Immiscible substances

If we suppose that a solution A of concentration f is in contact with an immiscible substance B (say air, or petroleum) over a surface S, there will be a different concentration of the solute in the immediate vicinity of S from that in the free bulk of A. 

Material barriers Contours of land Immiscible substances (lipids) in membranes Earth s mantle (oxides)... 

Emulsifier Substance that assists the dispersion of two immiscible substances. 

There is considerable evidence that whenever two immiscible substances are brought together a double layer at the interface results, but recent work has made it doubtful whether, in every case, the iso-electric point corresponds with the condition of maximum surface tension. 

Stabilizers Substance which makes it possible to maintain the physicochemical state of a foodstuff stabilizers include substances which enable maintenance of a homogenous dispersion of two or more immiscible substances in a foodstuff and include also substances which stabilize, retain or intensity an existing colour of a foodstuff... 

Emulsions are mixture of two (or more) immiscible substances. Everyday common examples are milk, butter (fats, water, salts), margarine, mayonnaise, skin creams, and others. In butter and margarine, the continuous phase consists of lipids. These lipids surround the water droplets (water-in-oil emulsion). All technical emulsions are prepared by some kind of mechanical agitation or mixing. Remarkably, the natural product, milk, is made by organisms without any agitation inside the mammary glands. 

Thus emulsion technology is basically concerned with preparing mixtures of two immiscible substances, oil and water by adding suitable surface-active agents (such as emulgators, cosurfactants, and polymers). 

Surfactant (water treatment) A compound that reduces surface tension between immiscible substances, like oil and water, which prevents them from separating. Examples include detergents and emulsifiers (compare with emulsification). 

A solute distributes itself between two immiscible (substances that do not mix) solvents so that the ratio of its concentrations in dilute solutions in the two solvents is constant, regardless of the actual concentration in either solvent. The solvents will form layers, since they do not mix. In this situation, both concentrations are assumed to be on the same volumetric basis (e.g., mol/L). 

Steam distillation will be employed in a number of experiments in this text. On a small scale steam is generated in the flask that contains the substance to be steam distilled by simply boiling a mixture of water and the immiscible substance. 

Monomers can be polymerized at the interface of two immiscible substances to form a membrane. An example is a nylon membrane resulting from polymerization of two monomers (typically dichloride and diamine) at the interface. A non-aqueous phase containing surfactant and an aqueous phase containing drugs and diamine are mixed to form a w/o... 

The oldest technique for obtaining values of 7 for immiscible substances in water is tually an estimation relating y of the comjx)nent in water to the invert of its solubility in wato. For example, consider two liquid phases in equilibrium with... 

The distillation of immiscible substances is most easily discussed from a different standpoint. Consider two immiscible liquids in equilibrium with vapor at a specified temperature (Fig. 15.5). The barrier only keeps the liquids apart since they are immiscible, removing the barrier would not change anything. The total vapor pressure is the sum of the... 

The total pressure exerted at equilibrium, in accord with the rule of thumb for immiscible substances, is equal to the sum of the pure-compo nent vapor pressures. 

Surfactant Surface active agent containing both hydrophUic and hydrophobic groups, enabling it to lower surface tension and solubilize or disperse immiscible substances in water. 

Microemulsions are microstructured mixtures of oil-water-emulsifiers-other substances. LCs are substances that exhibit special melting characteristics. Further, some mixtures of surfactant-water-co-surfactant may also exhibit LC (lyotropic crystals) properties. The anulsion technology is basically thus concerned in preparing mixtures of two immiscible substances ... 

Find out about the chemistry of emulsifying agents. How do these substances affect the dissolution of immiscible substances such as oil and water As part of your research on this topic, find out why eggs are an emulsifying agent for baking mixtures. 

Imagine that two immiscible substances containing a common dilute solute are brought into contact. Solute then diffuses from one of these substances into the other. Calculate the concentration profiles of the solute in each of the substances, assuming that each substance behaves as a semi-infinite slab. (S. Gehrke)... 

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