DOCSLIB.ORG

Acid – Base Indicators

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Acid – Base Indicators Acid – Base Indicators SECTION 6.3 PG. 245-247 Acid – Base Indicators Substances that change colour when the acidity of the solution changes are known as acid-base indicators A very common indicator used is litmus, which is obtained from lichen Litmus paper is prepared by soaking absorbent paper with litmus solution and then drying it. Acid – Base Indicators Acid-base indicators are unique chemicals because they can exist in two forms, each with a distinctly different colour The form of the chemical depends on the acidity of the solution. They usually have very complicated formulas, so simple abbreviations are used: Lt – litmus; Bb – bromothymol blue; In – indicator (generic) The two forms of any indicator depend on whether a particular hydrogen atom is present in the indicator’s molecule. In general, the lower pH form is designated HIn(aq) - In general, the higher pH form is designated In (aq) Acid – Base Indicators Other acid-base indicators: Because the chemical structure of each indicator is different, the pH at which - the indicator changes from the HIn(aq) form to the In (aq) form is different for each indicator. (See inside back cover of textbook) Common name Color of pH range of Color of In- HIn(aq) colour change (aq) Bromothymol blue Yellow 6.0-7.6 Blue Phenolphthalein Colourless 8.2-10.0 Pink A Close Look at Litmus Paper The colour changes of litmus are a little more complicated than what you have learned previously. There is a “fuzzy” region around the neutral point (pH=7) where the colour is not easily distinguished. Between 6.0-8.0, litmus is in the process of changing colour and you will see mixtures of red and blue. These intermediate colours are generally not useful, with the exception of bromothymol blue, where the green is a distinct colour in the middle of the range Common name Color of pH range of Color of In- HIn(aq) colour change (aq) Litmus Red 6.0-8.0 Blue Uses of Acid-Base Indicators Acid base indicators have two primary uses: 1) Indicators are commonly used to mark the end of a titration (you will learn more about this in Chapter 8) 2) Indicators are used to estimate the pH of a solution by using a number of different indicators. In this method, acid-base indicators are used to replace the more expensive pH meter, although indicators are not as accurate. Example: Solution After addition to samples of pH range implied by pH of solution the solution … each indicator ● methyl red was red pH must be < 4.8 Combining these A ● thymol blue turned yellow pH > 2.8 but < 8.0 results, the pH must be ● methyl orange turned red pH must be < 3.2 between 2.8 and 3.2 Practice Lab Exercise 6.B pg. 247 Complete the Analysis Portion of the lab below Solution After addition to samples of the pH range implied by pH of solution solution … each indicator ● methyl violet was blue ● methyl orange was yellow A ● methyl red was red ● phenolphthalein was colourless ● indigo carmine was blue ● phenol red was yellow B ● bromocresol green was blue ● methyl red was yellow ● phenolphthalein was colourless ● thymol blue was yellow C ● bromocresol green was yellow ● methyl orange was orange Practice (continued) Pg. 247 #1-3 (#4 BONUS) Mini Investigation “pH of a solution” pg. 246 .
Load more

Recommended publications
  • Bromothymol Blue
    Safety Data Sheet Bromothymol Blue 1. PRODUCT AND COMPANY IDENTIFICATION Product Name: Bromothymol Blue Synonyms/Generic Names: 4,4'-(3H-2,1-Benzoxathiol-3-ylidene)bis[2-bromo-3-methyl-6-(1- methylethyl)phenol]S,S-dioxide sodium salt SDS Number: 116.00 Product Use: For Educational Use Only Manufacturer: Columbus Chemical Industries, Inc. N4335 Temkin Rd. Columbus, WI. 53925 For More Information Contact: Ward's Science 5100 West Henrietta Rd. PO Box 92912-9012 Rochester, NY 14692 (800) 962-2660 (Monday-Friday 7:30-7:00 Eastern Time) In Case of Emergency Call: CHEMTREC - 800-424-9300 or 703-527-3887 (24 Hours/Day, 7 Days/Week) 2. HAZARDS IDENTIFICATION OSHA Hazards: No known OSHA hazards. Target Organs: None Signal Word: Warning Pictograms: None GHS Classification: Acute toxicity, Oral Category 5 GHS Label Elements, including precautionary statements: Hazard Statements: H303 May be harmful if swallowed. Precautionary Statements: P312 Call a POISON CENTER or doctor/physician if you feel unwell. Potential Health Effects Eyes May cause eye irritation. Inhalation May be harmful if inhaled. Causes respiratory tract irritation. Skin May be harmful if absorbed through skin. Causes skin irritation. Ingestion May be harmful if swallowed. Revised on 01/07/2013 Page 1 of 5 NFPA Ratings HMIS Ratings Health 1 Health 1 Flammability 1 Fire 1 Reactivity 0 Reactivity 0 Specific hazard Not Available Personal E 3. COMPOSITION/INFORMATION ON INGREDIENTS EINECS# / Molecular Component Weight % CAS # Formula ELINCS# Weight Bromothymol Blue 100 34722-90-2 N/A C27H27Br2NaO5S 646.36 g/mol 4. FIRST-AID MEASURES Eyes Rinse with plenty of water for at least 15 minutes and seek medical attention if necessary.
    [Show full text]
  • Dnazone Classroom Kit Classroom Kits Created by Carnegie Mellon University and the University of Pittsburgh the Center for Nucleic Acids Science and Technology
    DNAZone Classroom Kit Classroom kits created by Carnegie Mellon University and the University of Pittsburgh The Center for Nucleic Acids Science and Technology Kit title What is the pH? Chemistry of Acids and Bases Appropriate grade level Upper high school, AP Chemistry The concept of acids and bases is an important topic in any introductory chemistry course. It is also a crucial part of standardized exams. Because acids and bases are so prevalent in real life applications, learning the concept through hands-on experiments will enhance a student’s understanding of these topics Abstract and evoke curiosity and interest. The teaching plan of this kit follows the PPP model, which, stands for presentation, practice and production. The included set of activities involves using pH indicators to characterize the acidity of common household items and to gain understanding of the importance of acids and bases in controlling homeostasis in biological systems. Time Two 40-minute class periods Process Standards 3.4.12 A. Apply concepts about structure and properties of matter • Characterize and identify important classes of compounds (e.g. acids, bases, PA Department of salts) Education Standards Content Standards 3.1.12 B. Apply concepts of models as a method to predict and understand science and technology 3.1.12 C. Assess and apply patterns in science and technology A Demonstration of Acid Rain. http://www.ied.edu.hk/apfslt/v5_issue1/fongmw/index.htm#contents (accessed June 29, 2012). Exploring Acids and Bases. Kit adapted from: http://scifun.chem.wisc.edu/homeexpts/ACIDBASE.html (accessed June 29, 2012). Guare, Linette.
    [Show full text]
  • Thinking Like a Chemist About Acids and Bases Part V UNIT 6 DAY 10
    Thinking Like a Chemist About Acids and Bases Part V UNIT 6 DAY 10 What are we going to learn today? Explore Acid – Base Titrations Explore the concept of protonation and pKa Explore Behavior of Polyprotic Acids Acid Base Titration Why do a titration? You have a solution with an unknown property Unknown Concentration? Unknown Ka (Kb)? Both Slowly neutralize the solution by adding a strong base (acid) monitor the pH with each addition What do these plots tell you? How is the plot on the right different? Work with neighbors on Titration Discovery Activity Poll: Clicker Question The initial concentration of the HBr is: A) 7 M B) 0.7 M C) 0.007 M D) 0.0007 M E) 3.5 M Poll: Clicker Question The pKa for acetic acid is: A) 1.7 x 10-5 B) 1.6 x 10-9 C) 4.76 D) 8.32 E) 3.43 Chemical Equilibrium pH indicator Chemical Equilibrium pH indicator Bromothymol Blue, pKa = 7.1 Protonated form Deprotonated form yellow blue Poll: Clicker Question Chemical Equilibrium pH indicator Bromothymol Blue Bromophenol Blue has a pKa of around 7. When it is protonated (HA form) it is yellow, when it is deprotonated (A- form) it is blue. What color would in be in a solution in which the pH was 9? A. blue B. yellow C. green CH302 Vanden Bout/LaBrake Spring 2012 Polyprotic Acid Poll: Clicker Question Polyprotic Acid -4 Ka1 = 7.4 x 10 -5 Ka2 = 1.7 x 10 -7 Ka3 = 4.0 x 10 At pH = 2 how many of the acidic protons will be on the molecule? A.
    [Show full text]
  • Bromothymol Blue Indicator, 0.04-1% Aqueous
    SDS Safety Data Sheet 1. IDENTIFICATION Product Identifier: Bromothymol Blue Indicator, 0.04-1% w/v Aqueous Product Code(s): B1013, B1020, B1021 Synonyms: BTB, Sodium Salt Solution; 3,3’-Dibromothymolsulfonphthalein, Sodium Salt Solution Recommended Use: For manufacturing, industrial, and laboratory use only. Use as a laboratory reagent. Uses Advised Against: Not for food, drug, or household use. Supplier: Rocky Mountain Reagents, Inc. 4621 Technology Drive, Golden, CO 80403 Phone: (303) 762-0800 Fax: (303) 762-1240 Emergency Phone Number: For health emergency, call poison control: (800) 222-1222. 2. HAZARDS IDENTIFICATION Hazard Classifications: This product is classified as not hazardous under OSHA's Hazard Communication Standard, 29 CFR 1910.1200 (HCS) and the United Nations’ Globally Harmonized System of Classification and Labeling of Chemicals (GHS). However, all chemicals handled and used in the workplace should be treated with caution. Signal Word: Not applicable. Hazard Statements: Not applicable. Pictograms: Not applicable. Precautionary Statements: Prevention: Not applicable. Response: Not applicable. Storage: Not applicable. Disposal: Not applicable. Hazards Not Otherwise Not applicable. Classified: Toxicity Statement: Not applicable. Product: Bromothymol Blue Indicator, 0.04-1% w/v Aqueous Revision Date: 05/19/2016 1/7 3. COMPOSITION AND INFORMATION ON INGREDIENTS Component Common Name / Synonyms CAS# Chemical Formula % by Weight Water Water 7732-18-5 H2O ≥ 99.0 Bromothymol Blue, 3,3’-Dibromothymolsulfonphthalein, 34722-90-2 NaC27H27O5SBr2 ≤ 1.00 Sodium Salt Sodium Salt Trade Secret Statement: Not applicable. 4. FIRST AID MEASURES First Aid Procedures: Inhalation: Move to fresh air. If breathing is difficult, give oxygen. If not breathing, give artificial respiration. Call a physician if symptoms occur.
    [Show full text]
  • Practical Problems Revised Grading Scheme
    Student Code AAA-1 Practical Problems Revised Grading Scheme "Bonding the World with Chemistry" 49th INTERNATIONAL CHEMISTRY OLYMPIAD Nakhon Pathom, THAILAND Practical problems (official English version), 49th IChO 2017, Thailand 1 Student Code AAA-1 General Instructions. General Information In 0.1 mol dm-3 HCl, indicators are in the acidic form (HIn) only. In 0.1 mol dm-3 NaOH, indicators are in the basic form (In-) only. There will be no mark for the answer in the dotted line box. NOTE: Students are suggested to check the spectrophotometer before use by measuring the absorbance values of the instrument check solution at two different wavelengths, i.e., 430 and 620 nm. Spectrophotometer No. ________ is used throughout the experiment. Record the absorbance values of the instrument check solution A (at 430 nm) A (at 620 nm) Measured value ________________ ________________ Guided value 0.220 – 0.260 0.450 – 0.510 In case that the measured values are within the guided values, students can proceed with further experiments. If not, students can ask for assistance. Part a Absorbance measurement of an acid-base indicator (methyl orange) in strong acid and strong base 1. Pipette 1.50 cm3 of 2.00 10-4 mol dm-3 methyl orange indicator solution into a 25.00- cm3 volumetric flask, add 2.5 cm3 of 1 mol dm-3 HCl into the flask and make up to the volume using distilled water. Record the absorbance at 470 and 520 nm. 2. Pipette 2.00 cm3 of 2.00 10-4 mol dm-3 methyl orange indicator solution into a 25.00- cm3 volumetric flask, add 2.5 cm3 of 1 mol dm-3 NaOH into the flask and make up to the volume using distilled water.
    [Show full text]
  • Lab.10. Equilibrium. Determination of Dissociation Constant for a Weak Acid
    Lab.8. Equilibrium. Determination of dissociation constant for a weak acid Key words: Equilibrium, equilibrium constant, dissociation constant, electrolytes, non electrolyte, weak and strong acids (bases), dissociation, titration, buffer solutions, calculation the pH of buffer solution, the Henderson-Hasselbalch equation, the unique properties of buffer solution (effect of dilution, effect of added acids and bases, buffer capacity). Literature J. A. Beran; Laboratory Manual for Principles of General Chemistry, pp. 281-346. M. Hein and S. Arena: Introduction to Chemistry, 13th ed. Wiley 2011; pp. J. Crowe. T. Bradshaw, P. Monk, Chemistry for the Biosciences. The essential concepts., Oxford University Press, 2006; Chapter 16, 482 - 512. J. Brady, N. Jespersen, A. Hysop, Chemistry, International Student Version, 7thed. Wiley, 2015, Chapter 14, 686 – 709. P. Monk, Physical chemistry, Wiley 2004, Chapters, 5, 6, 177 – 229 and 233- 276, Theoretical background The Swedish chemist Arrhenius suggested that solutions that conduct electricity, so called electrolytes, do so because they dissociate into charged species called ions. Compounds of this type: acids, bases and salts may be classified as strong electrolytes dissociate in solution almost completely into ions, weak electrolytes dissociate only to a small extent in solution (only 10% or less ions are present in solution). Acids are compounds that ionize to release hydrogen ions, H+, to their surroundings. Bases are compounds that accept hydrogen ions, The equation for the ionization of a weak acid may be expressed as: HA ↔ H+ + A- (1) However, this suggests that protons exist free in solution. The reality is that protons are solvated in solution, that is they go around attached to a solvent (water) molecules.
    [Show full text]
  • Bogen Universal Indicator Solution
    Material Safety Data Sheet Bogen Universal Indicator Solution Revised: 06/25/2012 Replaces: 04/25/2012 Printed: 08/31/2012 Section 1 - Product Description Product Name: Bogen Universal Indicator Solution Product Code(s): 848263, 848265, C70402, C70403 Size: 100 ml, 500 ml, 4 oz, 15 ml Chemical Name: See Section 3 CAS Number: See Section 3 Formula: See Section 3 Synonyms: None known Distributor: Carolina Biological Supply Company, 2700 York Road, Burlington, NC 27215 Chemical Information: 800-227-1150 (8am-5pm (ET) M-F) Chemtrec 800-424-9300 (Transportation Spill Response 24 hours) Section 2 - Hazard Identification Emergency Overview: WARNING - Flammable. Irritating to eyes and skin. Potential Health Effects: Eyes: May cause irritation. Skin: May cause irritation to skin. Ingestion: May cause gastrointestinal discomfort. Inhalation: May cause irritation to respiratory tract. Section 3 - Composition / Information on Ingredients Principal Hazardous Components: Hexane (Denaturant) (CAS# 110-54-3) 0.5%; Methyl red (CAS# 493-52-7) 0.0185%; Bromothymol blue (CAS# 76-59-5) 0.06%; Phenolphthalein (CAS# 77-09-8) 0.064%; Ethanol (CAS# 64-17-5) 47.5%; Methyl isobutyl ketone (Denaturant) (CAS# 108-10-1; Water (CAS# 7732-18-5) Balance TLV units: ACGIH-TLV (Ethanol) 1000 ppm (TWA) ACGIH-TLV (Methyl Isobutyl Ketone) 50 ppm (TWA); 75 ppm (STEL) ACGIH-TLV (Hexane) 50 ppm (TWA) PEL units: OSHA-PEL (Ethanol) 1000 ppm (TWA) OSHA-PEL (Methyl Isobutyl Ketone) 100 ppm (TWA); 75 ppm (STEL) OSHA-PEL (Hexane) 500 ppm (TWA) Section 4 - First Aid Measures Emergency and First Aid Procedures: Eyes - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
    [Show full text]
  • Bromothymol Blue Solution 0 04 (S25207A) Canadasds En 2019
    Page: 1/8 Safety Data Sheet according to OSHA HCS (29CFR 1910.1200) and WHMIS 2015 Regulations Revision: July 05, 2019 1 Identification · Product identifier · Trade name: Bromothymol Blue Solution, 0.04% · Product code: S25207A · Recommended use and restriction on use · Recommended use: Laboratory chemicals · Restrictions on use: No relevant information available. · Details of the supplier of the Safety Data Sheet · Manufacturer/Supplier: AquaPhoenix Scientific, Inc. 860 Gitts Run Road Hanover, PA 17331 Phone: (717)632-1291 Toll-Free: (866)632-1291 [email protected] · Distributor: Fisher Science Education 6771 Silver Crest Road Nazareth, PA 18064 (800) 955-1177 · Emergency telephone number: ChemTel Inc. (800)255-3924 (North America) +1 (813)248-0585 (International) 2 Hazard(s) identification · Classification of the substance or mixture The product is not classified as hazardous according to the Globally Harmonized System (GHS). · Label elements · GHS label elements Not regulated. · Hazard pictograms: None. · Signal word: None · Hazard statements: None. · Precautionary statements: None. · Other hazards There are no other hazards not otherwise classified that have been identified. 3 Composition/information on ingredients · Chemical characterization: Mixtures · Components: 7732-18-5 Water >90% 34722-90-2 Sodium α-(3-bromo-5-isopropyl-4-oxo-2-methyl-2,5-cyclohexadienylidene)-2-(3- 5-10% bromo-4-hydroxy-5-isopropyl-2-methylphenyl)toluenesulphonate · Additional information: For the listed ingredient(s), the identity and/or exact percentage(s) are being withheld as a trade secret. For the wording of the listed Hazard Statements, refer to section 16. (Cont'd. on page 2) 49.4.0 Page: 2/8 Safety Data Sheet according to OSHA HCS (29CFR 1910.1200) and WHMIS 2015 Regulations Revision: July 05, 2019 Trade name: Bromothymol Blue Solution, 0.04% (Cont'd.
    [Show full text]
  • Development of Fluorescent Assay for Monitoring of Dehalogenase Activity
    BIOTECH METHOD Fluorescent Assays www.biotechnology-journal.com Development of Fluorescent Assay for Monitoring of Dehalogenase Activity Sarka Nevolova, Elisabet Manaskova, Stanislav Mazurenko, Jiri Damborsky, and Zbynek Prokop* accelerate the transition from the genetic The rapid accumulation of sequence data and powerful protein engineering pool to selected candidates, the subsequent techniques providing large mutant libraries have greatly heightened interest wet lab testing is often laborious, time- and in efficient methods for biochemical characterization of proteins. Herein is money-demanding. Development of high- throughput screening techniques is of reported a continuous assay for screening of enzymatic activity. The assay is great interest to accelerate experimental developed and tested with the model enzymes haloalkane dehalogenases and testing of novel enzymes. relies upon a fluorescent change of a derivative of 8-hydroxypyrene-1,3,6- Enzyme assays are used to make the trisulphonic acid due to the pH drop associated with the dehalogenation enzyme-catalyzed conversions visible and reactions. The assay is performed in a microplate format using a purified provide the functional basis for identifying [2] enzyme, cell-free extract or intact cells, making the analysis quick and simple. and selecting interesting enzymes. In the most convenient and informative enzy- The method exhibits high sensitivity with a limit of detection of 0.06 mM. matic profiling methods, reaction progress The assay is successfully validated with gas chromatography and then is monitored directly using either a applied for screening of 12 haloalkane dehalogenases with the environmental chromogenic or fluorogenic substrate or pollutant bis(2-chloroethyl) ether and chemical warfare agent sulfur mustard. a sensor for product formation without Six enzymes exhibited detectable activity with both substrates.
    [Show full text]
  • (12) United States Patent (10) Patent No.: US 8,062,902 B2 Mestrallet (45) Date of Patent: Nov
    US008062902B2 (12) United States Patent (10) Patent No.: US 8,062,902 B2 Mestrallet (45) Date of Patent: Nov. 22, 2011 (54) MAMMALLAN DISEASE DETECTION (56) References Cited SYSTEM U.S. PATENT DOCUMENTS (75) Inventor: Francois Mestrallet, Longvie (FR) 3,978,818. A * 9, 1976 Heldenbrand ................ 119, 170 5,005,572 A * 4, 1991 Raemer et al. ... 128.207.14 (73) Assignee: Nullodor USA LLC 5,143,023 A * 9/1992 Kuhns ........................... 119,173 5,267,532 A * 12/1993 Franklin et al. ... ... 119,173 (*) Notice: Subject to any disclaimer, the term of this 5,279,259 A * 1/1994 Rice et al. ...... ... 119,173 patent is extended or adjusted under 35 5.362,633 A * 1 1/1994 Pugia .............................. 435/28 U.S.C. 154(b) by 129 days. 5,371,054 A * 12/1994 Pluta et al. ...................... 5O2.62 5,830,765 A * 1 1/1998 Santioemmo et al. .......... 436.66 (21) Appl. No.: 12/394,220 5,970,915 A * 10/1999 Schlueter et al. ...... ... 119,171 6,382,132 B1* 5/2002 Steckel et al. ..... ... 119,171 (22) Filed: Feb. 27, 2009 7,485.466 B2 * 2/2009 Jenkins et al. .................. 436.86 7,670,845 B2* 3/2010 Wenzel et al. ... ... 436,163 (65) Prior Publication Data 2004/OO25798 A1* 2, 2004 Lee et al. .... 119,172 2005/014518.6 A1* 7/2005 Fung et al. 119,171 US 2009/03253O4 A1 Dec. 31, 2009 2006/0270.051 A1* 11/2006 Jenkins et al. .................. 436.86 Related U.S. Application Data * cited by examiner (60) Provisional application No.
    [Show full text]
  • Universal Indicator, Bogens in Alcohol Safety Data Sheet According to Federal Register / Vol
    Universal Indicator, Bogens in Alcohol Safety Data Sheet according to Federal Register / Vol. 77, No. 58 / Monday, March 26, 2012 / Rules and Regulations Date of issue: 04/25/2014 Revision date: 05/15/2018 Supersedes: 04/25/2014 Version: 1.1 SECTION 1: Identification 1.1. Identification Product form : Mixtures Product name : Universal Indicator, Bogens in Alcohol Product code : LC26500 1.2. Recommended use and restrictions on use Use of the substance/mixture : For laboratory and manufacturing use only. Recommended use : Laboratory chemicals Restrictions on use : Not for food, drug or household use 1.3. Supplier LabChem Inc Jackson's Pointe Commerce Park Building 1000, 1010 Jackson's Pointe Court Zelienople, PA 16063 - USA T 412-826-5230 - F 724-473-0647 [email protected] - www.labchem.com 1.4. Emergency telephone number Emergency number : CHEMTREC: 1-800-424-9300 or +1-703-741-5970 SECTION 2: Hazard(s) identification 2.1. Classification of the substance or mixture GHS-US classification Flammable liquids H225 Highly flammable liquid and vapour Category 2 Serious eye damage/eye H319 Causes serious eye irritation irritation Category 2A Specific target organ H336 May cause drowsiness or dizziness toxicity (single exposure) Category 3 Full text of H statements : see section 16 2.2. GHS Label elements, including precautionary statements GHS-US labeling Hazard pictograms (GHS-US) : GHS02 GHS07 Signal word (GHS-US) : Danger Hazard statements (GHS-US) : H225 - Highly flammable liquid and vapour H319 - Causes serious eye irritation H336 - May cause drowsiness or dizziness Precautionary statements (GHS-US) : P210 - Keep away from heat, hot surfaces, open flames, sparks.
    [Show full text]
  • Spectrophotometric Determination of the Pka of Bromothymol Blue
    Spectrophotometric Determination of the pKa of Bromothymol Blue INTRODUCTION Acid-base indicators are compounds that are simply weak acids (or bases) that exhibit different colors depending on whether they are present in solution as their acidic form (HIn) or as their basic form (In-). As the pH of a solution containing the indicator changes, the equilibrium shown below will be driven either towards reactants (HIn), or products (In-) causing the solution color to change depending on the concentration of each form present. For example, in strongly acidic solution, most of the indicator will be present in the form HIn, causing the solution color to correspond to that of HIn. In strongly basic solutions, most of the indicator will be in the In- form, resulting the color 2 dominating the solution. At intermediate pH values, the solution color will be a mix of color 1 and color 2, depending on the relative amounts of HIn and In- present. HIn = H+ +In- (1) Color 1 Color 2 Quantitatively, the relationship between the pH (really the hydronium ion concentration) and the - relative amounts of HIn and In in solution is described by the acid dissociation constant (Ka) for the indicator, as shown in Equation 2, where the square-bracketed terms represent the molar concentrations of each species in solution (M). [H + ][In − ] (2) K = a [HIn] In practice, we typically measure the pH of a solution, rather than the [H+], therefore, it is useful to perform a few mathematical manipulations to the Ka expression to get things in terms of experimentally-determined quantities.
    [Show full text]