Sodium oleate is the sodium salt of oleic acid. We will reveal the main physical and chemical properties of this compound, its scope.
Physical properties
Sodium oleate has a melting point of 220 degrees Celsius. Under normal conditions, it is a white or slightly yellowish powder that dissolves well in water, as well as in hot ethanol. Sodium oleate is not soluble in ether and acetone (ketone). This compound is included in modern detergents and soaps.
Sodium oleate has a hydrophobic effect. It can be explained by the formation of calcium soaps with alkaline components of the material.
Receipt options
How to get sodium oleate? The inorganic compound that forms the basis for its formation is sodium hydroxide. Salt is formed during the chemical interaction of alkali with oleic (organic) acid. This reaction is reversible; therefore, concentrated sulfuric acid is used to shift the equilibrium towards the formation of reaction products. It draws water molecules, since it is a hygroscopic substance.
Property Features
What is characterized by sodium oleate? The properties of this compound are divided into three groups:
- Collegative. They depend on the number of molecules. These include pressure, lowering or increasing temperature, volume.
- Additive. They are due to molecular forces, expressed as the sum of the properties of groups of atoms that are part of the molecules.
- Constructive. These properties include the color of the compounds, dipole moment.
Sodium oleate is a colloidal surfactant. It consists of eighteen carbon atoms that form a stable dispersed system of a heterogeneous type. This chemical compound, according to the classification associated with the chemical structure, is an anionic surfactant. This substance has a washing effect, belongs to the fourth group according to the classification of P.A. Rebinder. The cleaning effect is associated with contact between the aqueous solution of a given salt and the surfaces of solids. Solubilization, characteristic of sodium oleate, is the main component in the complex of its washing action.
Micelle formation is a spontaneous process. For him, the magnitude of the change in Gibbs energy has a negative exponent.
Application
Where is sodium oleate used? The use of this compound as an emulsifier is based on its good solubility in water. With its help it is possible to obtain stable emulsions of the oil-water type. After the introduction of calcium cations into the resulting solution, insoluble oleate precipitates, which changes the picture to the opposite process.
Due to the presence of an organic fragment in the salt molecule, adsorption occurs on the surface of benzene. After introducing the dye into the emulsion, for example, Sudan III, soluble in aromatic benzene, a dispersion medium and phase can be detected.
When treated with sodium oleate, the wettability of quartz and its electrokinetic potential are significantly reduced. Let us analyze the water-oleate sodium system. The magnitude of the surface tension of the salt leads to a shift in the inactivity region in the direction of a higher concentration. This emulsifier in high concentration has a direct effect on the stability of the foam.
In the surface layer, the concentration of this substance exceeds this indicator in its volume by tens of thousands of times. Magnetic treatment of an aqueous solution of this salt affects its sorption properties.
Contact with sodium oleate of various minerals that are in the magnetized suspension leads to a decrease in the heat of wetting, a decrease in the optical density of the solution.
To summarize, we say that among the main areas of application of this organic salt, it is necessary to note the introduction of soap. It is the hydrophobic properties of sodium oleate that made it a popular component in the cosmetic industry. Colloid chemistry, in which this compound is in demand, explains the physical and chemical characteristics of inorganic and organic solutions, the specifics of their practical application.