Chemical tests

What physical and chemical tests could you apply to the oxides and chlorides of Group IV elements to show the changes in their properties as the atomic number of the element increases At the... 

Lead formate is only slightly soluble in cold water, and insoluble in hot absolute ethanol it can therefore be readily distinguished from lead acetate or sugar of lead because, quite apart from chemical tests, the acetate is readily soluble in cold water and moderately soluble in ethanol. 

Suggest a chemical test that would permit you to distinguish between the two glycerol monobenzyl ethers shown... 

The procedures used for estimating the service life of solid rocket and gun propulsion systems include physical and chemical tests after storage at elevated temperatures under simulated field conditions, modeling and simulation of propellant strains and bond tine characteristics, measurements of stabilizer content, periodic surveillance tests of systems received after storage in the field, and extrapolation of the service life from the detailed data obtained (21—33). 

Detecting the presence of small, even invisible, amounts of blood is routine. Physical characteristics of dried stains give minimal information, however, as dried blood can take on many hues. Many of the chemical tests for the presence of blood rely on the catalytic peroxidase activity of heme (56,57). Minute quantities of blood catalyze oxidation reactions between colorless materials, eg, phenolphthalein, luco malachite green, luminol, etc, to colored or luminescent ones. The oxidant is typically hydrogen peroxide or sodium perborate (see Automated instrumentation,hematology). 

Liquid Fabric Softeners. The principal functions of fabric softeners are to minimize the problem of static electricity and to keep fabrics soft (see Antistatic agents). In these laundry additives, the fragrance must reinforce the sense of softness that is the desired result of their use. Most fabric softeners have a pH of about 3.5, which limits the materials that can be used in the fragrances. For example, acetals cannot be used because they break down and cause malodor problems in addition, there is the likelihood of discoloration from Schiff bases, oakmoss extracts, and some specialty chemicals. Testing of fragrance materials in product bases should take place under accelerated aging conditions (eg, 40°C in plastic bottles) to check for odor stabiUty and discoloration. 

Sacrificial adsorption agents such as lignosulfonates (148—151) can be used to reduce the adsorption of more expensive polymers and surfactants. Other chemicals tested include poly(vinyl alcohol) (152), sulfonated poly(vinyl alcohol) (153), sulfonatedpoly(vinylpyrrohdinone) (153), low molecular weight polyacrylates (154), and sodium carbonate (155). 

Analytical and Test Methods. In addition to the modem spectroscopic methods of detection and identification of pyrroles, there are several chemical tests. The classical Runge test with HCl yields pyrrole red, an amorphous polymer mixture. In addition, all pyrroles with a free a- or P-position or with groups, eg, ester, that can be converted to such pyrroles under acid conditions undergo the Ehrlich reaction with p-(dimethylamino)henzaldehyde to give purple products. 

The development of rehable uv analysis permitted the dependable detection and assay of the provitamins and vitamins. Prior to this, the Lieberman-Bouchard chemical test was used, but the color reaction gave many false positives and was relatively inaccurate. 

Eig. 1. The quasispeciftc effect ia the homologous series of o-alkyl-/)-chloropheaol derivatives agaiast A = Salmonella typhosa-, B = Staphyloccus aureus-, C = Mycobacterium tuberculosis-, D = Candidaalbicans. Pheaol coefficieat is the activity of the chemical tested compared to that of pheaol. 

Phenol Coefficient Test. The first important attempt at standardizing testing methods was known as the phenol coefficient test (96). It has been modified several times, and is an official AO AC screening test recognized by EPA and PDA. The phenol coefficient test compares the activity of disinfectants to that of phenol, under specific conditions, to give a number that measures the activity of the chemical tested with respect to that of phenol, ie, the phenol coefficient. The AO AC method employs visual examination of bacterial growth in a nutrient medium. The Kelsey-Sykes test (1969) is a modified method popular in British circles. 

Because alcohol intoxication may be simulated by many pathologic conditions, including diabetic acidosis, the postconvulsive depression of epilepsy, uremia, head injuries, and poisonings by any other central nervous depressant and some stimulants (280), a diagnosis of acute alcoholism should not be made casually chemical testing of blood, urine, or expired air is always desirable. 

Review of reactive chemicals test data for evidence of flamma-bihty charac teristics, exotherms, shock sensitivity, and other evidence of instability... 

The purpose of this report is creation of fast chemical test-systems with quite enough low detection limits and enough high selectivity. 

Reactive chemicals test results (thermal stability, calorimetric, ARC, DSC)... 

The important question, then, is not whether a substance is pure but whether a given sample is sufficiently pure for some intended purpose. That is, are the contaminants likely to interfere in the process or measurement that is to be studied. By suitable manipulation it is often possible to reduce levels of impurities to acceptable limits, but absolute purity is an ideal which, no matter how closely approached, can never be attained. A negative physical or chemical test indicates only that the amount of an impurity in a substance lies below a certain sensitivity level no test can demonstrate that a specified impurity is entirely al ent. 

Chemical tests for particular types of impurities, e.g. for peroxides in aliphatic ethers (with acidified KI), or for water in solvents (quantitatively by the Karl Fischer method, see Fieser and Fieser, Reagents for Organic Synthesis J. Wiley Sons, NY, Vol 1 pp. 353, 528, 1967, Library of Congress Catalog Card No 66-27894). 

HS(Gjl3 Electrical testing safety m chemical testing... 

Physical and chemical tests of the final product may need to address two concerns (1) whether the solidified waste exhibits any RCRA defined toxicity characteristics or could be delisted and (2) the potential long term fate of treated materials in the disposal environment. Three tests are available which address the first concern. These are the Extraction Procedure (EP Tox) (40 CFR 261, Appendix II, 1980) and the Toxicity Characteristic Leaching Procedure (TCLP) (40 CFR 261, Appendix II, 1986), and the Multiple Extraction Procedure Test (40 CFR 261, Appendix II, January 1989). It is important to note that these tests are not indicators of expected leachate quality but of potentials. A solidified product which cannot pass the appropriate test (EP Tox or TCLP) would be subject to classification as a hazardous waste. 

Reagent A pure chemical substance that is used to make new products or is used in chemical tests to measure, detect, or examine other substances. 

Until the second half of the twentieth century, the structure of a substance—a newly discovered natural product, for example—was determined using information obtained from chemical reactions. This information included the identification of functional groups by chemical tests, along with the results of experiments in which the substance was broken down into smaller, more readily identifiable fragments. Typical of this approach is the demonstration of the presence of a double bond in an alkene by catalytic hydrogenation and subsequent determination of its location by ozonolysis. After-considering all the available chemical evidence, the chemist proposed a candidate structure (or structures) consistent with the observations. Proof of structure was provided either by converting the substance to some already known compound or by an independent synthesis. 

Oil-related analysis encompasses a variety of physical and chemical tests such as viscosity, total acid number and particulate contamination. This is often extended to include the identification of wear debris, as an early warning of component failure, by either spectrographic... 

Caution is needed in applying the results of general chemical tests for glass durability across a wide spectrum of glass properties. Glass fibre strengths, for example, are sensitive to the physical, as well as the chemical, nature of the environment and should only be assessed by the direct strength measurements in conditions which closely approximate the final application situation . 

Table 19.3 Summary of chemical tests used for the determination of susceptibility to intergranular corrosion of iron-nickel Chromium alloys ...

Fig. 19.15 Schematic representation of range of corrosion potentials expected from various chemical tests for sensitisation in relation to the anodic dissolution kinetics of the matrix (Fe-l8Cr-IONi stainless steel) and grain boundary alloy (assumed to be Fe-lOCr-lONi) owing to depletion of Cr by precipitation of Cr carbides of a sensitised steel in a hot reducing acid (after Cowan and Tedmon )...

How would you distinguish between the following pairs of compounds using simple chemical tests Tell what you would do and what you would see. 

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