...Title Acid-base titration: Determination of the percentages (%) of sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) in a mixture Objective To determine the respective weight per cent of sodium carbonate and sodium hydroxide in a mixture by acid-base titration. Result and calculation Part A Titration 1 Titration number 1 2 3 Initial volume of burette( cm3) 5.10 2.70 9.70 Final volume of burette (cm3) 34.40 31.80 39.20 Total volume of HCl used (cm3) 29.30 29.10 29.50 Average volume of HCl required for titration =(29.30+29.10+29.50)/3 cm3 = 29.30 cm3 Titration 2 Titration number 1 2 3 Initial volume of burette( cm3) 4.50 14.00 2.70 Final volume of burette (cm3) 25.00 21.70 22.80 Total volume of HCl used (cm3) 20.50 20.30 20.10 Average volume of HCl required for titration =(20.50+20.30+20.10)/3 cm3 = 20.30 cm3 Part B Titration number Rough 1 2 3 Initial volume of burette( cm3) 4.9 4.80 3.60 2.20 Final volume of burette (cm3) 28.3 28.90 27.70 26.20 Total volume of HCl used until phenolphthalein decolourised (cm3) , x 23.4 24.10 24.10 24.00 Initial volume of burette after adding methyl orange indicator ( cm3) 28.3 28.90 27.70 26.20 Final volume of burette (cm3) 34.1 33.40 32.10 30.70 Total volume of HCl used until phenolphthalein decolourised (cm3) , y 5.8 4.50 4.40 4.50 Average volume of HCl required to react with Na2CO3 (2y) =2(4.50+4.40+4.50)/3 cm3 = 2(4.4667) cm3 ...
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...Fat and Oil Peroxide value of Oleic acid Redox titration by Automatic Potentiometric Titrator Standard Test Method for Analysis of Basic Fatty Material ISO 3960 1. Abstract The oleic acid is widely distributed in plant and animal fats. Measurement of peroxide value (POV) of oleic acid is demonstrated in this application according to the below quoted test method. The test sample is first dissolved in mixture of chloroform and acetic acid（2：3）. By flowing nitrogen gas through the sample to dispel residual oxygen, add potassium iodide, and then titrate free iodine with 0.01mol/L sodium thiosulfate. The endpoint is determined by the maximum inflexion point on titration curve. POV is calculated from titration volume of sodium thiosulfate. I2 + 2Na2S2O3 → Na2S4O6 + 2NaI 2. Reference 1) Test Method for Analysis of Basic Fatty Material by Japanese Oil Chemistry Society; Reference material 2.4-1996 Peroxide value （Chloroform Method） 2) ISO 3960 : 2007 Animal and vegetable fats and oils – Determination of peroxide value 3. Cautions in measurement 1) Do not use water containing carbon dioxide in preparing saturated potassium iodide solution. 2) To confirm saturation, add excessive potassium iodide to the saturated potassium iodide solution, and leave crystal in the solution. 3) Prepare fresh saturated potassium iodide each time. 4) If the sample does not change color to yellow due to free iodine when saturated potassium iodide is added, add more saturated potassium iodide...
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...EXPERIMENT 5 REDOX TITRATION: TITRATION USING SODIUM THIOSULPHATE Objectives 1. 2. To prepare a standard solution of potassium iodate for use to determine the concentration of sodium thiosulphate solution accurately. To acquire the proper techniques of carrying out a titration. Introduction Redox titrations using sodium thiosulphate as a reducing agent is known as iodometric titration since it is used specifically to titrate iodine. The reaction involved is: I2 + 2Na2S2O3 I2 + 2S2O322NaI + Na2S4O6 2I- + S4O62- In this equation I2 has been reduced to I- :2S2O32I2 + 2e S4O62- + 2e 2I- The iodine/thiosulphate titration is a general method for determining the concentration of an oxidising agent solution. A known volume of an oxidising agent is added into an excess solution of acidified potassium iodide. The reaction will release iodine:Example: (a) With KMnO4 2MnO4- + 16H+ + 10I(b) With KIO3 IO3- + 5I+ 6H+ 3I2 + 3H2O 2Mn2+ + 5I2 + 8H2O The iodine that is released is titrated against a standard thiosulphate solution. From the stoichiometry of the reaction, the amount of iodine can be determined and from this, the concentration of the oxidising agent which released the iodine, can be calculated. In an iodometric titration, a starch solution is used as an indicator as it can absorb the iodine that is released. This absorption will cause the solution to change to a dark blue colour. When this dark blue solution is titrated with the standardised thiosulphate solution, iodine...
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...equivalence point using pH titration of Potassium Hydrogen Phalate and 0.1 N Sodium Hydroxide with phenolphthalein indicator By Lee Binks (12647892), Penny Jinks (12993456) and Hong Links 13504733) Date submitted: Sept 18th , 2013 Abstract- The experiment described elucidates the fundamental principle of potentiometric titrations and determination of equivalence point using pH titration of Potassium Hydrogen Phalate and 0.1 N Sodium Hydroxide with the use of phenolphthalein indicator. The present study revealed the equivalence point by using simple titration curve which was further confirmed by using first and second derivative plots and pKa value of the Potassium Hydrogen Phalate. Introduction- The pH meter measures the pH of a solution and provides a direct method of obtaining a titration curve which is a graph of measured pH values versus the volume of titrant added in milliliters. The equivalence point is the point at which a stoichiometrically equivalent amount of base has been added to the acid. It does not mean that pH will be necessarily 7. KHP is a monoprotic acid. The neutralization with NaOH takes place in a 1:1 ratio HOOCC6H4COOK (aq) + NaOH ( aq) ---> C6H4 ( COO)2 2- (aq) + K+ (aq) + Na+ (aq) The equivalence point occurs in the region where there is a relatively large change in pH with a relatively small change in volume on the titration curve. The steeper the curve the more precisely equivalence point can be established. Once a titration curve is constructed...
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...CHEM. 201, EXPERIMENT 4 TITRATION CURVES PROCEDURE: See the pre-lab report on page 15 of my laboratory notebook for an outline of the general procedure. The unknown acid number was 6553, and the concentration of NaOH used in the experiment was .09912 M. Also, three drops of phenolphthalein indicator were added to the initial titration and the titration curve. EXPERIMENTAL DATA: Initial Titration: * Volume of NaOH added at the endpoint was 29.8 mL Titration Curve: * Volume of NaOH added at the endpoint was 29.0 mL CALCULATED RESULTS: Acid concentration from first titration was .118M Ka from initial pH was 1.08x10^-5 Acid concentration from titration curve was .115M Titration | Volume of NaOH (mL) | pH | (base)/(acid) | pKa | Ka | 1/4 | 7.25 | 4.1 | 1/3 | 4.577 | 2.65x10^-5 | 1/2 | 14.5 | 4.6 | 1 | 4.6 | 2.55x10^-5 | 3/4 | 21.8 | 5.19 | 3 | 4.713 | 1.94x10^-5 | Average: | | | | 4.663 | 2.18x10^-15 | DISCUSSION: The purpose of the experiment was to titrate a weak acid of unknown concentration with a strong base, NaOH, and then utilizing an initial titration and titration curve to determine that acid concentration and Ka. After performing the initial titration of the acid concentration, we calculated it to be 0.118 M, with a Ka of 1.08x10^-5. On the other hand, when we performed the titration curve, it calculated an acid concentration of 0.115 M and a Ka of 2.18x10^-5. The results I obtained seemed reasonable...
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...POINT LISAS CAMPUS Esperanza Road, Brechin Castle, Couva www.utt.edu.tt LAB 1 Decomposition reaction Aim: Determination of the number of moles of water molecules of crystallization present in hydrated Magnesium Sulphate (MgSO4.xH2O) Apparatus: Mass balance, test tube, test tube holder, heat-proof mat and bunsen burner. Reagents: Hydrated sodium carbonate. Theory: Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simple compounds. A more specific type of decomposition is thermal decomposition or thermolysis, which is caused by heat. ABA+B, the reaction is endothermic, since heat is required to break the chemical bonds. Most decomposition reaction require energy either in the form of heat, light or electricity. Absorption of energy causes the breaking of the bonds present in the reacting substance which decomposes to give the product. When a hydrated salt is heated it decomposes into a pure form of the salt and water. MgSO4.xH2O MgSO4 + H2O Procedure: Refer to Handout Results: A. Mass of test tube/g = 21.77 B. Mass of the tube and salt/g = 24.0 A table showing the mass of the test tube and salt after 3 consecutive heating: Heating | Mass of the test tube and salt/g | 1st | 23.96 | 2nd | 23.81 | 3rd | 23.81 | Calculations: G. Mass of anhydrous magnesium sulphate/g = F - A = 23.81 – 21.77= 2.04 H. Mass of water of crystallization evaporated/g...
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...(4) Acid-base Titration using Method of Double Indicators Student Handout Purposes To determine the composition of the following mixture by double indicator method: 1. NaOH(aq) and Na2CO3(aq) 2. NaHCO3(aq) and Na2CO3(aq) Introduction Consider a mixture of NaOH(aq) and Na2CO3(aq). Reaction between HCl(aq) and Na2CO3(aq) takes place in two stages: HCl(aq) + Na2CO3(aq) ⎯→ NaHCO3(aq) + H2O(l) …………………. (1) HCl(aq) + NaHCO3(aq) ⎯→ NaCl(aq) + CO2(g) + H2O(l) …………. (2) While that between HCl(aq) and NaOH(aq) completes in only one step: HCl(aq) + NaOH(aq) ⎯→ NaCl(aq) + H2O(l) ……………….………. (3) Solution mixture of reaction (1) at the equivalence point is alkaline, that of reaction (2) is acidic and that of reaction (3) is neutral. Thus the whole titration should have three breaks in the pH curve, corresponding to the above three stages. Reactions (1) and (3) can be indicated by phenolphthalein and that of reaction (2) can be indicated by methyl orange. Stoichiometry confines each of the above pH reactions to react according to a mole ratio of 1 : 1. This means, say from equation (2), the number of mole of HCl(aq) determined from the methyl orange titration is equal to the number of mole of NaHCO3(aq). Likewise, total number of moles of NaOH(aq) and Na2CO3(aq) in the solution mixture can be calculated according to the volumes of HCl(aq) added at the end point Vol. of HCl indicated by the colour change of the phenolphthalein indicator. Alternatively, the Fig. 1: Titration curve for a mixture...
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...Telicia Peet ENG 231 3/15/2014 How to Titrate a Solution A titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution (ChemMed). In a titration a solution of a known solute (titrant) is added to a solution with an unknown solute (analyte). The chemical composition of a substance is very intricate, and learning how to titrate a solution is the most fundamental step toward determining the chemical makeup of that substance”. When a substance becomes synthesized, it is important to know that it has the chemical makeup expected. The point at which the solutions meet is known as the equivalence point; here the amounts of the two substances are stoichiometrically equivalent. The endpoint is the point at which the titration is complete (Princeton). There are numerous ways to determine the composition and structure of a substance, yet this manual demonstrates how to titrate a solution. To conduct this experiment, he or she will need a burette, an Erlenmeyer flask, a lab coat, goggles, and an unknown solution to titrate. Typically this is done in a laboratory but anywhere with an ample amount of space is fine. The burette is used to dispense accurate volumes of a substance. Attached to the burette is a stopcock that is used to release or withhold a substance. Normally the titrated solution is purple, but the color of the titrant may vary also. An Erlenmeyer flask is a piece of glassware used to pour the substance...
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...Elijah Kim Mrs. Dobler Course 2 2/10/15 Titration lab Titration is used to find the specific amount of a standard solution in an amount of unknown liquid. Titration in this lab is performed with the chemical reactions between acids and liquids. During titration, we have to stop at the point where stoichiometric amounts of acids and bases are reacting. We can find that point by looking for indicators, for example in this lab the indicators were changes in color. So the purpose of all this is to determine the concentration of some acid solutions. 1. Measure 10 mL of your acid solution using graduated cylinder and and it to the Erlenmeyer flask 2. Add about 25 mL of distilled water to the flask 3. Place your Erlenmeyer flask under the buret and a white piece of paper under you Erlenmeyer flask 4. Record the initial buret reading 5. Start adding the NaOH to the flask dropwise, stopping at a faint pink point. 6. Record final buret reading 7. Repeat for a second and third trial Trial one Trial two Trial three Volume of acid sample: 10 mL 10 mL 10 mL Final Buret reading: 20.22 29.8 40.1 Initial Buret reading: 10.63 20.22 29.8 Net volume NaOH used: 9.6 9.6 10.3 Calculations Trial one Trial two Trial three Moles NaOH reacted: ...
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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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...In the lab, All That Glitter, students learned to calculate and differentiate the density of different forms of matter. Students calculated the density of pre-1982 pennies, post-1982 pennies, and an unknown metal sample. In order to complete the lab, students first took ten pre-1982 and post-1982 pennies and carefully dried them. Afterwards, the pennies were placed on a digital scale in order to find the mass. Students then found the volume of the pennies by filling the graduated cylinder with 20 mL of water and tilting it on its side in order to slowly place the pennies in without making the water splash. To get an exact value we gently turned the graduated cylinder right side up and tapped it to release any air bubbles. Looking at...
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...out in a flask containing the liquid or dissolved sample. Titrant solution is volumetrically delivered to the reaction flask using a burette. Delivery of the titrant is called a titration. The titration is complete when sufficient titrant has been added to react with all the analyte. This is called the equivalence point. An indicator is often added to the reaction flask to signal when all of the analyte has reacted. The titrant volume where the signal is generated is called the end point. The equivalence and end points are rarely the same. SUCCESSFUL TITRATIONS A few rules of thumb for designing a successful titration are: 1. The titrant should either be a standard or should be standardized. 2. The reaction should proceed to a stable and well defined equivalence point. 3. The equivalence point must be able to be detected. 4. The titrant’s and sample’s volume or mass must be accurately known. 5. The reaction must proceed by a definite chemistry. There should be complicating side reactions. 6. The reaction should be nearly complete at the equivalence point. In other words, chemical equilibrium favors products. 7. The reaction rate should be fast enough to be practical. TYPES OF TITRATIONS 1. ACID-BASE TITRATION a. These titrations are based on the neutralization reaction that occurs between an acid and a base, when mixed in solution. b. The acid (resp....
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...CHEMISTRY: MATTER AND EQUILIBRIUM Indigestion and Titration: An Acid-Base Titration Imagine yourself as the Lead Analytical Chemist at Kaplan Industries. Your first big assignment is to investigate the strength of several commercial antacids for the Food and Drug Administration (FDA). They have sent five antacids to be tested with a back-titration that works as follows: • • • First, each antacid tablet is mixed with 40 mL of 0.1 M HCl—this acidic solution is the same stuff that is in stomach acid, and one antacid pill is nowhere near enough to neutralize all 40 mL of the acid. So, to see how much extra help each antacid pill needs to neutralize 40 mL of 0.1 M HCL, you add 0.05 M NaOH drop-by-drop to back-titrate the solution until the pH is neutral. What this means is that, the stronger the antacid tablet, the less NaOH it will take to help bring the acid to neutral. (In other words, the stronger antacid tablets counteract more of the original HCl, leaving the solution closer to neutral before the NaOH is added.) Here are your results: Maalox Mass of one dose antacid mL NaOH used in backtitration 20.0 g Tums 21.0 g Mylanta 18.0 g CVS brand 18.3 g Rennies 17.5 g 24.1 mL 22.4 mL 20.0 mL 19.9 mL 24.4 mL 1. Which is the strongest antacid, on a single-dose basis? Which is the weakest? Explain and show your calculations. 2. Which are the strongest and weakest, on a by-weight (mass) basis? 3. When people do back titrations, they usually watch the solution for a color...
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...NATIONAL QUALIFICATIONS CURRICULUM SUPPORT Chemistry A Practical Guide Support Materials [REVISED ADVANCED HIGHER] [pic] The Scottish Qualifications Authority regularly reviews the arrangements for National Qualifications. Users of all NQ support materials, whether published by Education Scotland or others, are reminded that it is their responsibility to check that the support materials correspond to the requirements of the current arrangements. Acknowledgement © Crown copyright 2012. You may re-use this information (excluding logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/ or e-mail: psi@nationalarchives.gsi.gov.uk. Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned. Any enquiries regarding this document/publication should be sent to us at enquiries@educationscotland.gov.uk. This document is also available from our website at www.educationscotland.gov.uk. Contents Introduction 5 Chemical analysis 6 Qualitative and quantitative analysis 6 Volumetric analysis 6 Gravimetric analysis 14 Colorimetric analysis 17 Organic techniques 22 Introduction 22 Preparation 22 Isolation 24 Purification 29 Identification 33 Percentage yield 37 Errors 39 Accuracy and precision 39 Repeatability and reproducibility...
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...instruments __________________________________________________________________ Series A. Basic Quantitative Techniques Introductory Experiments (A-1) Experiment 1 Use of the Analytical Balance (page 727) (A-2) Experiment 2 Use of the Pipet and Buret and Statistical Analysis (page 729) Gravimetric Analysis (A-3) Experiment 3 Gravimetric Determination of Chloride (page 730) Volumetric Analysis Acid-Base Titrations Neutralization Titrations (A-4) Experiment 6 Determination of Replaceable Hydrogen in Acid by Titration with Sodium Hydroxide (page 736) (A-5) Experiment 7 Determination of Total Alkalinity of Soda Ash (page 738) Complexometric Titrations (A-6) Experiment 9 Determination of Water Hardness with EDTA (page 742) Precipitation Titrations (A-7) Experiment 11 Determination of Chloride in a Soluble Chloride: Fajan’s Method (page 745) Statistical Comparison of the results obtained from Exp 3 and Exp 11 Reduction-Oxidation Titrations...
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