A Solubility Tests

Solubility tests should be performed on every unknown. They are extremely important in determining the nature of the main functional group of the imknown compound. The tests are very simple and require only small amounts of the unknown. In addition, solubility tests reveal whether the compoimd is a strong base (amine), a weak acid (phenol), a strong acid (carboxylic acid), or a neutral substance (aldehyde, ketone, alcohol, ester). The common solvents used to determine solubility types are 

Solubility chart for compounds containing various functional groups. The most common functional groups in each class are printed in bold-face type. 

Also given is a series of explanations detailing the reasons that compounds having specific functional groups are soluble only in specific solvents. This is accomplished by indicating the type of chemistry or the type of chemical interaction that is possible in each solvent. 

Dispose of all aqueous solutions in the container designated for aqueous waste. Any remaining organic compounds must be disposed of in the appropriate organic waste container. 

Strong acids soluble in NaHCOg and NaOH (carboxylic acids) 

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Fuels such as diesel and kerosene readily absorb hydrocarbon vapors, the total uptake and absorption rate depending on both chemical and physical factors. If a soluble test gas is introduced above a charged test oil the concentration of flammable test gas therefore decreases with time. Liquid mist and spray produced by charged liquid increase the absorption rate relative to a quiescent liquid surface. As discussed in A-5-4, absorption could lead to an underestimation of test gas MIE near the liquid surface unless the rate of test gas introduction is sufficiently high to offset the rate of removal. Table 3-8.1.2 shows solubilities of a selection of gases in a mineral-based transformer oil at ambient temperature and pressure [200]. 

To control the reaction rate, the pH value is measured continuously, which is re-adjusted by adding formic acid. When the end-point of the reaction is reached, determined by a solubility test with water, the reaction mixture is brought to pH 7 with caustic soda lye. The condensation is complete and the resin is evaporated under reduced pressure. The vapor is condensed in a tubular condenser and collected in a receiver. 

A) Solubility. Test the solubility of the following acids acetic, butyric, n-capraic, stearic, and benzoic acids. 

Confirm the identity of your fabric by performing a burning or a solubility test on your unknown materials. 

The low molecular weight hydrocarbon resins have solubility parameter values in the range of 8.2 to 9.5. This might seem narrow, but the solubility behavior of the various resins is quite different and parameter values to the second decimal point are required in choosing a formulation. Usually a solubility test in specific solvents and a cloud point determination are needed for precise control. 

In order to better clarify the importance of temperature on the preoxidation step, a solubility test was performed after this procedure, as described in Sections 2.3 and 2.4. The results are presented in Table 4. 

Amount of Material Required in Solubility Tests.—The quantity of the unknown used in a solubility test will naturally depend upon the amount available. Usually it is convenient to use 0.10 g. 

An example will probably help. An aqueous solution of a yellow wool dye was prepared at a concentration of 100 g/liter in a solubility test. Now, you wish to know the % dye strength of the original sample. The absorptivity at 428 m/x in water has previously been determined to be 54 liters/g-cm. 

The behavior of plastic materials in various organic solvents often indicates the type of material. The solubility data found in the literature is of a general nature and consequently difficult to use at times. A partial solubility of some plastics in different solvents and a high concentration of additives such as plasticizers further complicate identification by the solubility test. However, a solubility test is very useful in distinguishing between the different types of the same base polymer. For example, cellulose acetate can be distinguished from cellulose acetate butyrate because the acetate is completely soluble in furfuryl alcohol whereas the butyrate is only partially soluble (1). Types of nylons and polystyrenes can be identified... 

A paper was published by Ishiaku and co-workers [11], who investigated the optimum concentration of DeLink to use in the devulcanisation of a sulfur-cured, NR-hased powder that had originated from waste rubber balls and artificial eggs. A solubility test was also developed to assess the degree of crosslink destruction that had taken place. The results obtained showed that the optimum... 

In Fig. 4 the result of a solubility test of a coumarin derivative in SCCO2 is shown. As long as the CO2 pressure is below the critical point, no solubility of the substrate is found. When reaching the critical point, the coumarin dissolves in the SCCO2 phase and the fluorescence of the dissolved substrate increases. 

Oxidation, (a) Unsaturation test. Dissolve about o-i g. of cinnamic acid or of a soluble cinnamate in about 5 ml. of 10% NajCOg solution. To the cold solution add 1% aqueous KMn04 drop by drop. Immediate decolorisation denotes unsaturation. (Note. Many easily oxidisable substances, e.g.y formic acid, acetaldehyde, etc.y also rapidly decolorise alkaline permanganate. Cinnamates, however, do not reduce Fehling s solution.)... 

The chloroplatinates prepared as above are sufficiently pure for direct analysis without recrystallisation. The chloroplatinates of the amines are usually freely soluble in hot water, but recrystallisation (when required) should not be attempted until the process has been found to be successful with a small test-portion of the chloroplatinate. The chloroplatinates of many primary and secondary amines decompose in hot water, the amine being oxidised, and the chloroplatinate reduced to the metal some amines furthermore co-ordinate readily with the metal when the chloroplatinate is boiled with water and a mixed product is obtained on cooling. 

Add 1 drop (0 05 ml.) of concentrated nitric acid to 2 0 ml. of a 0 5 per cent, aqueous solution of paraperiodic acid (HjIO,) contained in a small test-tube and shake well. Then introduce 1 op or a small crystal of the compound. Shake the mixture for 15 seconds and add 1-2 drops of 5 per cent, aqueous silver nitrate. The immediate production of a white precipitate (silver iodate) constitutes a positive test and indicates that the organic compound has been oxidised by the periodic acid. The test is based upon the fact that silver iodate is sparingly soluble in dilute nitric acid whereas silver periodate is very soluble if too much nitric acid is present, the silver iodate will not precipitate. 

This may be determined roughly by treating a small test portion with 3-4 ml. of hot water and acidifying with concentrated hydrochloric acid the absence of a precipitate in the warm solution indicates the essential completeness of the reaction. Salicylic acid is sparingly soluble and p-hydroxybenzoic acid is relatively soluble under these conditions. 

Group I. This includes the lower members of the various homologous series (4-5 atoms in a normal chain) that contain oxygen and/or nitrogen in their structures they are soluble iu water because of their low carbon content. If the compound is soluble in both water and ether, it would also be soluble in other solvents so that further solubility tests are generally unnecessary the test with sodium bicarbonate solution should, however, be performed (see Section XI,6). 

Solubility in ether. Use 0 -10 g. of solid or 0 -20 ml. of a liquid in a dry test-tube and proceed exactly as in testing the solubility in water, but do not employ more than 3 0 ml. of solvent. 

Solubility in 5 per cent, sodium hydroxide solution. Note whether there is any rise in temperature. If the compound appears insoluble, remove some of the supernatant liquid by means of a dropper to a semimicro test-tube (75 X 10 mm.), add 5 per cent, hydrochloric acid dropwise until acid, and note whether any precipitate (or turbidity) is formed. The production of the latter will place the compound in Group III. 

Both aldehydes and ketones contain the carbonyl group, hence a general test for carbonyl compounds will Immediately characterise both classes of compounds. The preferred reagent is 2 4-dinilrophenylhydrazine, which gives sparingly soluble phenylhydrazones with carbonyl compounds ... 

Alkali or alkaline-earth salts of both complexes are soluble in water (except for Ba2[Fe(CN)g]) but are insoluble in alcohol. The salts of hexakiscyanoferrate(4—) are yellow and those of hexakiscyanoferrate(3—) are mby red. A large variety of complexes arise when one or more cations of the alkah or alkaline-earth salts is replaced by a complex cation, a representative metal, or a transition metal. Many salts have commercial appHcations, although the majority of industrial production of iron cyanide complexes is of iron blues such as Pmssian Blue, used as pigments (see Pigments, inorganic). Many transition-metal salts of [Fe(CN)g] have characteristic colors. Addition of [Fe(CN)g] to an unknown metal salt solution has been used as a quaUtative test for those transition metals. 

Corrective Action Application In Massachusetts, a municipal wastewater treatment plant receives a number of wastestreams containing heavy metals from local industries. When tested, the dewatered sludge failed the EP toxicity test. In order to permit landfill disposal of the sludge, solidification processes were examined. A soluble, silicate-based system, developed by Chemfix, was ultimately selected which produced a product whose leachate passed the EP toxicity test (Sullivan, 1984). 

With the exception of the fluorides, the halides are all very water-soluble and deliquescent, Precipitation of the insoluble fluorides can be used as a qualitative test for these elements. The distinctive ability of Sc to form complexes is illustrated by the fact that an excess of F causes the first-precipitated SCF3 to redissolve as... 

We have seen in Experiment 8 that silver chloride has low solubility in water. This is also true for silver bromide and silver iodide. In fact, these low solubilities provide a sensitive test for the presence of chloride ions, bromide ions, and iodide ions in aqueous solutions. If silver nitrate... 

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