(Click on lesson name to see description.)
#01 Examination of the Degradation and Weathering of Polymeric Materials
#02 Investigation of Crystallinity in Polymeric Materials
#03 The Study of Molecular Orientation by Linear Dimension Change of Polymeric Films
#04 Simplified Vertical Rebound Testing
#05 Properties and Perfectly Polymeric Sodas
#06 Simple Tensile Testing of Polymeric Films and Sheeting
#07 Water and Polymers
#08 Slime and Intermolecular Attractions
#09 Condensation Polymerization: Preparation of Nylon 6/10
#10 Condensation Polymerization: Preparation of Nylon 6/6
#11 Condensation Polymerization: Preparation of Thiokol (Polysulfide Rubber)
#12 Condensation Polymerization: Preparation of Two Types of Polyesters
#13 Addition Polymerization: Preparation of Polystyrene Using Two Types of Initiators
#14 Determination of Plasticizer in PVC by IR or FTIR and a Precipitation Method
#15 Elastomers: The Best Bungee Cord
#16 How to Clean up an Oil Slick
#17 What Is Special About Polyethylene Food Storage Bags?
#18 Determination of the Set Time for Epoxy Adhesive
#20 The Influence of Initiator Concentration on the Molecular Weight of Polystyrene
#21 Films, Fibers, and Solubility
#22 Chemical Resistance and Synthetic Polymers
#23 Glass Transition in a Rubber Ball
#24 How Much Air Is In Foamed Polystyrene Products?
#25 Investigating the Effect Of Successive Heat and Cool Cycles on a Thermoplastic Material
#26 Intrinsic Viscosity, Evaluating the Polymerization Pattern in Polyvinyl Alcohol
#27 A Search for Automated Plastics Recycling Separation
A High School Instrumentation Enrichment Course
Analytical Problem Solving
Atomic Absorption Determination of Zinc and Copper in a Multivitamin
Bloodstain Pattern Simulations: A Physical Analysis
Characterization of the Bioluminescence (Lux +) Gene in the Microorganism E. coli
Chromatographic Separation of Methylene Blue and Fluorescein
Chromatography Is a Gas: Inquiry-Based Introduction to Gas Chromatography
Color Me Analytical
Determination of Phosphorus Content in River Water
Determining Cutting Site Locations
Determining the Accuracy of Selected Laboratory Glassware
DNA Fingerprinting: The Great Cafeteria Caper
DNA on a Stick
Drug Analysis Using Thin-Layer Chromatography
Experimenting with Copper (II) Solutions
Gas Chromatography: Introduction and Application
Gravimetric Determination of the Nonvolatile Content of Paint
Historical Background of Paint and Coatings
HPLC Determination of Acetaminophen in an Analgesic
Innocent or Guilty: A Lab on DNA Gel Electrophoresis
Introduction to the Chemistry Lab: Safety Comes First
Investigating a Sewage Lagoon
Investigating the Relationship between the Mass of a Liquid and its Volume
Laboratory Safety Orientation
Laboratory Ventilation and Risk Assessment Exercise
Making a Surface Coating
Manufacturing Paint and Coatings
Measuring Nitrate by Cadmium Reduction
Polyacrylamide Gel Electrophoresis (PAGE) of Egg Proteins
Polyacrylamide Slab Gel Electrophoresis of Proteins
Producing a Strain of E. coli that Glows in the Dark
Restriction Analysis of Lambda DNA
Sample Preparation for Hand Lotion Analysis
Shrinky Dink Palettes
Spectroscopy as a Tool for Forensic Chemists
The Aspirin Shelf-Life Scenario
Transformation of Competent Cells with a Recombinant Plasmid
Using a Controlled Experiment to Identify Two Unknown Plasmids
Using Blood-Typing to Determine Causes of Death in Surgery Patients
Using Bottled Water as a Problem Solving Exercise in Chemical Identification
Using Plant Pigments to Link a Suspect to a Crime
|#01 Examination of the Degradation and Weathering of Polymeric Materials
This lab investigates issues of degradation and weathering of polymeric materials during their useful life. The first activity will look at the qualitative changes in film materials when exposed to weathering. This activity will also have students evaluate photodegradable plastics and their viability as an environmental solution for litter. The second activity will have students investigate the qualitative changes in other polymer products when exposed to weather.
|#02 Investigation of Crystallinity in Polymeric Materials
This series of qualitative activities provides a visual introduction to the amorphous and crystalline nature of polymers. Students will observe the inherent crystalline nature of various polymers using polarized light. Students will also compare the degree of crystallinity of low- and high-density polyethylene and polypropylene.
|#03 The Study of Molecular Orientation by Linear Dimension Change of Polymeric Films
This lab will provide students an opportunity to investigate the linear dimension change of heated plastic film and relate the results to processing and service use of the materials. Students will cut samples from film and prepare them for testing. The students will make pre-and post-measurements to calculate percent change in dimension as related to anisotropy (differences in properties according to the direction of measurement) and molecular reorientation.
|#04 Simplified Vertical Rebound Testing
This activity involves rebound testing of elastomers. Students will produce rebound data and determine the kinetic energy transformed by the impact of a free falling ball.
|#05 Properties and Perfectly Polymeric Sodas
The following activities can be used in the instruction of physical properties, chemical properties, interfaces, and forms of plastic. The concepts of thermoplastic and thermosetting materials will also be introduced and related to recycling. Students will use polycaprolactone to demonstrate a thermoplastic material and physical changes. Epoxy putty is used to demonstrate a thermosetting material and a chemical reaction. The students will also create a foam (a “perfectly polymeric soda”) to study interfaces and multiple forms of plastics.
|#06 Simple Tensile Testing of Polymeric Films and Sheeting
These activities investigate the tensile strength and percent elongation of various polymer films or sheeting. Student will pull tensile bars applying stress and feeling the differing strain produced. They will also calculate percent elongation of different materials comparing the differences between plastics and elastomers. These are modifications of ASTM D-638 which is the industrial standard for tensile testing.
|#07 Water and Polymers
These activities represent both qualitative and quantitative investigations based on the interaction between water and various polymers. Hydrogen bonding between water and different polymers is the basis of the investigations. Students will determine the percent moisture contained in various plastics along with a qualitative procedure to determine if water is present in a plastic sample. Students will also perform a modified industrial test to determine the percent moisture absorbed by various plastics.
|#08 Slime and Intermolecular Attractions
This is a perennial favorite for students young and old which provides an excellent visual example of the strength of intermolecular attractions. The same type of interactions that causes water absorption in plastics causes liquids to turn into slimy masses. Students will also compare the difference in the physical properties of sheet and powdered polyvinyl alcohol (PVAl) with polyvinyl acetate (PVAc) and relate these to molecular structure and additives.
|#09 Condensation Polymerization: Preparation of Nylon 6/10
One of the classic experiments in the preparation of nylon is the interfacial polymerization. Students produce nylon 6/10 by the reaction between a diacid chloride and a diamine. This reaction occurs at the interface of two solutions. The material is wound up on a spool or other device and at some point it seems that the winding will never end.
|#10 Condensation Polymerization: Preparation of Nylon 6/6
Nylon 6/6 is produced here by the melt method. Students will first produce “nylon salt” from the reaction of hexamethylene diamine (HMDA) and adipic acid. In this particular case, the stoichiometric equivalence of the functional groups is achieved by isolating the 1:1 salt before allowing the condensation to take place. Then the nylon salt is converted, under pressure and heat, to nylon 6/6.
|#11 Condensation Polymerization: Preparation of Thiokol (Polysulfide Rubber)
Students will prepare a synthetic elastomer called Thiokol®. This polysulfide was the first synthetic rubber produced by Dr. Joseph C. Patrick in the 1920s. Students will synthesize this material by combining an alkylene dichloride and sodium polysulfide. This is an interfacial polymer reaction but unlike the nylon 6/10 the polymer forms at the bottom of the beaker.
|#12 Condensation Polymerization: Preparation of Two Types of Polyesters
In this lab, students will synthesize two examples of condensation polymers, a linear polyester and a cross-linked polyester. Both esters are produced by the reaction of an acid anhydride (phthalic anhydride) and an alcohol. Phthalic anhydride is the anhydride of phthalic acid, 1,2-benzenedicarboxylic acid. In the case of the linear polyester, the alcohol is a diol (ethylene glycol). Thus both the alcohol and the acid (anhydride) have two reaction sites and a linear polyester is produced. This polyester is similar to the more familiar Dacron. When more than two functional groups are present in one of the monomers, the polymer chains can be cross-linked to make a three-dimensional network. The alcohol used in the synthesis of the cross-linked polymer is the triol, glycerol. This polyester (Glyptal®) has a structure which is more rigid than the linear structure and therefore has different properties.
|#13 Addition Polymerization: Preparation of Polystyrene Using Two Types of Initiators
This is an excellent lab to introduce students to addition polymerization and to the concept of initiators. Addition polymerization usually must be catalyzed (initiated) by a base, an acid, or free radical. There are three steps that are involved in addition polymerization no matter what initiator is used. These three steps are initiation, propagation, and termination. The students will polymerize styrene using two types of initiators, benzoyl peroxide (free radical) and anhydrous aluminum chloride (cationic). They will then compare the properties of the products.
|#14 Determination of Plasticizer in PVC by IR or FTIR and a Precipitation Method
Students in this experiment will isolate and determine the amount of plasticizer in polyvinyl chloride (PVC). Students will use Infrared Spectroscopy (IR) or Fourier Transform Infrared Spectroscopy (FTIR) and gravimetric techniques in this experiment. Plasticizers are organic compounds added to polymers, like PVC, to facilitate processing and to increase flexibility and toughness of the final product by internal modification of the polymer morphology. Important plasticizers include esters of phthalic acid, and epoxidized soybean oil esters. The most common used plasticizer in PVC is the diester, dioctyl phthalate (DOP).
|#15 Elastomers: The Best Bungee Cord
Students will determine the strength of a single rubber band, the strength of two rubber bands working in parallel, and the strength of three rubber bands working in parallel. A simple tensile strength testing apparatus will be set up using 2 L containers, string, and a sturdy ring stand. The students will use this apparatus to determine the tensile strength, percent elongation, and plot stress vs strain graphs for each experiment. The students will design a small bungee cord, giving a rationale for the design. After submitting their design, the students will take a bungee cord apart and see how their design compares to the bungee cords on the market today.
|#16 How to Clean up an Oil Slick
The task of cleaning up and recovering oil from an oil spill is not easily accomplished. In this laboratory exercise, the students will learn about how an oil spill is contained and cleaned up. They will investigate an oil absorbing polymer that is hydrophobic, absorbs up to 19 times its own weight in nonpolar liquids, floats on water, and can be reused or disposed of by incineration or burial in accordance with local regulations.
|#17 What Is Special About Polyethylene Food Storage Bags?
In this investigation students compare a polyethylene bag designed for recycling or garbage disposal with a polyethylene food storage bag. For food product safety, it is essential that materials in the container not contaminate the food. The bags intended for food storage contain measurably less hexane extractables (low molecular weight oligomers and additives) than the bags intended for waste handling. Bags are cleanly cut into two centimeter squares, weighed and exposed to warm hexane solvent for a specified time. After the time is up, the hexane is removed and allowed to evaporate. (Two rinses of the bag pieces with small amounts of hexane may be performed.) Once the hexane has evaporated, the residue is weighed (ideally at the next laboratory period), and the percent hexane extractables calculated. The procedure is similar to that suggested in the Code of Federal Regulations (see references).
|#18 Determination of the Set Time for Epoxy Adhesive
Most epoxy glues or adhesives, as well as epoxy resins, are produced when the epoxy group reacts with a difunctional backbone monomer producing a thermoset polymer. Thermoset polymers are mostly unchanged when heated after being cured while thermoplastic polymers soften and eventually flow when subjected to increased heat and pressure. The set or gel time of a specific thermoset polymer is important to know. It determines the length of time the material may be worked prior to hardening. Many epoxy glues are sold with specific set times for specific adhesive applications. In chemistry, the set time of an epoxy is similar to the time it takes a reaction to occur. Hence, a study of epoxy set times is very similar to a study of chemical kinetics. The set time may be determined by testing the gel every so often with a stick to observe its tackiness or, possibly more elegantly, by observing the disappearance of the epoxide IR band and the appearance of the IR O-H stretching frequency. The temperature profile of the reaction may also be monitored; however, it, as well as gel time, is dependent upon the volume of material mixed. Reproducible data may be obtained when the tests are performed reproducibly.
|#20 The Influence of Initiator Concentration on the Molecular Weight of Polystyrene
Polystyrene (PS) is a hard, rigid, transparent plastic with good dimensional stability. The material has good chemical resistance to many aqueous solutions but it is soluble in many aromatic and halogenated solvents. It cannot be used at elevated temperatures (maximum 60 °C continuous, 70 °C for short periods) and it may break when subject to mechanical stress. Polystyrene polymerizes with a chain reaction. Chain reactions require initiator molecules, like the free radical formed when benzoyl peroxide breaks up. Free radicals have single electrons, which makes them very reactive. Monomers for chain reactions often have carbon-carbon double bonds, which then are attacked by the initiator molecule to form a reactive molecule. This reactive molecule then attacks another monomer, so the chain gets longer and longer. The total number of polymer molecules formed depends on the number of initiator fragments. The more initiator you use, the more polymer molecules. That is, for the same amount of monomer, you get smaller polymer molecules by using more initiator, because there are more reactive sites competing for monomers. Students will synthesize polystyrene and explore the influence that initiator concentration has on the molecular weight of the product.
|#21 Films, Fibers, and Solubility
These activities will introduce how the differences in solubility of materials are used in the manufacture of fibers and films. The various processes used to make films and fibers will be introduced to the student and completed on a small scale.
|#22 Chemical Resistance and Synthetic Polymers
These activities look at the chemical resistance of synthetic polymers. The activities include immersion, stain resistance, and stress cracking labs and both qualitative and quantitative analysis. Immersion testing is a alternative method for teaching solubility in which the polymer is the solute rather than typical salts and sugar which are often used. Chemical resistance can be used as one method to identify polymers, as well as being used to look at property changes which will effect service performance and aesthetics. The stain resistance lab offers students an opportunity to develop and carry out a procedure of their own design.
|#23 Glass Transition in a Rubber Ball
This experiment provides a dramatic way to illustrate the changes in the properties of a material at its glass transition point. Students gather data which they use to construct graphs to learn about elastic modules versus absorption modulus, tangent delta, and the effect of impact speed on the glass transition temperature.
|#24 How Much Air Is In Foamed Polystyrene Products?
In this experiment students are challenged to come up with a good estimate of the amount of air in foamed polystyrene products. It is ultimately a gas evolution experiment and as such has students measure the gas generated when foamed polystyrene is degassed and dissolved or dispersed in an organic solvent. The volume of the air is measured by water displacement with the twist that the organic solvent utilized is mostly water immiscible and floats on the water but has a vapor pressure significantly greater than water at room temperature and pressure. Gas laws calculations can be utilized in determining the amount of air present in the sample. The vapor of the organic solvent contributes to the total gas pressure so it must be considered in the calculations.
|#25 Investigating the Effect Of Successive Heat and Cool Cycles on a Thermoplastic Material
In this investigation, a mini glue gun is used as both an injection molding simulator and a melt index viscometer. Hot melt glue is squeezed into rubber tubing sections and allowed to cool. A slit in the side of the rubber tubing allows the cooled hot melt glue sections to be removed and remelted in the hot melt glue gun; hence samples of successive heated and cooled thermoplastic can be produced. The samples are then evaluated by weighing the glue extruded over a constant time period.
|#26 Intrinsic Viscosity, Evaluating the Polymerization Pattern in Polyvinyl Alcohol
In this experiment, a high molecular weight polyvinyl alcohol polymer is treated with potassium periodate. Potassium periodate reacts with 1,2 (vicinal) glycols, cleaving the bond between the 1 and 2 carbons and producing two aldehydes. Potassium periodate does not react with 1,3-glycols. The regular repeating unit of polyvinyl alcohol is similar to a 1,3-glycol. Polyvinyl alcohol is usually made by hydrolysis of polyvinyl acetate. Vinyl acetate normally polymerizes head to tail producing the alternating 1,3-acetate and, by hydrolysis, the alternating 1,3-alcohol. Formation of a 1,2-glycol thus represents an abnormal head to head addition of monomer to the growing chain. Treatment of polyvinyl alcohol with periodate ion thus determines the number of abnormal head to head polymerizations. In this experiment, the viscosity of polyvinyl alcohols of varying molecular weights will be measured. From a graph of viscosity versus molecular weight, the approximate molecular weight of the periodate treated polymer can be determined. The number of head to head polymerizations is estimated from the ratio of the average molecular weight of untreated polymer to the average molecular weight of periodate cleaved polymer.
|#27 A Search for Automated Plastics Recycling Separation
Recycling efforts of recent years have been hampered by the high cost of manually separating the materials. This is particularly true of plastics. Students will be challenged to investigate the physical and chemical properties of plastics and use these properties to design a system that could be used to separate them. First-year chemistry students were steered in the direction of using density for separation. They were directed to use information gathered from handbooks and the Internet to prepare a series of solutions with different densities which could be used to separate the plastics. A flow chart was developed to describe and outline this process. Second-year chemistry students were given the problem during a study of infrared spectroscopy. During discussion they were directed to search for absorption peaks unique to each plastic. Again a flow chart was used to summarize the process design. Third-year chemistry students with some limited experience in chemical instrumentation were given the problem as an independent study.
|A High School Instrumentation Enrichment Course
This guide describes seven activities for use in a special after-school enrichment course on chemical instrumentation for high school students. The course is designed to give high school students exposure to the field of chemical technology as a viable career choice and to actively engage these prospective chemical technology students in using chemical instrumentation to solve problems technicians regularly confront in the workplace.
|Analytical Problem Solving
This set of activities uses a “just in time” principle of parceling information and supplies to students in an analytical chemistry course. The idea behind this approach is that students have time to think about the questions posed, and if necessary, find information from other sources. This makes them active participants in the learning process. Before the students begin the laboratory activity, they receive a brief introduction to the topic to be studied that raises questions to think about before entering the lab, discusses a real-world issue related to the chemistry topic, or reviews specific safety or procedural considerations. No theoretical introduction is provided since the intent of the approach is to lead students to figure out the concepts for themselves. During the lab, students are given only the necessary information when they need it and ask for it, and they discover for themselves what information and factors are extraneous. Students must decide what their needs are for each activity and then request specific chemicals or equipment. They learn to use available analytical instruments as needed for each activity.
|Atomic Absorption Determination of Zinc and Copper in a Multivitamin
Atomic absorption spectroscopy (AAS) is an important analytical technique based upon the absorption of radiation by free atoms. Virtually all metallic elements can be directly detected with excellent accuracy, precise quantitation, and very sensitive detection limits. This technique can also be used to indirectly detect and measure the amounts of some nonmetallic elements. Atomic absorption requires a surprisingly simple apparatus. Students compare the amount of zinc and copper listed on a vitamin bottle to the value obtained using AAS.
|Bloodstain Pattern Simulations: A Physical Analysis
Following graphical and vector analysis, this lab exercise is an open-ended or discovery activity. Students receive bloodstain pattern evidence from a crime scene. They must then answer a series of questions through inquiry, observation, measurement, and analysis. To complete this challenge, students reconstruct the evidence through four standard models to derive qualitative characteristics and quantitative relationships that address the evidence at the crime scene. In addition, students will utilize the following impact equation and the concept of free fall in which an object falls from rest.
|Characterization of the Bioluminescence (Lux +) Gene in the Microorganism E. coli
Students grow E. coli strain HB101, which contains the plasmid pUCD607 with the bioluminescence (Lux +) gene. The plasmid containing the Lux + gene is isolated from the E. coli, then characterized by restriction analysis. The bioluminescence biochemical process and the nature of its phenotypic expression in E. coli HB101 is explained.
|Chromatographic Separation of Methylene Blue and Fluorescein
This lab has been modified from a common cookbook lab on column chromatography to be more of an inquiry-based lab on both thin-layer and column chromatography. The goal of the lab is to help students explore the roles of the stationary and mobile phases in chromatography. The students begin with a TLC lab in which they change the mobile phase and record the effects. They then do the same experiment using a column. The stationary phase is alumina (column) instead of silica gel (TLC). The students witness a reverse of the order in which the components are eluted. They must arrive at a hypothesis on why this happens. They are then given a real-life scenario problem in which they must figure out a method to separate methylene blue from fluorescein with fluorescein being eluted first. They must choose the correct stationary phase and mobile phase to obtain the desired separation.
|Chromatography Is a Gas: Inquiry-Based Introduction to Gas Chromatography
This chromatography exercise was designed to introduce students to the theory of chromatographic separation of mixtures and packed column chromatography. The students will become familiar with basic operation of the gas chromatograph and explore the relationship between temperature and retention time of individual components in a mixture. A section on instrument trouble-shooting may be included as an additional optional activity.
|Color Me Analytical
This lab is an introduction to colorimetry on two levels. First, the students learn how to physically manipulate the colorimeters (it should be noted that this lab presumes the students will already be familiar with the PCs and Vernier software). Secondly, the students start on a pathway of discovery to one of the most important principles in analytical chemistry: Beer’s Law. The lab is inquiry-based, designed to be completed by the student one page at a time (i.e., students must check their answers for each page with the teacher before they receive the next page). The lab is designed for students to work cooperatively in teams of 3-4.
|Determination of Phosphorus Content in River Water
In this experiment,students discover that a pure sample can become contaminated during preparation for analysis. The students colorimetrically analyze water samples from a river for phosphorus. During the sample preparation,one group of students (Gila Laboratory) decolorizes the “murky ” water with activated carbon,,while the other group (Graham Laboratory)decolorizes the water with activated carbon that has been acid washed. Activated carbon contains small amounts of phosphorus. Acid washing removes the phosphorus. The data is compared,and the students then try to determine why the results differed.
|Determining Cutting Site Locations
The following activity introduces DNA restriction mapping.Students cut pieces of paper into lengths representing those produced when specific enzymes are used to cut a strand of DNA.
|Determining the Accuracy of Selected Laboratory Glassware
Students determine the accuracy of several pieces of laboratory volumetric glassware while learning to use pipettes and bulbs, burets, and top-loading balances. Through their calculations they experience the relationships between mass, volume, and density and determine the actual volumes contained by the various pieces of glassware. Students will need to determine the density of water based on the temperature of the water they use for this experiment. The ultimate goal is to have students recognize what pieces of glassware to use to obtain the best accuracy and when they should use this glassware. This experiment is a good introduction to the chemistry laboratory and some of the glassware that is commonly used.
|DNA Fingerprinting: The Great Cafeteria Caper
Students will extract DNA from their own hair roots. A DNA fingerprinting simulation kit with standard DNA samples will also be used in this experiment.The DNA will be digested with a variety of restriction enzymes (e.g.,B am H I and Hin d III).Students will run an electrophoresis gel to examine patterns of their DNA along with standard DNA.The experiment will be based on a crime scene scenario.
|DNA on a Stick
What is the chemical basis of life? What kind of chemical is DNA? The first step in the genetic manipulations involved in biotechnology is the isolation of DNA. This project describes one method of chromosomal DNA isolation with minimum breaks. There are several basic steps in DNA extraction. The cell must first be lysed (broken open) to release the nucleus. The nucleus must also be opened to release the DNA. At this point the DNA must be protected from enzymes that will degrade it, causing shearing. Once the DNA is released, it must then be precipitated in alcohol.
|Drug Analysis Using Thin-Layer Chromatography
The majority of evidence submitted to crime labs comes from drug-related crimes. Often, this evidence includes unidentified powders that may be illegal drugs. In order to prosecute individuals for possession of illegal substances, it is necessary for forensic scientists to positively identify any suspected drugs submitted to the laboratory. In addition, forensic toxicologists must determine the identity of drugs found in the bodies of drug-overdose victims. Although illegal substances can cause overdose, people also overdose on common over-the-counter (OTC) drugs, like aspirin, when attempting to take their own lives. Thin-layer chromatography (TLC) is one technique used to identify unknown drugs. Chromatography is simple to perform, is straightforward to interpret, and works equally well for legal and illegal substances. This experiment uses TLC to identify the active ingredients in some common OTC painkillers.
|Experimenting with Copper (II) Solutions
This experiment helps students determine that the relative concentration of copper ions in water can be determined by a color comparison. Students make a copper(II) sulfate solution of a given concentration. Students dilute their initial solutions until their solutions are colorless. Students work in groups of 3-4, comparing solutions to discover any relationship between color and concentration. A portion of each solution will be mixed with concentrated ammonia solution, forming a dark blue copper-ammonia complex. Students decide if the complex can be used to find the useful concentration of copper ions in a swimming pool water sample.
After a lecture/discussion on fingerprinting techniques, students recover latent prints by iodine fuming, cyanoacrylate fuming, and dusting with powder.Each student will provide a fingerprint for identification by another student. A database of fingerprints of the class will be made to help in the identification of the unknown print.
|Gas Chromatography: Introduction and Application
This laboratory exercise introduces students to gas chromatography using a discovery-based approach. The student is presented with a scenario/industrial application where their job is to verify that the company’s mouthwash contains a specific percentage of ethanol. They must discover that ethanol can be detected by gas chromatography and that peak height can be related to percentage of ethanol. This requires preparation of standard ethanol solutions. A batch of mouthwash is then suspected of isopropyl alcohol contamination and the student must develop a method to determine whether there is contamination. The technique of indirect determination by a standard addition method is introduced here.
|Gravimetric Determination of the Nonvolatile Content of Paint
This activity provides the student with an introduction to gravimetric procedures and at the same time introduces the basic components of paints. A small amount of paint is weighed into one of two aluminum foil weighing dishes. Nesting the second dish in the first covers the paint sample, making it possible to weigh the sample without weight loss due to evaporation of volatile components, which begins to occur as soon as the paint is exposed to the atmosphere. The paint sample is then spread into a film by pressing the nested (second) dish against the first. The two dishes are separated and the paint films on them are dried in a forced-air oven. After 30 minutes of drying, the dishes are reweighed. The mass data is used to calculate the percent nonvolatile matter in the paint sample.
|Historical Background of Paint and Coatings
Provides historical background information on this topic. No laboratory activity is included.
|HPLC Determination of Acetaminophen in an Analgesic
High Performance Liquid Chromatography (HPLC) has resulted from the application of gas chromatography instrumental techniques to classical liquid chromatography. This experiment will utilize reverse phase chromatography with an octadecyl (C-18)column and a polar mobile phase consisting of methanol,acetonitrile,and water.
|Innocent or Guilty: A Lab on DNA Gel Electrophoresis
This lesson, based on EDVOTEK Kit #109, “DNA Fingerprinting I: Identification of DNA by Restriction Fragmentation Patterns,” presents a simulation of a DNA fingerprint (RFLP—Restriction Fragment Length Polymorphism). The prelab section introduces the importance of DNA fingerprinting—a form of identification that is being accepted by both scientific and legal experts. The procedure is used in forensic work, paternity suits, missing-person cases, archeology, and animal breeding. The protocol for the lab is introduced. The lab involves students preparing a gel for electrophoresis. DNA fragments, which have been predigested using two different restriction enzymes, will be run on a gel electrophoresis apparatus, and the results will be analyzed to determine which suspect committed the crime. The post-lab section concentrates on the ethical implications of DNA fingerprinting.
|Introduction to the Chemistry Lab: Safety Comes First
One of the most important things that a chemistry instructor can teach students is how to handle themselves in a safe manner and how to react when and if an emergency should occur. Many students find learning a lot easier when they are actually obtaining the information on their own and through demonstrations rather than having someone simply tell them what they should and should not do. Discovery-based learning is an effective tool in educating safety. A safety unit was developed such that students will learn not only how to use the various safety devices in the laboratory, but also how to research the chemicals they will be working with prior to lab. Demonstrations prior to lab will further help students visualize the importance of safety.
|Investigating a Sewage Lagoon
Sewage lagoon systems for treatment of wastewater, also called total containment ponds, are becoming an attractive, cost-effective alternative for single residences and small communities. A sewage lagoon system in a residential or small institutional setting usually consists of two ponds and a wetland area. Sewage is pumped into the first pond, where settling and some decomposition take place. Water flows through a pipe into a second pond where further decomposition takes place. It then flows into a wetlands area. In very wet weather, the wetlands area discharges into a creek. Using kits such as those produced by Hach, CHEMets, and LaMotte, students can investigate various analytes such as dissolved oxygen, phosphates, ammonia, and nitrates. In addition, they can investigate conditions such as temperature and pH. By comparing differences among the three areas of the system and/or changes in the system over time, students can assess the condition, progression, and effectiveness of the system.
|Investigating the Relationship between the Mass of a Liquid and its Volume
Students fill a buret with one of five liquids, note the initial volume, and mass an empty beaker. They then deliver a portion of the liquid into the beaker, note the buret reading, and mass the beaker with the liquid. This process is repeated nine more times, adding the liquid to that which is already in the beaker. Students share data for all five liquids. Using a spreadsheet program, the students enter the data for each liquid, plot a graph of mass vs. volume for each liquid, and obtain the slope, y-intercept, and R 2 regression value for each line. The students then draw conclusions, answer questions, and form hypotheses based on the data and spreadsheet analysis.
|Laboratory Safety Orientation
As a laboratory manager, one of this author’s primary concerns is safety training of his student employees, many of whom are pursuing careers in chemistry or chemical technology. It is very important to instill the proper safety habits and knowledge that will be required in professional laboratories. Nothing can replace hands-on or individual training, but time restrictions have led the author to require that the employees go through a web-based self-study course prior to active employment in the laboratory work area. The information presented here is the text that can be accessed at http://www.delta.edu/~slime/pact.html via the internet.
|Laboratory Ventilation and Risk Assessment Exercise
Students are presented with a scenario that requires them to decide if it is safe to do an experiment in which certain amounts of volatile organic solvents are vaporized in a particular laboratory room. They need to find the TLV data for the solvents under consideration from the MSDS (Material Safety Data Sheets) for the compounds which can be retrieved on the Internet. They will also need to measure the volume of a laboratory room and the ventilation rate of the fume hoods in the laboratory.
|Making a Surface Coating
In this activity students prepare a nonaqueous surface coating by first making a polymeric resin and then adding an organic solvent. The product is a basic varnish that hardens by loss of organic solvent to the air. A simple paint can be made by adding pigment to the varnish. An oleoresinous varnish can be made by adding an oil, such as linseed. Certain properties of the varnishes and paint film can be tested and compared: drying time, hardness, flexibility, and degradation of film or underlying substrate due to long-term exposure to ultraviolet radiation.
|Manufacturing Paint and Coatings
Provides background information on this topic. No laboratory activity is included.
|Measuring Nitrate by Cadmium Reduction
In this experiment, each student is assigned the task of designing an experiment to evaluate the effects of various treatments on the nitrogen cycle in a freshwater aquarium. The students are required to maintain a laboratory notebook of all work, measure the key analytes of the bio-system at periodic intervals, analyze and interpret data through appropriate tables and graphs, and write a formal report at the end of the term. The students set up the experiment using small goldfish bowls and incorporate some treatment, for example, a freshwater plant. This arrangement might have a bowl with fish only, one with a plant only, one with fish plus plant, and one with neither plant nor fish. A variety of techniques for analyzing for nitrate and ammonia are included depending on the time available and level of sophistication desired. Since nitrite is typically not observed in this experiment, a technique for its determination is not included.
|Polyacrylamide Gel Electrophoresis (PAGE) of Egg Proteins
Charged groups or ions will migrate in an electric field. Proteins carry a charge (except at their isoelectric point), and they too will migrate in an electric field with the rate of migration dependent upon the ratio of charge to mass. The application of an electric field to a mixture of proteins will result in different proteins moving at different rates within the field. In PAGE, a supporting medium (polyacrylamide) is used so that the proteins can be fixed in their final migration positions and analyzed.
|Polyacrylamide Slab Gel Electrophoresis of Proteins
Polyacrylamide gel electrophoresis (PAGE) is a powerful analytical technique used by biochemists and molecular and cell biologists to characterize and assay the purity of various biological macromolecules. The method is based on the principle that macromolecules can be separated according to their unique size and charge when placed in a gel matrix under an electrical field. In this experiment, the student will become familiar with one of the more popular versions; the sodium dodecyl sulfate (SDS) PAGE.
|Producing a Strain of E. coli that Glows in the Dark
In this exercise,students will create a luminescent population of bacteria by introducing into Escherichia coli (E.coli)a plasmid that contains the lux operon.This operon is found in the luminescent bacterium Vibrio fischeri and contains two genes that code for luciferase (the enzyme that catalyzes the light-emitting reaction)and several genes that code for enzymes that produce the luciferins (the substrates for the light-emitting reaction).The success of the transformation is readily apparent,since E.coli colonies that take up this plasmid glow in the dark.In another group,a control plasmid (pUC18)that does not contain the lux operon will be introduced into E.coli,and these cells will not glow in the dark.Both plasmids contain an ampicillin-resistant gene,and therefore both cell types will grow in the presence of the antibiotic.Each resistant colony growing on ampicillin- nutrient agar plates represents a single transformation event,and only those colonies that have taken up the plasmids will grow on the agar.The bioluminescent colonies represent bacteria that can successfully express a metabolic marker.
|Restriction Analysis of Lambda DNA
This lab is separated into two different sections due to lab time allowed for each session over a two-week period. During the first lab session,students will prepare their first digests and the control, using the three different restriction enzymes.During the second lab period,the students will get their digests from the instructor;cast the agarose gel;set up and run the electrophoresis;and photograph, analyze,and graph the results.
|Sample Preparation for Hand Lotion Analysis
In this experiment,students prepare a sample of a commercial hand lotion for analysis by HPLC to determine the percent composition of two common cosmetic preservatives,methylparaben and propylparaben.The product will be inspected for uniformity,standards will be prepared,the hand lotion sample will be prepared for analysis,the HPLC analysis will be performed,and the data will be evaluated.The significance and consequences of using syringe filters as a final sample purification step will be explored.In an optional pre-lab assignment,students are challenged to research their choice of syringe filter.
|Shrinky Dink Palettes
This activity is designed to provide practice for students using equations for finding wavelength, given values for energy and frequency (lv=c, E=hv, and l=ch/E). They then apply the results in a creative project to make key rings or earrings.
|Spectroscopy as a Tool for Forensic Chemists
This hands-on unit will introduce students to atomic emission and absorption spectra. Chemistry students will “fingerprint” some elements and identify them in some common sources. They will then create spreadsheets to relate the Bohr model of the atom to the observed spectral lines of the hydrogen atom. Raman spectra are used to solve a forensic case study. Finally, students will examine a commercial application of photochemistry called the cyanotype process. This unit will strengthen the students’ organizational and analytical thinking skills through the creation of spreadsheets and will involve the students in some practical applications of quantum chemistry.
|The Aspirin Shelf-Life Scenario
This quantitative exercise is designed to give students experience using the Spec-20 in determining species concentration. It also allows the students to determine if salicylic acid is present in commercial aspirin and the amount that may be present as the aspirin decomposes. In the lab, students determine the proper wavelength to use in checking for salicylic acid concentration. They also create a known concentration curve for the colored complex. The students also develop a long-term testing program involving the type of packaging material used for the aspirin and the possible environmental storage procedures the consumer may use and their effect on the shelf-life of the aspirin.
|Transformation of Competent Cells with a Recombinant Plasmid
This exercise demonstrates the use of competent Escherichia coli (E.coli)cells in the take-up of plasmids to cause their transformation.The strain used in this exercise is JM83;competent cells may be acquired from UC Davis,or they could be made competent in a previous exercise.These cells are made to take up pUC19,which contains two engineered genes,one for ampicillin resistance (ampicillin-resistance gene)and the other (• -galactosidase gene)to convert X-gal in nutrient agar to a blue color.
|Using a Controlled Experiment to Identify Two Unknown Plasmids
This activity can serve as an assessment following a unit on biotechnology.For a biotechnology unit including lecture and laboratory sessions on DNA structure,plasmids,restriction enzymes,gel electrophoresis,gel analysis following electrophoresis,and bacterial transformation,the student activity described below could serve as a “practicum” of sorts to assess what was learned in the unit. Alternatively,the protocol written in the instructor’s notes could be given to the student as a traditional lab exercise.
|Using Blood-Typing to Determine Causes of Death in Surgery Patients
In this activity, students will determine whether a higher-than-normal death rate among surgery patients in a hospital was caused by faulty blood-typing. They will be given a sheet that contains the blood types on record for the patients, the type of blood each patient received, and whether or not each survived the surgery. The students will be provided with simulated samples of each patient’s blood and of the blood provided to each patient during surgery and a blood-typing kit. Students will use the information and materials to determine correct blood types for each patient and bag. They will also be able to determine whether patients were given the correct type of blood or not.
|Using Bottled Water as a Problem Solving Exercise in Chemical Identification
In this exercise, students are divided into groups of two or three. The groups are given four unidentified bottled waters in unmarked containers and the chemical characteristics taken from the labels on the bottled waters. The students must devise and carry out a plan to match the water in the unmarked containers with the appropriate labels. This lab is appropriate after a discussion on water quality so that students have a basic knowledge of hardness, alkalinity, pH, metals, and nutrients found in unprocessed water. A typed proposal outlining the methods, chemicals, equipment, and instruments needed for analysis, with references, must be approved by the instructor before students analyze the samples. Students are coached on the appropriate methods without dictating exact procedures.
|Using Plant Pigments to Link a Suspect to a Crime
Students will use chromatography to separate plant pigments collected from a fictitious crime scene and suspects. Students will then compare the R f values of the plant pigments to determine whether the plant pigments found on any of the suspects match the plant pigments found at the crime scene. Matching plant pigments would be one piece of evidence linking the suspect to the crime scene.