Introduction. Depolymerization of Poly(lactic acid) Cups to Lactic Acid. Experiment
|
|
- Emery Henry
- 7 years ago
- Views:
Transcription
1 Experiment Depolymerization of Poly(lactic acid) Cups to Lactic Acid 6 Introduction Poly(lactic acid), or PLA, is a biobased polymer that is a promising alternative to fossil-fuel based plastics. PLA is derived from corn, a renewable resource, and its total production uses 25-50% less fossil energy than the production of conventional petroleum-derived plastics. i To prepare PLA, corn is fermented into lactic acid, which is then manufactured into a low molecular weight pre-polymer. This prepolymer can then be used to form the high molecular weight PLA plastic that can be made into anything from plastic cups, to clothing, to medical sutures. ii iii Pure high-molecular weight PLA is brittle. Therefore, most commercial uses of PLA incorporate other plastics into a PLA blend depending on the rigidity of the plastic needed for a specific application. iv PLA is classified as a number 7 plastic. 79
2 PLA is a polymer it consists of individual components of stable monomers chained together. In this experiment, PLA will be broken down into its lactic acid monomers, which will be quantitatively measured through a potentiometric titration. The conversion of PLA to lactic acid is called a saponification reaction. The saponification reaction is an organic hydrolysis reaction that is used to make soap. (Some green household cleaners use lactic acid as an active ingredient). Each C-O-C bond that binds two lactic acid units together is cleaved to form 2 C-O-H units. Because the reaction occurs in a basic solution, an acidic work-up is needed to convert the deprotonated lactic acid unit (present in the form of a sodium lactate salt) into the desired protonated lactic acid form: The depolymerization of PLA also demonstrates important principles of Green Chemistry: - Prevents waste: The solvent (50% ethanol) can be reused. Therefore, the E-factor, or the grams of byproduct (waste) divided by grams of product, is low. - High Atom Economy: The molecular weight of the products divided by the molecular weight of the reagents, or atom economy, is a measure of the efficiency of the reaction. What is the atom economy in this reaction? - Designing safer chemicals: lactic acid, also known as milk acid, is a naturally-occurring chemical and is therefore, biodegradable. - Safer solvents: this reaction takes place in 50% ethanol, as opposed to harmful organic solvents. - Design for Energy Efficiency: the entire hydrolysis takes place in an hour, or 15 minutes if using a microwave oven. Also, the manufacture of PLA uses less energy and fossil fuels than that of conventional fossil-fuel based plastics. - Renewable Feedstock: PLA is generally derived from corn or potato starches, which are renewable resources. - Design for degradation: the depolymerization of PLA recycles the original lactic acid used to manufacture PLA. This lactic acid can be isolated for various other uses including reincorporation into PLA. Why do the structures differ with changes in ph? Use Le Chatelier s Principle to explain the dominant species at ph 2 vs. ph 12. In this lab you will be performing a potentiometric titration of your sample of lactic acid with a known NaOH standard, using a ph meter to track changes in the ph of the acid solution as you add measured volumes of base. We usually represent such data in the form of a titration curve. 80
3 Titration of a Monoprotic Weak Acid with Strong Base 4 ph V base 1) Start- Solution is just an acid in water since no base has been added. HA + H 2 O A - + H 3 O + The ph depends on the strength of the acid and its concentration. 2) Before equivalence- A buffer exists, a mixture of HA and A - because HA is only partly neutralized by base. HA + OH - A - + H 2 O ph pk a log [A ] [HA] When exactly half of the acid has been neutralized, the ph reading gives you a very important piece of information. What is so special about the ph at ½ equivalence? Think about the proportions of A - and HA in solution. 3) At equivalence- HA and OH - react completely to give only A - in solution. The ph of this solution depends on the chemical properties of A -. Often A - is a weak base so the reaction of a weak base with the water must be considered. 4) After equivalence- The is ph dominated by the excess of the strong base added. Challenge: What would the curve look like for the titration of a weak base with a strong acid? How would you predict the ph of the buffer regions? 81
4 Prelab: Complete the following tasks in your lab notebook. Work in small groups in lab and share your thoughts with your classmates. 1. Write a fully balanced chemical equation for the conversion of lactic acid to PLA include the acidic work-up. 2. Draw the form of the PLA polymer, the product after the depolymerization, the product after the acidic work-up, and the product after the titration. 3. What is the pka of lactic acid? 4. Of the following indicators, which one(s) would be suitable for finding the endpoint in the titration? Explain your reasoning. Phenolphthalein Bromocresol Green Bromothymol Blue 5. How many lactic acid monomer molecules do you expect in a 1g sample of PLA? (Hint: what is the molar mass of the repeating lactic acid monomer unit in PLA?) 6. How much NaOH will you need to completely react with the PLA? 7. How much HCl will you need for the acidic work-up step, assuming the reaction goes to completion? 82
5 Depolymerization of Poly(lactic acid) to Lactic Acid v Experimental The Problem Depolymerize a sample of poly(lactic acid) into lactic acid in basic solution. Quantitatively measure the amount of lactic acid in the final solution through a potentiometric titration. The Approach Work in groups of 2 depending on the availability of ph meters in your lab room. Equipment needed: PLA cups Standardized NaOH solution (~3M for the depolymerization and ~0.1M for the titration) 50mL Erlenmeyer flask stir bar watch glass hot plate 50% HCl solution ice ph meter phydrion strips buret clamps Gravity Filtration ph Meter Potentiometric Titration Apparatus Buret 24 ph Meter Clamp Hayden-McNeil Publishing, Inc. Hayden-McNeil Publishing, Inc. 83
6 1. Cut PLA cup into small pieces (the smaller the pieces, the faster the reaction why?). Measure out ~1 gram and put the pieces into a 50mL Erlenmeyer flask. Be sure to record the exact mass of the PLA in your notebook. 2. Measure out 10 ml of 3M NaOH in 50% ethanol. Add to the 50mL Erlenmeyer flask. 3. Add a stir bar to the solution and cover the top of the 50mL Erlenmeyer flask with a watch glass. 4. Heat the reaction for approximately one hour (or until all of the polymer pieces appear reacted) on a hot plate set to a medium heat. Make sure to observe any changes in the solution. The solution should be boiling, but not so much that the watch glass begins to rattle. 5. Once all the solid PLA is reacted, place the reaction mixture in a shallow ice water bath and let cool for ~5-10 minutes. 6. Take the ice bath with your reaction mixture into the fume hood. Slowly add 50% HCl until the ph is ~1-2. Test the solution with the ph paper provided. 7. Gravity filter the solution and collect the filtrate. 8. Obtain 50 ml of ~0.1M NaOH solution from the fume hood. Be sure to record the exact concentration of the solution in your notebook 9. Set up the apparatus for your titration. Obtain a buret clamp from the lab shelf. Clean your buret with soap and water, then rinse with just a few ml (~5 ml) of NaOH solution before filling the buret with the base (remember, don t fill past the 0.00 ml mark). Record your initial volume. 10. Calibrate your ph meter by following the steps in the appendix of your lab manual. Be sure to have a large beaker to collect solution from rinsing the probe with distilled water. Kim wipes can be obtained from your GSI to gently pat dry the probe. Do not use paper towels. 11. Prepare your lactic acid solution for titration. Using a pipette, remove a 1.00 ml aliquot of the filtrate and dispense into a 150mL beaker. Add 50 ml of deionized water using a graduated cylinder. Add a stir bar to your flask. 12. Clamp the probe of the ph meter to the metal rod at your station. Make sure the probe is immersed in your dilute solution past the small hole on the side of the probe, near the bulb. The stir bar must not collide with the ph meter. Your GSI will demonstrate the proper setup of the apparatus for you. 13. To perform your rough titration, start by recording the initial ph of your unknown solution. It would be helpful to have a table in your notebook where you can record the ph of the solution corresponding to the amount of base you have added. 14. With gentle stirring, add 1.00 ml of the NaOH solution to the PLA solution. Allow a few moments for the ph to stabilize, and then record the ph in your table. Repeat this step until you either reach a ph of 12 or have added 25 ml of base. 15. Draw a rough graph of the titration in your notebook to identify the equivalence point volumes. 84
7 16. Set up your precise titration following the same procedure as above. Dispose of your solution in the proper container and be sure to wash and dry the beaker thoroughly before adding a new diluted lactic acid solution. 17. Perform the precise titration. Add 1 ml increments of base as you did above (recording ph readings as you go), but when you come within 1 ml of an equivalence point, slow down the titration and add smaller amounts of base (dropwise, around 0.2 ml). You ll need to make an Excel graph of your precise titration, so be sure to collect as much data around the equivalence points as you can. 18. Place excess acid and base solutions in the appropriately labeled containers near the fume hood. A five gallon bucket will be provided for collection of all the solutions from this experiment. Calculating Equivalence Points from Titration Data The solid line above shows how ph changes during a titration of nitric acid, HNO 3, with the strong base sodium hydroxide, NaOH. The ph changes dramatically around 16 ml, indicating the equivalence point has been reached in the titration. To accurately determine equivalence point it is best to compute the first derivative of the titration curve. The first derivative (dotted line) shows a maximum when the slope is the steepest, which should coincide with the equivalence point of the titration. Using this data the equivalence volume is actually ml. Accurate determination of the equivalence point depends on the quality of the data. For this method to work well, it is important to add base is very small increments around the equivalence point. In the data set below the student added 0.05 ml of base at a time. Adding even smaller amounts, fractions of a drop, will produce even greater accuracy. Vbase ph dph/dv
8 (this page intentionally left blank) 86
9 Experiment 6- Depolymerization of Poly(lactic acid) Cups to Lactic Acid Report Sheet GSI Name Partners Generate a good graph of ph vs. Volume Titrant for your sample and attach it to this report. Also graph the first derivative of the ph graph versus volume titrant. (Hint: If you use Excel, the SLOPE function will be useful). Data: 1. Attach a copy of your titration curve to this report. 2. Label important data points and regions on the curve. Results and Discussion: 1) Determine the amount of lactic acid titrated in the solution. 2) What evidence suggests that lactic acid is actually in the final solution? (Hint: Calculate the pka of the acid.) Are any assumptions being made about the final solution that would affect the data from the titration? 3) What assumptions were made when calculating the amount of NaOH that would be needed to react the entire PLA sample? How do you think using a real-world reagent versus a pure chemical affects the data? 4) Draw the molecular structure of PLA before and after the depolymerization step. 5) How does the molecule change after the acidic-work-up? 87
10 6) What different species are in your solution immediately after the depolymerization? 7) What different species are in your solution after the acidic work-up? Green Chemistry Connections Read through the green chemistry principles provided in the beginning of the lab manual. 8) What principles are illustrated through this depolymerization of PLA? 9) Another way to depolymerize the PLA is to heat the plastic with store bought white vinegar for 65 hours. Which method is greener, the NaOH/HCl or the vinegar? i Vink, Erwin T.H., et. al. Applications of Life Cycle Assessment to NatureWorks polylactide (PLA) production. Science Direct [Online] Nov 11, 2002, p (accessed July 31, 2011). ii NatureWorks LLC. Products and Applications. Applications.aspx (accessed Aug 3, 2011). iii Gruber, Patrick and Michael O Brien. Polylactides NatureWorks PLA. Wiley-VCH [online], p (accessed July 31, 2011). iv Gruber, Patrick. Commodity Polymers from Renewable Resources: Polylactic Acid. National Center for Biotechnology Information [Online]. (accessed Aug 1, 2011). v Boice, Jennifer N. et. al. Molecular Recycling: Application of the Twelve Principles of Green Chemistry in the Diversion of Post-consumer Poly(lactic acid) Waste. The Journal of Materials Education [Online] May 5, (accessed Aug 3, 2011). 88
To determine the equivalence points of two titrations from plots of ph versus ml of titrant added.
Titration Curves PURPOSE To determine the equivalence points of two titrations from plots of ph versus ml of titrant added. GOALS 1 To gain experience performing acid-base titrations with a ph meter. 2
More informationAcid Base Titration: ph Titration Curve
Acid Base Titration: ph Titration Curve OVERVIEW In this experiment, you will perform a ph-monitored titration of acetic acid and of an unknown acid. From the ph titration of the acetic acid, you will
More informationAcid Base Titrations
Acid Base Titrations Introduction A common question chemists have to answer is how much of something is present in a sample or a product. If the product contains an acid or base, this question is usually
More informationph: Measurement and Uses
ph: Measurement and Uses One of the most important properties of aqueous solutions is the concentration of hydrogen ion. The concentration of H + (or H 3 O + ) affects the solubility of inorganic and organic
More informationDetermining the Identity of an Unknown Weak Acid
Purpose The purpose of this experiment is to observe and measure a weak acid neutralization and determine the identity of an unknown acid by titration. Introduction The purpose of this exercise is to identify
More informationChem 1B Saddleback College Dr. White 1. Experiment 8 Titration Curve for a Monoprotic Acid
Chem 1B Saddleback College Dr. White 1 Experiment 8 Titration Curve for a Monoprotic Acid Objectives To learn the difference between titration curves involving a strong acid with a strong base and a weak
More informationThe introduction of your report should be written on the on the topic of the role of indicators on acid base titrations.
Experiment # 13A TITRATIONS INTRODUCTION: This experiment will be written as a formal report and has several parts: Experiment 13 A: Basic methods (accuracy and precision) (a) To standardize a base (~
More informationACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND
#3. Acid - Base Titrations 27 EXPERIMENT 3. ACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND Carbonate Equilibria In this experiment a solution of hydrochloric
More informationExperiment 6 Titration II Acid Dissociation Constant
6-1 Experiment 6 Titration II Acid Dissociation Constant Introduction: An acid/base titration can be monitored with an indicator or with a ph meter. In either case, the goal is to determine the equivalence
More informationExperiment 4 (Future - Lab needs an unknown)
Experiment 4 (Future - Lab needs an unknown) USING A ph TITRATION TO DETERMINE THE ACID CONTENT OF SOFT DRINKS 2 lab periods Reading: Chapter 9, 185-197; Chapter 10, pg 212-218; Chapter 14 pg 317-323,
More information15. Acid-Base Titration. Discover the concentration of an unknown acid solution using acid-base titration.
S HIFT INTO NEUTRAL 15. Acid-Base Titration Shift into Neutral Student Instruction Sheet Challenge Discover the concentration of an unknown acid solution using acid-base titration. Equipment and Materials
More informationEXPERIMENT 10: TITRATION AND STANDARDIZATION
EXPERIMENT 10: TITRATION AND STANDARDIZATION PURPOSE To determine the molarity of a NaOH solution by titrating it with a standard HCl solution. To determine the molarity of acetic acid in vinegar using
More informationEvaluation copy. Titration of a Diprotic Acid: Identifying an Unknown. Computer
Titration of a Diprotic Acid: Identifying an Unknown Computer 25 A diprotic acid is an acid that yields two H + ions per acid molecule. Examples of diprotic acids are sulfuric acid, H 2 SO 4, and carbonic
More informationDetermination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration
Determination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration GOAL AND OVERVIEW Antacids are bases that react stoichiometrically with acid. The number of moles of acid that
More informationTo see how this data can be used, follow the titration of hydrofluoric acid against sodium hydroxide below. HF (aq) + NaOH (aq) H2O (l) + NaF (aq)
Weak Acid Titration v120413 You are encouraged to carefully read the following sections in Tro (2 nd ed.) to prepare for this experiment: Sec 4.8, pp 158-159 (Acid/Base Titrations), Sec 16.4, pp 729-43
More informationTITRATION OF AN ACID; USING A ph METER. The ph meter is an instrument that measures the ph of a solution and affords a
62 Experiment #5. Titration of an Acid; Using a ph Meter TITRATION OF AN ACID; USING A ph METER Introduction The ph meter is an instrument that measures the ph of a solution and affords a direct method
More informationGA/7 Potentiometric Titration
Rev. 7/99 7-1 INTRODUCTION GA/7 Potentiometric Titration The potentiometric titration is a useful means of characterizing an acid. The ph of a solution is measured as a function of the amount of titrant
More informationAcid-Base Titrations Using ph Measurements
Acid-Base Titrations Using ph Measurements Introduction According to the Brønsted Lowry definition, an acid is a substance that donates a hydrogen ion and a base is a substance which will accept a hydrogen
More informationExperiment 7: Titration of an Antacid
1 Experiment 7: Titration of an Antacid Objective: In this experiment, you will standardize a solution of base using the analytical technique known as titration. Using this standardized solution, you will
More informationVolumetric Analysis. Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115
Volumetric Analysis Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115 Experimental Aims To prepare and standardize (determine concentration) a NaOH solution Using your standardized NaOH calculate
More informationExperiment 17: Potentiometric Titration
1 Experiment 17: Potentiometric Titration Objective: In this experiment, you will use a ph meter to follow the course of acid-base titrations. From the resulting titration curves, you will determine the
More informationPREPARATION AND PROPERTIES OF A SOAP
(adapted from Blackburn et al., Laboratory Manual to Accompany World of Chemistry, 2 nd ed., (1996) Saunders College Publishing: Fort Worth) Purpose: To prepare a sample of soap and to examine its properties.
More informationSTANDARDIZATION OF A SODIUM HYDROXIDE SOLUTION EXPERIMENT 14
STANDARDIZATION OF A SODIUM HYDROXIDE SOLUTION EXPERIMENT 14 OBJECTIVE The objective of this experiment will be the standardization of sodium hydroxide using potassium hydrogen phthalate by the titration
More informationLab #10 How much Acetic Acid (%) is in Vinegar?
Lab #10 How much Acetic Acid (%) is in Vinegar? SAMPLE CALCULATIONS NEED TO BE DONE BEFORE LAB MEETS!!!! Purpose: You will determine the amount of acetic acid in white vinegar (sold in grocery stores)
More informationPART I: PREPARATION OF SOLUTIONS AND STANDARDIZATION OF A BASE
TITRATION: STANDARDIZATION OF A BASE AND ANALYSIS OF STOMACH ANTACID TABLETS 2009, 1996, 1973 by David A. Katz. All rights reserved. Reproduction permitted for education use provided original copyright
More informationEXPERIMENT 2 THE HYDROLYSIS OF t-butyl CHLORIDE. PURPOSE: To verify a proposed mechanism for the hydrolysis of t-butyl Chloride.
PURPOSE: To verify a proposed mechanism for the hydrolysis of t-butyl Chloride. PRINCIPLES: Once the Rate Law for a reaction has been experimentally established the next step is its explanation in terms
More informationAcid Dissociation Constants and the Titration of a Weak Acid
Acid Dissociation Constants and the Titration of a Weak Acid One of the most important applications of equilibria is the chemistry of acids and bases. The Brønsted-Lowry acid-base theory defines an acid
More informationDissolving of sodium hydroxide generates heat. Take care in handling the dilution container.
TITRATION: STANDARDIZATION OF A BASE AND ANALYSIS OF STOMACH ANTACID TABLETS 2009, 1996, 1973 by David A. Katz. All rights reserved. Reproduction permitted for education use provided original copyright
More informationThe Determination of Acid Content in Vinegar
The Determination of Acid Content in Vinegar Reading assignment: Chang, Chemistry 10 th edition, pages 153-156. Goals We will use a titration to determine the concentration of acetic acid in a sample of
More informationDETERMINATION OF PHOSPHORIC ACID CONTENT IN SOFT DRINKS
DETERMINATION OF PHOSPHORIC ACID CONTENT IN SOFT DRINKS LAB PH 8 From Chemistry with Calculators, Vernier Software & Technology, 2000 INTRODUCTION Phosphoric acid is one of several weak acids that present
More informationNeutralizing an Acid and a Base
Balancing Act Teacher Information Objectives In this activity, students neutralize a base with an acid. Students determine the point of neutralization of an acid mixed with a base while they: Recognize
More informationAscorbic Acid Titration of Vitamin C Tablets This lab will be completed individually! Make sure you come prepared!
Ascorbic Acid Titration of Vitamin C Tablets This lab will be completed individually! Make sure you come prepared! Introduction Vitamin C (also known as ascorbic acid, HC6H7O6) is a necessary ingredient
More informationTITRATION OF VITAMIN C
TITRATION OF VITAMIN C Introduction: In this lab, we will be performing two different types of titrations on ascorbic acid, more commonly known as Vitamin C. The first will be an acid-base titration in
More information18 Conductometric Titration
Lab Activity 18 CONDUCTOMETRIC TITRATION LAB ACTIVITY 18 Conductometric Titration Background Titration is the a method of determining the concentration of an unknown solution (the analyte) by reacting
More informationLab 25. Acid-Base Titration and Neutralization Reactions: What Is the Concentration of Acetic Acid in Each Sample of Vinegar?
Lab 25. Acid-Base Titration and Neutralization Reactions: What Is the Concentration of Acetic Acid in Each Sample of Vinegar? Introduction Vinegar is basically a solution of acetic acid (CH3COOH). It is
More informationElectrical Conductivity of Aqueous Solutions
Electrical Conductivity of Aqueous Solutions PRE-LAB ASSIGNMENT: Reading: Chapter 4.-4.3 in Brown, LeMay, Bursten & Murphy.. Using Table in this handout, determine which solution has a higher conductivity,.
More informationDetermination of calcium by Standardized EDTA Solution
Determination of calcium by Standardized EDTA Solution Introduction The classic method of determining calcium and other suitable cations is titration with a standardized solution of ethylenediaminetetraacetic
More informationexperiment5 Understanding and applying the concept of limiting reagents. Learning how to perform a vacuum filtration.
81 experiment5 LECTURE AND LAB SKILLS EMPHASIZED Synthesizing an organic substance. Understanding and applying the concept of limiting reagents. Determining percent yield. Learning how to perform a vacuum
More informationChemistry 112 Laboratory Experiment 6: The Reaction of Aluminum and Zinc with Hydrochloric Acid
Chemistry 112 Laboratory Experiment 6: The Reaction of Aluminum and Zinc with Hydrochloric Acid Introduction Many metals react with acids to form hydrogen gas. In this experiment, you will use the reactions
More informationCHM 130LL: ph, Buffers, and Indicators
CHM 130LL: ph, Buffers, and Indicators Many substances can be classified as acidic or basic. Acidic substances contain hydrogen ions, H +, while basic substances contain hydroxide ions, OH. The relative
More informationDetermination of Aspirin using Back Titration
Determination of Aspirin using Back Titration This experiment is designed to illustrate techniques used in a typical indirect or back titration. You will use the NaH you standardized last week to back
More informationMASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry 5.310 Laboratory Chemistry THE POTENTIOMETRIC TITRATION OF AN ACID MIXTURE 1
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry 5.310 Laboratory Chemistry EXPERIMENT #5 THE POTENTIOMETRIC TITRATION OF AN ACID MIXTURE 1 I. PURPOSE OF THE EXPERIMENT In this experiment
More informationCOMMON LABORATORY APPARATUS
COMMON LABORATORY APPARATUS Beakers are useful as a reaction container or to hold liquid or solid samples. They are also used to catch liquids from titrations and filtrates from filtering operations. Bunsen
More informationProperties of Acids and Bases
Lab 22 Properties of Acids and Bases TN Standard 4.2: The student will investigate the characteristics of acids and bases. Have you ever brushed your teeth and then drank a glass of orange juice? What
More informationPOTENTIOMETRIC TITRATION OF A WEAK ACID
POTENTIOMETRIC TITRATION OF A WEAK ACID A Weak Acid/Strong Base Titration For this experiment: 1. Complete the Prelab and obtain a stamp before you begin the experiment. 2. Write your lab notebook prelab
More informationAmino Acids, Peptides, and Proteins
1 Amino Acids, Peptides, and Proteins Introduction Amino Acids Amino acids are the building blocks of proteins. In class you learned the structures of the 20 common amino acids that make up proteins. All
More informationAnalysis of Vitamin C Using Iodine. Introduction
Analysis of Vitamin C Using Iodine Introduction Vitamin C (ascorbic acid) is oxidized to dehydroascorbic acid using a mild oxidizing agent such as iodine. The oxidation is a two- electron process, following
More informationChem 100 Lab Experiment #9 - ACID/BASE INDICATORS
Lab #9 Chem 100 Lab Experiment #9 - ACID/BASE INDICATORS Name: Purpose: In this laboratory we will investigate how indicators can be used to test for the presence of acids or bases in a number of common
More informationAcetic Acid Content of Vinegar: An Acid-Base Titration E10-1
Experiment 10 Acetic Acid Content of Vinegar: An Acid-Base Titration E10-1 E10-2 The task The goal of this experiment is to determine accurately the concentration of acetic acid in vinegar via volumetric
More informationCalcium Analysis by EDTA Titration
Calcium Analysis by EDTA Titration ne of the factors that establish the quality of a water supply is its degree of hardness. The hardness of water is defined in terms of its content of calcium and magnesium
More informationChemistry 119: Experiment 7. Potentiometric Titration of Ascorbic Acid in Vitamin C Tablets
Chemistry 119: Experiment 7 Potentiometric Titration of Ascorbic Acid in Vitamin C Tablets Vitamin C is another name for ascorbic acid (C 6 H 8 O 6, see below ), a weak acid that can be determined by titration
More informationph units constitute a scale which allows scientists to determine the acid or base content of a substance or solution. The ph 0
ACID-BASE TITRATION LAB PH 2.PALM INTRODUCTION Acids and bases represent a major class of chemical substances. We encounter them every day as we eat, clean our homes and ourselves, and perform many other
More informationJuice Titration. Background. Acid/Base Titration
Juice Titration Background Acids in Juice Juice contains both citric and ascorbic acids. Citric acid is used as a natural preservative and provides a sour taste. Ascorbic acid is a water-soluble vitamin
More informationAnalyzing the Acid in Vinegar
Analyzing the Acid in Vinegar Purpose: This experiment will analyze the percentage of acetic acid in store bought vinegar using titration. Introduction: Vinegar can be found in almost any home. It can
More informationMolar Mass of Polyvinyl Alcohol by Viscosity
Molar Mass of Polyvinyl Alcohol by Viscosity Introduction Polyvinyl Alcohol (PVOH) is a linear polymer (i. e., it has little branching) of Ethanol monomer units: -CH 2 -CHOH- Unlike most high molar mass
More informationDetermination of a Chemical Formula
1 Determination of a Chemical Formula Introduction Molar Ratios Elements combine in fixed ratios to form compounds. For example, consider the compound TiCl 4 (titanium chloride). Each molecule of TiCl
More informationLab 2 Biochemistry. Learning Objectives. Introduction. Lipid Structure and Role in Food. The lab has the following learning objectives.
1 Lab 2 Biochemistry Learning Objectives The lab has the following learning objectives. Investigate the role of double bonding in fatty acids, through models. Developing a calibration curve for a Benedict
More information9. Analysis of an Acid-Base Titration Curve: The Gran Plot
9. Analysis of an Acid-Base Titration Curve: The Gran Plot In this experiment, you will titrate a sample of pure potassium hydrogen phthalate (Table 10-4) with standard NaOH. A Gran plot will be used to
More informationColorimetric Determination of Iron in Vitamin Tablets
Cautions: 6 M hydrochloric acid is corrosive. Purpose: To colorimetrically determine the mass of iron present in commercial vitamin tablets using a prepared calibration curve. Introduction: Iron is considered
More information(1) Hydrochloric acid reacts with sodium hypochlorite to form hypochlorous acid: NaOCl(aq) + HCl(aq) HOCl(aq) + NaCl(aq) hypochlorous acid
The Determination of Hypochlorite in Bleach Reading assignment: Chang, Chemistry 10 th edition, pages 156-159. We will study an example of a redox titration in order to determine the concentration of sodium
More informationRecovery of Elemental Copper from Copper (II) Nitrate
Recovery of Elemental Copper from Copper (II) Nitrate Objectives: Challenge: Students should be able to - recognize evidence(s) of a chemical change - convert word equations into formula equations - perform
More informationTITRATION CURVES, INDICATORS, AND ACID DISSOCIATION CONSTANTS
TITRATION CURVES, INDICATORS, AND ACID DISSOCIATION CONSTANTS Adapted from "Chemistry with Computers" Vernier Software, Portland OR, 1997 INTRODUCTION Titration is the volumetric measurement of a solution
More informationExtraction: Separation of Acidic Substances
Extraction: Separation of Acidic Substances Chemists frequently find it necessary to separate a mixture of compounds by moving a component from one solution or mixture to another. The process most often
More informationAcid-Base Titrations. Setup for a Typical Titration. Titration 1
Titration 1 Acid-Base Titrations Molarities of acidic and basic solutions can be used to convert back and forth between moles of solutes and volumes of their solutions, but how are the molarities of these
More informationEXPERIMENT 12 A SOLUBILITY PRODUCT CONSTANT
PURPOSE: 1. To determine experimentally the molar solubility of potassium acid tartrate in water and in a solution of potassium nitrate. 2. To examine the effect of a common ion on the solubility of slightly
More informationExperiment 8 Synthesis of Aspirin
Experiment 8 Synthesis of Aspirin Aspirin is an effective analgesic (pain reliever), antipyretic (fever reducer) and anti-inflammatory agent and is one of the most widely used non-prescription drugs. The
More informationEXPERIMENT INTRODUCTION TO INDICATORS AND ACID-BASE TITRATIONS
EXPERIMENT INTRODUCTION TO INDICATORS AND ACID-BASE TITRATIONS By Dale A. Hammond, PhD, Brigham Young University Hawaii LEARNING OBJECTIVES The objectives of this experiment are... an introduction to ph
More informationEXPERIMENT 7 Electrochemical Cells: A Discovery Exercise 1. Introduction. Discussion
EXPERIMENT 7 Electrochemical Cells: A Discovery Exercise 1 Introduction This lab is designed for you to discover the properties of electrochemical cells. It requires little previous knowledge of electrochemical
More informationSYNTHESIS AND ANALYSIS OF A COORDINATION COMPOUND OF COPPER
Chemistry 111 Lab: Synthesis of a Copper Complex Page H-1 SYNTHESIS AND ANALYSIS OF A COORDINATION COMPOUND OF COPPER In this experiment you will synthesize a compound by adding NH 3 to a concentrated
More informationEXPERIMENT 4 Acid Strength
EXPERIMENT 4 Acid Strength Introduction Many common substances are either acids or bases. Some acids, like stomach acid are necessary for our health, while others, like sulfuric acid are dangerous and
More informationExperiment 5 Preparation of Cyclohexene
Experiment 5 Preparation of yclohexene In this experiment we will prepare cyclohexene from cyclohexanol using an acid catalyzed dehydration reaction. We will use the cyclohexanol that we purified in our
More informationDetermination of Citric Acid in Powdered Drink Mixes
Determination of Citric Acid in Powdered Drink Mixes Citric acid and its salts (sodium citrate and potassium citrate) are found in many foods, drinks, pharmaceuticals, shampoos, and cosmetics. The tartness
More informationEnzyme Pre-Lab. Using the Enzyme worksheet and Enzyme lab handout answer the Pre-Lab questions the pre-lab must be complete before beginning the lab.
Enzyme Pre-Lab Using the Enzyme worksheet and Enzyme lab handout answer the Pre-Lab questions the pre-lab must be complete before beginning the lab. Background: In this investigation, you will study several
More informationPhysical Properties of a Pure Substance, Water
Physical Properties of a Pure Substance, Water The chemical and physical properties of a substance characterize it as a unique substance, and the determination of these properties can often allow one to
More informationThe Empirical Formula of a Compound
The Empirical Formula of a Compound Lab #5 Introduction A look at the mass relationships in chemistry reveals little order or sense. The ratio of the masses of the elements in a compound, while constant,
More informationExperiment 6 Coffee-cup Calorimetry
6-1 Experiment 6 Coffee-cup Calorimetry Introduction: Chemical reactions involve the release or consumption of energy, usually in the form of heat. Heat is measured in the energy units, Joules (J), defined
More informationCHEM 2423 Recrystallization of Benzoic Acid EXPERIMENT 4 - Purification - Recrystallization of Benzoic acid
EXPERIMENT 4 - Purification - Recrystallization of Benzoic acid Purpose: a) To purify samples of organic compounds that are solids at room temperature b) To dissociate the impure sample in the minimum
More informationSyllabus OC18 Use litmus or a universal indicator to test a variety of solutions, and classify these as acidic, basic or neutral
Chemistry: 9. Acids and Bases Please remember to photocopy 4 pages onto one sheet by going A3 A4 and using back to back on the photocopier Syllabus OC18 Use litmus or a universal indicator to test a variety
More informationAN EXPERIMENT IN ALCHEMY: COPPER TO SILVER TO GOLD 2005, 2000, 1996 by David A. Katz. All rights reserved
AN EXPERIMENT IN ALCHEMY: COPPER TO SILVER TO GOLD 2005, 2000, 1996 by David A. Katz. All rights reserved INTRODUCTION One of the goals of the ancient alchemists was to convert base metals into gold. Although
More informationNeutralization Reactions. Evaluation copy
Neutralization Reactions Computer 6 If an acid is added to a base, a chemical reaction called neutralization occurs. An example is the reaction between nitric acid, HNO 3, and the base potassium hydroxide,
More information1. To perform a potentiometric titration of a sample of Liquid Drano with hydrochloric acid.
INTRODUCTION ANALYSIS OF DRAIN CLEANER (Revised: 1-25-93) Many common household cleaners contain acids or bases. Acidic cleaners, such as toilet bowl cleaners, often contain hydrochloric acid or sodium
More informationPET Recycling. Nicholas Robusto Maggie Ifarraguerri Nathaniel Lawton Isabel Hefner
PET Recycling Nicholas Robusto Maggie Ifarraguerri Nathaniel Lawton Isabel Hefner OBJECTIVES Hydrolyze a sample of Polyethylene Terephthalate (PET) obtained from used soda bottles, and synthesize a dimer
More informationEXPERIMENT 7. Identifying a Substance by Acid-Base Titration
EXPERIMENT 7 Identifying a Substance by Acid-Base Titration SAFETY WARNING In this experiment you will be working with NaOH pellets and using 0.25 M NaOH as a titrant. Sodium hydroxide is extremely basic,
More informationPre-Lab Notebook Content: Your notebook should include the title, date, purpose, procedure; data tables.
Determination of Molar Mass by Freezing Point Depression M. Burkart & M. Kim Experimental Notes: Students work in pairs. Safety: Goggles and closed shoes must be worn. Dispose of all chemical in the plastic
More informationOXIDATION-REDUCTION TITRATIONS-Permanganometry
Experiment No. Date OXIDATION-REDUCTION TITRATIONS-Permanganometry INTRODUCTION Potassium permanganate, KMnO 4, is probably the most widely used of all volumetric oxidizing agents. It is a powerful oxidant
More informationOrganic Chemistry Lab Experiment 4 Preparation and Properties of Soap
Organic Chemistry Lab Experiment 4 Preparation and Properties of Soap Introduction A soap is the sodium or potassium salt of a long-chain fatty acid. The fatty acid usually contains 12 to 18 carbon atoms.
More informationCHM220 Nucleophilic Substitution Lab. Studying S N 1 and S N 2 Reactions: Nucloephilic Substitution at Saturated Carbon*
CHM220 Nucleophilic Substitution Lab Studying S N 1 and S N 2 Reactions: Nucloephilic Substitution at Saturated Carbon* Purpose: To convert a primary alcohol to an alkyl bromide using an S N 2 reaction
More informationGreen Principles Atom Economy Solventless Reactions Catalysis
Lab 5: The Aldol Reaction Solventless vs Traditional Reactions: (Melting Point Study & Recrystallization) (adapted from Doxsee, K.M. and Hutchison, J.E., Green Organic Chemistry and John Thompson; Lane
More information# 12 Condensation Polymerization: Preparation of Two Types of Polyesters
# 12 Condensation Polymerization: Preparation of Two Types of Polyesters Submitted by: Arturo Contreras, Visiting Scholar, Center for Chemical Education, Miami University, Middletown, OH; 1996 1997. I.
More informationSolubility Curve of Sugar in Water
Solubility Curve of Sugar in Water INTRODUCTION Solutions are homogeneous mixtures of solvents (the larger volume of the mixture) and solutes (the smaller volume of the mixture). For example, a hot chocolate
More informationDYES AND DYEING 2003 by David A. Katz. All rights reserved. Permission for classroom use provided original copyright is included.
DYES AND DYEING 2003 by David A. Katz. All rights reserved. Permission for classroom use provided original copyright is included. Dyeing of textiles has been practiced for thousands of years with the first
More informationph Measurements of Common Substances
Chem 100 Section Experiment 10 Name Partner s Name Introduction ph Measurements of Common Substances The concentration of an acid or base is frequently expressed as ph. Historically, ph stands for the
More informationMixtures and Pure Substances
Unit 2 Mixtures and Pure Substances Matter can be classified into two groups: mixtures and pure substances. Mixtures are the most common form of matter and consist of mixtures of pure substances. They
More informationNon-polar hydrocarbon chain
THE SCIENCE OF SOAPS AND DETERGENTS 2000 by David A. Katz. All rights reserved Reproduction permitted for educational purposes as long as the original copyright is included. INTRODUCTION A soap is a salt
More informationLab #11: Determination of a Chemical Equilibrium Constant
Lab #11: Determination of a Chemical Equilibrium Constant Objectives: 1. Determine the equilibrium constant of the formation of the thiocyanatoiron (III) ions. 2. Understand the application of using a
More informationAP FREE RESPONSE QUESTIONS ACIDS/BASES
AP FREE RESPONSE QUESTIONS ACIDS/BASES 199 D A chemical reaction occurs when 100. milliliters of 0.200molar HCl is added dropwise to 100. milliliters of 0.100molar Na 3 P0 solution. (a) Write the two net
More informationEDTA Titrations 1: Standardization of EDTA and Analysis of Zinc in a Supplement Tablet. by Professor David Cash. September, 2008
CHEMICAL, ENVIRONMENTAL, AND BIOTECHNOLOGY DEPARTMENT EDTA Titrations 1: Standardization of EDTA and Analysis of Zinc in a Supplement Tablet by Professor David Cash September, 2008 Mohawk College is the
More informationTopic 18 Acids and Bases. 18.1 Exercises
Topic 18 Acids and Bases 18.1 Exercises 1. Define: (a) ph The negative log of the hydrogen ion concentration in a solution. i.e. ph = log[h 3 O + ] (b) poh The negative log of hydroxide ion concentration
More informationSynthesis of Aspirin and Oil of Wintergreen
Austin Peay State University Department of hemistry hem 1121 autions Purpose Introduction Acetic Anhydride corrosive and a lachrymator all transfers should be done in the vented fume hood Methanol, Ethanol
More informationPhenolphthalein-NaOH Kinetics
Phenolphthalein-NaOH Kinetics Phenolphthalein is one of the most common acid-base indicators used to determine the end point in acid-base titrations. It is also the active ingredient in some laxatives.
More information