Esam Gomaa - Academia.edu (original) (raw)
Papers by Esam Gomaa
Physical chemistry, Aug 31, 2012
The external poles of a permanent magnet of power 1.26 kG were used to study their effect on the ... more The external poles of a permanent magnet of power 1.26 kG were used to study their effect on the conductance values of FeCl 3 plus 10% by weight , PVA (polyvinylalcohol) in 50 % by weight mixed ethanol-water solutions. A new equation for 1:3 asymmetric association constant was derived and used for calculating the association constants (K A) for FeCl 3 solutions in 50 % ethanol (EtOH)-H 2 O mixture in presence of PVA and also in absence and presence of an external magnetic field. The new equation was derived from the Fuoss-Shedlovsky equation and Ostwald dilution law and the evaluated values are discussed.
Southern Brazilian Journal of Chemistry, Dec 20, 2009
The association constants KA for CoC/ 2 aqueous solutions were calculated using the experimental ... more The association constants KA for CoC/ 2 aqueous solutions were calculated using the experimental conductivity values at different salt concentrations. The molar conductivities were measured in the absence and presence of a magnetic field with an average power of 0. 677 KGauss. A new equation for asymmetric 1:2 salts was suggested and used .This equation was derived from Ostwald, Arrhenius and Fuoss-Shedlovsky theories. The results obtained were discussed and the effect of the magnetic field on the association constants was explained RESUMO As constantes de associar;iio, KA, para solur;oes aquosas de CoC/ 2 foram calculadas a partir de valores experimentais da condutividade para varias concentrar;oes do sa/. As condutividades mo/ares foram medidas na ausencia e na presen<;a de um campo magnetico medio de 0. 677 KGauss. Uma nova equa<;iio Joi sugerida para sais assimetricos 1 :2 e Joi usada. Esta equa<;iio Joi derivada a partir das teorias de Ostwald, Arrhenius e Fuoss-Shed/ovsky. Os resultados obtidos foram discutidos e o efeito do campo magnetico sobre as constantes de associa<;iio Joi explicado.
Bulletin of the Chemical Society of Ethiopia
ABSTRACT. For lump and nanocobalt sulfate (CoSO4) in pure water, the affiliation and thermodynami... more ABSTRACT. For lump and nanocobalt sulfate (CoSO4) in pure water, the affiliation and thermodynamic association characteristics were measured at 298.15, 303.15, 308.15, and 313.15 K. Based on the bulk and nano CoSO4 molar conductance, estimates were made for the parameters of the solvation, such as the activity coefficient, free energy of association, enthalpy of association, association constant, and entropy of association. We discussed about each of these solvation parameters. Two stoichiometric complexes were formed by the interaction of bulk and nano CoSO4.7H2O with fuchsin acid: 1:1 and 1:2 In the case of 1:1 (CoSO4.7H2O/fuchsin acid) compared to 1:2 (fuchsin acid in pure water as solvent), the complex Kf and ∆Gf are higher, indicating simpler complex formation. The temperature increase resulted in a drop in the formation constants. The complexation's negative ∆Gf values demonstrate that the process of complex synthesis was spontaneous and that the temperature improved the s...
Advanced journal of chemistry. section A, Jan 30, 2019
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally u... more Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode put in saturated KCl solution were used. The complex characters for the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were studied with the use of different Ceftriaxone disodium salt (Cefs) concentrations at 298.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rate and different kinetic parameters resulted from the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were also evaluated and their values were discussed. Cyclic voltammetry Cobalt chloride Ceftriaxone disodium salt (Cefs) Oxidation reduction mechanisms Stability constants Kinetic parameters
Science and technology, Aug 31, 2012
The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary... more The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary mixtures (0-100 % MeOH-DMF) at different temperatures (298.15-313.15) were measured by conductometric t itrations. The conductance data in all cases were analysed using the Fuoss-Shedlovsky and Fuoss-Kraus methods to get the limiting molar conductance (Λ 0 and the association constant (K A) simu ltaneously. Accordingly, the co mputer program of Fuoss equation has been used. The conductance studies indicate the formation of 1:1 co mplex between the Cd 2+ ion and Kryptofix 22. Fro m the conductivity data obtained, the values of the Walden products (Λ o η o) were also calculated. Based on the composition dependence of Walden products, the influence of the solvent composition on the solvation of the ion has been discussed. Thermodynamic parameters as well as refractive indices have been determined for Cd 2+ ion in the mixed solvents at different temperatures with respect to solute-solvent interaction. This work gives a lot of data for cadmiu m ions which help in analysis.
Advanced journal of chemistry. section A, Jan 30, 2019
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally u... more Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode put in saturated KCl solution were used. The complex characters for the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were studied with the use of different Ceftriaxone disodium salt (Cefs) concentrations at 298.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rate and different kinetic parameters resulted from the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were also evaluated and their values were discussed. Cyclic voltammetry Cobalt chloride Ceftriaxone disodium salt (Cefs) Oxidation reduction mechanisms Stability constants Kinetic parameters
Egyptian Journal of Chemistry
Science and technology, Aug 31, 2012
The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary... more The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary mixtures (0-100 % MeOH-DMF) at different temperatures (298.15-313.15) were measured by conductometric t itrations. The conductance data in all cases were analysed using the Fuoss-Shedlovsky and Fuoss-Kraus methods to get the limiting molar conductance (Λ 0 and the association constant (K A) simu ltaneously. Accordingly, the co mputer program of Fuoss equation has been used. The conductance studies indicate the formation of 1:1 co mplex between the Cd 2+ ion and Kryptofix 22. Fro m the conductivity data obtained, the values of the Walden products (Λ o η o) were also calculated. Based on the composition dependence of Walden products, the influence of the solvent composition on the solvation of the ion has been discussed. Thermodynamic parameters as well as refractive indices have been determined for Cd 2+ ion in the mixed solvents at different temperatures with respect to solute-solvent interaction. This work gives a lot of data for cadmiu m ions which help in analysis.
European Journal of Advanced Chemistry Research
The electrochemical behavior of the complexation between copper chloride salt and succinic hydraz... more The electrochemical behavior of the complexation between copper chloride salt and succinic hydrazide can be explained using cyclic voltammetric measurements. The complex is formed through the interaction with nitrogen and hydroxyl group or carbonyl group of succinic hydrazides. This interaction can be observed by decreasing in the height peak of current and measuring the (anodic/cathodic) shift of the potentials. All the solvation and thermodynamic parameters for the interaction of copper ions with succinic hydrazide as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. Finally, the activity of the formed complex was compared with the succinic hydrazide by comparing their effects on different types of gram-negative bacteria and fungi indicating high activity of the formed complex and its ability to be used in different medical applications.
Education, May 9, 2012
On using conductometric technique, the apparent association constant (K A) of Ca (NO 3) 2 were me... more On using conductometric technique, the apparent association constant (K A) of Ca (NO 3) 2 were measured in
Journal of Molecular Structure
Egyptian Journal of Chemistry
Egyptian Journal of Chemistry
European Journal of Advanced Chemistry Research
The electrochemical behavior of the complexation between copper chloride salt and succinic hydraz... more The electrochemical behavior of the complexation between copper chloride salt and succinic hydrazide can be explained using cyclic voltammetric measurements. The complex is formed through the interaction with nitrogen and hydroxyl group or carbonyl group of succinic hydrazides. This interaction can be observed by decreasing in the height peak of current and measuring the (anodic/cathodic) shift of the potentials. All the solvation and thermodynamic parameters for the interaction of copper ions with succinic hydrazide as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. Finally, the activity of the formed complex was compared with the succinic hydrazide by comparing their effects on different types of gram-negative bacteria and fungi indicating high activity of the formed complex and its ability to be used in different medical applications.
Journal of Molecular Liquids
Journal of Molecular Structure
Journal of Molecular Structure
Egyptian Journal of Chemistry
Physical chemistry, Aug 31, 2012
The external poles of a permanent magnet of power 1.26 kG were used to study their effect on the ... more The external poles of a permanent magnet of power 1.26 kG were used to study their effect on the conductance values of FeCl 3 plus 10% by weight , PVA (polyvinylalcohol) in 50 % by weight mixed ethanol-water solutions. A new equation for 1:3 asymmetric association constant was derived and used for calculating the association constants (K A) for FeCl 3 solutions in 50 % ethanol (EtOH)-H 2 O mixture in presence of PVA and also in absence and presence of an external magnetic field. The new equation was derived from the Fuoss-Shedlovsky equation and Ostwald dilution law and the evaluated values are discussed.
Southern Brazilian Journal of Chemistry, Dec 20, 2009
The association constants KA for CoC/ 2 aqueous solutions were calculated using the experimental ... more The association constants KA for CoC/ 2 aqueous solutions were calculated using the experimental conductivity values at different salt concentrations. The molar conductivities were measured in the absence and presence of a magnetic field with an average power of 0. 677 KGauss. A new equation for asymmetric 1:2 salts was suggested and used .This equation was derived from Ostwald, Arrhenius and Fuoss-Shedlovsky theories. The results obtained were discussed and the effect of the magnetic field on the association constants was explained RESUMO As constantes de associar;iio, KA, para solur;oes aquosas de CoC/ 2 foram calculadas a partir de valores experimentais da condutividade para varias concentrar;oes do sa/. As condutividades mo/ares foram medidas na ausencia e na presen<;a de um campo magnetico medio de 0. 677 KGauss. Uma nova equa<;iio Joi sugerida para sais assimetricos 1 :2 e Joi usada. Esta equa<;iio Joi derivada a partir das teorias de Ostwald, Arrhenius e Fuoss-Shed/ovsky. Os resultados obtidos foram discutidos e o efeito do campo magnetico sobre as constantes de associa<;iio Joi explicado.
Bulletin of the Chemical Society of Ethiopia
ABSTRACT. For lump and nanocobalt sulfate (CoSO4) in pure water, the affiliation and thermodynami... more ABSTRACT. For lump and nanocobalt sulfate (CoSO4) in pure water, the affiliation and thermodynamic association characteristics were measured at 298.15, 303.15, 308.15, and 313.15 K. Based on the bulk and nano CoSO4 molar conductance, estimates were made for the parameters of the solvation, such as the activity coefficient, free energy of association, enthalpy of association, association constant, and entropy of association. We discussed about each of these solvation parameters. Two stoichiometric complexes were formed by the interaction of bulk and nano CoSO4.7H2O with fuchsin acid: 1:1 and 1:2 In the case of 1:1 (CoSO4.7H2O/fuchsin acid) compared to 1:2 (fuchsin acid in pure water as solvent), the complex Kf and ∆Gf are higher, indicating simpler complex formation. The temperature increase resulted in a drop in the formation constants. The complexation's negative ∆Gf values demonstrate that the process of complex synthesis was spontaneous and that the temperature improved the s...
Advanced journal of chemistry. section A, Jan 30, 2019
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally u... more Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode put in saturated KCl solution were used. The complex characters for the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were studied with the use of different Ceftriaxone disodium salt (Cefs) concentrations at 298.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rate and different kinetic parameters resulted from the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were also evaluated and their values were discussed. Cyclic voltammetry Cobalt chloride Ceftriaxone disodium salt (Cefs) Oxidation reduction mechanisms Stability constants Kinetic parameters
Science and technology, Aug 31, 2012
The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary... more The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary mixtures (0-100 % MeOH-DMF) at different temperatures (298.15-313.15) were measured by conductometric t itrations. The conductance data in all cases were analysed using the Fuoss-Shedlovsky and Fuoss-Kraus methods to get the limiting molar conductance (Λ 0 and the association constant (K A) simu ltaneously. Accordingly, the co mputer program of Fuoss equation has been used. The conductance studies indicate the formation of 1:1 co mplex between the Cd 2+ ion and Kryptofix 22. Fro m the conductivity data obtained, the values of the Walden products (Λ o η o) were also calculated. Based on the composition dependence of Walden products, the influence of the solvent composition on the solvation of the ion has been discussed. Thermodynamic parameters as well as refractive indices have been determined for Cd 2+ ion in the mixed solvents at different temperatures with respect to solute-solvent interaction. This work gives a lot of data for cadmiu m ions which help in analysis.
Advanced journal of chemistry. section A, Jan 30, 2019
Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally u... more Cyclic Voltammetry of Cobalt chloride with different concentrations was measured experimentally using DY2000 potentiostat. We used 0.1 M KCl as supporting electrolyte. Glassy carbon working electrode was used, purified and polished before use. The other two electrodes are platinum wire and Ag/AgCl electrode put in saturated KCl solution were used. The complex characters for the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were studied with the use of different Ceftriaxone disodium salt (Cefs) concentrations at 298.65 K. The oxidation, reduction mechanisms and the stability constants of the complexes formed are discussed. Scan rate and different kinetic parameters resulted from the interaction of CoCl2 with Ceftriaxone disodium salt (Cefs) were also evaluated and their values were discussed. Cyclic voltammetry Cobalt chloride Ceftriaxone disodium salt (Cefs) Oxidation reduction mechanisms Stability constants Kinetic parameters
Egyptian Journal of Chemistry
Science and technology, Aug 31, 2012
The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary... more The interaction between Cd 2+ ion and Kryptofix 22 in pure MeOH and DMF solvents and their binary mixtures (0-100 % MeOH-DMF) at different temperatures (298.15-313.15) were measured by conductometric t itrations. The conductance data in all cases were analysed using the Fuoss-Shedlovsky and Fuoss-Kraus methods to get the limiting molar conductance (Λ 0 and the association constant (K A) simu ltaneously. Accordingly, the co mputer program of Fuoss equation has been used. The conductance studies indicate the formation of 1:1 co mplex between the Cd 2+ ion and Kryptofix 22. Fro m the conductivity data obtained, the values of the Walden products (Λ o η o) were also calculated. Based on the composition dependence of Walden products, the influence of the solvent composition on the solvation of the ion has been discussed. Thermodynamic parameters as well as refractive indices have been determined for Cd 2+ ion in the mixed solvents at different temperatures with respect to solute-solvent interaction. This work gives a lot of data for cadmiu m ions which help in analysis.
European Journal of Advanced Chemistry Research
The electrochemical behavior of the complexation between copper chloride salt and succinic hydraz... more The electrochemical behavior of the complexation between copper chloride salt and succinic hydrazide can be explained using cyclic voltammetric measurements. The complex is formed through the interaction with nitrogen and hydroxyl group or carbonyl group of succinic hydrazides. This interaction can be observed by decreasing in the height peak of current and measuring the (anodic/cathodic) shift of the potentials. All the solvation and thermodynamic parameters for the interaction of copper ions with succinic hydrazide as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. Finally, the activity of the formed complex was compared with the succinic hydrazide by comparing their effects on different types of gram-negative bacteria and fungi indicating high activity of the formed complex and its ability to be used in different medical applications.
Education, May 9, 2012
On using conductometric technique, the apparent association constant (K A) of Ca (NO 3) 2 were me... more On using conductometric technique, the apparent association constant (K A) of Ca (NO 3) 2 were measured in
Journal of Molecular Structure
Egyptian Journal of Chemistry
Egyptian Journal of Chemistry
European Journal of Advanced Chemistry Research
The electrochemical behavior of the complexation between copper chloride salt and succinic hydraz... more The electrochemical behavior of the complexation between copper chloride salt and succinic hydrazide can be explained using cyclic voltammetric measurements. The complex is formed through the interaction with nitrogen and hydroxyl group or carbonyl group of succinic hydrazides. This interaction can be observed by decreasing in the height peak of current and measuring the (anodic/cathodic) shift of the potentials. All the solvation and thermodynamic parameters for the interaction of copper ions with succinic hydrazide as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. Finally, the activity of the formed complex was compared with the succinic hydrazide by comparing their effects on different types of gram-negative bacteria and fungi indicating high activity of the formed complex and its ability to be used in different medical applications.
Journal of Molecular Liquids
Journal of Molecular Structure
Journal of Molecular Structure
Egyptian Journal of Chemistry