Laboratory exercise

Vitha, M. F. Carr, P. W. A Laboratory Exercise in Statistical Analysis of Data, /. Chem. Educ. 1997, 74, 998-1000. Students determine the average weight of vitamin E pills using several different methods (one at a time, in sets of ten pills, and in sets of 100 pills). The data collected by the class are pooled together, plotted as histograms, and compared with results predicted by a normal distribution. The histograms and standard deviations for the pooled data also show the effect of sample size on the standard error of the mean. 

I exercises are suitable as either homework or laboratory exercises, and they... 

Reid and Shah (2007) have provided evidence supporting pre-laboratory exercises. However, pre-experimental activities constitute a phase that most often is missing from laboratory irrstruction. According to research findings, only about 3% of the laboratory time is applied to developing research questions for experiments (Tobin Capie, 1982 Neber Heumarm-Ruprecht, 2006). 

This method has been extensively validated in two international laboratory exercises (Basketter et al., 1991 Loveless et al., 1996). In the earlier work (Basketter... 

When red cabbage is boiled in water, pigments called anthocyanins are extracted. These pigments can be used to indicate pH. In this laboratory exercise, you will observe the color of red cabbage extract as a function of pH, match each color with a color in the color palette of Microsoft PowerPoint, and, using Microsoft PowerPoint, present your findings to the class. You will work in groups of two or three for this activity. 

In the early Gatterman s preparative chemistry book, " the one-pot synthesis of dUiydropyridine derivatives like those formed by the Hantzsch reaction was one of practical laboratory exercises. 

Before carrying out any of the following laboratory exercises, the appropriate safety audits should be performed. In particular, attention is drawn to the Control of Substances Hazardous to Health (COSHH) regulations. 

Object of the Course.—In the laboratory exercises which constitute the working portion of this text, directions are given for the preparation of a number of chemical substances in more or less pure condition. 

The purpose of each laboratory exercise in this book is to observe and measure characteristics of a biomolecule or a biological system. The characteristic is often quantitative, a single number or a group of numbers. These measured characteristics may be the molecular weight of a protein, the pH of a buffer solution, the absorbance of a colored solution, the rate of an enzyme-catalyzed reaction, or the radioactivity associated with a molecule. If you measure a quantitative characteristic many times under identical conditions, a slightly different result will most likely be obtained each time. For... 

G.23 In a laboratory exercise, a student mixes 25.0 g of ethanol, C2H5OH, with 150 g of water, (a) What is the mole fraction of ethanol in the solution (b) What is the molality of ethanol in the solution ... 

Several years ago a student came up to me in the laboratory, quietly explained that she was pregnant, and asked if there would be anything the class might be working with that day that she should avoid. She was asking a very good and important question, but I was surprised to hear her ask it. No one had ever asked me that question before. Fortunately, the laboratory exercise that day involved metric measurements and density determinations, and I could tell her with confidence that it posed no risk. But could I tell her that every week Probably not. 

Beyond test development and validation, inter-calibration exercises (also known as round robin or inter-laboratory exercises ) are mandatory steps that must be undertaken if a toxicity test method is intended for standardization. These exercises... 

The forensic science course offered can be a four-hour course that combines lectures with laboratory exercises or three hours of instruction consisting of lectures and several laboratory demonstrations. A brief outline of the course curriculum is presented for both the lecture and laboratory components of the course. 

The concerns of colleges and universities about the efficacy of large group lectures and verification laboratory exercises, as well as the lack of opportunities for students to experience the methods and attitudes associated with science research, have prompted the development of many alternative approaches to the teaching of college-level chemistry. 

TABLE 8.3 Level of Openness in Laboratory Exercises (Schwab 1962 Herron 1971)... 

Students are learning about equilibrium in a chemistry laboratory exercise. The relevant materials include an aqueous solution of C0CI2, concentrated HCI, water, a hot water bath, an ice-water bath, and all necessary glassware. CoCI2 dissociates in water into Cl- ions and Co2+ ions which form the hydrated complex [Co(H20)6]2+. This ionic complex turns the solution pink. When HCI is added, the additional Cl reacts with [Co(H20)6]2+ in a mildly endothermic reversible reaction to form [C0CI4]2-. This ion turns the solution blue. 

Use of Time in Laboratory. In preparation work it is frequently necessary to wait for considerable periods of time for evaporations, crystallizations, etc., to take place. This time may be utilized for work upon the study questions and experiments, but even then it is advisable to have usually more than a single preparation under way. Thus no time need be wasted by the energetic student who plans his work well. A program of work should be made out in advance of the laboratory exercise. 

TABLE 3.1 LABORATORY EXERCISES THAT ARE RECOMMENDED BY THE COLLEGE BOARD... 

Naturally occurring polysaccharides are made up of a variety of monosaccharides connected by glyco-sidic bonds. Often, these polysaccharides are linked to proteins and lipids. The function of such polysaccharides is often critically dependent on the composition and sequence of their monomeric units. Determination of the structure of polysaccharides is a multistep process. In the early stages, it is crucial to ascertain both the relative amount and the chemical identity of the monomers. After a polysaccharide has been broken down to its monomeric units by hydrolytic or enzymatic digestion, a variety of analytical techniques can be employed to identify and quantify each monomer. Three of these techniques will be demonstrated in this laboratory exercise. 

Safety Precaution This laboratory exercise utilizes radioisotopes (3H and IAC). Use caution when handling these compounds. Avoid ingesting and skin contact with these radioisotopes. Wear gloves and safety glasses at all times. Consult the instructor for information on how to properly dispose of the radioactive material produced in this experiment. 

In this laboratory exercise, you will study the effects of phosphorylation and allosteric regulation on the activity of glycogen phosphorylase. In the first experiment, you will phosphorylate glycogen phosphorylase b in vitro using y-[32P]ATP and glycogen phosphorylase kinase. In the second experiment, you will study the effect of phosphorylation on glycogen phosphorylase activity, as well as the effect of AMP on glycogen phosphorylase b activity with the use of a coupled enzymatic (kinetic) assay (Fig. 15-3). 

Dolan, E. Zhang, Y. Klarup, D. G. The Distribution Coefficient of Atrazine with Illinois Soils A Laboratory Exercise in Environmental Chemistry, / Chem. Educ. 1998, 75, 1609-1610. Dorman, S. C. Using the Local Watershed as an Outdoor Laboratory A Campus-Community Partnership , 225th Am. Chem. Soc. National Meeting, New Orleans, LA, March 23-27, 2003. Chem. Ed. Division Paper 130. Favaretto, L. An Inexpensive Device for Collection of Samples of Water for Dissolved Oxygen Determination without Air Contact, J. Chem. Educ. 1990, 67, 509. 

The errors inherent in measuring the activity of polonium, uranium, and plutonium can be assessed by determining radionuclides in CRMs in international laboratory exercises and using the CRM produced by the International Atomic Energy Agency... 

D. Mtiller-Schwarze, Hands-On Chemical Ecology Simple Field and Laboratory Exercises, DOI 10.1007/978-l-4419-0378-5 l, Springer Science+Business Media, LLC 2009... 

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