The Classification Tests

For all tests given in this section, drops of reagents are measured out using Pasteur pipets. 

INSTRUCTOR PREPARATION. The reagent is prepared by dissolving 4.0 g of ceric ammonium nitrate [(NHf)2Ce(N03)6] in 10 mL of 2 MHNO3. Warming may be necessary. 

Primary, secondary, and tertiary alcohols with fewer than 10 carbon atoms give a positive test as indicated by a change in color from yellow to red  

Place 5 drops of test reagent on a white spot plate. Add 1-2 drops of the unknown sample (5 mg if a soUd). Stir with a thin glass rod to mix the components and observe any color change. 

If the alcohol is water insoluble, 3-5 drops of dioxane may be added, but run a blank to make sure the dioxane is pure. Efficient stirring gives positive results with most alcohols. 

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The classification tests (summarized in Table 31.2), when properly done, can distinguish between various types of aldehydes and ketones. However, these tests alone may not allow for the identification of a specific unknown aldehyde or ketone. A way to correctly identify an unknown compound is by using a known chemical reaction to convert it into another compound that is known. The new compound is referred to as a derivative. Then, by comparing the physical properties of the unknown and the derivative to the physical properties of known compounds listed in a table, an identification can be made. 

The 500g burning test (H) The classification test for The Fire Service Law for Class 1 substances... 

The classification test for Class 1 dangerous oxidizing solids... 

Figure 15.12 displays the classification tests performed for two of the flames. The test case on the left ( 5)... 

The classification test determines the relative compatibility between an aggregate filler of specific gradation and an emulsified bitumen residue. 

The classification test is also included in the mix design method proposed by ISSA A143 (2010) and is carried out using a similar procedure described in ISSA TB-144 (1990). 

The shaking abrasion test is carried out according to CEN EN 1227A-7. The test method determines the suitability of aggregates and cationic emulsions for slurry surfacings, and where appropriate, the effect of individual additives. The test is almost similar to the classification test described in ASTM D 6372 (2010), a brief description of which is given in Section 6.8.3.2. 

The samples, after being abraded, do not follow a boiling stage, as required by the classification test as described in ASTM D 6372 (2010). 

Place 2 mL of a solution of 2,4-dinitrophenylhydrazine (prepared as described for the classification test in Experiment 52D) in a test tube and add 0.15 g of the unknown compound. If the unknown is a solid, it should be dissolved in the minimum amount of 95% ethanol or 1,2-dimethoxyethane before it is added. If crystallization is not immediate, gently warm the solution for a minute in a hot water bath (90°C) and then set it aside to crystallize. Collect the product by vacuum filtration. 

Tollens s test is designed to distinguish between aldehydes and ketones. A complete discussion of this test together with an experimental procedure is included with the classification tests for aldehydes in Section 25.7C. 

List the classification tests that may be used to determine whether a sugar is a reducing sugar. 

B.11.3.1 The classification procedure for self-heating chemicals need not be applied if the results of a screening test can be adequately correlated with the classification test and an appropriate safety margin is applied. 

The procedure outlined in the Classification Test Section for aldehydes and ketones (p. 642) is used. Since the derivative to be isolated is a solid, it may be convenient to run the reaction in a 3-mL vial or in a small test tube. Double the amount of the reagents used. If necessary, the derivative can be recrystallized from 95% ethanol. 

There are several different devices for determination of dust explosion characteristics. All devices include a vessel which may be op>en or closed, an ignition source which may be an electrical spark or electrically heated wire coil and a supply of air for dispersion of the dust. The simplest apparatus is known as the vertical tube apparatus and is shown schematically in Figure 15.4. The sample dust is placed in the dispersion cup. Delivery of dispersion air to the cup is via a solenoid valve. Ignition may be either by electrical spark across electrodes or by heated coil. The vertical tube apparatus is used for the classification test and for determination of minimum dust concentration for explosion, minimum energy for ignition and in a modified form for minimum oxygen for combustion. 

Certification is not to be construed to mean that tests of any kind were necessarily conducted on samples of the specific material shipped. Tests on such material may, or may not, have been conducted. The basis for the certification required by the specification is the classification test of representative material cited above, and the Manufacturer s Quality Assurance Program in AWS A5.01M/A5.01 (ISO 14344 MOD). 

If the preliminary examination has indicated the presence of one or more particular functional groups, tests for these will naturally be made at once. Otherwise, it is important that the classification tests for the different functional groups be performed in the order given in the text. 

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