1) A mathematical titration model is constructed to determine the concentration of an unknown acid through acid-base titration.
2) The model relates the volume of base added to the pH of the solution based on chemical equations describing acid-base reactions and acid dissociation.
3) Using the model and experimental data, the dissociation constant, theoretical concentration, and actual concentration of the unknown acid are calculated, with the actual concentration found to be 0.044465437 M.
Application of Statistical and mathematical equations in Chemistry -Part 6Awad Albalwi
Application of Statistical and mathematical equations in Chemistry Part 6
Strong Acid and Base Titrations, Weak Acid and Strong Base Titration, Strong Acid and Weak Base Titrations ,Precipitation
Percentage calculation
This experiment determined the concentration of acetic acid in three vinegar samples (A, B, C) through acid-base titration. Sample A had an acetic acid concentration of 11.2 moles, sample B had 0.432 moles, and sample C had 0.8064 moles. These values were found by titrating the vinegar samples with a base solution and recording the amount of titrant added at the endpoint using a buret. Repeating the titrations and averaging the results improved the accuracy of the determined concentrations.
Volumetric analysis, also known as titrimetric analysis, is a quantitative chemical analysis technique where the concentration of an unknown substance is determined by reacting it with a known primary standard solution. There are different types of volumetric analysis including acid-base titration, redox titration, and complexometric titration. The procedure involves carefully measuring the volume of a solution of known concentration, called the titrant, required to completely react with a specific amount of the unknown analyte. This allows the concentration of the analyte to be calculated. Buffers are often used to maintain a stable pH during titrations.
The document summarizes an experiment to identify an unknown weak acid through titration with a standardized sodium hydroxide solution and measurement of pH. Key results include:
- The unknown acid was titrated and a titration curve was generated, from which two pKa values were estimated: 3.73 and 4.79.
- Calculations based on the titration data determined the molecular weight of the unknown to be 172.782 g/mol.
- Based on the pKa values and molecular weight, the unknown acid was identified as phthalic acid.
A poor solubility in water limits in a drastic way the effi cacy of a drug, because the absorption phenomenon requires the drugs be in dissolution. The therapeutic activity of a drug is depending of its acid-base dissociation constant (pKa) and solubility, the knowledge of pKa values being thus of great worth. The solubility method can be very useful in spite of their limitations if an appropriate method is available to carry out the solubility measurements of scarce solubility compounds. Some examples taken from the bibliography whose behaviour is well adapted to conventional acid-base dissociation equilibria without further complications are selected for study: Calcein blue, butaperazine, sulfadiazine, tyrosine, 8-hydroxiquinoleine and nifl umic acid. The pKa values have been recalculated applying the single least squares method and the classic monoprotic acid bilogarithmic model. A slope-intercept procedure is also applied to get the evaluation of acidity constants of overlapping equilibria (pKa2 and pKa3 of tyrosine). Results obtained in all cases are compared with literature data.
This document discusses several methods for determining the endpoint in acid-base titrations, including:
1) Using acid-base indicators that change color at the endpoint.
2) Locating the inflection point on a titration curve by plotting pH vs volume, where the steepest slope corresponds to the endpoint.
3) Monitoring temperature changes during the exothermic acid-base reaction and identifying the intersection of the titration and excess titrant branches.
Module
Analytical Measurement
Tutor
Code
ICA
Excel simulation of a titration involving strong acid and a weak base (or v.v.)
2nd Marker
Weight
50%
Type
Online submission
Produce an Excel spreadsheet based on simulation to illustrate the variation of the pH of the solution that occurs when strong acid is added to a weak base (or strong alkali and weak acid). The spreadsheet should demonstrate the change in the pH of the mixture as the titrant is added for a range of concentration of both components. Particular attention should be paid to the behaviour close to the end point (or equivalence point). Graphs should be generated on a range of scales showing in detail the likely behaviour around the end point.
The exact calculations for all situations can be quite involved so it may be useful to divide the titration into various segments in which various equations and approximations are valid and then stitch these together.
Write a report explaining the design of your spreadsheet and describe the graphs, which you should import.
Write a short description of the theory of buffer solutions and give examples of their applications.
The report should be a word document and an Excel spreadsheet. Describe the background theory and the methodology behind the construction of the simulation, and include the realisation of the system equations in Excel formulae. Graphs of pH against added solution over various ranges and around particular key points – such as the equivalence point or “end point”.
[60 marks]
The report should also include a discussion of the concept of buffer solutions and give examples of their use either in industrial processes or naturally occurring phenomena. Any sources should be appropriately referenced (Harvard).
[40 marks]
assignhints(1).pptx
Hints for the Assignment Weak Monoprotic AcidsNameFormulaValue of KaMonochloracetic acid
Hydrofluoric acid
Nitrous acid
Formic acid
Lactic acid
Benzoic acid
Acetic acid
Hydrated aluminum(III) ion
Propanoic acid
Hypochlorous acid
Hypobromous acid
Hvdrocyanic aid
Boric acid
Ammonium ion
Phenol HC2H3ClO2
HF
HNO2
HCO2H
HC3H5O3
HC7H502
HC2H3O2
[Al (H20)6]3+
HC3H5O2
HOCl
HOBr
HCN
H3BO3
NH4+
HOC6H5
HOI 1.35 x 10 -3
7.2 x 10-4
4.0 x 10-4
1.8 x 10-4
1.38 x 10-4
6.4 x 10-5
1.8 x 10-5
1.4 x 10-5
1.3 x 10-5
3.5 x 10-8
2 x 10-9
6.2 x 10-10
5.8 x 10-10
5.6 x 10-10
1.6 x 10-10
2 x 10-11
Weak Alkalis or BasesFormulaNameKbNH3ammonia
1.8 x 10 -5CH3NH2methylamine
4.4 x 10 -4C5H5Npyridine
1.5 x 10 -9C6H5NH2aniline4.3 x 10 -10
It is possible to set up a simulated titration between a weak acid and a strong base.
It is easier to work backwards from pH to the added volume of titrant using the equations below as [H+] = 10(-pH)
It is possible to generate the curve with just one formula going backwards.
However we know by working forwards from added volume to pH that there are certain key points of interest, namely where φ = 0, 0.5, 1 and >1.
...
This document discusses buffers and buffered solutions. It begins by defining buffers as compounds that resist changes in pH upon the addition of small amounts of acid or alkali. It then discusses the components and properties of common buffer systems using weak acids and their conjugate bases or weak bases and their conjugate acids. Specific examples are provided of acetate and phosphate buffers. The key concepts of buffer capacity, Henderson-Hasselbalch equation, and factors that influence buffer capacity are explained. The importance of buffers in biological and pharmaceutical systems is highlighted. Methods for preparing buffered solutions and considerations for isotonicity are also covered.
Application of Statistical and mathematical equations in Chemistry -Part 6Awad Albalwi
Application of Statistical and mathematical equations in Chemistry Part 6
Strong Acid and Base Titrations, Weak Acid and Strong Base Titration, Strong Acid and Weak Base Titrations ,Precipitation
Percentage calculation
This experiment determined the concentration of acetic acid in three vinegar samples (A, B, C) through acid-base titration. Sample A had an acetic acid concentration of 11.2 moles, sample B had 0.432 moles, and sample C had 0.8064 moles. These values were found by titrating the vinegar samples with a base solution and recording the amount of titrant added at the endpoint using a buret. Repeating the titrations and averaging the results improved the accuracy of the determined concentrations.
Volumetric analysis, also known as titrimetric analysis, is a quantitative chemical analysis technique where the concentration of an unknown substance is determined by reacting it with a known primary standard solution. There are different types of volumetric analysis including acid-base titration, redox titration, and complexometric titration. The procedure involves carefully measuring the volume of a solution of known concentration, called the titrant, required to completely react with a specific amount of the unknown analyte. This allows the concentration of the analyte to be calculated. Buffers are often used to maintain a stable pH during titrations.
The document summarizes an experiment to identify an unknown weak acid through titration with a standardized sodium hydroxide solution and measurement of pH. Key results include:
- The unknown acid was titrated and a titration curve was generated, from which two pKa values were estimated: 3.73 and 4.79.
- Calculations based on the titration data determined the molecular weight of the unknown to be 172.782 g/mol.
- Based on the pKa values and molecular weight, the unknown acid was identified as phthalic acid.
A poor solubility in water limits in a drastic way the effi cacy of a drug, because the absorption phenomenon requires the drugs be in dissolution. The therapeutic activity of a drug is depending of its acid-base dissociation constant (pKa) and solubility, the knowledge of pKa values being thus of great worth. The solubility method can be very useful in spite of their limitations if an appropriate method is available to carry out the solubility measurements of scarce solubility compounds. Some examples taken from the bibliography whose behaviour is well adapted to conventional acid-base dissociation equilibria without further complications are selected for study: Calcein blue, butaperazine, sulfadiazine, tyrosine, 8-hydroxiquinoleine and nifl umic acid. The pKa values have been recalculated applying the single least squares method and the classic monoprotic acid bilogarithmic model. A slope-intercept procedure is also applied to get the evaluation of acidity constants of overlapping equilibria (pKa2 and pKa3 of tyrosine). Results obtained in all cases are compared with literature data.
This document discusses several methods for determining the endpoint in acid-base titrations, including:
1) Using acid-base indicators that change color at the endpoint.
2) Locating the inflection point on a titration curve by plotting pH vs volume, where the steepest slope corresponds to the endpoint.
3) Monitoring temperature changes during the exothermic acid-base reaction and identifying the intersection of the titration and excess titrant branches.
Module
Analytical Measurement
Tutor
Code
ICA
Excel simulation of a titration involving strong acid and a weak base (or v.v.)
2nd Marker
Weight
50%
Type
Online submission
Produce an Excel spreadsheet based on simulation to illustrate the variation of the pH of the solution that occurs when strong acid is added to a weak base (or strong alkali and weak acid). The spreadsheet should demonstrate the change in the pH of the mixture as the titrant is added for a range of concentration of both components. Particular attention should be paid to the behaviour close to the end point (or equivalence point). Graphs should be generated on a range of scales showing in detail the likely behaviour around the end point.
The exact calculations for all situations can be quite involved so it may be useful to divide the titration into various segments in which various equations and approximations are valid and then stitch these together.
Write a report explaining the design of your spreadsheet and describe the graphs, which you should import.
Write a short description of the theory of buffer solutions and give examples of their applications.
The report should be a word document and an Excel spreadsheet. Describe the background theory and the methodology behind the construction of the simulation, and include the realisation of the system equations in Excel formulae. Graphs of pH against added solution over various ranges and around particular key points – such as the equivalence point or “end point”.
[60 marks]
The report should also include a discussion of the concept of buffer solutions and give examples of their use either in industrial processes or naturally occurring phenomena. Any sources should be appropriately referenced (Harvard).
[40 marks]
assignhints(1).pptx
Hints for the Assignment Weak Monoprotic AcidsNameFormulaValue of KaMonochloracetic acid
Hydrofluoric acid
Nitrous acid
Formic acid
Lactic acid
Benzoic acid
Acetic acid
Hydrated aluminum(III) ion
Propanoic acid
Hypochlorous acid
Hypobromous acid
Hvdrocyanic aid
Boric acid
Ammonium ion
Phenol HC2H3ClO2
HF
HNO2
HCO2H
HC3H5O3
HC7H502
HC2H3O2
[Al (H20)6]3+
HC3H5O2
HOCl
HOBr
HCN
H3BO3
NH4+
HOC6H5
HOI 1.35 x 10 -3
7.2 x 10-4
4.0 x 10-4
1.8 x 10-4
1.38 x 10-4
6.4 x 10-5
1.8 x 10-5
1.4 x 10-5
1.3 x 10-5
3.5 x 10-8
2 x 10-9
6.2 x 10-10
5.8 x 10-10
5.6 x 10-10
1.6 x 10-10
2 x 10-11
Weak Alkalis or BasesFormulaNameKbNH3ammonia
1.8 x 10 -5CH3NH2methylamine
4.4 x 10 -4C5H5Npyridine
1.5 x 10 -9C6H5NH2aniline4.3 x 10 -10
It is possible to set up a simulated titration between a weak acid and a strong base.
It is easier to work backwards from pH to the added volume of titrant using the equations below as [H+] = 10(-pH)
It is possible to generate the curve with just one formula going backwards.
However we know by working forwards from added volume to pH that there are certain key points of interest, namely where φ = 0, 0.5, 1 and >1.
...
This document discusses buffers and buffered solutions. It begins by defining buffers as compounds that resist changes in pH upon the addition of small amounts of acid or alkali. It then discusses the components and properties of common buffer systems using weak acids and their conjugate bases or weak bases and their conjugate acids. Specific examples are provided of acetate and phosphate buffers. The key concepts of buffer capacity, Henderson-Hasselbalch equation, and factors that influence buffer capacity are explained. The importance of buffers in biological and pharmaceutical systems is highlighted. Methods for preparing buffered solutions and considerations for isotonicity are also covered.
Bio 1121 unit 2 written assignmentdirectionsaccurately meassodhi3
This document provides instructions and questions for an assignment on preparing and working with phosphate buffered saline (PBS) solutions. Students are asked to calculate molecular masses and molar concentrations of compounds used to make a 10x concentrate of PBS, then use this to prepare a 1x working solution. They are also asked questions about laboratory techniques like weighing chemicals, measuring volumes, and adjusting pH.
NCHE 211 UNIT 2 VOLUMETRY and Complexometry titration.pdfKagisoEagle
This module consists of six study units that are further divided into study sections. The study units include basic concepts, volumetry, gravimetry, surface characterization, atomic spectrometry, and separation methods. The document then provides an overview of analytical chemistry and its branches, classification of quantitative analysis methods, and learning outcomes related to volumetric analysis and titrations. [/SUMMARY]
Scanned with CamScanner1 STANDARIZATION OF A B.docxtodd331
This document provides instructions for a two-part experiment involving titration. In part A, students will standardize a NaOH solution by titrating it against a primary standard of KHP. In part B, students will use their standardized NaOH solution to determine the concentration of acetic acid in a vinegar sample through titration. Key steps and concepts discussed include buret usage, endpoint determination, stoichiometric calculations to determine concentration from titration data, and the purpose and characteristics of primary standards.
You will accomplish several acid-base titration exercises to complet.docxemelyvalg9
You will accomplish several acid-base titration exercises to complete this Case Assignment at the following Virtual Laboratory website:
Strong acid versus strong base titration and weak acid versus strong base titration
http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/a_b_phtitr.html
First read the following article about pH indicators:
http://chemwiki.ucdavis.edu/Physical_Chemistry/Acids_and_Bases/Case_Studies/Acid_and_Base_Indicators
In this experiment you will be analyzing the neutralization between a strong acid and a strong base. According to the Arrhenius Acid-base Theory, when dissolved in water, an acid raises the concentration of hydrogen ion, H
+
while a base increases the hydroxide ion, OH
-
concentration. When reacted together the acid and base will neutralize each other according to the net ionic equation (1).
H
+
(aq) + OH
‐
(aq) → H
2
O(l) (1)
An acid is considered to be strong if it completely ionizes in water. In this lab, you will be using the strong acid, hydrochloric acid, HCl, to neutralize the strong base, sodium hydroxide, NaOH, according to the neutralization reaction below.
HCl(aq) + NaOH(aq) → NaCl(aq) + H
2
O(l) (2)
The progression of the reaction will be observed using a pH meter and a titration curve will be created using the experimental data. You will start with a sample containing only the acid and indicator and slowly add your standardized base. A titration curve is simply a plot of the pH of an acid versus the volume of base added, or vice versa. The titration curve gives a good description of how an acid-base reaction proceeds. The pH will start out low and acidic, then increase as it approaches the equivalence point, where the concentration of acid equals that of the base. Then as the solution becomes more basic, it will slowly rise and level off as an excess amount of base is added. Note that the equivalence point is slightly different from the endpoint of a titration. The endpoint is when the indicator changes color. This does not always correspond to the equivalence point.
As pre-laboratory preparation it is critical that you review the ideas on strong acid-strong base titration presented in your class readings.
Strong acid versus strong base
With your first sample, select an indicator from the two options and do a quick titration by adding 1 mL increments until you reach pH 2.5; then dropwise increments until you reach pH 10.7; after that add 1 mL increments until pH 11.5. Record your buret readings after the addition of each increment. Allow time for the reaction vessel to become equilibrated and for the pH reading to become stabilized and then record the pH value in your notebook alongside the buret reading. Leave an empty column between the buret reading and the pH in which to place the volume of NaOH added (difference between present buret reading and initial buret reading). Stop the titration when you have reach.
The document summarizes an experiment on acid-base titrations. Sodium hydroxide was standardized and used to titrate hydrochloric acid, phosphoric acid, and an unknown acid. Titrations of hydrochloric acid showed the equivalence point was pH 7. Phosphoric acid titration showed two equivalence points, determining its two pKa values. Titration of the unknown acid found its molecular weight to be 76.09 g/mol, identifying it as tartaric acid. A final potassium hydrogen phthalate titration found the experimental curve nearly identical to the theoretical curve.
The document summarizes an experiment on acid-base titrations. Sodium hydroxide was standardized and used to titrate hydrochloric acid, phosphoric acid, and an unknown acid. Titrations of hydrochloric acid showed the equivalence point was pH 7. Phosphoric acid titration showed two equivalence points, determining its two pKa values. Titration of the unknown acid found its molecular weight to be 76.09 g/mol, identifying it as tartaric acid. A final potassium hydrogen phthalate titration found the experimental and theoretical titration curves nearly identical.
This document describes the process of acid-base titration to determine the concentration of an unknown solution. A titration involves using a solution of known concentration (the standard solution) to neutralize a precisely measured volume of the unknown solution. An indicator is used to detect the endpoint of the titration reaction. The concentrations and volumes are then used to calculate the concentration of the unknown solution. The document provides instructions for using titration to determine the concentration of sodium hydroxide and white vinegar solutions. Sodium hydroxide is standardized against a primary standard potassium hydrogen phthalate solution before being used to titrate the vinegar.
An acid-base titration involves using a solution of known concentration (the standard solution) to neutralize a precisely measured volume of an unknown solution. The titration endpoint is detected using an indicator that changes color at neutralization. The volumes and concentrations are then used to calculate the concentration of the unknown solution. This document describes how to use a standard NaOH solution to determine the concentration of vinegar through titration.
The document describes an experiment involving potentiometric titration and determination of acid dissociation constants. Key steps included:
1) Calibrating a pH meter in buffer solutions and measuring the pH of hair conditioners.
2) Titrating acetic acid with sodium hydroxide while monitoring pH.
3) Constructing a titration curve and identifying the endpoint using the first derivative.
4) Calculating the acid dissociation constant of acetic acid and obtaining 11.43% relative error.
The document provides a 5-step process for requesting writing assistance from HelpWriting.net:
1. Create an account with a password and valid email.
2. Complete a 10-minute order form providing instructions, sources, deadline, and attaching a writing sample.
3. Review bids from writers and choose one based on qualifications, history, and feedback and place a deposit.
4. Review the completed paper and authorize final payment if pleased, with free revisions available.
5. Request multiple revisions to ensure satisfaction, with plagiarized work resulting in a full refund.
IELTS Academic Essay Writing Tips For A Better ScoreJeff Brooks
The document provides tips for getting a better score on the IELTS Academic Essay Writing exam. It outlines 5 steps: 1) Create an account; 2) Complete an order form providing instructions, sources, and deadline; 3) Review bids from writers and choose one; 4) Ensure the paper meets expectations and authorize payment; 5) Request revisions to ensure satisfaction and get a refund for plagiarized work. The document stresses choosing HelpWriting.net for high-quality, original content and customer satisfaction.
Posted On March 31, 2017. Online assignment writing service.Jeff Brooks
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Best Custom Writing Service. Best Custom Writing ServiceJeff Brooks
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Introduction About Yourself Essay Examples SitedoctJeff Brooks
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The document provides instructions for seeking assignment writing help from HelpWriting.net. It outlines a 5-step process: 1) Create an account with a password and email. 2) Complete a 10-minute order form providing instructions, sources, and deadline. 3) Review bids from writers and choose one. 4) Review the completed paper and authorize payment. 5) Request revisions to ensure satisfaction, with a full refund option for plagiarized work.
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The document discusses the ideal classroom of the future that utilizes advanced technology. It describes a classroom equipped with an interactive whiteboard, laptops for each student, a plasma screen and projector for presentations, and computer simulations. It provides examples of specific products like an interactive whiteboard system and wireless access points that could bring these technologies into the classroom.
Bio 1121 unit 2 written assignmentdirectionsaccurately meassodhi3
This document provides instructions and questions for an assignment on preparing and working with phosphate buffered saline (PBS) solutions. Students are asked to calculate molecular masses and molar concentrations of compounds used to make a 10x concentrate of PBS, then use this to prepare a 1x working solution. They are also asked questions about laboratory techniques like weighing chemicals, measuring volumes, and adjusting pH.
NCHE 211 UNIT 2 VOLUMETRY and Complexometry titration.pdfKagisoEagle
This module consists of six study units that are further divided into study sections. The study units include basic concepts, volumetry, gravimetry, surface characterization, atomic spectrometry, and separation methods. The document then provides an overview of analytical chemistry and its branches, classification of quantitative analysis methods, and learning outcomes related to volumetric analysis and titrations. [/SUMMARY]
Scanned with CamScanner1 STANDARIZATION OF A B.docxtodd331
This document provides instructions for a two-part experiment involving titration. In part A, students will standardize a NaOH solution by titrating it against a primary standard of KHP. In part B, students will use their standardized NaOH solution to determine the concentration of acetic acid in a vinegar sample through titration. Key steps and concepts discussed include buret usage, endpoint determination, stoichiometric calculations to determine concentration from titration data, and the purpose and characteristics of primary standards.
You will accomplish several acid-base titration exercises to complet.docxemelyvalg9
You will accomplish several acid-base titration exercises to complete this Case Assignment at the following Virtual Laboratory website:
Strong acid versus strong base titration and weak acid versus strong base titration
http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/a_b_phtitr.html
First read the following article about pH indicators:
http://chemwiki.ucdavis.edu/Physical_Chemistry/Acids_and_Bases/Case_Studies/Acid_and_Base_Indicators
In this experiment you will be analyzing the neutralization between a strong acid and a strong base. According to the Arrhenius Acid-base Theory, when dissolved in water, an acid raises the concentration of hydrogen ion, H
+
while a base increases the hydroxide ion, OH
-
concentration. When reacted together the acid and base will neutralize each other according to the net ionic equation (1).
H
+
(aq) + OH
‐
(aq) → H
2
O(l) (1)
An acid is considered to be strong if it completely ionizes in water. In this lab, you will be using the strong acid, hydrochloric acid, HCl, to neutralize the strong base, sodium hydroxide, NaOH, according to the neutralization reaction below.
HCl(aq) + NaOH(aq) → NaCl(aq) + H
2
O(l) (2)
The progression of the reaction will be observed using a pH meter and a titration curve will be created using the experimental data. You will start with a sample containing only the acid and indicator and slowly add your standardized base. A titration curve is simply a plot of the pH of an acid versus the volume of base added, or vice versa. The titration curve gives a good description of how an acid-base reaction proceeds. The pH will start out low and acidic, then increase as it approaches the equivalence point, where the concentration of acid equals that of the base. Then as the solution becomes more basic, it will slowly rise and level off as an excess amount of base is added. Note that the equivalence point is slightly different from the endpoint of a titration. The endpoint is when the indicator changes color. This does not always correspond to the equivalence point.
As pre-laboratory preparation it is critical that you review the ideas on strong acid-strong base titration presented in your class readings.
Strong acid versus strong base
With your first sample, select an indicator from the two options and do a quick titration by adding 1 mL increments until you reach pH 2.5; then dropwise increments until you reach pH 10.7; after that add 1 mL increments until pH 11.5. Record your buret readings after the addition of each increment. Allow time for the reaction vessel to become equilibrated and for the pH reading to become stabilized and then record the pH value in your notebook alongside the buret reading. Leave an empty column between the buret reading and the pH in which to place the volume of NaOH added (difference between present buret reading and initial buret reading). Stop the titration when you have reach.
The document summarizes an experiment on acid-base titrations. Sodium hydroxide was standardized and used to titrate hydrochloric acid, phosphoric acid, and an unknown acid. Titrations of hydrochloric acid showed the equivalence point was pH 7. Phosphoric acid titration showed two equivalence points, determining its two pKa values. Titration of the unknown acid found its molecular weight to be 76.09 g/mol, identifying it as tartaric acid. A final potassium hydrogen phthalate titration found the experimental curve nearly identical to the theoretical curve.
The document summarizes an experiment on acid-base titrations. Sodium hydroxide was standardized and used to titrate hydrochloric acid, phosphoric acid, and an unknown acid. Titrations of hydrochloric acid showed the equivalence point was pH 7. Phosphoric acid titration showed two equivalence points, determining its two pKa values. Titration of the unknown acid found its molecular weight to be 76.09 g/mol, identifying it as tartaric acid. A final potassium hydrogen phthalate titration found the experimental and theoretical titration curves nearly identical.
This document describes the process of acid-base titration to determine the concentration of an unknown solution. A titration involves using a solution of known concentration (the standard solution) to neutralize a precisely measured volume of the unknown solution. An indicator is used to detect the endpoint of the titration reaction. The concentrations and volumes are then used to calculate the concentration of the unknown solution. The document provides instructions for using titration to determine the concentration of sodium hydroxide and white vinegar solutions. Sodium hydroxide is standardized against a primary standard potassium hydrogen phthalate solution before being used to titrate the vinegar.
An acid-base titration involves using a solution of known concentration (the standard solution) to neutralize a precisely measured volume of an unknown solution. The titration endpoint is detected using an indicator that changes color at neutralization. The volumes and concentrations are then used to calculate the concentration of the unknown solution. This document describes how to use a standard NaOH solution to determine the concentration of vinegar through titration.
The document describes an experiment involving potentiometric titration and determination of acid dissociation constants. Key steps included:
1) Calibrating a pH meter in buffer solutions and measuring the pH of hair conditioners.
2) Titrating acetic acid with sodium hydroxide while monitoring pH.
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Undergraduate Journal of Mathematical
Undergraduate Journal of Mathematical
Modeling: One + Two
Modeling: One + Two
Volume 10 | 2019 Fall 2019 Article 8
2019
Acid-Base Titration
Acid-Base Titration
David Pierre
University of South Florida
Advisors:
Arcadii Grinshpan, Mathematics and Statistics
Ruidong Ni, Chemistry
Problem Suggested By: Ruidong Ni
Follow this and additional works at: https://scholarcommons.usf.edu/ujmm
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Recommended Citation
Recommended Citation
Pierre, David (2019) "Acid-Base Titration," Undergraduate Journal of Mathematical Modeling: One + Two:
Vol. 10: Iss. 1, Article 8.
DOI: https://doi.org/10.5038/2326-3652.10.1.4913
Available at: https://scholarcommons.usf.edu/ujmm/vol10/iss1/8
2. Acid-Base Titration
Acid-Base Titration
Abstract
Abstract
Titration is an analytical method used in biomedical sciences and analytical chemistry laboratories to
determine the quantity or the concentration of a known or unknown substance. There are many kinds of
titrations, but this investigation is fundamentally based on acid-base titration, in which the development of
a mathematical titration model is explained and determined. In a titration experiment, the concentration
and volume of the base added is proportionally equal to those of the acid. The concentration of the
substance is determined by following this principle. Moreover, these calculations are usually approximate.
Thus, the construction of a titration model is done to minimize the percent errors, simultaneously
describing the effect of titration, and also allowing the determination of the characteristics of the
unknown substance used. Furthermore, the values generated by the titration model are compared to the
theoretical ones. It allows the verification of the mathematical model constructed. Subsequently, the
efficiency of titration model is further tested by using a theoretical problem to exclude the errors from the
experiment. This verification displays the accuracy of the accepted titration model. The concentration of
the unknown acid is found by using this mathematical model.
Keywords
Keywords
titration model, titration experiment, acid, base
Creative Commons License
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.
This article is available in Undergraduate Journal of Mathematical Modeling: One + Two:
https://scholarcommons.usf.edu/ujmm/vol10/iss1/8
3. 1
PROBLEM STATEMENT
A mathematical titration model is constructed to display the effects of the titration which is also
used to accurately determine the concentration of the unknown acid. The accurate determination
of the concentration of the unknown substance will prevent confusion between two mislabeled
substances that have different concentrations.
MOTIVATION
Titration is an analytical method used to quantify a substance from a solution. There are many
kinds of titration, the most common ones are acid-base, reduction-oxidation, and precipitation as
well as complexometric titrations. This inquiry is based on acid-base titration which is used in
the determination of the unknown concentration of the considered substance. In acid-base
titration, the data recorded are named as paired values (volume of base added and the pH of
solution). Our intention is to construct a graph (volume of base added vs the pH of the solution)
from the paired values (titration curve) which is used to calculate the unknown concentration of
the substance. The usable part of this curve is restricted to the equivalence point; which is found
by locating the region where the most rapid increase occurs. This determination is essentially
done by observation, which means that the calculation is based on estimation (Salem). Thus, if
two substances having different concentrations are mislabeled then their dissociation constants
are unknown; the variation between the concentrations allows the experimenter to identify them.
So, the objective is to use more data to minimize the percent errors. The additional data allow the
determination of the more accurate concentration. Having an accurate concentration prevents
confusion between two substances even if they have close concentration values.
Pierre: Acid-Base Titration
Produced by The Berkeley Electronic Press, 2019
4. 2
Furthermore, to facilitate the integration of the new data, a mathematical titration model is
constructed to demonstrate the correlation between the volume of base added and the pH of the
solution.
MATHEMATICAL DESCRIPTION AND SOLUTION APPROACH
Our objective is to create a mathematical model that represents the interaction between acid and
base, and between the volume of the titrant added and pH of the solution. In this paper, a weak
acid is used as solvent with a strong base.
In an acid-base reaction, the molecule of acid would react with the base to generate an anion of
the acid and water molecule:
HA (acid) + OH-
(base) A-
+ H2O (Salem)
Therefore, the amount of mole of the acid prior the reaction occurs is equal to the volume times
the concentration (A∙a) and the base also follows the same principle (B∙b). Moreover, the reaction
reaches its equivalence point when enough base is added so A∙a=B∙b, and the solution is
monitored by measuring the pH of every drop base added. However, a weak acid does not
completely dissociate before reaching its equilibrium (Salem),
Dissociation Reaction: HA H+
+ A-
(Salem),
which means that the amount of moles of the acid present in this solution is equal to the amount
of moles of hydrogen ion. Therefore, to keep track of the concentration of the substance, the
amount of moles of each compound is divided by the total volume (a+b) used in this experiment
(Salem).
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
https://scholarcommons.usf.edu/ujmm/vol10/iss1/8
DOI: https://doi.org/10.5038/2326-3652.10.1.4913
5. 3
The concentration of the compound prior to the dissociation is determined by formulas (1) and
(2):
[𝐻𝐴] =
𝐴∙𝑎−𝐵∙𝑏
𝑎+𝑏
(1)
[A−
] =
𝐵∙𝑏
𝑎+𝑏
(2)
The titration model is created by using the dissociation constant formula:
𝐾𝑎 =
[𝐻+]∙[𝐴−]
[𝐻𝐴]
(3)
By equations (1), (2), and (3), the dissociation constant formula can be rewritten in terms of A, a,
B, b, and X= [𝐻+] :
𝐾𝑎 =
𝑋(
𝐵∙𝑏
𝑎+𝑏
)
𝐴∙𝑎−𝐵∙𝑏
𝑎+𝑏
=
𝑋∙𝐵∙𝑏
𝐴∙𝑎−𝐵∙𝑏
(4)
By solving (4) for X we have:
X=
𝐾𝑎(𝐴∙𝑎−𝐵∙𝑏)
𝐵∙𝑏
(5)
By knowing 𝑋 = [𝐻+
], the pH of the solution (a measure of the molar concentration of hydrogen
ions) is:
pH = − log [𝐻+] (6)
and the p𝐾𝑎 of the solution is:
𝑝𝐾𝑎 = −log (𝐾𝑎) (7)
Pierre: Acid-Base Titration
Produced by The Berkeley Electronic Press, 2019
6. 4
By equations (5), (6), and (7), we obtain:
−log 𝑋 = − log (
𝐾𝑎[𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏]
[𝐵 ∙ 𝑏]
),
− log[𝐻+] = − log(𝐾𝑎[𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏]) + log (𝐵 ∙ 𝑏),
pH = log(𝐵 ∙ 𝑏) − log(𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏) + 𝑝𝐾𝑎 (8)
In titration, any data beyond the equivalence point are irrelevant and unusable; thus, the model is
limited to 0< b < {b at the equivalence point}, and the equation for P (b) represents the pH of the
solution at the different volume of base added. Hence and by (8) the titration model is
𝑃(𝑏) = log(𝐵 ∙ 𝑏) − log(𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏) + 𝑝𝐾𝑎, (9)
where 0< b < {b at the equivalence point} and 𝐴 ∙ 𝑎 > 𝐵 ∙ 𝑏.
Experimental Problem
In this inquiry, the titration of an unknown acid is done with NaOH (base) which has a
concentration of 0.09141 M and the volume of solution before adding any base is 0.10 L
(Salem).
Data :
Volume of Acid: 0.10 L
Volume total of Base added: 0 .05400 L
Concentration of Base: 0.09141 M
Concentration of Acid: Unknown
𝑝𝐾𝑎: Unknown
𝐾𝑎: Unknown
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
https://scholarcommons.usf.edu/ujmm/vol10/iss1/8
DOI: https://doi.org/10.5038/2326-3652.10.1.4913
7. 5
Determination of the equivalence point
By observing the titration curve, a rapid increase between pH 6 and pH 10 is noticed, and the
equivalence point is found around this area. Moreover, the estimation is done by searching the
volume that is responsible for this increase. We obtain that the volume of NaOH at the
equivalence point is 0.04L (see Appendix).
Determination of the dissociation constant
Determination of the dissociation constant 𝐾𝑎 is done by knowing that at half-equivalence
dissociation point the number of moles of base is equal to the number of moles of acid.
Therefore, 𝐾𝑎 is calculated at half-equivalence point, [𝐴−
] = [HA], V=V (equiv.)/2 (Reijenga
Jetse).
pH at half-equivalence point:
V= 0.04L/2=0.02 L
Hence the estimation for the pH at half-equivalence point is 5.40, where the volume is 0.02L or
close to it (see Appendix).
Determination of dissociation constant of the unknown acid by assuming that the pH at
half-equivalence point is 5.40
𝑝𝐾𝑎 = −log (𝐾𝑎)
𝐾𝑎 = 10−𝑝𝐾𝑎
𝐾𝑎 = 10−5.40
≈ 3.981 × 10−6
𝑀
Pierre: Acid-Base Titration
Produced by The Berkeley Electronic Press, 2019
8. 6
Determination of the theoretical concentration of the unknown acid
𝐶1 × 𝑉1(𝑀1) = 𝐶2(𝑀2) × 𝑉2
0.09141𝑀 × 0.054𝐿 = 𝐶2 × 0.1𝐿
𝐶2(𝑀2) = 0.09141𝑀 ×
0.054𝐿
0.1𝐿
= 0.04936𝑀
(C2: Theoretical concentration of the unknown acid)
Determination of the concentration of the unknown acid at pH 5.50 using the titration
model ( see (9) and Appendix)
𝑃(𝑏) = log(𝐵 ∙ 𝑏) − log(𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏) + 𝑝𝐾𝑎
5.50 = log(0.09141𝑀 × 0.02711𝐿) − log (A×0.1L−0.09141M×0.02711L) +5.40
𝑆𝑜𝑙𝑣𝑒𝑑 𝑓𝑜𝑟 𝐴 (Concentration of acid)
−5.50 + log(0.09141𝑀 × 0.02711𝐿) + 5.40 = log ((A×0.10L)−(0.09141M ×0.02711L))
−2.705877 𝑚𝑜𝑙𝑒𝑠 = log (0.1𝐿 𝐴 − 2.4781 × 10−3
𝑚𝑜𝑙𝑒𝑠)
10−2.705877
𝑚𝑜𝑙𝑒𝑠 = 0.1𝐿 𝐴 − 2.4781 × 10−3
𝑚𝑜𝑙𝑒𝑠
0.1𝐿𝐴 = 10−2.705877
𝑚𝑜𝑙𝑒𝑠 + 2.4781 × 10−3
𝑚𝑜𝑙𝑒𝑠
A =
4.4465437×10−3𝑚𝑜𝑙𝑒𝑠
0.1 𝐿
= 0.044465437 M (moles/L)
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
https://scholarcommons.usf.edu/ujmm/vol10/iss1/8
DOI: https://doi.org/10.5038/2326-3652.10.1.4913
9. 7
VERIFICATION
Verification (Step 1) of the titration model (Experimental Problem)
Determination of percent error (Titration model deviation+ Experimental errors):
|
𝑇ℎ𝑒𝑜𝑟𝑖𝑐𝑎𝑙 𝑣𝑎𝑙𝑢𝑒−𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
𝑇ℎ𝑒𝑜𝑟𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
| × 100% = |
0.04936𝑀−0.044465𝑀
0.04936𝑀
| × 100% ≈ 9.92%
Therefore, the percent of efficiency of titration model with the experimental errors is
approximately 90.08%.
Verification (Step 2) of the titration model (Theorical Problem)
For the titration of 25.00 mL of CH3CO2H with 12.50 mL of 0.100 M NaOH:
𝐾𝑎 = 1.8 × 10−5
for CH3CO2H, pH =4.74. What is the concentration of the weak acid? (B.C)
Determination of the concentration of the acid (traditional method)
pH = 𝑝𝐾𝑎 + log
[𝐵𝑎𝑠𝑒]
[𝐴𝑐𝑖𝑑]
(Bletry),
𝑝𝐾𝑎 = − log(1.8 × 10−5) = 4.7447,
4.74 = 4.7447 + log
0.100𝑀
[CH3CO2H]
,
[CH3CO2H] = 0.10109𝑀
Determination of the concentration using the titration model (9)
𝑃(𝑏) = log(𝐵 ∙ 𝑏) − log(𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏) + 𝑝𝐾𝑎
4.74 = log(0.1𝑀 × 0.0125𝐿) − log(𝐴 × 0.025𝐿 − 0.1𝑀 × 0.0125𝐿) + 4.7447
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2.898 = −log (𝐴 × 0.025 𝐿 − 0.1 × 0.0125 𝑚𝑜𝑙𝑒𝑠)
−2.898 = log (A × 0.025 L − 0.1 × 0.0125 moles)
10−2.898
+ (0.1 × 0.0125 𝑚𝑜𝑙𝑒𝑠) = 𝐴 × 0.025𝐿
A=
2.515×10−3 𝑚𝑜𝑙𝑒𝑠
0.025 𝐿
= 0.10059 M (moles/L)
The percent of efficiency (Theoretical Problem):
Determination of the (titration model) deviation:
|
𝑇ℎ𝑒𝑜𝑟𝑖𝑐𝑎𝑙 𝑣𝑎𝑙𝑢𝑒−𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
𝑇ℎ𝑒𝑜𝑟𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
| × 100% = |
0.100𝑀−0.10059𝑀
0.100𝑀
| × 100% = 0.59%
Therefore, the percent of efficiency of the titration model with no experimental errors would be
99.41%.
Determination of the experimental errors :
% 𝐸𝑟𝑟𝑜𝑟 = 𝐷𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛(%) + 𝐸𝑥𝑝. 𝐸𝑟𝑟𝑜𝑟(%)
𝐸𝑥𝑝. 𝐸𝑟𝑟𝑜𝑟(%) = 9.08% − 0.59% = 8.49%
LIMITATION OF THE TITRATION MODEL
The volume of the base added in the titration model is restricted between 0 and the equivalence
point. However, the amount of moles of base and acid also influences the titration model. The
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
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DOI: https://doi.org/10.5038/2326-3652.10.1.4913
11. 9
titration model is constructed on weak acid /strong base reaction in which the concentration of
the weak acid is lower than the base concentration. Moreover, what happens if the number of
moles of the acid tends to be equal to those of the base in the titration model? :
𝐴 ∙ 𝑎 ≈ 𝐵 ∙ 𝑏, 𝑝𝐾𝑎 ≈ P (b),
𝑃(𝑏) = log(𝐵 ∙ 𝑏) − log(𝐴 ∙ 𝑎 − 𝐵 ∙ 𝑏) + 𝑝𝐾𝑎,
0 = log(𝐵 ∙ 𝑏) − " log(0 +)" → log(𝐵 ∙ 𝑏) + "∞"
Therefore, 𝑃(𝑏) 𝑑𝑜𝑒𝑠 𝑛𝑜𝑡 𝑒𝑥𝑖𝑠𝑡 𝑤ℎ𝑒𝑛 𝐴 ∙ 𝑎 ≈ 𝐵 ∙ 𝑏.
DISCUSSION
The purpose of this experiment is to create a mathematical model that determines an accurate
concentration of an unknown substance. By using the titration model, the result is approximately
0.044465 M which is close to the theoretical value (0.04936 M) of the substance. The percent
error of the titration model is approximately 9.1 % which is acceptable. However, the percent
error of the titration model also includes the experimental errors. Thus, by applying the titration
model in a theoretical problem, the deviation of the titration model is ~0.6% (as predicted),
because the titration model is created by considering any elements that can impact the result. If
the titration model has ~0.6% deviation in the theoretical problem, the deviation of titration
should be about the same under any circumstances. Therefore, the experiment errors were
calculated by using this equation: %Error = Deviation (%) + Exp. Errors (%).
So, the acid-base titration contains ~8.5 % of experimental errors and the titration model has
~0.6% deviation. A mathematical model with no deviation would likely generate accurate
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12. 10
values, and there will be no confusion between two substances that have close concentration
values. However, the deviation of the titration model is independent to the experimental errors,
which means the titration model cannot influence the experimental errors, but the experimental
errors can alter the result. Therefore, an accurate concentration is guaranteed if the experimental
error is low. Furthermore, the identification of the unknown substance would be easily done.
Thus, the titration model has accomplished its objective because the concentration of the
unknown substance (weak acid) is determined with a low percent error and the correlation
between pH and the volume of base added is demonstrated. However, the titration model has its
limitations which are:
1. The volume used should be between 0 and the volume of the base at the equivalence
point.
2. The amount of moles of acid and base present should not be equal.
CONCLUSION AND RECOMMENDATION
The mathematical model is based on acid-base titration and its development allows the
determination of the concentration of the acid used. The model is constructed by following the
dissociation constant rules and the amount of moles present. Its purpose is to minimize the
percent error as low as possible (<1%) which is achieved. By comparing the values generated by
the titration model to theoretical one, the percent efficiency is ~99.4% which is remarkable.
However, the titration model cannot minimize the experimental errors, which means the titration
model cannot erase any errors made during the experiment. The percent error in this experiment
is ~9%, which means the calculation, or the determination of the equivalence point is slightly off.
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
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DOI: https://doi.org/10.5038/2326-3652.10.1.4913
13. 11
Therefore, to minimize the experimental errors, the use of computer algebra system is needed to
lower the percent error in the dissociation constant; and the acid-base titration should be repeated
several times. Besides, the titration model has an efficiency of ~99.4%, which means that any
value generated would be accurate. Moreover, the titration model displays a correlation between
pH, 𝑝𝐾𝑎, volumes, and concentrations. This correlation allows the determination of any one of
those four elements. Therefore, this mathematical model also describes the different
characteristics (pH, 𝑝𝐾𝑎, volume, concentration) of the substances used (acid or base).
In conclusion, the accurate concentration of the acid is found by using this model, see (9).
And any other characteristics (pH, 𝑝𝐾𝑎, volume) of the substances used could be also
determined.
Hypothetically, if two acidic substances are mislabeled they have different concentration values,
and the constant of dissociation are unknown. Those two substances could be easily identified by
using the titration model constructed in this paper, and the confusion between those two
substances would be elucidated.
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NOMENCLATURE(S)
Table 1. List of symbols used in this paper:
Symbols Descriptions Units
H+ Hydrogen Ion moles
A- Base moles
HA Acid moles
NaOH Sodium hydroxide moles
A Concentration of acid used M = moles/liter
B Concentration of base used M = moles/liter
a Initial volume of acid solution L=liter
b Total volume of base added L=liter
H2O Water molecule moles
Aa # of moles of the acid moles
Bb # of moles of the base moles
a+b Total volume of the system L=liter
pH -log[H+
] none
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15. 13
[H+] Concentration of the Hydrogen Ion M = moles/liter
𝒑𝑲𝒂 -log[𝐾𝑎] none
[Base] or
[A-]
Concentration of the base used M = moles/liter
[Acid] or
[HA]
Concentration of the acid used M = moles/liter
𝑲𝒂 Dissociation constant of acid M = moles/liter
V(equiv.) Volume at equivalence point L=liter
V(equiv.)/2 Volume at half-equivalence point L=liter
P(b) pH of the solution at different volume of base added None
This table describes the symbols used in our
experiment with their units (SI)
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16. 14
REFERENCES
B.C Open Textbook. ‘’ Acid-Base Titrations’’, Chemistry Open Textbook, ch.14, Custom
edition B.C Campus (OpenStax),Quebec, Canada.(B.C)
https://opentextbc.ca/chemistry/chapter/14-7-acid-base-titrations/
Bletry Marc, ‘’Henderson Hasselbach relationship and weak acid titration’’ Univeristé Paris-
Est Créteil, ICMPE-CNRS, Thiais, France. Published by Academia.(Bletry)
https://www.academia.edu/36251379/Henderson_Hasselbalch_relationship_and_w
eak_acid_titration.
Burton J.O and Acree S.F, ‘’Calculation of the Concentration and Dissociation Constant of
Each Acid Group in A Mixture from the pH Titration Curve of the mixture’’.US
Department of Commerce National Bureau Standards. 1936.(Burton)
https://nvlpubs.nist.gov/nistpubs/jres/16/jresv16n6p525_a1b.pdf
Reijenga Jetse, Van Hoof Arno, Van Loon Antonie and Teunissen Bram, ‘’Development of
Methods for the Determination of pKa Values’’ , Department of Chemical
Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The
Netherlands, Published online 2013 Aug 8, NCBI.(Reijenga Jetse)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3747999/
Salem Anita, Paula Shorter and Dale Harak.’’ Titration’’ Mathematics and Chemistry
Department of Rockhurst University, Connected Curriculum Project, 1999-2000.
Published by Duke university.(Salem)
https://services.math.duke.edu/education/ccp/index.html.
Undergraduate Journal of Mathematical Modeling:One +Two, Vol. 10, Iss. 1 [2019], Art. 8
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DOI: https://doi.org/10.5038/2326-3652.10.1.4913
17. 15
APPENDIX
Graph 1- Titration Curve
The titration curve is constructed by using data from Table 2 which shows the relation between
the pH of the solution and the volume NaOH added.
Table 2: Result collected
(L of base added) pH of solution
0.00 4.54
0.00101 4.55
0.00220 4.61
0.00329 4.70
0.00419 4.72
0.00517 4.79
0.00623 4.81
0.00740 4.88
0.00858 4.90
0.00963 4.97
0.01074 5.00
0.01150 5.02
0.01290 5.04
0.01399 5.11
0
2
4
6
8
10
12
0 0.01 0.02 0.03 0.04 0.05 0.06
pH
of
solution
Volume of NaOH added (L)
Titration Curve
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19. 17
0.04251 10.15
0.04275 10.20
0.04300 10.21
0.04401 10.29
0.04510 10.38
0.04625 10.43
0.04733 10.49
0.04839 10.50
0.04949 10.52
0.05069 10.59
0.05189 10.60
0.05289 10.61
0.05400 10.62
Determination of the dissociation constant using Table 2 (Observational Method)
The 𝐾𝑎 is found by calculating the volume at half-equivalence point:
V= 0.04L/2=0.02,
𝑝𝐾𝑎 ≈ 5.40 (observation from data),
𝐾𝑎 = 10−5.40
≈ 3.981 × 10−6
𝑀
Therefore, the dissociation constant of the acid is ≈ 3.981 × 10−6
𝑀.
Data used in the determination of the concentration of the unknown acid (using the titration
model).
pH= 5.50 𝑝𝐾𝑎= 5.40
b= 0.02711 ≈0.03 L B= 0.09141≈0.09 M
a= 0. 1L A= ? M
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