The document describes an experimental study that measured the electrical conductances of sodium polystyrenesulfonate solutions in mixed solvent media containing varying proportions of 2-ethoxyethanol and water, in the presence of sodium chloride at different temperatures. The conductance data is analyzed based on an equation developed to model conductivity of polyelectrolyte solutions with added salts. There is excellent agreement between experimental results and those predicted by the developed equation.
This document discusses the influence of various factors on counterion condensation in aqueous solutions of sodium polystyrenesulfonate polyelectrolyte. Electrical conductivity measurements were used to analyze the interactions between the polyion and counterions. The extent of counterion condensation was found to be affected by the polyelectrolyte concentration and molecular weight, added electrolyte concentration, and temperature. The results provide insight into how polyelectrolyte molecular weight influences counterion condensation behavior in the presence of added electrolytes.
The document discusses the Linear Free Energy Relationship known as the Hammett Equation. It describes how the Hammett Equation can be used to investigate organic reaction mechanisms by studying the effects of substituents on reaction rates. The key aspects are:
1) The Hammett Equation relates the logarithm of reaction rates or equilibrium constants to substituent constants (σ) using the reaction constant (ρ).
2) σ values describe electronic properties of substituents, with electron-withdrawing groups having positive σ and electron-donating groups having negative σ.
3) ρ indicates how sensitive a reaction is to substituents, relating the electronic demand of the reaction transition state. Its sign and magnitude provide insight into
Spectroscopic and Thermal Characterization of Charge-Transfer Complexes Forme...IJMER
1) The document describes the formation and characterization of three charge-transfer complexes formed from the reaction of 2-amino-6-ethylpyridine with different π-electron acceptors.
2) Spectroscopic analysis revealed the complexes had formulas of [(2A6EPy)(TCNE)2], [(2A6EPy)2(DDQ)], and [(2A6EPy)4(TBCHD)], which were supported by elemental analysis.
3) The complexes showed intense absorption bands in the visible region associated with electronic transitions. Thermal and spectroscopic properties of the complexes were analyzed.
This document describes a study that used a modified NMR experiment called SOLEXSY to measure intrinsic amide proton exchange rates (kint) for a dynamic loop in the protein chymotrypsin inhibitor 2 (CI2) in buffer and in E. coli cell lysates. The study found that kint values did not change significantly when CI2 was crowded with up to 100 g/L of E. coli lysate. This suggests that kint values measured in buffer experiments can be applied to studies conducted under cellular conditions in the presence of macromolecular crowding.
Hydrogen bonding and molecular design (BrazMedChem 2010)Peter Kenny
This document discusses hydrogen bonding and its importance in molecular design for drug discovery. It provides examples of how measuring and modeling hydrogen bond strength can help predict properties like solubility, potency and permeability. Electrostatic potential is shown to correlate with experimental hydrogen bond acidities and basicities. The document advocates considering hydrogen bonding explicitly in molecular properties and modeling, rather than only focusing on parameters like lipophilicity. It also questions some common assumptions and provides references for further reading on quantifying hydrogen bonding.
Mechanism of the Reaction of Plasma Albumin with Formaldehyde in Ethanol - Wa...IOSR Journals
The Spectrophotometric determination of the acid dissociation/ionisation constant (pKa) of plasma albumin-formaldehyde adduct in both water solution and Ethanol solutions was carried out in this study. The pKa values obtained in both media were used to establish the Bronsted-linear type constants from plots of pKa against logarithm of second order rate constants obtained at varying pHs in the study. The result of the pKa values obtained in both water solution and ethanol-water mixtures were found to be in the range of 5.0 - 8.0. This pointed to the fact that only lysine residue with pKa value 8.3 that might have possibly reacted with formaldehyde in this reaction of all the known amino acid residues in plasma albumin. The corresponding Brønsted-type plots proportionality constants (β) for the reaction in water and ethanol-water mixtures were found to be β = 0.059 and 0.0057 respectively. The reaction mechanisms that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer (Cox et al, 1988). Thus, one would suggest that the cross-linking of formaldehyde with plasma albumin in water and ethanol-water mixtures proceeds through little proton transfer
The document discusses the Hammett plot, which is a linear free-energy relationship analysis used to model the electronic effects of substituents on aromatic systems. It describes how σ values are derived from ionization reactions to indicate whether a substituent is electron-donating or electron-withdrawing. These σ values can then be used to analyze reaction mechanisms and optimize reaction conditions for similar processes. Examples are given of how split Hammett plots reveal changing mechanisms depending on the electronic nature of the substituent. Problems involving interpreting ρ values in Hammett plots to determine reaction pathways are also presented.
Abstract The study of dielectric liquid behaviour under different exposure is one of the most fascinating frontiers in solid state physics. It has undoubtedly render considerable service to every physicist doing research in this field. The increasing desire to understand the molecular interactions have led to conduct the present study, which deals with a certain group of polar compounds such as (i) Acetonitrile (AN), (ii) Acetophenone (AP) and (iii) 2-Propanol (2-P) with a non-polar compound benzene. The dielectric behaviour of individual compound, binary mixtures and their ratios have been studied at microwave frequency of 21.68GHz in non-polar solvent (benzene) at constant temperature 300K. Different dielectric parameters like dielectric constant ε’ and dielectric loss ε” at microwave frequency, static dielectric constant εs at 1 KHz frequency, dielectric constant ε∞ at optical frequency have been determined. Using these dielectric data, dipole moment μ, various relaxation time viz (i) molecular relaxation time τ(1) (ii) overall relaxation time of a molecule τ(2) and (iii) average relaxation time τ(υ), distribution parameter (α) of individual compound, binary mixtures and their ratios in dilute solutions of benzene also have been determined experimentally. Weight fraction method is used for changing the concentration of solute in solvent. The observed results are discussed on the basis of various types if relaxation processes, which change with the size, shape and type of interaction. Key Words: Molecular Iteraction, Relaxation Time and Dielectric Constant
This document discusses the influence of various factors on counterion condensation in aqueous solutions of sodium polystyrenesulfonate polyelectrolyte. Electrical conductivity measurements were used to analyze the interactions between the polyion and counterions. The extent of counterion condensation was found to be affected by the polyelectrolyte concentration and molecular weight, added electrolyte concentration, and temperature. The results provide insight into how polyelectrolyte molecular weight influences counterion condensation behavior in the presence of added electrolytes.
The document discusses the Linear Free Energy Relationship known as the Hammett Equation. It describes how the Hammett Equation can be used to investigate organic reaction mechanisms by studying the effects of substituents on reaction rates. The key aspects are:
1) The Hammett Equation relates the logarithm of reaction rates or equilibrium constants to substituent constants (σ) using the reaction constant (ρ).
2) σ values describe electronic properties of substituents, with electron-withdrawing groups having positive σ and electron-donating groups having negative σ.
3) ρ indicates how sensitive a reaction is to substituents, relating the electronic demand of the reaction transition state. Its sign and magnitude provide insight into
Spectroscopic and Thermal Characterization of Charge-Transfer Complexes Forme...IJMER
1) The document describes the formation and characterization of three charge-transfer complexes formed from the reaction of 2-amino-6-ethylpyridine with different π-electron acceptors.
2) Spectroscopic analysis revealed the complexes had formulas of [(2A6EPy)(TCNE)2], [(2A6EPy)2(DDQ)], and [(2A6EPy)4(TBCHD)], which were supported by elemental analysis.
3) The complexes showed intense absorption bands in the visible region associated with electronic transitions. Thermal and spectroscopic properties of the complexes were analyzed.
This document describes a study that used a modified NMR experiment called SOLEXSY to measure intrinsic amide proton exchange rates (kint) for a dynamic loop in the protein chymotrypsin inhibitor 2 (CI2) in buffer and in E. coli cell lysates. The study found that kint values did not change significantly when CI2 was crowded with up to 100 g/L of E. coli lysate. This suggests that kint values measured in buffer experiments can be applied to studies conducted under cellular conditions in the presence of macromolecular crowding.
Hydrogen bonding and molecular design (BrazMedChem 2010)Peter Kenny
This document discusses hydrogen bonding and its importance in molecular design for drug discovery. It provides examples of how measuring and modeling hydrogen bond strength can help predict properties like solubility, potency and permeability. Electrostatic potential is shown to correlate with experimental hydrogen bond acidities and basicities. The document advocates considering hydrogen bonding explicitly in molecular properties and modeling, rather than only focusing on parameters like lipophilicity. It also questions some common assumptions and provides references for further reading on quantifying hydrogen bonding.
Mechanism of the Reaction of Plasma Albumin with Formaldehyde in Ethanol - Wa...IOSR Journals
The Spectrophotometric determination of the acid dissociation/ionisation constant (pKa) of plasma albumin-formaldehyde adduct in both water solution and Ethanol solutions was carried out in this study. The pKa values obtained in both media were used to establish the Bronsted-linear type constants from plots of pKa against logarithm of second order rate constants obtained at varying pHs in the study. The result of the pKa values obtained in both water solution and ethanol-water mixtures were found to be in the range of 5.0 - 8.0. This pointed to the fact that only lysine residue with pKa value 8.3 that might have possibly reacted with formaldehyde in this reaction of all the known amino acid residues in plasma albumin. The corresponding Brønsted-type plots proportionality constants (β) for the reaction in water and ethanol-water mixtures were found to be β = 0.059 and 0.0057 respectively. The reaction mechanisms that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer (Cox et al, 1988). Thus, one would suggest that the cross-linking of formaldehyde with plasma albumin in water and ethanol-water mixtures proceeds through little proton transfer
The document discusses the Hammett plot, which is a linear free-energy relationship analysis used to model the electronic effects of substituents on aromatic systems. It describes how σ values are derived from ionization reactions to indicate whether a substituent is electron-donating or electron-withdrawing. These σ values can then be used to analyze reaction mechanisms and optimize reaction conditions for similar processes. Examples are given of how split Hammett plots reveal changing mechanisms depending on the electronic nature of the substituent. Problems involving interpreting ρ values in Hammett plots to determine reaction pathways are also presented.
Abstract The study of dielectric liquid behaviour under different exposure is one of the most fascinating frontiers in solid state physics. It has undoubtedly render considerable service to every physicist doing research in this field. The increasing desire to understand the molecular interactions have led to conduct the present study, which deals with a certain group of polar compounds such as (i) Acetonitrile (AN), (ii) Acetophenone (AP) and (iii) 2-Propanol (2-P) with a non-polar compound benzene. The dielectric behaviour of individual compound, binary mixtures and their ratios have been studied at microwave frequency of 21.68GHz in non-polar solvent (benzene) at constant temperature 300K. Different dielectric parameters like dielectric constant ε’ and dielectric loss ε” at microwave frequency, static dielectric constant εs at 1 KHz frequency, dielectric constant ε∞ at optical frequency have been determined. Using these dielectric data, dipole moment μ, various relaxation time viz (i) molecular relaxation time τ(1) (ii) overall relaxation time of a molecule τ(2) and (iii) average relaxation time τ(υ), distribution parameter (α) of individual compound, binary mixtures and their ratios in dilute solutions of benzene also have been determined experimentally. Weight fraction method is used for changing the concentration of solute in solvent. The observed results are discussed on the basis of various types if relaxation processes, which change with the size, shape and type of interaction. Key Words: Molecular Iteraction, Relaxation Time and Dielectric Constant
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This chapter discusses carbocations, which are positively charged carbon-containing ions that are highly reactive intermediates in organic chemistry. Carbocations have six electrons in the outer shell of the central carbon atom. They are stabilized by electron-donating groups and destabilized by electron-withdrawing groups. Carbocations undergo various reactions including reactions with nucleophiles, elimination reactions, rearrangement reactions, and additions to unsaturated systems. Non-classical carbocations are also discussed.
Computation of Dielectric Constant and Loss Factor of Water and Dimethylsulph...Scientific Review
This study examined the computation of the dielectric constant (ε′) and dielectric loss factor (ε′′) of water and dimethylsulphoxide (DMSO)at temperature 20oc, 30oc, 40oc and 500C within the frequency range of f GHz using Debye equations. The Debye equations were derived, and the experimental values of the static dielectric constant (εs), dielectric constant at high frequency (ε ) and the relaxation time (τ) of water and DMSO at those temperatures were substituted into the derived equations and the dielectric constant (ε′) and loss factor (ε′′) of water and DMSO were computed with aid of maple-13 and results were generated. These results revealed that the method is capable of reproducing good results forwork done using single Debye and that of the reflection cell ofdimethylsulphoxide.
Kinetic Study of Esterification of Acetic Acid with n- butanol and isobutanol...Hugo Balderrama
The document summarizes a study on the kinetics of esterification reactions between acetic acid and n-butanol or isobutanol catalyzed by ion exchange resin. The effects of temperature, catalyst loading, and initial molar ratios on reaction rates were examined. Activation energies for the reactions were determined to be 28.45 kJ/mol for n-butanol and 23.29 kJ/mol for isobutanol. The study found reaction rates increased with higher temperatures, catalyst loadings, and molar ratios of alcohol to acid.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
The document discusses further developing the solvent model parameterization in the ONETEP software for recent exchange-correlation functionals. It aims to re-examine the parameters established previously using outdated approximations and to compare results using functionals like VV10 and B97M-V to PBE and LDA. The author finds the exchange functional makes little difference to solvation energy accuracy. Parameters may need minor adjustments and more research is needed, particularly for anions. Validation of the model for 60 molecules using different functionals finds B3LYP and B97M-V have the lowest error compared to experiment.
The Brønsted catalysis relationship is a Linear Free Energy Relationship (LFER) that relates ionization of an acid or base which catalyzes a reaction and the rate of the reaction.
Contributed by: Quincy Davis, Jonathan Greenhalgh, Joshua Visser (Undergraduates), University of Utah, 2016
The document discusses Taft's steric factor (Es) as a way to quantify steric effects in organic compounds. Es is based on rate constants of ester hydrolysis reactions and accounts for how bulky substituents affect reaction rates by blocking nucleophilic attack. The Taft equation combines Es with other substituent constants to model steric and electronic effects. Examples show Es is more negative for bulkier groups like t-Bu, indicating their stronger steric hindrance of hydrolysis. Es can be used to understand and predict steric influences on other chemical reactions and biological activities.
The document summarizes a study of magnetite nanoparticles prepared by a modified Massart method using water and alcohol as solvents. Three key findings are:
1) Nanoparticles prepared in alcohol were smaller (8 nm) than those in water (12-13 nm) according to TEM analysis.
2) Longer reaction times improved the stoichiometry of the nanoparticles, as seen by an increasing β ratio in Mossbauer spectra.
3) The transition to superparamagnetic behavior occurred around 8 nm for magnetite nanoparticles coated with TBAOH, as evidenced by changes in Mossbauer spectra.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Isotopes are two atoms of the same element that have the same number of protons but different numbers of neutrons. Isotopes are specified by the mass number.
The document summarizes the results of a study that measured the standard enthalpies of ionization of 21 substituted anilinium ions using calorimetry. It found that both the enthalpies and entropies of ionization correlated well with the Gibbs free energies of ionization. The experimental results were analyzed according to Hepler's theory of substituent effects and compared to predictions of electrostatic theory.
Concept of rate of reaction.
Factors effecting rate of reaction.
Concept of order of reaction.
Methods for the determination of order of reaction.
Pharmaceutical importance and applications of rate and order of reaction.
Influence of Tetra Alkyl Ammonium Cation and Temperature on Molecular Interac...IOSRJAC
Ultrasonic velocity (u), density (ρ), viscosity (η) and related acoustical parameters such as adiabatic compressibility (β), free energy (∆G), internal pressure (πi), relaxation time (τ) and acoustic impedance (z) have been computed using standard relation for tetra alkyl ammonium cation (Et4N + , Pr4N + , Bu4N + , and Pen4N + ) in binary liquid mixtures of 1, 4 - Dioxane and N, N – Dimethyl Formamide was prepared of 0.14M on different percentage compositions over the temperature range from 303.15K to 323.15K with the interval of 10K under room pressure to investigate inter - ionic interactions. The densities were measured by Magnetic Float Densitometer. Transport properties provide a deep and meaningful insight of various interactions taking place. It has been observed that the influence of small as well as large alkyl chain length of tetra alkyl ammonium cations (R4N + ), in terms of shape and ionic size with the DMF solvent in the presence of Dioxane, is helpful in investigating the molecular interactions, molecular rearrangement, molecular association etc
This document reports on research measuring the strength of silicon-hydrogen bonds in various silane compounds using photoacoustic calorimetry. The main findings are:
1) Silicon-hydrogen bond strengths are significantly weakened by the successive substitution of silyl groups, with the bond in tris(trimethylsilyl)silane having one of the weakest bond strengths measured at 79.0 kcal/mol.
2) Steric effects and radical stabilization may contribute to the weakening of the silicon-hydrogen bond from additional silyl substitutions, though the exact origin is unclear.
3) The weak silicon-hydrogen bond in tris(trimethylsilyl)silane
This document discusses a study of the kinetics of self-reducing mixtures composed of iron ore, steel mill waste (BOF dust), and biomass from elephant grass. Kinetic runs were performed using thermogravimetric analysis at temperatures from 900-1100°C and carbon contents of 15-30%. The reaction fractions over time showed good agreement with first-order kinetics. Activation energies were estimated, with the highest kinetic constants occurring at 1100°C with 30% carbon: 0.0037 s-1 for the Fe3O4→FeO reaction and 0.0258 s-1 for FeO→Fe. The kinetic behavior supported chemical reaction control over diffusion control for self-reducing pellet reactions.
Introduction to Quantitative Structure Activity RelationshipsOmar Sokkar
This document discusses Quantitative Structure Activity Relationships (QSAR), which quantifies the relationship between physicochemical properties and biological activity of compounds. QSAR allows prediction of biological activity for novel analogs based on their physicochemical properties, reducing the number that need to be synthesized. Commonly studied properties include hydrophobicity, electronic effects, and steric effects. Hydrophobicity is quantified using partition coefficients, while electronic effects are quantified using Hammett constants and inductive constants. Steric effects are quantified using Taft steric factors, molar refractivity, and Verloop steric parameters. The Hansch equation relates biological activity to multiple physicochemical properties simultaneously. Craig plots and Topliss schemes help identify optimal substituents based
The document summarizes a study on the thermal degradation of three natural polymers: sodium hyaluronate, xanthan, and methylcellulose. Thermogravimetric analysis showed sodium hyaluronate and xanthan had lower thermal stability than methylcellulose. Kinetic parameters like activation energy were determined using the Ozawa and Freeman-Carroll methods, which suggested changes in degradation mechanism with mass loss. Activation energies from Freeman-Carroll were higher, accounting for thermal history effects. Infrared spectroscopy observed scission of side groups at low temperatures and backbone links at high temperatures, agreeing with kinetic parameters.
Montagu trading company 2015 - Greg WatsonGreg Watson
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise boosts blood flow, releases endorphins, and promotes changes in the brain which help regulate emotions and stress levels.
Manovich argues that describing all contemporary media as "digital" is problematic and suggests alternatives. He contrasts his view with Murray's by pointing out that the properties of digital media depend on the software used to interact with it, not the media itself, questioning the idea of defining properties of "the digital."
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This chapter discusses carbocations, which are positively charged carbon-containing ions that are highly reactive intermediates in organic chemistry. Carbocations have six electrons in the outer shell of the central carbon atom. They are stabilized by electron-donating groups and destabilized by electron-withdrawing groups. Carbocations undergo various reactions including reactions with nucleophiles, elimination reactions, rearrangement reactions, and additions to unsaturated systems. Non-classical carbocations are also discussed.
Computation of Dielectric Constant and Loss Factor of Water and Dimethylsulph...Scientific Review
This study examined the computation of the dielectric constant (ε′) and dielectric loss factor (ε′′) of water and dimethylsulphoxide (DMSO)at temperature 20oc, 30oc, 40oc and 500C within the frequency range of f GHz using Debye equations. The Debye equations were derived, and the experimental values of the static dielectric constant (εs), dielectric constant at high frequency (ε ) and the relaxation time (τ) of water and DMSO at those temperatures were substituted into the derived equations and the dielectric constant (ε′) and loss factor (ε′′) of water and DMSO were computed with aid of maple-13 and results were generated. These results revealed that the method is capable of reproducing good results forwork done using single Debye and that of the reflection cell ofdimethylsulphoxide.
Kinetic Study of Esterification of Acetic Acid with n- butanol and isobutanol...Hugo Balderrama
The document summarizes a study on the kinetics of esterification reactions between acetic acid and n-butanol or isobutanol catalyzed by ion exchange resin. The effects of temperature, catalyst loading, and initial molar ratios on reaction rates were examined. Activation energies for the reactions were determined to be 28.45 kJ/mol for n-butanol and 23.29 kJ/mol for isobutanol. The study found reaction rates increased with higher temperatures, catalyst loadings, and molar ratios of alcohol to acid.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
The document discusses further developing the solvent model parameterization in the ONETEP software for recent exchange-correlation functionals. It aims to re-examine the parameters established previously using outdated approximations and to compare results using functionals like VV10 and B97M-V to PBE and LDA. The author finds the exchange functional makes little difference to solvation energy accuracy. Parameters may need minor adjustments and more research is needed, particularly for anions. Validation of the model for 60 molecules using different functionals finds B3LYP and B97M-V have the lowest error compared to experiment.
The Brønsted catalysis relationship is a Linear Free Energy Relationship (LFER) that relates ionization of an acid or base which catalyzes a reaction and the rate of the reaction.
Contributed by: Quincy Davis, Jonathan Greenhalgh, Joshua Visser (Undergraduates), University of Utah, 2016
The document discusses Taft's steric factor (Es) as a way to quantify steric effects in organic compounds. Es is based on rate constants of ester hydrolysis reactions and accounts for how bulky substituents affect reaction rates by blocking nucleophilic attack. The Taft equation combines Es with other substituent constants to model steric and electronic effects. Examples show Es is more negative for bulkier groups like t-Bu, indicating their stronger steric hindrance of hydrolysis. Es can be used to understand and predict steric influences on other chemical reactions and biological activities.
The document summarizes a study of magnetite nanoparticles prepared by a modified Massart method using water and alcohol as solvents. Three key findings are:
1) Nanoparticles prepared in alcohol were smaller (8 nm) than those in water (12-13 nm) according to TEM analysis.
2) Longer reaction times improved the stoichiometry of the nanoparticles, as seen by an increasing β ratio in Mossbauer spectra.
3) The transition to superparamagnetic behavior occurred around 8 nm for magnetite nanoparticles coated with TBAOH, as evidenced by changes in Mossbauer spectra.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Isotopes are two atoms of the same element that have the same number of protons but different numbers of neutrons. Isotopes are specified by the mass number.
The document summarizes the results of a study that measured the standard enthalpies of ionization of 21 substituted anilinium ions using calorimetry. It found that both the enthalpies and entropies of ionization correlated well with the Gibbs free energies of ionization. The experimental results were analyzed according to Hepler's theory of substituent effects and compared to predictions of electrostatic theory.
Concept of rate of reaction.
Factors effecting rate of reaction.
Concept of order of reaction.
Methods for the determination of order of reaction.
Pharmaceutical importance and applications of rate and order of reaction.
Influence of Tetra Alkyl Ammonium Cation and Temperature on Molecular Interac...IOSRJAC
Ultrasonic velocity (u), density (ρ), viscosity (η) and related acoustical parameters such as adiabatic compressibility (β), free energy (∆G), internal pressure (πi), relaxation time (τ) and acoustic impedance (z) have been computed using standard relation for tetra alkyl ammonium cation (Et4N + , Pr4N + , Bu4N + , and Pen4N + ) in binary liquid mixtures of 1, 4 - Dioxane and N, N – Dimethyl Formamide was prepared of 0.14M on different percentage compositions over the temperature range from 303.15K to 323.15K with the interval of 10K under room pressure to investigate inter - ionic interactions. The densities were measured by Magnetic Float Densitometer. Transport properties provide a deep and meaningful insight of various interactions taking place. It has been observed that the influence of small as well as large alkyl chain length of tetra alkyl ammonium cations (R4N + ), in terms of shape and ionic size with the DMF solvent in the presence of Dioxane, is helpful in investigating the molecular interactions, molecular rearrangement, molecular association etc
This document reports on research measuring the strength of silicon-hydrogen bonds in various silane compounds using photoacoustic calorimetry. The main findings are:
1) Silicon-hydrogen bond strengths are significantly weakened by the successive substitution of silyl groups, with the bond in tris(trimethylsilyl)silane having one of the weakest bond strengths measured at 79.0 kcal/mol.
2) Steric effects and radical stabilization may contribute to the weakening of the silicon-hydrogen bond from additional silyl substitutions, though the exact origin is unclear.
3) The weak silicon-hydrogen bond in tris(trimethylsilyl)silane
This document discusses a study of the kinetics of self-reducing mixtures composed of iron ore, steel mill waste (BOF dust), and biomass from elephant grass. Kinetic runs were performed using thermogravimetric analysis at temperatures from 900-1100°C and carbon contents of 15-30%. The reaction fractions over time showed good agreement with first-order kinetics. Activation energies were estimated, with the highest kinetic constants occurring at 1100°C with 30% carbon: 0.0037 s-1 for the Fe3O4→FeO reaction and 0.0258 s-1 for FeO→Fe. The kinetic behavior supported chemical reaction control over diffusion control for self-reducing pellet reactions.
Introduction to Quantitative Structure Activity RelationshipsOmar Sokkar
This document discusses Quantitative Structure Activity Relationships (QSAR), which quantifies the relationship between physicochemical properties and biological activity of compounds. QSAR allows prediction of biological activity for novel analogs based on their physicochemical properties, reducing the number that need to be synthesized. Commonly studied properties include hydrophobicity, electronic effects, and steric effects. Hydrophobicity is quantified using partition coefficients, while electronic effects are quantified using Hammett constants and inductive constants. Steric effects are quantified using Taft steric factors, molar refractivity, and Verloop steric parameters. The Hansch equation relates biological activity to multiple physicochemical properties simultaneously. Craig plots and Topliss schemes help identify optimal substituents based
The document summarizes a study on the thermal degradation of three natural polymers: sodium hyaluronate, xanthan, and methylcellulose. Thermogravimetric analysis showed sodium hyaluronate and xanthan had lower thermal stability than methylcellulose. Kinetic parameters like activation energy were determined using the Ozawa and Freeman-Carroll methods, which suggested changes in degradation mechanism with mass loss. Activation energies from Freeman-Carroll were higher, accounting for thermal history effects. Infrared spectroscopy observed scission of side groups at low temperatures and backbone links at high temperatures, agreeing with kinetic parameters.
Montagu trading company 2015 - Greg WatsonGreg Watson
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise boosts blood flow, releases endorphins, and promotes changes in the brain which help regulate emotions and stress levels.
Manovich argues that describing all contemporary media as "digital" is problematic and suggests alternatives. He contrasts his view with Murray's by pointing out that the properties of digital media depend on the software used to interact with it, not the media itself, questioning the idea of defining properties of "the digital."
Hossam Hussein is seeking a position as a courier with excellent driving skills and a thorough knowledge of local roads and highways. He has over 10 years of experience as a courier, equipment operator, and assembly technician with a proven record of safety, on-time deliveries, and completing tasks efficiently. His most recent role as a courier had no accidents or violations over 7,000 miles.
This certificate recognizes that Alexander Gonzalez successfully completed a course on diagnosing the financial health of businesses by October 14th, 2014. He passed individual modules on the balance sheet, income statement, statement of cash flows, and assessing financial performance, achieving scores ranging from 60% to 100% and an overall final score of 83%.
A Comissão Permanente de Meio Ambiente, Transporte e Trânsito da Câmara Municipal do Recife analisou projetos anteriores sobre restrição de veículos e decidiu designar um relator para apresentar um projeto substitutivo. O relatório analisa os problemas de mobilidade na cidade e propõe um programa de restrição de veículos com base nos dígitos finais das placas.
El documento describe los principales componentes de diseño de un aeropuerto, incluyendo las instalaciones en el lado aire (campo de vuelos) y tierra (terminal de pasajeros, carga, hangares, pistas de rodaje). En tierra también se incluyen oficinas, torre de control, industria aeronáutica y estación meteorológica. Se detallan los sistemas sanitarios, HVAC, eléctricos, de gas, combustible, transporte de equipaje, contraincendios e IT distribuidos a lo largo del aerop
This research article studied the coiling and uncoiling behavior of sodium polystyrenesulfonate (NaPSS) in mixed solvent systems of water and 2-ethoxyethanol at varying temperatures through viscosity measurements. Precise viscosity measurements were taken of NaPSS solutions in water and 2-ethoxyethanol-water mixtures containing different amounts of 2-ethoxyethanol at temperatures from 308.15K to 323.15K. The intramolecular contributions to reduced viscosity and Huggins constants were determined using isoionic dilution to interpret the effects of solvent and temperature on polyelectrolyte conformation and interactions. The results showed that NaPSS chains coiled upon addition of 2-
The document discusses a study that measured the electrical conductivity of solutions of sodium polystyrenesulphonate in mixed solvent systems of 2-ethoxyethanol and water at varying concentrations, temperatures, and solvent compositions. The results showed that equivalent conductivity increased slightly with decreasing polymer concentration. Equivalent conductivity also increased with increasing temperature and relative permittivity of the solvent system. However, the experimentally determined conductivities did not fully match what was predicted by Manning's counterion condensation theory. Reasons for this discrepancy are discussed.
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2010_JCED
1. Electrical Conductances of Sodium Polystyrenesulfonate in 2-Ethoxyethanol (1) +
Water (2) Mixed Solvent Media in the Presence of Sodium Chloride at (308.15,
313.15, 318.15, and 323.15) K
Ranjit De and Bijan Das*
Department of Chemistry, North Bengal University, Darjeeling 734013, India
The electrical conductances of solutions of an anionic polyelectrolyte sodium polystyrenesulfonate in
2-ethoxyethanol (1) + water (2) mixed solvent media containing (0.25, 0.40, and 0.50) mass fractions of
2-ethoxyethanol (w1) have been reported at (308.15, 313.15, 318.15, and 323.15) K in the presence of sodium
chloride. The conductance data have been analyzed on the basis of an equation developed in this study
following the model for the electrical conductivity of salt-free polyelectrolyte solutions using the scaling
description for the configuration of a semidilute polyion chain according to Dobrynin et al. (Macromolecules
1995, 28, 1859-1871). Excellent quantitative agreement between the experimental results and those obtained
using the equation developed here was observed.
Introduction
We have reported the results of conductivity measurements
on salt-free solutions of sodium polystyrenesulfonate in 2-ethox-
yethanol (1) + water (2) mixtures in an earlier communication.1
The addition of salts to a polyelectrolyte solution might change
its conductivity behavior considerably, and hence studies on
the conductivity of polyelectrolytes in the presence of a salt
might help elucidate polyion-counterion interactions in poly-
electrolytes with added salts.
Although the polyelectrolyte conductivities have been well-
understood in salt-free solutions2
using the scaling description
for the configuration of a polyion chain according to Dobrynin
et al.,3
the situation is quite unsatisfactory for salt-containing
polyelectrolyte solutions.
Devore and Manning4
first attempted to describe the electric
transport properties of polyelectrolyte solutions containing a
simple salt using the Manning counterion condensation theory5
without much success. In view of the inadequacy of the Manning
theory of the electrical transport of salt-containing polyelectro-
lyte solutions, a phenomenological treatment of the results of
conductance experiments in terms of the additivity (commonly
known as the “primitive additivity”) of contributions of the
polyelectrolyte and the simple salt to the total specific conduc-
tance was made.6-9
Traditionally, this approach takes the form of an assumed
additivity of the specific conductance of the polyelectrolyte and
of the salt, which gives the specific conductance (κ) of the
polyelectrolyte in a salt solution through the equation,
κ ) κp + κs (1)
where κp is the specific conductance of the polyelectrolyte in
the absence of a simple salt and κs is the specific conductance
of the simple salt in the absence of polyelectrolyte.
However, earlier investigations10-14
suggest that the experi-
mentally obtained specific conductances for salt-containing
polyelectrolyte solutions do not, in general, agree with those
predicted by simple additivity, eq 1.
Ander et al.10,11
modified the “primitive” additivity by taking
into account the Debye-Hu¨ckel interactions between the
polyion and the salt ions to give the polyelectrolyte specific
conductance in a polyelectrolyte-salt solution as
κ ) κp + κs(D2/D2
0
) (2)
where D2 and D2
0
are the co-ion self-diffusion coefficients in a
salt-containing polyelectrolyte solution and in an infinitely dilute
polyelectrolyte-free salt solution, respectively. The ratio of self-
diffusion coefficients D2/D2
0
has been used as a quantitative
measure5
of the effective interaction of uncondensed small ions
in the presence of the polyelectrolyte, and hence the effective
specific conductance of the added simple salt would be κs(D2/
D2
0
).
Although the “modified” additivity has been shown to be
somewhat better than the “primitive” one, departures from the
experimental results are still prominent.10-14
Later Bordi et al.15
evaluated equivalent conductances for a hydrophilic polyion in
the presence of a salt in light of the scaling approach3
and
compared them with the experimental values. The agreement
is rather good, although a quantitative description is still
awaiting.
In this paper, a simple model is introduced to analyze the
conductivity of the polyelectrolyte in the presence of an added
electrolyte based on scaling theory for the conductivity of
polyelectrolyte solutions.2
This model has been extensively
tested with data on sodium polystyrenesulfonate in the presence
of sodium chloride in 2-ethoxyethanol-water mixed solvent
media at different temperatures. The data set used here considers
a number of parameters, for example, the relative permittivity
of the medium, temperature, and concentration of the added
salt. Moreover, three decades of concentration of the polyelec-
trolyte were covered. Very good quantitative agreement with
only one adjustable parameter has been observed.
Theory
Here we introduce a simple equation for describing the
conductivity behavior of polyelectrolyte in salt solutions fol-* Corresponding author. E-mail: bijan_dasus@yahoo.com.
J. Chem. Eng. Data 2010, 55, 2108–21152108
10.1021/je900725w 2010 American Chemical Society
Published on Web 04/02/2010
2. lowing the model for the electrical conductivity of solutions of
polyelectrolytes without salt proposed by Colby et al.2
using
the scaling description for the configuration of a polyion chain
according to Dobrynin et al.3
In semidilute solutions, the polyion chain is modeled as a
random walk of Nξ correlation blobs of size ξ0, each of them
containing g monomers. Each blob bears an electric charge
qξ ) zefg (z being the counterion valence and e is the
electronic charge), and the complete chain, of contour length
L ) Nξξ0, bears a charge Qp ) Nξqξ ) zefgNξ, where f is
the fraction of uncondensed counterions. Because of the
strong electrostatic interactions within each correlation blob,
the chain is a fully extended conformation of ge electrostatic
blobs of size ξe. This means that for length scales less than
ξ0, the electrostatic interactions dominate (and the chain is
a fully extended conformation of electrostatic blobs of size
ξe); for length scales greater than ξ0, the electrostatic
interactions are screened, and the chain is a random walk of
correlation blobs of size ξ0.
Following Colby et al.,2
the specific conductivity of a salt-
free semidilute polyelectrolyte solution (κp) is given by
κp ) fcp[λc
0
+
cpξ0
2
e2
f
3πη0
ln(ξ0
ξe
)] (3)
where cp is the number density of monomers, λc
0
the limiting
equivalent conductivity of the counterions, and η0 the coefficient
of the viscosity of the medium.
The interactions between the polyion and the counterions will
be modified in the presence of an electrolyte and this will result
in a different level of counterion condensation, that is, in a
different value of f (designated as f′). The effective specific
conductivity due to the polyelectrolyte in the presence of a
simple salt can be expressed as
κp(eff) ) f cp[λc
0
+
cpξ0
2
e2
f
3πη0
ln(ξ0
ξe
)] (4)
Thus the total specific conductivity (κ) of a polyelectrolyte
solution with added simple electrolyte should be equal to the
sum of the specific conductivity of the simple salt in the absence
of a polyelectrolyte and the effective specific conductivity due
to the polyelectrolyte in the presence of a simple salt and is
given by
κ ) κs + f cp[λc
0
+
cpξ0
2
e2
f
3πη0
ln(ξ0
ξe
)] (5)
This equation (eq 5) has one adjustable parameter, f′, and this
could be obtained by the method of a least-squares fit of the
experimental specific conductivity of the polyelectrolyte solution
(κ) in the presence of a salt to eq 5 using the measured specific
conductance (κs) of the salt in the absence of the polyelectrolyte.
This value of f′ takes care of the changed polyion-counterion
interactions under the influence of the added salt. The second
term in eq 5 is the actual contribution of the polyelectrolyte
species toward the total specific conductivity in the presence
of an added salt.
Experimental Section
2-Ethoxyethanol (Merck) was distilled with phosphorus
pentoxide and then redistilled over calcium hydride. The
purified solvent had a density of 0.92497 g · cm-3
and a
coefficient of viscosity of 1.8277 mPa · s at 308.15 K; these
values are in good agreement with literature values.6
Triply
distilled water with a specific conductance of about 10-6
S · cm-1
at 308.15 K was used for the preparation of the
mixed solvents. The relative permittivities of 2-ethoxyethanol
(1) + water (2) mixtures at the experimental temperatures
were obtained with the equations as described in the
literature4
using the literature density and relative permittivity
data of the pure solvents,6,16
and the densities of the mixed
solvents are given in Table 1.
The sodium salt of polystyrenesulfonate (NaPSS) employed
in these investigations was purchased from the Aldrich Chemical
Co. The average molecular weight of the sample was about
70 000 g·mol-1
, and a degree of sulfonation of 1.0 was purified
by dialysis.17,18
The molecular weight reported by the manu-
facturer agreed well with that determined in the present study
obtained in the presence of 0.05 M sodium chloride (NaCl) at
298.15 K using the Mark-Houwink relationship,19
[η] )
1.39·10-4
M0.72
, where [η] is the intrinsic viscosity and M is
the average molecular weight. The absorption coefficient of the
NaPSS solutions used at 261 nm, which is considered to be a
characteristic indicator of the sample purity,18
is found to be
400 dm3
·cm-1
·mol-1
. A spectroscopic examination of the
polyelectrolyte sample using this criterion was employed
periodically to substantiate the sample purity. Sodium chloride
(Fluka) was of puriss grade. This was dried in vacuo for a
prolonged period immediately before use and was used without
further purification.
Conductance measurements were carried out on a Pye-
Unicam PW 9509 conductivity meter at a frequency of 2000
Hz using a dip-type cell with a cell constant of 1.15 cm-1
and
having an uncertainty of 0.01 %. The cell was calibrated by
the method of Lind and co-workers16
using aqueous potassium
chloride solution. The measurements were made in a water bath
maintained within ( 0.01 K of the desired temperature. The
details of the experimental procedure have been described
earlier.9,20
Several independent solutions were prepared, and runs
were performed to ensure the reproducibility of the results.
To avoid moisture pickup, all solutions were prepared in a
dehumidified room with utmost care. In all cases, the experi-
ments were performed at least in three replicates. The experi-
mental uncertainties in density, viscosity, and conductivity were
always within 0.02 %, 0.80 %, and 0.30 %, respectively.
Results and Discussion
The experimental values of specific conductivities (κ) of
sodium polystyrenesulfonate in the presence of varying con-
Table 1. Properties of 2-Ethoxyethanol (1) + Water (2) Mixtures
Containing 0.25, 0.40, and 0.50 Mass Fraction of 2-Ethoxyethanol at
(308.15, 313.15, 318.15, and 323.15) K
T density η0
K g·cm-3
mPa·s ε
w1 ) 0.25
308.15 0.99758 1.8430 60.13
313.15 0.99245 1.5293 58.70
318.15 0.98807 1.2738 57.37
323.15 0.98394 1.0923 56.11
w1 ) 0.40
308.15 0.99747 1.9545 50.54
313.15 0.99101 1.7015 49.28
318.15 0.98696 1.4274 48.14
323.15 0.98378 1.2317 47.10
w1 ) 0.50
308.15 0.99361 1.9234 44.30
313.15 0.98514 1.7195 43.03
318.15 0.98004 1.4552 41.95
323.15 0.97610 1.2762 40.96
Journal of Chemical & Engineering Data, Vol. 55, No. 6, 2010 2109
6. centrations of sodium chloride in 2-ethoxyethanol (1) + water
(2) mixtures have been listed as a function of the equivalent
polyelectrolyte concentration (cp) at (308.15, 313.15, 318.15,
and 323.15) K in Table 2. The specific conductivities of NaPSS
as a function of the polymer concentration at given temperatures
and solvent compositions in 2-ethoxyethanol (1) + water (2)
mixtures with varying amounts of added NaCl are shown in
the representative Figures 1 through 4. Figures 5 and 6, on the
other hand, demonstrate the influence of temperature on the
specific conductivity versus the polymer concentration profiles.
From these figures and also from Table 2, it is apparent that
for all of the solutions studied the specific conductivities increase
with polyelectrolyte concentration. The addition of salt increases
the specific conductances of the polyelectrolyte-salt solutions
as expected. The specific conductances of the polyelectrolyte-salt
systems are, in general, found to decrease with an increasing
amount of 2-ethoxyethanol in the mixed solvent media (shown
in the representative Figure 7).
Since the present 2-ethoxyethanol (1) + water (2) mixtures
are poor solvents for the uncharged polymer polystyrene, the
electrostatic blob is collapsed into a dense globule, and we use
a value of 5 Å as the effective monomer size (b) as suggested
by Colby et al.2
Table 2 Continued
308.15 K 313.15 K 318.15 K 323.15 K
cp ·10-4
κ cp ·10-4
κ cp ·10-4
κ cp ·10-4
κ
eqv·L-1
µS·cm-1
eqv·L-1
µS·cm-1
eqv·L-1
µS·cm-1
eqv·L-1
µS·cm-1
0.14 59.42 0.13 64.80 0.13 72.72
0.10 59.36 0.10 64.68 0.10 72.71
0 59.10 0 64.50 0 72.70
cNaCl ) 0.01 mol·L-1
100.29 587.00 117.62 680.00 101.43 751.00 101.52 872.00
75.21 571.00 88.21 638.00 76.07 716.00 76.14 805.00
56.41 555.00 66.16 608.00 57.05 675.00 57.11 755.00
42.31 543.00 49.62 587.00 42.79 635.00 42.83 721.00
31.73 529.00 37.22 566.00 32.09 612.00 32.12 700.00
23.80 522.00 27.91 553.00 24.07 599.00 24.09 681.00
17.85 517.00 20.93 541.00 18.05 586.00 18.07 668.00
13.39 511.00 15.70 536.00 13.54 576.00 13.55 656.00
10.04 508.00 11.78 527.00 10.15 567.00 10.16 648.00
7.53 502.00 8.83 518.00 7.62 563.00 7.62 641.00
5.65 500.00 6.62 511.00 5.71 557.00 5.72 636.00
4.24 498.00 4.97 509.00 4.28 556.10 4.29 631.00
3.18 496.00 3.73 506.50 3.21 554.70 3.22 629.00
2.38 494.00 2.79 502.20 2.41 553.80 2.41 627.00
1.79 493.00 2.10 499.00 1.81 553.00 1.81 625.50
1.34 492.00 1.57 497.00 1.36 551.70 1.36 624.10
1.01 491.00 1.18 495.00 1.02 551.40 1.02 624.00
0.75 490.89 0.88 493.40 0.76 551.20 0.76 623.80
0.57 490.60 0.66 493.20 0.57 551.00 0.57 623.60
0.42 490.49 0.50 493.00 0.43 550.80 0.43 623.40
0.32 490.41 0.37 492.80 0.32 550.60 0.32 623.20
0.24 490.29 0.28 492.71 0.24 550.40 0.24 623.10
0.18 490.18 0.21 492.49 0.18 550.30 0.18 623.04
0.13 490.14 0.16 492.28 0.14 550.17 0.14 623.01
0.10 490.11 0.12 492.25 0.10 550.12 0.10 623.01
0 489.97 0 492.00 0 550.00 0.00 623.00
Figure 1. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at 308.15 K in a 2-ethoxyethanol (1) + water (2) mixture
with w1 ) 0.25. Experimental: open symbols represent experimental values,
whereas the dashed lines are according to eq 5. Circles, squares, and triangles
represent the polyelectrolyte solutions in the presence of (0.0001, 0.001,
and 0.01) mol·L-1
NaCl, respectively (see text).
Figure 2. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at 313.15 K in a 2-ethoxyethanol (1) + water (2) mixture
with w1 ) 0.40. Experimental: open symbols represent experimental values,
whereas the dashed lines are according to eq 5. Circles, squares, and triangles
represent the polyelectrolyte solutions in the presence of (0.0001, 0.001,
and 0.01) mol·L-1
NaCl, respectively (see text).
Journal of Chemical & Engineering Data, Vol. 55, No. 6, 2010 2113
7. Under poor solvent conditions, the electrostatic blob size (ξe)
and the correlation blob size (ξ0) are given by2
ξe ) bf'-2
ξ-1/3
(6)
ξ0 ) (cb)-1/2
f'-2
ξ-1/3
(7)
The specific conductivity values of the polyelectrolyte-salt
system as a function of polyelectrolyte concentration in a given
solvent medium at a given temperature and for a given salt
concentration were fitted to eq 5 by the method of least-squares
analysis. The best-fitted f′ values along with the standard
deviations are reported in Table 3. In the representative Figures
1 to 4 we compare the calculated specific conductivities using
the f′ values obtained in the semidilute regime (reported in Table
3) with those obtained experimentally. From the standard
deviations recorded in Table 3, as well as from an inspection
of these figures, it is directly evident that the present method
of analysis reproduced the experimental results even in dilute
solutions quite satisfactorily. It should be noted that this vigorous
test of the proposed model has been performed with 36 sets of
data considering the effects of medium, temperature, and
concentration of the added simple salt. We have, thus, been
able to develop a simple model in describing the specific
conductivity behavior of polyelectrolyte solutions with added
salt. Further studies on the application of this model to other
polyelectrolyte-salt systems in different mixed solvent media
are presently under investigation.
Figure 3. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at 318.15 K in a 2-ethoxyethanol (1) + water (2) mixture
with w1 ) 0.50. Experimental: open symbols represent experimental values,
whereas the dashed lines are according to eq 5. Circles, squares, and triangles
represent the polyelectrolyte solutions in the presence of (0.0001, 0.001,
and 0.01) mol·L-1
NaCl, respectively (see text).
Figure 4. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at 323.15 K in a 2-ethoxyethanol (1) + water (2) mixture
with w1 ) 0.25. Experimental: open symbols represent experimental values,
whereas the dashed lines are according to eq 5. Circles, squares, and triangles
represent the polyelectrolyte solutions in the presence of (0.0001, 0.001,
and 0.01) mol·L-1
NaCl, respectively (see text).
Figure 5. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at temperatures of O, 308.15 K; 0, 313.15 K; 4, 318.15
K; and b, 323.15 K in a 2-ethoxyethanol (1) + water (2) mixture with w1
) 0.25 in the presence of 0.01 mol·L-1
NaCl. Lines are used to guide the
eye.
Figure 6. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at temperatures of O, 308.15 K; 0, 313.15 K; 4, 318.15
K; and b, 323.15 K in a 2-ethoxyethanol (1) + water (2) mixture with w1
) 0.50 in the presence of 0.0001 mol·L-1
NaCl. Lines are used to guide
the eye.
Figure 7. Specific conductivities of NaPSS as a function of the polymer
concentration (cp) at a temperature of 308.15 K in a 2-ethoxyethanol (1) +
water (2) mixture with w1 ) O, 0.50; 0, 0.40; and 4, 0.50 in the presence
of 0.0001 mol·L-1
NaCl. Lines are used to guide the eye.
2114 Journal of Chemical & Engineering Data, Vol. 55, No. 6, 2010
8. Conclusions
The electrical conductances of the solutions of sodium
polystyrenesulfonate in 2-ethoxyethanol (1) + water (2) mixed
solvent media containing (0.25, 0.40, and 0.50) mass fractions
of 2-ethoxyethanol (w1) have been reported at (308.15, 313.15,
318.15, and 323.15) K in the presence of sodium chloride. The
conductance data have been analyzed on the basis of a simple
equation with only one adjustable parameter developed in the
present study following the model for the electrical conductivity
of solutions of semidilute polyelectrolytes without salt proposed
by Colby et al.2
using the scaling description for the configu-
ration of a polyion chain according to Dobrynin et al.3
Excellent
agreement between the experimental results and those obtained
using eq 5 has always been observed. We expect that the model
proposed here provides a universal description of the specific
conductivities of polyelectrolyte solutions in the presence of
an added electrolyte. Further studies on the application of this
model to other polyelectrolyte-salt systems in various other
mixed solvent media are presently under investigation.
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Received for review September 04, 2009. Accepted March 19, 2010.
Financial support by the Special Assistance Programme of the
University Grants’ Commission, New Delhi, India is gratefully
acknowledged. The authors also thank the University of North Bengal
for partial financial support to this project.
JE900725W
Table 3. Fraction of Uncondensed Counterions (f′) and the
Standard Deviations (σ) of Fit for Sodium Polystyrenesulfonate
(NaPSS) in the Presence of NaCl at Temperatures (308.15, 313.15,
318.15, and 323.15) K in 2-Ethoxyethanol (1) + Water (2) Mixed
Solvent Media as Obtained According to Equation 5
temperature CNaCl
K
mass
fraction (w1) mol·L-1
f′ σ·106
308.15 0.25 1·10-4
0.40 3.09
1·10-3
0.38 4.59
1·10-2
0.34 10.06
0.40 1·10-4
0.25 1.14
1·10-3
0.23 1.82
1·10-2
0.21 2.37
0.50 1·10-4
0.25 0.74
1·10-3
0.24 1.52
1·10-2
0.21 2.91
313.15 0.25 1·10-4
0.40 5.19
1·10-3
0.35 6.29
1·10-2
0.33 6.82
0.40 1·10-4
0.23 3.40
1·10-3
0.21 4.01
1·10-2
0.18 3.77
0.50 1·10-4
0.25 1.13
1·10-3
0.23 1.65
1·10-2
0.18 5.60
318.15 0.25 1·10-4
0.38 3.84
1·10-3
0.35 4.26
1·10-2
0.32 5.67
0.40 1·10-4
0.25 2.45
1·10-3
0.22 3.62
1·10-2
0.17 8.48
0.50 1·10-4
0.23 1.69
1·10-3
0.21 2.76
1·10-2
0.18 5.08
323.15 0.25 1·10-4
0.34 6.33
1·10-3
0.31 7.65
1·10-2
0.28 7.57
0.40 1·10-4
0.24 4.87
1·10-3
0.22 5.61
1·10-2
0.20 7.69
0.50 1·10-4
0.23 2.32
1·10-3
0.22 3.90
1·10-2
0.19 5.10
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