...concentration of an analyte in a solution. The first part of the this experiment involves the calibration of an item of volumetric glassware(a pipette)by repeated measurement of the volume that it delivers. The second part of the experiment requires that you determine the concentration of an unknown solution of phosphoric acid, using a sodium hydroxide solution of known concentration that is provided to us. In the third part, we are required to prepare a solution of hydrochloric acid and measure its concentration(standardization)by titration with sodium hydroxide solution of known concentration using neutral indicator. Materials Equipments: analytical balance, 500 mL beaker, wash bottle, watch glass, measuring cylinder, Gooch crucibles, Gooch crucible rubber collar, oven, hot plate, vacuum flask, stirring rod, Chemicals: 1:1 ration HCl solution, 5M ammonia solution, deionized water, 2.0% ammonium oxalate solution, Methyl red indicator. Methods (1) Calculation of volume delivered by pipette Record the room temperature indicated on the wall-mounted thermometer( we assume that the water temperature is the same as the room temperature), the volume of the pipette can be calculated from the weight of water discharged and the density of the water at water temperature. The experiment has to be repeated 6 times. The results should be averaged and the standard deviation calculated. (2) Titration of an aliquot of phosphoric acid solution Firstly, rinse the calibrated...
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...2012 Objective Titrate a solution of unknown acid to the half-reacted point and use the pH of the solution at that point to determine ka for the unknown acid. Titrate a solution containing a weighed amount of solid unknown acid to the half-reacted point and use the PH of the solution at that point to determine Ka for the unknown Ka for the unknown acid. Introduction When an uncharged weak acid is added to water, a heterogeneous equilibrium forms in which aqueous acid molecules, HA(aq), react with liquid water to form aqueous hydronium ions and aqueous anions, A-(aq). The latter are produced when the acid molecules lose H+ ions to water. HA(aq) + H2O(l) H3O+(aq) + A-(aq) Water is not included in the acid-dissociation equilibrium expression because the [H2O] has no effect on the equilibrium. Acid + Base→ Salt+ Water Materials Used 10, 50 and 100-mL graduated cylinder 125-mL flask 3.5-mL of 6M NaOH Solution Distilled Water Glass stirring rod Beaker 50-mL of Unknown Acid Solution 25- or 50-mL buret Ringstand with buret clamp 10-mL pipet 125mL flask Phenolphthalein indicator Short range pH paper pH meter Procedure A. Determination of Ka for an Unknown Acid in Solution * Measure and deposit approximately 50-mL of unknown acid into a clean dry 100-mL beaker * Wash and rinse a 25- or 50-mL buret with 5-mL of the previously prepared NaOH solution * Fill buret with NaOH (previously prepared) solution and mount on...
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...12.097 Environmental Chemistry of Boston Harbor – IAP 2006 Lab 1: DETERMINATION OF DISSOLVED OXYGEN BY WINKLER TITRATION 1. Background Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples. 2. Scope and field of application This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water)...
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...Chapter 4 TABLE OF CONTENTS Dissolved Oxygen Measurement Page Section 1: Dissolved Oxygen (DO) Introduction 2 Section 2: Glossary 2 Section 3: Approved Methods 3 Section 4: Safety and Hygiene 3-4 Section 5: Sampling 4-5 Section 6: Effects of Temperature on DO 5 Section 7: Interpretations 5 Quiz 4.1 6 Section 8: Modified Winkler Method 6-9 Quiz 4.2 9 Section 9: The Electrometric Meter Method 9-11 Quiz 4.3 12 Section 10: QA/QC 12 Answers to Quizzes 13-14 Appendix A: References Appendix B: Dissolved Oxygen Reagents Appendix C: Sample Bench Sheets Chapter 4 DISSOLVED OXYGEN MEASUREMENT Section 1 : DISSOLVED OXYGEN (DO) INTRODUCTION The DO determination measures the amount of dissolved (or free) oxygen present in water or wastewater. Aerobic bacteria and aquatic life such as fish must have DO to survive. Aerobic wastewater treatment processes use aerobic and facultative bacteria to break down the organic compounds found in wastewater into more stable products that will not harm the receiving waters. Wastewater treatment facilities such as lagoons or ponds, trickling filters and activated sludge plants depend on these aerobic bacteria to treat sewage. The same type of aerobic wastewater treatment process occurs naturally in streams and ponds if organic matter is present, turning these bodies of water into “aerobic wastewater treatment plants.” If sufficient oxygen is not naturally supplied through wind and turbulence to replace...
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...Outcome I Acids and Bases Define acid and base using Arrhenius, Bronsted-Lowry, and Lewis definitions. Classify common items as acid or base by their characteristics such as taste, reaction with indicators, etc. Calculate the pH and pOH of solutions and use pH to classify them as acids or bases Perform titration calculations using pH, pOH and molarities Definitions: Acid Base Arrhenius model Brønsted-Lowry model Conjugate Acid Conjugate Base Conjugate acid-base pair Amphoteric Lewis model Hydronium Strong acid Stron base Weak acid Weak base Ion product constant for water pH pOH Logarithm Neutralization reaction Salt Titrant Equivalence point End point Titration Indicator Questions and Calculations 1) a.What is Kw? b. What is the concentration of H3O+ in pure water? c. What is the concentration of OH- in pure water? d. What are the properties of a neutral solution? 2) Identify each of these as an acid, a base, both or neither | |Acid |Base |Both |Neither | |Fe | | | | X | |NaOH | | | | | |H2SO4 | ...
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...12.097 Environmental Chemistry of Boston Harbor – IAP 2006 Lab 1: DETERMINATION OF DISSOLVED OXYGEN BY WINKLER TITRATION 1. Background Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples. 2. Scope and field of application This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water)...
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...using EDTA – complexometry method. In this lecture, you will be introduced to a few experiments in chemistry. These experiments complement the theory you have learned in chemical equilibrium and kinetics. 38.1 Acid-Base Titrations: Acid-base reactions are of great practical importance in analysis, not only because of their use in titrating a large number of inorganic and organic substances, but also because the hydrogen ion concentration of a solution often is of great importance in controlling reactions. Titration : The process of determining the volume of a given solution of a reagent equivalent to the amount of another reactant present in a standard solution is known as titration. Equivalent Weight of Acids and Bases : The equivalent weight of an acid is that weight which yields one mole of hydrogen ions in the reaction employed whereas the equivalent weight of a base is that weight which reacts with one mole of hydrogen ions in the reaction. Normal solution : A solution containing one equivalent weight of solute per litre of solution. Equivalence Point : When the number of equivalents of acid (respectively base) added is equal to the number of equivalents of base (respectively acid) taken initially, we have reached the equivalence point. Acid-Base...
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...you replace the Metal with H, you get H2O =/= Acid * However, water can be considered an acid, sometimes * Nitrates | * All soluble | * Sulfates | * All soluble except clb (calcium lead barium) | * | * Mnemonics: Chinese language b | * Chloride | * All soluble except lms (lead, mercury, silver | * | * Learning management system, | * Carbonate | * All insouluble except spa (sodium, potassium, ammonium) | * | * Science practical assessment | * Precipitation: Prepare insoluble salt: 2 aqueous solutions combine to fom an insoluble solution * Method 2: Excess method. If acid +MCB(insol), use excesss * Method 3: Titration, Acid + MCB(sol), use titration * HNO3 + NaOH= NaNO3. Since Na2CO3 is soluble, use titration * Why use Naoh instead of Na2Co3, bcos, after reaction na2co3 liberates co2, which increases acidity of solution. innacurate * How to determine method...
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...Titrations Revisited By Drew Rutherford Concordia College Introduction The first experiment today will be the titration of acetic acid in vinegar. Vinegar is a solution of acetic acid, an organic acid of formula CH3COOH (MW = 60.0526 g/mole). In order to be sold as vinegar, it needs to meet the FDA’s guideline of 5.00% acetic acid by mass. Knowing that the density of vinegar is 1.04 g/mL and analyzing this solution by titration, chemists can determine the mass percentage of acetic acid in a sample of vinegar. The titration reaction is given below: CH3COOH + NaOH ( CH3COONa + H2O Reaction 1 A customer has purchased a vinegar solution at a local thrift store at a 20% discount and he believes that the sample of vinegar he has purchased does not meet FDA regulations. He is suing the thrift store for the $0.36 he feels that he has been cheated out of. The court has asked you to analyze the sample and render your verdict. Does this sample conform to the FDA guideline? If 2.00 mL of the thrift store vinegar required 9.73 mL of 0.150 M NaOH to reach the endpoint, then 0.00877 g of acetic acid was present. 9.73 mL NaOH x 1 liter NaOH x 0.150 mole NaOH x 1 mole CH3COOH x 60.0526 g CH3COOH 1000 mL 1 liter 1 moles NaOH 1 mole CH3COOH = 0.0876 grams CH3COOH in sample 2.00 mL vinegar x 1.04 g vinegar = 2.08 g vinegar 1 mL 0.0876 g CH3COOH x 100 = 4.21 % CH3COOH by mass 2...
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...Chapter 4 TABLE OF CONTENTS Dissolved Oxygen Measurement Page Section 1: Dissolved Oxygen (DO) Introduction 2 Section 2: Glossary 2 Section 3: Approved Methods 3 Section 4: Safety and Hygiene 3-4 Section 5: Sampling 4-5 Section 6: Effects of Temperature on DO 5 Section 7: Interpretations 5 Quiz 4.1 6 Section 8: Modified Winkler Method 6-9 Quiz 4.2 9 Section 9: The Electrometric Meter Method 9-11 Quiz 4.3 12 Section 10: QA/QC 12 Answers to Quizzes 13-14 Appendix A: References Appendix B: Dissolved Oxygen Reagents Appendix C: Sample Bench Sheets Chapter 4 DISSOLVED OXYGEN MEASUREMENT Section 1 : DISSOLVED OXYGEN (DO) INTRODUCTION The DO determination measures the amount of dissolved (or free) oxygen present in water or wastewater. Aerobic bacteria and aquatic life such as fish must have DO to survive. Aerobic wastewater treatment processes use aerobic and facultative bacteria to break down the organic compounds found in wastewater into more stable products that will not harm the receiving waters. Wastewater treatment facilities such as lagoons or ponds, trickling filters and activated sludge plants depend on these aerobic bacteria to treat sewage. The same type of aerobic wastewater treatment process occurs naturally in streams and ponds if organic matter is present, turning these bodies of water into “aerobic wastewater treatment plants.” If sufficient oxygen is not naturally supplied through wind and turbulence to replace...
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...Objective : 1 Preparation of standard solution and standardization of hydrochloric acid To prepare a standard solution of sodium carbonate and use it to standardize a given solution of dilute hydrochloric acid. Anhydrous sodium carbonate is a suitable chemical for preparing a standard solution (as a primary standard). The molarity of the given hydrochloric acid can be found by titrating it against the standard sodium carbonate solution prepared. The equation for the complete neutralization of sodium carbonate with dilute hydrochloric acid is Na2CO3(aq) + 2HCl(aq) → 2NaCl(aq) + CO2(g) + H2O(l) The end-point is marked by using methyl orange as indicator. Introduction : Chemicals : Apparatus : Procedure : solid sodium carbonate, 0.1 M hydrochloric acid 1. 2. 3. 4. 5. 6. 7. 8. Weight out about 1.3 g of anhydrous sodium carbonate accurately using the method of “weighing by difference”. Transfer the weighed carbonate to a beaker and add about 100 cm3 of distilled water to dissolve it completely. After dissolving, transfer the solution to a 250.00 cm3 volumetric flask. Rinse the beaker thoroughly and transfer all the washes into the volumetric flask. Remember not to overshoot the graduation mark of the flask. Make up the solution to the mark on the neck by adding water. Pipette 25.00 cm3 of sodium carbonate solution to a clean conical flask. Add 2 drops of methyl orange indicator to the carbonate solution. Titrate the carbonate solution with the given dilute hydrochloric...
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...permanganate solution and use it to determine the amount of iron, specifically Fe2+, in iron pills. Overview: Titration is the volumetric measurement of a solution of known concentration when it reacts completely with a measured volume or mass of another substance. In the first part of this experiment, the potassium permanganate solution, the titrant, is standardized, by quantitatively reacting it with iron (II) ammonium sulfate hexahydrate, Fe(NH4)2(SO4)2•6H2O (abbreviated FAS). The second part of the lab uses the standardized potassium permanganate to determine the amount of the analyte, also iron (II), in iron supplement pills. In this experiment, a purple-colored solution of potassium permanganate, KMnO4, with an approximate concentration of 0.02 M will be added to solutions containing Fe2+ ions. In redox titration the chemical reaction is an oxidation-reduction reaction with electrons transferred from one species to another. The total number of electrons lost in the oxidation half-reaction is equal to the total number of electrons gained in the reduction half-reaction. The permanganate ion, MnO4-, is a strong oxidizing agent which causes the Fe2+ to be oxidized to Fe3+ ions. The manganese gains five electrons and is reduced from a 7+ oxidation state in the permanganate ion to form colorless Mn2+ ions. The Fe2+ loses one electron as it is oxidized to Fe3+. The end point is indicated when the reaction is complete at the point when all of the Fe2+ ions in solution are oxidized...
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...are listed in the table below. While designing a training course, the relationship between this module and the others, would be maintained by keeping them close together in the syllabus and place them in a logical sequence. The actual selection of the topics and the depth of training would, of course, depend on the training needs of the participants, i.e. their knowledge level and skills performance upon the start of the course. No. 1 Module title Basic water quality concepts Basic chemistry concepts Code WQ - 01 • • • • • 3 How to prepare standard solutions WQ - 04 • • • 2 WQ - 02 Objectives Discuss the common water quality parameters List important water quality issues Convert units from one to another Discuss the basic concepts of quantitative chemistry Report analytical results with the correct number of significant digits. Select different types of glassware Use an analytical balance and maintain it. Prepare standard solutions. 4 How to measure dissolved...
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...determination in water; understand principles of the underlying chemistry; to understand standardization procedures of chemical solutions; perform sodium thiosulfate standardization; perform Winkler titrations; examine experimenter error and intra-experimenter error. Examine “kits”. Outcomes: Ability to determine under what conditions Winkler chemistry is appropriate for determination of DO in water; ability to relate details of chemical reactions to and knowledge of indirect determinations; perform titrations and calculate titration standards, as well as mass of DO in samples; assess individual and among individual errors associated with method. General description: You have received a new O2 meter that the person giving to you ensures is ‘perfectly calibrated’ and ‘ready-to-go’. You are heading out on a one-shot chance to sample in the arctic, are you going to trust this person to have gotten it right. How do you check that your probe is actually giving you a believable number (yes does the light in the fridge really turn off when yo close the door?) You will find out in this lab how to check your sensor. Your tasks: 1) Familiarize yourself with the Winkler titration chemistry so you know what you are doing once you get your hands on the bottles and chemicals. 2) Standardize the Sodium thiosulfate, so you know how much to mix for making a 0.025 N solution 3) Titrate up to five (5) individuals Winkler samples (BOD) bottles - with up to three replicates in each. 4) Calculate the mass of...
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...Acid-Base Indicators (NOTE: The second video is sort of a supplement to the first, and shows how this applies to your daily life. Feel free to try some of the things listed in the video, but be sure to report back to the class regarding the results of your experiments!) After you watch the above video, answer the questions below in sufficient detail: (a) (1 pts.) In YOUR OWN WORDS, what is a titration? What type of reaction is it? Be detailed and specific...
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