Laboratory instructors

Seldom does one have the opportunity to read and use a textbook that is completely useful, one that does not need substitutions and deletions. Zu-brick s book is this type of resource for undergraduate organic students and their laboratory instructors and professors. I must heartily recommend this book to any student taking the first laboratory course in organic chemistry. 

Obtain a set of ball-and-stick molecular models from the laboratory instructor. The set contains the following parts (other colored spheres may be substituted as available) ... 

After a radioactive spill or other contamination of persons or environment, immediately notify the laboratory instructor so that he/she can inform the... 

At the conclusion of the laboratory period or an experiment, and when leaving the laboratory area for any reason, monitor hands, feet, head, body, and clothing with a hand-held radiation counter before exiting, as specified by your instructor. Your laboratory instructor will demonstrate the proper technique and show you the proper instruments for the type of radiation you that you will use. 

Return all radioactive and chemical materials to their place of storage. This may simply mean returning the radioactive materials to the laboratory instructor and the chemicals to their storage cabinets. 

Keep all laboratory equipment and materials in the radiological work areas. They should not be transported to non-radiological work areas unless given permission by the laboratory instructor. 

Step 6. Ask your laboratory instructor to approve your experiment before performing the tests. 

Step 1. Measure 1 to 4 L of a previously acidified water sample with a graduated cylinder and record the volume to the nearest 1 mL. (The laboratory instructor will specify the volume to be used for the experiment.) Filter the sample through a fluted filter paper and collect the sample in a clean beaker appropriate to the sample volume. [When analyzing a small sample volume,... 

The procedure given below provides operating information for a specific instrument (the Finnegan Element 1). Follow guidance by the laboratory instructor to operate the instrument that is being used. 

Some experiments show traces of acetone, methylene chloride, chloroform, benzene, and dioxane in the air. Only in one instance (chloroform) was a TLV exceeded. However, pump error may have caused this result. When many solvents or air contaminants coexist in the environment, a total or equivalent exposure must be calculated. The equivalent exposure reflects the contribution of each contaminant to the total exposure. In these studies this value was very low and can be noted in the next to last column of Table II. Solvents like benzene, chloroform, and dioxane are presently suspected carcinogens (j>) and laboratory instructors should replace these compounds with safe substitutes whenever possible. 

Use Plexiglas shields when working directly with the radioisotope. Cover your work surface with absorbent paper to localize any spills that may occur. Consult the laboratory instructor for the proper disposal of the solid and liquid radioactive waste that will be produced in this experiment. 

A 10- to 20-Hz Nd YAG laser is very convenient as an excitation source for this experiment, since the doubled output at 532 nm is near the broad 550-nm ruby absorption and the laser pulse is short (5 to 10 ns) compared to the excited Cr radiative lifetime. The student should note the cavity construction of such a laser and, following the directions of the laboratory instructor, adjust the doubling crystal for optimum green output. A 532-nm output of 0.1 to 1 mJ is adequate for the experimeut, so a small and relatively inexpensive flashlamp- or diode-pumped pulsed laser is sufficient. Also suitable as an excitation source would be a dye laser operated near 550 nm and pumped by a nitrogeu or excimer laser. (An incoherent pulsed source such as a strobe light can also be used if the pulse is about 10 /ts or less and if appropriate band-pass filters are used.) For all laser experiments, safety goggles must be worn to minimize hazard due to the high intensity of these sources. The instructor will provide instructions about any special features of the lasers and their safe operation. 

Chemicals and solutions to be stored at low temperatures must be in stoppered or sealed vessels. Do not store aqueous solutions below 0°C since freezing can occur and, with the resulting expansion of the volume, the vessel may crack. Solutions containing flammable solvents should only he stored in specialized spark-proof fridges consult your laboratory instructor. 

Run the infrared spectrum of an unknown carbonyl compound obtained from the laboratory instructor. Be particularly careful that all apparatus and solvents are completely free of water, which will damage the sodium chloride cell plates. The spectrum can be calibrated by positioning the spectrometer pen at a wavelength of about 6.2 p without disturbing the paper, and rerunning the spectrum in the region from 6.2 to 6.4 p while holding the polystyrene calibration film in the sample beam. This will superimpose a sharp calibration peak at 6.246 p (1601 cm ) and a less intense peak at 6.317 p (1583 cm ) on the spectrum. Determine the frequency of the carbonyl peak and list the possible types of compounds that could correspond to this frequency (Table 2). 

The influence of structure on the acute toxicity of nitriles can be used in a lecture to illustrate the fundamental structure-hazard link. Many chemists who have participated in an organic chemistry laboratory section will remember the warning that the aroma of burnt almonds may indicate that cyanide has been released. An opportunity exists for the laboratory instructor to explain where and how cyanide evolved and that it is an acutely dangerous chemical.. This example that can be incorporated into the first-day lab overview is to include a discussion of the source and toxicity of nitriles to humans. Nitriles are ubiquitous in a synthetic laboratory and can liberate cyanide under certain circumstance. The structural features that are associated with a greater chance of cyanide being liberated from a nitrile have been studied and reported (14). 

In case of fire or accident call the laboratory instructor at once if possible. But there are times when seconds count, and the student should be ready in such cases to administer first aid to himself and others and to put out a fire before it spreads. 

Equip a millivolt/pH meter with a silver-indicating electrode. The laboratory instructor will demonstrate the proper use of the instrument. 

Through the column, in 20 ml portions, run a sample of de-ionized water equal in volume to the above eluent and titrate it as a background blank. Repeat the procedure with the other two samples. The column can be used numerous times without recharging. When the dark bands have moved about two-thirds of the way down the length of the resin bed, the resin should be discarded or recharged with HC1. (Note consult the laboratory instructor.)... 

A laboratory procedure calls for oxidizing 2-propanol to acetone using an acidic solution of K2Cr20y. An insufficient amount of K2Cr20y is on hand, however, so the laboratory instructor decides to use an acidic solution of KMn04 instead. What mass of KMn04 is required to carry out the same amount of oxidation as 1.00 g of KyCryOy ... 

An almost infinite combination of the compounds described above and molecular or ionic guests can be considered for investigation by interested and well-motivated undergraduates. The investigations may require the students to prepare the molecules themselves or to investigate supramolecular phenomena using compounds prepared by the laboratory instructor. Either way, the vast scope of supramolecular chemistry should continue to inspire future generations of scientists. 

Safety note Steam lines are very dangerous and you should not attempt to use them without direct supervision from your laboratory instructor. 

Although the greatest care has been exercised in the preparation of this information, the author, speaking for himself, and for the classroom and laboratory instructors, and the publisher, expressly disclaim any liability to users of these procedures for consequential damages of any kind arising out of or connected with their use. 

We have mentioned a few precautions in the use of volumetric flasks, pipets, and burets. Your laboratory instructor will supply you with detailed instructions in the use of each of these tools. A discussion of some general precautions and good laboratory technique follows. 

After two years of research at Oxford, Soddy served as a demonstrator (laboratory instructor) at McGill University in Montreal, Canada (1900-1902), where he worked with Ernest Rntherford, studying the gaseous emanation of radinm and showing that radioactivity involved the disintegration of radioactive atoms to form new elements. He called the process transmutation, a term that he borrowed from alchemy. 

FIGURE 73. Depictions of glassware and metaphors from Porta s De Distillatione (Figure 70) (a) Common retort and appropriate bird (b) fractional distillation apparatus and depiction of a seven-headed beast (or perhaps the Organic Chemistry Laboratory Instructor). 

This becomes the mantra for those not atigned with either of the two extreme camps. The research to date indicates that the teaching laboratory is a complex environment. In this environment, there are interactions between students and the activity, students and the equipment, students and laboratory instructors, and students and each other. To make matters worse, all these interactions can be viewed as occurring within the broader framework of the cogititive, affective, and psychomotor domains. 

Note-. None of the sample preparation methods described here should be attempted without approval, written instructions, and close supervision by your professor or laboratory instructor. The methods described present many potential hazards. Many methods use concentrated acids, flammable solvents, and/or high temperatures and high pressures. Reactions can generate harmful gases. The potential for runaway reactions and even explosions exists with preparation of real samples. Sample preparation should be performed in a laboratory fume hood for safety. Goggles, lab coats or aprons, and gloves resistant to the chemicals in use should be worn at all times in the laboratory. 

When you return from Spring vacation in the Bahamas, you find that you are being pressed into service as a laboratory instructor in a work-study position. Two labels (to be designated bv vour laboratory instructor) have fallen off reagent bottles over the Spring break, and one of your first tasks is to determine what samples are contained in the two bottles from which these labels came. The two IcJsels are... 

Again, you will first find the HPLC instrument in the off position use hands on to activate the instrument and allow at least 15 min for the detector to warm up and stabilize. Ask your laboratory instructor for assistance if necessary. Observe the variability in baseline absorbance. Absorbance should not vary much above a AA of 0.0100. Significant variability is most often due to tapped air bubbles due to insufficient degassing of the mobile phase. Inform your instructor if this baseline absorbance variation is significant. 

The most appropriate IS needs to be selected from the above list of candidates. Consult with your laboratory instructor and proceed to inject one or more ISs and base your decision on an interpretation of the chromatogram. 

Place exactly 40 mL of unknown sample into the 70-mL SPE reservoir which sits atop a prevously conditioned Cig sorbent according to specific instructions given to you by your laboratory instructor. Add distilled, deionized water (DDI) to the reservoir so as to fill to near capacity. Pass the aqueous sample through the cartridge which contains approximately 200 mg of Cig chemically bonded silica gel. Use a wash bottle which contains DDI to rinse the residual sample from both the reservoir and the cartridge. 

While the school principal or college president is ultimately responsible for the safety of students in courses that involve laboratory activity, the laboratory instructor carries direct responsibility for what actually takes place under his or her direction. The instructor is responsible for developing the positive attitudes and habits of the culture of laboratory safety as well as the necessary skills for handling chemicals safely. 

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