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MindMap Gallery analytical chemistry
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analytical chemistry
This is a mind map about errors and analytical data processing. The main contents include: statistical processing of limited experimental data, significant figures and their operation rules, and the accuracy and precision of measured values.
Edited at 2024-12-05 22:11:47- Lemon 8 registration and login flow chart
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- 稲盛和夫氏 私の今世の経験は、全部をまとめると、この36つだけです！
これは稲盛和夫に関するマインドマップです。私のこれまでの人生のすべての経験は、ビジネスの明確な目的と意味、強い意志、売上の最大化、業務の最小化、そして運営は強い意志に依存することを主な内容としています。
- 計画テンプレート - 月次計画ボード
かんばんボードのデザインはシンプルかつ明確で、計画が一目で明確になります。毎日の進捗状況を簡単に記録し、月末に要約を作成して成長と成果を確認することができます。 実用性が高い：読書、早起き、運動など、さまざまなプランをカバーします。 操作簡単：シンプルなデザイン、便利な記録、いつでも進捗状況を確認できます。 明確な概要: 毎月の概要により、成長を明確に確認できます。 小さい まとめ、今月の振り返り掲示板、今月の習慣掲示板、今月のまとめ掲示板。
analytical chemistry
- Lemon 8 registration and login flow chart
Find a streamlined guide created using EdrawMind, showcasing the Lemon 8 registration and login flow chart. This visual tool facilitates an effortless journey for American users to switch from TikTok to Lemon 8, making the transition both intuitive and rapid. Ideal for those looking for a user-centric route to Lemon 8's offerings, our flow chart demystifies the registration procedure and emphasizes crucial steps for a hassle-free login.
- 稲盛和夫氏 私の今世の経験は、全部をまとめると、この36つだけです！
これは稲盛和夫に関するマインドマップです。私のこれまでの人生のすべての経験は、ビジネスの明確な目的と意味、強い意志、売上の最大化、業務の最小化、そして運営は強い意志に依存することを主な内容としています。
- 計画テンプレート - 月次計画ボード
かんばんボードのデザインはシンプルかつ明確で、計画が一目で明確になります。毎日の進捗状況を簡単に記録し、月末に要約を作成して成長と成果を確認することができます。 実用性が高い：読書、早起き、運動など、さまざまなプランをカバーします。 操作簡単：シンプルなデザイン、便利な記録、いつでも進捗状況を確認できます。 明確な概要: 毎月の概要により、成長を明確に確認できます。 小さい まとめ、今月の振り返り掲示板、今月の習慣掲示板、今月のまとめ掲示板。
- Recommended to you
- Outline
Error and analytical data processing
Statistical processing of limited amount of experimental data
Suspicious data selection
Q test
Determine whether outliers should be discarded
G test method (Grubbs method)
Determine whether outliers should be discarded
Significance test
t-test
Used to compare the average value with the standard value or the average value of two groups
Determine whether there is a systematic error
F test
Used to test whether there is a significant difference in the precision of two sets of data
Accuracy and precision of measured values
Accuracy
Characterizes the degree of agreement between the measured value and the true value
expressed as error
The smaller the error, the higher the accuracy.
Contains absolute error and relative error
Affected by systematic errors
Precision
Characterizes the degree to which parallel measurements agree with each other.
expressed as deviation
The smaller the deviation, the higher the precision.
There are expression methods such as average deviation, relative average deviation, standard deviation and relative standard deviation.
Affected by accidental error
relation
Precision is the prerequisite for ensuring accuracy
High precision does not necessarily mean high accuracy
After eliminating systematic errors, high precision leads to high accuracy.
Valid figures and their operation rules
Meaning and digits of significant figures
actual measurable numbers
The number of digits is determined by the accuracy of the instrument
Affects the relative error of measurement
Zero has different effects in different positions
The number of significant digits for a logarithmic value depends on the decimal part
Amendment rules
"Round to six and leave even."
Round to the required number of digits at one time
Avoid multiple revisions
Calculation rules
For addition and subtraction, the data with the fewest digits after the decimal point shall prevail.
Multiplication and division are based on the data with the fewest number of significant digits.
If the first digit is ≥8, you can remember one more significant digit.
Calculation results retain the correct number of digits
Titration analysis results generally retain four significant figures.
Deviation shall be kept to two significant figures.
Chapter 7 Gravimetric Analysis and Precipitation Titration-24 Traditional Chinese Medicine.pptx
Content summary
This chapter describes the principles and conditions of the three indicating end points of the silver method, including the requirements for precipitation by gravimetric analysis, precipitation conditions, weighing form of precipitation and calculation of results, as well as factors affecting the purity of precipitation. This chapter focuses on the definition, application, titration curve, and classification of silver methods, including the selection of indicators such as Mohr's method, Forhard's method, and Fayant's method. It also explains how to use different indicators. Direct titration and back titration with titrant are carried out, and the precautions for determination of Cl- by Forhard method are described in detail.
This article mainly introduces the principle of adsorption indicators, the application of Fayang Judicial and the factors affecting the solubility of precipitation.
Keywords
Gravimetric analysis
silver measurement
indicator
adsorption indicator
fayang justice
Precipitate solubility
Key sentences
Gravimetric analysis and precipitation titration are the focus of this chapter, and they have important applications in the principles and conditions of the indicated end point of the silver assay.
Mohr's method is one of the silver measurement methods. The indicator is potassium chromate, which is suitable for measuring Cl-, Br- plasma. Pay attention to the acidity of the solution and the amount of indicator.
The Forhard method is suitable for measuring Cl-, Br-, I- plasma. It should be noted that errors may occur if you forget to add nitrobenzene during the measurement process, and violent shaking should be avoided during the titration process to prevent the results from being affected.
When selecting an indicator, the size of the titration jump depends on the concentration of the solution and the solubility product constant of the precipitation. The larger the Ksp, the larger the titration jump. Therefore, the appropriate indicator and solution concentration should be selected according to the actual situation during operation.
The principle of the adsorption indicator is that when the colored organic dye is adsorbed by the charged precipitated colloidal particles, the color changes due to structural changes.
Fayang Judi took the titration of Cl- with Ag as an example. The selection of indicators and titration conditions are the focus of the article.
Factors affecting the solubility of precipitation include salt effect, coexisting ion effect, acid effect and coordination effect.
In the precipitation method, the precipitation form and the weighing form can be the same or different, which is related to the properties of crystalline precipitation and amorphous precipitation.
The article summarizes the introduction of key knowledge points such as the classification of gravimetric methods and factors affecting precipitation solubility.
Content analysis summary
Chapter 1: Silver Measurement Method and Its Application
The silver method is a measurement method that utilizes the reaction to generate poorly soluble silver salts, and can be used to measure a variety of ions.
Chapter 2: Titration curve and titration conditions
Draw a titration curve for titrating a silver nitrate solution to a NaCl solution, and calculate the ion concentration based on the volume of the titrant added and the concentration of the solution.
Before titrating to the stoichiometric point, when 19.98ml (-0.1%) AgNO3 solution is added, 99.9% of Cl- combines with Ag to form a precipitate.
At the stoichiometric point, add 20.02ml (0.1%) AgNO3 solution. At this time, there is an excess of Ag.
After the stoichiometric point, when the AgNO3 solution is continued to be added, there are no more chloride ions in the precipitate.
Titration conditions include indicator dosage, solution acidity, shaking speed and treatment of interfering ions.
The dosage of indicator should be appropriate. Excessive dosage will cause the endpoint to appear early, while insufficient dosage will cause the endpoint to lag behind.
The acidity of the solution should be within the weak alkaline range (pH=6.5~7.2). Too high or too low acidity will affect the formation of precipitation.
Violent shaking should be avoided when shaking to prevent the release of precipitated and adsorbed chloride ions, which will affect the end point judgment.
Interfering ions related to precipitation generation should be removed in advance or corresponding measures should be taken for treatment.
Chapter 3: Mohr’s method and its applications
Mohr's method is a silver method with K2CrO4 as the indicator. It can be used to determine chloride ions, bromide ions and thiocyanate ions in two ways: direct titration and back titration.
Titration in acidic media can prevent hydrolysis of iron ions and interference from phosphates and arsenates.
When measuring the chlorine content in salts, the Mohr method requires a pH value of about 6.5 to 10.5. Too high or too low acidity will have an impact.
In terms of application scope, Mohr's method is suitable for the determination of chlorine content in the following salts, such as KCl, BaCl2, etc.
Chapter 4: Forhard’s method and its applications
Forhard's method is a silver method based on iron ammonium vanadium indicator, which can be used to determine halogen ions (such as Cl-, Br-, I-, etc.).
When measuring halide ions in acidic media, attention should be paid to the influence of interfering ions in the solution.
When using the Forhard method to measure chloride ions, organic solvents such as nitrobenzene should be added first to cover the precipitation.
Summary: This report provides a detailed analysis and summary of the silver method and its application, titration curve and titration conditions, Mohr's method and its application, Forhard's method and its application.
Argyrometry: A commonly used chemical analysis method that can be used to determine a variety of ions.
Titration curve: Draw the titration curve of silver nitrate solution titrating NaCl solution, and calculate the ion concentration based on the volume of added titrant and the concentration of the solution.
Titration conditions: Including factors such as indicator dosage, solution acidity, shaking speed, and treatment of interfering ions.
Mohr's method: The silver method with K2CrO4 as the indicator is suitable for the determination of chlorine content in various salts.
Forhard method: A silver method based on iron ammonium vanadium indicator, suitable for the determination of halogen ions.
The above content is generated based on your article, if you need more details or need to expand on other topics, please feel free to let me know.
Gravimetric analysis
volatilization method
direct method
Absorbents absorb volatile components
Add amount to calculate content
Suitable for volatile substances
indirect method
Weigh the residue after evaporation
Calculate volatile component content based on mass difference
Extraction method
solvent extraction separation
Utilize the dissolution properties of the component being measured
Involving concepts
partition coefficient
Distribution ratio
Extraction efficiency
liquid-liquid extraction
Applications in daily life and chemical analysis
Carbon tetrachloride extracts iodine
Laundry etc.
Solid-liquid extraction (leaching)
Applications in daily life and chemical analysis
Wide range of applications
precipitation method
Precipitation reaction between reagent and component to be tested
After treatment, the precipitate was weighed to calculate the content.
Precipitated form requirements
Low solubility
pure
Large particles
Easy to convert to weighing form
Weighing form requirements
Composition determined
Stable properties
High molar mass
Factors affecting precipitation solubility
Same ion effect
salt effect
acid effect
coordination effect
Effect of precipitation purity
Co-precipitation
Post-precipitation
Precipitation condition selection
According to the type of sedimentation
Analysis result calculation
According to the chemical reaction measurement relationship
Gravimetric analysis and precipitation titration
Overview of precipitation titration
Principles and conditions
Based on precipitation reaction
Precipitation requires low solubility
Rapid response and quantitative
Adsorption does not affect titration and end point judgment
Have appropriate means of indicating endpoints
The silver method is a commonly used precipitation titration method.
For determination of specific ions and related organic compounds
Titration curve and jump range
Take pM or pX as the ordinate
The volume of titrant is on the abscissa
The jump range depends on the solution concentration and the precipitation solubility product constant.
The greater the concentration and the smaller the Ksp, the larger the jump range.
Classification and application of silver measurement method
Morfa
Use K₂CrO₄ as indicator
Direct titration of Cl⁻, Br⁻ under neutral and weakly alkaline conditions
Titration conditions include controlling indicator dosage, acidity
Shake vigorously during titration
Be aware of interfering ions
Can directly titrate Cl⁻, Br⁻, CN⁻
Back titration Ag⁺
It is not suitable to measure I⁻ and SCN⁻
Forhard method
in acidic solution
Use NH₄Fe(SO₄)₂ as indicator
NH₄SCN or KSCN titration
Ag can be titrated directly⁺
Backtitration of halides and thiocyanates
When back titrating Cl⁻, measures must be taken to prevent precipitation transformation
Wide range of applications
Less interference
fayang justice
Adsorption indicator
The endpoint is indicated by a color change caused by adsorption of indicator ions by precipitation.
Titration conditions include
Increase precipitation surface area
Control pH
Avoid exposure to bright light
Ensure that the measured ion concentration is not too dilute
Can measure X⁻, SCN⁻, Ag⁺ plasma
Application of Redox Titration
iodometric method
direct iodometric method
Determination of reducing substances
Suitable for determining the content of reducing substances
For example, the measurement of vitamin C
Source of error
Error caused by I₂ volatilization
Error caused by oxidation of I⁻
Things to note
Control solution acidity
Acidity affects reaction rates and equilibrium
Avoid exposure to bright light
Prevent I₂decomposition
indicator
starch
Starch forms a blue complex with I₂ as an endpoint indication
I₂self
Color change of I₂ as end point indicator
Standard solution calibration
I₂ solution and Na₂S₂O₃ solution need to be calibrated in advance
Ensure titration accuracy
Wide range of applications
Determination of available chlorine content in bleaching powder
Determination of hydrogen peroxide content
Determination of copper content in bile vitriol
indirect iodometric method
Determination of oxidizing substances
Indirect determination of the content of oxidizing substances through reducing agents
For example, measuring the content of certain oxidizing substances
Source of error
Same as direct iodometric method
Things to note
Same as direct iodometric method
indicator
Same as direct iodometric method
Standard solution calibration
Same as direct iodometric method
Wide range of applications
Same as direct iodometric method
Potassium permanganate method
advantage
Strong oxidizing ability
Can oxidize a variety of reducing substances
No additional indicator required
The color change of potassium permanganate itself serves as an endpoint indicator
shortcoming
Standard solution is unstable
Potassium permanganate solution is easy to decompose
complex reaction
Possible side effects
Poor selectivity
Not very selective for the oxidation of certain substances
The reaction products are different at different acidities
Acidity affects reaction specificity and endpoint judgment
application
direct titration
Determination of various reducing substances
Such as measuring H₂O₂ content
backtitration
Determination of oxidizing substances
Such as measuring the calcium content in calcium salts
indirect titration
Determination of certain non-oxidizing substances
Such as determining the content of certain specific substances
Titration conditions
Need strict control
Including factors such as temperature and acidity
Other methods
potassium dichromate method
advantage
Can be used to measure a variety of substances
application
Determination of total iron content in iron ore
Determination of total iron content by redox reaction
Sodium nitrite method
application
Titration of organic amines
Titration using the oxidizing properties of sodium nitrite
Cerium measurement method
Utilize Ce⁴⁺oxidizing properties
Determination of reducing substances
Determination of reducing agent content by redox reaction
Potassium bromate method
Prepare standard solution directly
Calibration by reaction with I⁻
Calibration using the reaction of potassium bromate and iodide
application
Determine certain substances
Such as determining the content of certain specific substances
Titration with calibrated potassium bromate solution
redox titration
redox balance
Nernst equation
Calculate the electrical counter electrode potential
Reflects the influence of oxidation and reduction concentration
Effects of temperature and other factors on electrode potential
Conditional electrode potential correction
Effect of ionic strength
Side effects
A constant under certain conditions
Redox reaction direction
Judgment basis
counter electrode potential
reaction conditions
Electromotive force E > 0
response measure
equilibrium constant
Relationship with counter electrode potential
conditional equilibrium constant
Consider side effects
Conditional equilibrium constants for redox reactions
Calculation method
Derived from the Nernst equation
When the reaction reaches equilibrium, the potentials of the two opposite electrodes are equal.
Influencing factors
Reaction electron transfer number
counter electrode potential
Judgment of completeness of response
Conditional equilibrium constant requirements
Large enough to ensure complete reaction
Effect of reaction type
Different reaction types such as 1:1 type, 1:2 type, etc.
Potential difference requirements
Usually the conditional potential difference between the two pairs is greater than 0.4V
Factors affecting the rate of redox reactions
Reactant concentration
The greater the concentration, the faster the reaction
Possibility limited by other factors
temperature
Raising temperature speeds up reaction
Excessively high temperatures can cause problems
Decomposition of reactants
Increased side effects
catalyst
positive catalytic effect
speed up reaction rate
example
Mn²⁺ catalyzes certain redox reactions
induction
One reaction promotes another reaction
Principle of redox titration
Titration curve
abscissa
Adding amount of titrant
ordinate
Electrode potential
Jump range
Depends on Eθ’ and medium conditions
Independent of titrant concentration
Stoichiometric point potential value and sudden jump range calculation
Calculated through relevant formulas
Indicator selection
self-indicator
Use the color change of the standard solution or the substance being measured itself
special indicator
Produce special colors with oxidizing or reducing agents
redox indicator
Endpoint indication based on color change between oxidized and reduced states
Selection principle
The conditional potential of the indicator falls within the titration jump interval.
Try to be consistent with the stoichiometric point potential
Methods to improve the selectivity of coordination titrations
Control acidity
Differences in stability based on the complexes formed between metal ions and EDTA
Selective titration at different acidities
selective titration discriminant
Δlgc·K stable ≥ 6
When cM = cN
ΔlgK stable ≥ 6
Effect of acidity on titration
Affects the formation of complexes
Too high or too low acidity may inhibit the formation of complexes
Acidity range for selective titration
Need to be determined based on the properties of the specific metal ion
Use masking agents
coordination masking method
Add masking agent to reduce interfering ion concentration
Masking agents form stable complexes with interfering ions
Thereby reducing the impact of interfering ions on titration
Choose the right masking agent
Need to be selected based on the nature of the interfering ions
Types of masking agents
organic masking agent
Such as citric acid, tartaric acid, etc.
Inorganic masking agent
Such as cyanide, sulfide, etc.
precipitation masking
Precipitate interfering ions
Add specific reagents to precipitate interfering ions
Does not participate in titration reaction after precipitation
Choose the right precipitant
Need to be determined based on the solubility of interfering ions
redox masking
Change the valence state of interfering ions
through redox reactions
Convert interfering ions into forms that do not interfere with the titration
Choose the right redox agent
Need to be selected based on the redox properties of interfering ions
Use of unblocking agents
Release masked ions under specific conditions
Allow masked ions to re-participate in the titration reaction
Improve titration selectivity
Types and conditions of use of unblocking agents
Need to be selected according to the nature of the masking agent and titration requirements
Other ways to improve selectivity
Choose the right indicator
Color change range of indicator
Need to match the titration range of the titrated ion
Indicator sensitivity and selectivity
Affects the accuracy and selectivity of titration
temperature control
Effect of temperature on reaction rates and equilibrium
Proper temperature can improve reaction selectivity
Titration speed control
Choice of fast titration and slow titration
Determine the titration rate based on the kinetics of the reaction
Stirring of solution
Increase solution uniformity
Helps improve reaction selectivity and accuracy
potentiometric titration
Titration using potential changes
Suitable for certain systems that are difficult to titrate using traditional methods
Spectrophotometry
Titration using spectral changes
Suitable for systems with obvious spectral changes
Fluorometric titration
Titration using changes in fluorescence intensity
Suitable for titration analysis of fluorescent substances
mass spectrometry
Titration using mass analysis
Ideal for analyzes requiring high sensitivity and selectivity
NMR
Titration using NMR signal changes
Suitable for systems sensitive to specific atomic environments
chromatography
Titration using separation techniques
Suitable for titration analysis of specific components in complex systems
coordination titration
EDTA and EDTA metal complexes
EDTA properties
Ethylenediaminetetraacetic acid (H₄Y) and its disodium salt (Na₂H₂Y)
Acidic and coordinating properties
There are different forms of existence at different pH
Solubility is different
Complexes formed with metal ions are stable
Coordination ratio is simple
Fast response
Good water solubility
Color changes regularly
Side reactions and condition stability constants in EDTA titration
Side reaction coefficient
The acid effect coefficient of complexing agent Y (αY(H)) is affected by H⁺
The coordination effect coefficient of metal ion M is affected by other complexing agents
The side reaction coefficient is used to correct the impact of side reactions on the main reaction
conditional stability constant
Stability constant after considering the influence of side reactions
Reflects the actual progress of the reaction
Side reaction coefficients need to be combined with the calculation
Its size affects the feasibility and jump range of coordination titration.
Titration curve and condition selection for coordination titration
Titration curve
Taking pM as the ordinate
The volume of the titrant or the completeness of the reaction is the abscissa
The jump range is related to the metal ion concentration and the stability of the MY complex
The greater the concentration, the higher the stability, and the larger the jump range.
Condition selection
Accurate titration requires lg(cM·K'MY) ≥ 6
Acidity plays an important role in titration
Need to be controlled between the highest acidity (pHmin) and the lowest acidity (pHmax)
The maximum acidity is calculated from lgαY(H) = lgKMY – 8
Minimum acidity prevents hydrolysis of metal ions
metal ion indicator
How indicators work
Metal ions and indicators form color complexes (MIn)
During the titration process, a displacement reaction occurs between MIn and MY.
Solution color change indicates endpoint
The indicator should have a color complex that is significantly different from the color of the indicator.
The stability of MIn is lower than that of MY and other conditions
Indicator selection and application
Select the indicator based on the metal ion pM jump range near the stoichiometric point
Make its discoloration point within this range
Commonly used indicators include chrome black T, xylenol orange, etc.
When using, attention should be paid to the applicable pH range and selectivity of metal ions.
Non-aqueous acid-base titration method
Solvent classification and properties
protic solvent
Basic protic solvent
neutral protic solvent
acidic protic solvent
aprotic solvent
Appearly basic aprotic solvent
Inert aprotic solvent
Effect of solvent properties
Effect of dissociation on titration
Effect of acidity and alkalinity on titration
Effect of polarity on titration
Leveling effect and differentiation effect
leveling effect
Acids or bases of different strengths exhibit the same strength in a specific solvent
Conditions and applications of leveling effect
Discrimination effect
Can distinguish the strength of acid or base
Distinguish conditions and applications of effects
Determination of mixed acid and base components
Use the leveling effect and discrimination effect to determine separately or step by step
Determination methods and procedures
Basic principles of acid-base titration
Titration of Strong Acid and Strong Base
Titration curve reflects changes in pH
Changes in pH as titrant is added
The shape of the titration curve is related to the concentration of acid and base
Jump range size
Relationship between jump range and acid-base concentration
The jump range affects the accuracy of titration
Indicator selection
The color change point of the indicator should be within the sudden jump range
Commonly used indicators such as methyl orange, phenolphthalein
One-way weak acid (base) titration
Titration of weak acids with strong bases
The response is not complete
The jump range is affected by the nature and concentration of the acid
Discriminant for accurate titration of weak acids
Ca • Ka ≥ 10⁻⁸
Ca is the concentration of acid, Ka is the dissociation constant of acid
Indicator selection
Phenolphthalein that changes color in the alkaline range, etc.
Titration of strong acid and weak base
The response is not complete
The jump range is affected by the nature and concentration of the alkali
Discriminant for accurate titration of weak bases
Cb • Kb ≥ 10⁻⁸
Cb is the concentration of the base, Kb is the dissociation constant of the base
Indicator selection
Methyl orange that changes color in the acidic range, etc.
Polybasic acid (base) titration
Step titration conditions
Satisfies Ca • Kai ≥ 10⁻⁸
Kai / Kai 1 ≥ 10⁴
Kai is the dissociation constant at all levels
Calculate stoichiometric point pH
Calculated based on dissociation constants at various levels
Choose the right indicator
Choose indicator based on pH value
Acid-base titration
Theoretical basis of acid-base balance
Acid-base definition and reaction essence
Acid is a substance that donates protons
Bases are substances that can accept protons
The essence of acid-base reaction is proton transfer
Achieved via solvent and protons
Conjugate acid-base pairs transform into each other in reactions
Solvent proton autotransfer reaction
Proton transfer reaction between solvent molecules
Equilibrium constant affects acid-base titration jump range
Acid-base strength and dissociation constant
The strength of an acid or base depends on its ability to donate or accept protons
The product of the dissociation constant of a conjugate acid-base pair is equal to the ionic product constant of water
Calculation of pH of acid and alkali solutions
Strong acid and strong base solution
Calculate hydrogen ion concentration or hydroxide ion concentration based on solution concentration
Then get the pH value
Weak acid and weak base solution
Consider acid or base dissociation equilibrium
Get pH value by approximation or precise calculation
Polymeric weak acids and weak bases need to consider all levels of dissociation
Amphoteric substance solution or weak acid and weak base salt
Calculate pH value based on its proton conditional expression and related equilibrium constants
buffer solution
Composed of a weak acid and its conjugate base or a weak base and its conjugate acid
It has the ability to resist the influence of a small amount of strong acid and alkali and maintain a relatively stable pH.
pH value can be calculated by the formula
Acid-base indicator
Color changing principle
Based on the color difference between acidic and basic forms
Changes in solution pH cause structural changes in the indicator
cause color change
Such as methyl orange, phenolphthalein, etc.
Discoloration range
pH=pKHIn±1
The narrower the discoloration range, the more sensitive the color change is.
Affected by factors such as temperature, electrolyte, indicator dosage, etc.
Indicator selection principles
Bring the color change point close to the stoichiometric point
Or the color change range falls within the titration jump range
Introduction to Titration Analysis
Fundamentals of Titration Analysis
basic terminology
Add the standard solution drop by drop to the test solution
chemical reaction occurs
The color change of the indicator indicates the end point of the titration
Calculate the content of the tested component based on the concentration and volume of the standard solution
Inconsistency between the stoichiometric point and the titration endpoint results in endpoint error
Titration curves and jumps
Take the standard solution volume or titration percentage as the abscissa
The characteristic parameters of the content change of the measured substance are plotted as the ordinate.
The sudden jump range reflects the sudden change in the concentration of the measured substance before and after the stoichiometric point.
The color change point of the indicator should be within the sudden jump range
Titration analysis requirements
Chemical reactions are quantitative, complete, and rapid
There is a simple and reliable way to determine the end point
Titration method
direct titration
Applicable conditions
backtitration
Applicable conditions
displacement titration
Applicable conditions
indirect titration
Applicable conditions
Standard solutions and reference materials
Standard solution with known accurate concentration
Reference materials are used to directly prepare or calibrate standard solutions
It needs to meet the conditions of high purity, stability, constant composition, and large molar mass.
Preparation methods include direct method and calibration method
Titration analysis calculation
Concentration expression method
Amount concentration of substance (c)
Titer (T)
The two can be converted into each other
Calculation principle
Determine based on chemical reaction measurement relationship
Involving standard solution preparation and calibration
Analysis result calculation
Includes liquid-liquid calibration
Calibrate with reference material
Concentration calculation in cases such as direct preparation
and percentage calculation
Introduction to Analytical Chemistry
The tasks and functions of analytical chemistry
Study chemical information such as substance composition, content, structure and form
Material composition analysis
Determine the type of element in the sample
Identify functional groups in compounds
Determination of substance content
Quantify the concentration or mass percentage of each component in a sample
structural analysis
Explore the three-dimensional structure of molecules
Study the relationship between structure and material properties
Morphological analysis
Analyze morphological characteristics such as valence state and crystalline state of substances
Used in many fields such as industry, medicine, environment, etc.
Raw material analysis
Determine the purity and composition of raw materials
Assess raw material quality
Quality control
Monitor quality changes during production
Ensure product quality meets standards
disease diagnosis
Using biomarkers for diagnosis
Analyze body fluid or tissue samples
Environmental monitoring
Monitor pollutants in air, water and soil
Assess environmental quality status
Classification of Analytical Chemistry
Classified by tasks
Qualitative analysis
Determine the constituent elements or functional groups of a substance
Identify elements using spectroscopy
Identifying functional groups through chemical reactions
Quantitative analysis
Determine the content of each component
Precise measurements using titration
Apply gravimetric method to determine mass fraction
structural analysis
Explore the three-dimensional structure and its relationship with performance
Analyzing molecular structure using X-ray crystallography
Applying Nuclear Magnetic Resonance (NMR) Technology to Study Molecular Dynamics
Morphological analysis
Pay attention to valence state, crystal state and other forms
Analysis of redox status using electrochemical methods
Using microscopy techniques to observe crystal morphology
Classify by object
Inorganic analysis
Study the chemical properties of inorganic substances
Analyze metallic and non-metallic elements
Study the properties of inorganic compounds
organic analysis
Study the chemical properties of organic matter
Analyze the structure of organic compounds
Study organic reactions and mechanisms
Classification by method
chemical analysis
Titration analysis
Determination of pH value using acid-base titration
Analysis of oxidizing or reducing agent content by redox titration
gravimetric analysis
Isolation and weighing of specific components by precipitation
Application of volatilization method to determine the content of volatile components
Instrumental analysis
Electrochemical analysis
Determination of ion concentration using potentiometric method
Conductivity measurement using galvanic method
Spectral analysis
Analyzing organic molecules using UV-visible spectroscopy
Application of infrared spectroscopy to study molecular vibrational modes
Chromatography
Separation of mixture components by gas chromatography
Analyze complex samples using high-performance liquid chromatography
Development history and trends of analytical chemistry
Development history
Sprung from Ancient Alchemy
Preliminary exploration of material changes and transformations
Form the accumulation of early chemical knowledge
Experienced the promotion of Boyle and Lavoisier
Boyle proposed laws of chemical reactions
Lavoisier laid the foundation of modern chemistry
Gradually developed into modern analytical chemistry
Experienced three major changes
Transition from technology to science
Evolution from classic to modern
Analytical methods that provide comprehensive information
Development trend
Develop towards high sensitivity and selectivity
Improve detection limits and accuracy
Develop new detection technologies
Optimize analytical method selectivity
Fast, automatic, simple and economical
Improve analysis speed and efficiency
Enables rapid sample processing and analysis
Reduce labor and time costs
Instrument automation, mathematics, and computerization
Use computer to control instrument operation
Automate data collection and processing
Applying mathematical models to optimize the analysis process
The degree of intelligence and bionics continues to deepen
Leveraging Artificial Intelligence to Optimize Analytical Decisions
Develop intelligent algorithms to aid data analysis
Designing new sensors using bionics principles