The Asian Journal of Experimental Chemistry

P. Bahadur ¹, Simmi Tyagi ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN

Abstract

Metal carboxylates-higher carboxylates of alkali (Soaps) and other metals (metallic soaps)-are used in many areas of daily life and industry. While the basic colloidal and other physicochemical properties of these derivatives have already been extensively studied, there has recently been a revival of interest in the various modes of bonding exhibited by metal carboxylates. Many metal carboxylates have been known from ancient times. The oldest organic derivatives of metals are the alkali metal carboxylates, commonly known as soaps. These soaps are soluble in water, with which they readily produce foam, commonly used for washing or cleansing purposes. Carboxylates of metal other than alkali metals (with the exception of lithium) are generally insoluble in water and are called Metallic soaps. The first use of such soaps in the form of lead linoleates appears to have been made quite early in paints for mummification. Metallic soaps are, therefore, simple carboxylates of alkaline earths or other polyvalent metals with the general formula, M(O₂CR)n, where 'M' is a metal in oxidation state 'n' and 'R' is an organic radical containing at least 6-7-carbon atoms. The term metallic soaps is restricted by some of the salts of fatty acids (i.e. those in which R is an aliphatic radical) although in the broad sense the term also includes salts of certain cyclic acids.

Keywords

Heavy Metal Soaps, Tensides, Surfactants, Metal Carboxylates.

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P. Bahadur ¹, Simmi Tyagi ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN

Abstract

Operation and effects of surfactants can be understood as follows; Surfactants reduce the surface tension of water by adsorbing at the liquid-gas interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. Many surfactants can also assemble in the bulk solution into aggregates. Some of these aggregates are known as micelles. The concentration at which surfactants begin to form micelles in known as the critical micelle concentration or cmc. When micelles form in water, their tails form a core that can encapsulate an oil droplet, and their (ionic/ polar) heads form an outer shell that maintains favourable contact with water. When surfactants assemble in oil, the aggregate is referred to as a reverse micelle. In a reverse micelle, the heads are in the core and the tails maintain favourable contact with oil. Surfactants are also often classified into four primary groups; anionic, cationic, non-ionic and zwt terionic (dual charge). Thermodynamics of the surfactant systems are of great importance, theoretically and practically. This is because surfactant systems represent systems between ordered and disordered states of matter. Surfactant solutions may contain an ordered phase (micelles) and a disordered phase (free surfactant molecules and / or ions in the solution). Ordinary washing up (dishwashing) detergent, for example, will promote water penetration in soil, but the effect would only last a few days (although many standard laundry detergent powders contains levels of chemicals such as sodium and boron, which can be damaging to plants, so these should not be applied to soils). Commercial soil wetting agents will continue to work for a considerable period, but they will eventually be degraded by soil micro-organisms. Some can however, interfere with the life-cycles of some aquatic organism, so care should be taken to prevent run- off of these products into streams, and excess product should not be washed down gutters. When a water droplet is in the air, surface tension, a force to reduce the surface area acts on the surface of the water, resulting in spherical water droplets. When water and oil are present in a container, they do not mix together even after stirring and separate in two layers (Fig. 1).

Keywords

Interfacial Chemistry, Interface, Food Emulsifiieres.

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Anil Kumar ¹, Deepti Tyagi ¹, Simmi Tyagi ², Deepika Shukla ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN
2 Central Building Research Institute, CBRI (A Constitutent Establishment of CSIR), Ministry of Science and Technology (Government of India), Roorkee (Uttarakhand), IN

Abstract

The specific conductance, k (mS cm^-1) of alkaline earth metal (Mg/Ca/Sr/Ba) laurates in mixed solvent (50% methanol +50% chloroform) has been measured (30-50^oC) in order to look into the dissociation / association behaviour of these surfactant systems. The data for critical micelle concentration (c.m.c) help characterising their micellar behaviour. The significant parameters viz. degree of dissociation (α), dissociation constant(K_D) and limiting equivalent conductance at infinite dilution (μ_o) have been deduced for pre-micellar region (dilute range).Thermodynamic parameters viz., enthalpy, free energy and entropy changes for both dissociation and association processes have also been computed.

Keywords

Metal Laurates, Conductance, Dissociation, Association, Critical Micelle Concentration (C.M.C), Thermodynamic Parameters.

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Anil Kumar ¹, Deepti Tyagi ¹, Simmi Tyagi ², Deepika Shukla ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN
2 Central Building Research Institute, CBRI (A Constitutent Establishment of CSIR), Ministry of Science and Technology (Government of India), Roorkee (Uttarakhand), IN

Abstract

The density measurement, ρ (gcm^-3) for alkaline earth metal (Mg/Ca/Sr/Ba) laurates in non-aqueous medium (50% methanol +50% chloroform) at different temperatures (30-50^oC) has been used to evaluate various significant parameters viz. apparent molar volume (Φ_v) and expansibility (E⁰_surf) to explore their solution behaviour. The critical micclle concentration (c.m.c.) as ascertained from ρ-C plots, is found to decrease with increasing temperature and vary with different metals as Mg>Ca>Sr>Ba. Density for these solutions increases with increasing surfactant concentration and decreasing temperature. Partial molar volume (Φ^o_v) and experimental limiting slope (Sv) as obtained from Masson's equation provide information on solute-solvent and solute-solute interactions, respectively. Apparent molar volume (Φ_v) is found to increase with increasing concentration and increasing temperature.

Keywords

Alkaline Earth Metal Laurates, Critical Micelle Concentration (c.m.c), Density (ρ), Apparent Molar Volume (Φ_v), Partial Molar Volume (Φ^o_v), Expansibility.

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Anil Kumar ¹, Seema Maan ¹, Simmi Tyagi ²

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN
2 Central Building Research Institute, CBRI (A Constitutent Establishment of CSIR), Ministry of Science and Technology (Government of India), Roorkee (Uttarakhand), IN

Abstract

The infrared and X-ray diffraction techniques have been used to study the structure of uranyl (II) stearate in solid state, whereas the structural changes of the metal soap in the solvent-mixture of 50% dimethylformamide and 50% benzene(V/V) at 40°C have been studied by the ultrasonic method. The appearance of two absorption bands at 1570 and 1440 cm^-1 which may be assigned to as υ_as COO^- and υ_s COO^- modes of carboxylate group of uranyl stearate indicate the ionic nature of this group in the soap. The XRD analysis reveals that uranyl soap has a single layer structure as proposed by vold and Hattiangdi for disoaps. Ultrasonic velocity measurement is employed to obtain various acoustic parameters and the critical micelle concentration, CMC(5.55×10^-4 mol. dm^-3) for the soap solutions. The values of ultrasonic velocity and acoustic impedance are found to decrease while adiabatic compressibility and intermolecular free length increase with increasing soap concentration.

Keywords

Metal Soap, Critical Micelle Concentration, Infrared, X-Ray, Ultrasonic Velocity, Acoustic Parameters.

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