracy
measure temperature
Linear range and potential equilibrium time
Solution properties
interfering ions
Make the electrode produce a certain response
The coexisting ions and the ions to be measured complex or precipitate.
Potential measurement error
potentiometric titration
Titration key
Quickly titrate to find the approximate range of the stoichiometric point. When approaching a sudden jump, the volume of each drop should be controlled at 0.1ml. The end point is when a sudden jump in potential occurs.
Indicate electrode selection
Acid-base titration
pH glass electrode
redox titration
Zero-order electrode (commonly used Pt electrode)
coordination titration
some kind of ion electrode
Hg electrode
precipitation titration
If silver ions are involved in the reaction, a silver electrode can be used
Features
Compared with direct potentiometric method
advantage
More measurement objects and wider application units
There is no need to accurately measure the electrode potential and it is not affected by external factors such as temperature.
shortcoming
Titration takes a long time
Compared with ordinary titration method
advantage
It is better for the titration end point to coincide with the stoichiometric point
It can be used for titration of turbid or colored solutions where it is not suitable to observe color changes.
Can be used for continuous titration and automatic titration, suitable for micro analysis
shortcoming
The equipment is complex and costly
End point determined