Substances, Mixtures, and Solubility

Why do drink mixes come in powder form What would happen if you dropped a big chunk of drink mix into the water Would it dissolve quickly Powdered drink mix dissolves faster in water than chunks do because it is divided into smaller particles, exposing more of the mix to the water. See for yourself how particle size affects the rate at which a substance dissolves. 

Carefully grind a bouillon cube into powder using a mortar and pestle. 

Place the bouillon powder into one beaker and drop a whole bouillon cube into the second beaker. 

Think Critically Write a paragraph in your Science Journal comparing the color of the two liquids and the amount of undissolved bouillon at the bottom of each beaker. How does the particle size affect the rate at which a substance dissolves  

The air you breathe, the water you drink, and even parts of your body are all solutions. 

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The proportions do not make much difference as far as the yield is concerned, but the substance is more soluble in mixtures rich in benzene. About 10-12 cc. of the 3 1 mixture is required for each gram of anthrone. The anthrone may be more readily dissolved if it is added to the estimated quantity of hot benzene on the steam bath, and the petroleum ether is then added. About two-thirds of the mother liquor may be distilled off through a condenser and used in later runs. The residual mother liquor deposits about 12 g. of rather impure anthrone. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

The preparations of luciferin (Ln, an electron acceptor) and soluble enzyme used were crude or only partially purified. The luciferase was an insoluble particulate material, possibly composed of many substances having various functions. Moreover, the luciferin-luciferase reaction was negative when both luciferin and luciferase were prepared from certain species of luminous fungus. It appears that the light production reported was the result of a complex mechanism involving unknown substances in the test mixture, and probably the crucial step of the light-emitting reaction is not represented by the above schemes. 

Worker safety studies are not likely to normally include a control substance (i.e., a material used in the study to serve as basis of comparison with the test substance). However, if a control substance is included as a treatment group, then it must (1) be fully characterized as to its identity, purity (or strength), and stability (and solubility, if appropriate) (2) be appropriately tested in mixtures with any carrier used and (3) meet all the other GLP recordkeeping, labeling, and storage requirements, as specified for the test substance. There is some regulatory relief here, however, in that water, by definition, is excluded from being considered a control substance, and vehicles (those substances added to enhance solubilization or dispersion of the test substance) are addressed separately in the FIFRA GLP Standards. 

The extraction apparatus is used chiefly for dissolving out sparingly soluble constituents from mixtures, and for isolating natural products from (dry) vegetable or animal material. Occasionally it is very useful for recrystallising sparingly soluble substances from the extraction thimble by means of an appropriate solvent (especially ether). As a rule, crystals of the dissolved material separate already from the solution in the flask during the process of extraction. This solution soon becomes supersaturated even while hot. 

Cohn, E.J., McMeekin, T.L., Edsall, J.T., and Weare, J.H. Studies in the physical chemistry of amino acids, peptides and related substances. II. The solubility of a-amino acids in water and in alcohol-water mixtures, J. Am. Chem. Soc., 44(3) 451-460, 1922. 

Organic matter extracted from earth materials usually is fractionated on the basis of solubility characteristics. The fractions commonly obtained include humic acid (soluble in alkaline solution, insoluble in acidic solution), fulvic acid (soluble in aqueous media at any pH), hymatomelamic acid (alcohol-soluble part of humic acid), and humin (insoluble in alkaline solutions). This operational fractionation is based in part on the classical definition by Aiken et al. (1985). It should be noticed, however, that this fractionation of soil organic matter does not lead to a pure compound each named fraction consists of a very complicated, heterogeneous mixture of organic substances. Hayes and Malcom (2001) emphasize that biomolecules, which are not part of humic substances, also may precipitate at a pH of 1 or 2 with the humic acids. Furthermore, the more polar compounds may precipitate with fulvic acids. 

The submitters state that the compound may be recrystallized by boiling with acetone under an upright condenser and adding ethanol cautiously down the condenser until the solid just dissolves. The substance is appreciably soluble in the cold solvent mixture. It is necessary to distil the mother liquor and recrystallize the residue from acetone-ethanol, for otherwise a considerable loss of product will occur. The checkers used isopropyl alcohol for crystallization. 

Extraction is a process whereby a mixture of several substances in the liquid phase is at least partially separated upon addition of a liquid solvent in which the original substances have different solubilities. When some of the original substances are solids, the process is called leaching. In a sense, the role of solvent in extraction is analogous to the role of enthalpy in distillation. The solvent-rich phase is called the extract, and the solvent-poor phase is called the raffinate. A high degree of separation may be achieved with several extraction stages in series, particularly in countercurrent flow. 

SOLUBILITY. A property of a substance by virtue of which it forms mixtures with other substances which are chemically and physically homogeneous throughout The degree of solubility is die concentration of a solute in a saturated solution at any given temperature. The degree of solubility of most substances increases widi a rise in temperature, but dicrc arc cases (notably the organic salts of calcium) where a substance is more soluble in cold Ilian in hot solvents. 

In this paragraph only two physical properties are discussed viz. the boiling point and solubility. These properties are affected by the attractive forces which the particles of the pure substance or in a mixture exert on each other. Particles attract when they are charged, so when they are ions, when they possess a dipole or when they are able to form hydrogen bridges. 

When the best solvent or solvent mixture and the appropriate proportions of solute and solvent have been determined by these preliminary tests or have been obtained from reference books containing solubility data,39,40 the solid substance is placed in a round-bottomed flask of suitable size fitted with a reflux condenser (Fig. 2.54) and slightly less than the required quantity of solvent is added together with a few pieces of porous porcelain to prevent bumping (see... 

To determine the stability and, when relevant to the conduct of the experiment, the solubility of the test, control, or reference substance in the mixture before the experimental start date. Determination of the stability and solubility of the test, control, or reference substance in the mixture shall be done under the environmental conditions specified in the protocol and as required by the conditions of the experiment. Where periodic analysis of the mixture is required by the protocol, there shall be written standard operating procedures that shall be followed. 

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