Chelate formation between lead(II) and 1,2,5,8-tetrahydroxyanthraquinone (quinalizarin): Spectrophotometric studies on the composition and stability

1967 ◽  
Vol 20 (7) ◽  
pp. 1385 ◽  
Author(s):  
KC Srivastava ◽  
SK Banerji
Keyword(s):  
Free Energy ◽  
Aqueous Ethanol ◽  
Free Energy Change ◽  
Energy Change ◽  
Variation Method ◽  
Ratio Method ◽  
Chelate Formation ◽  
Mole Ratio Method ◽  
Continuous Variation Method ◽  
Absorbance Data

The formation of a bluish violet chelate between bivalent lead and 1,2,5,8-tetrahydroxyanthraquinone (quinalizarin) with maximum absorption at 520mμ has been studied. The chelate is soluble in aqueous ethanol. The composition of the chelate has been determined by three methods. The chelate has a composition of 1 : 1 and is stable at pH 6.1-8.5. The values of log K determined in 50% ethanolic medium by the method of Dey et al., the continuous variation method, and the mole ratio method, using absorbance data, are 4.1 � 0.1, 4.0 � 0.0, and 4.1� � 0.1 respectively at 30�, pH 6.3. The free energy change of formation, calculated from the three values of log K, is -5.7 � 0.1, -5.6 � 0.0, and -5.7 � 0.1 kcal respectively.

scholarly journals Determination of Stability Constants and Thermodynamic parameters of Cefotaxime –Fe(III) Complex at Different Temperatures

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
O. V. Ikpeazu ◽  
I. E. Otuokere ◽  
K. K. Igwe
Keyword(s):  
Stability Constants ◽  
Chelating Agent ◽  
Continuous Variation ◽  
Molar Ratio ◽  
Variation Method ◽  
Ratio Method ◽  
Lactam Antibiotic ◽  
Different Temperatures ◽  
Mole Ratio Method ◽  
Continuous Variation Method

Cefotaxime, a β-lactam antibiotic, has a structure which enables it to act as a chelating agent. The formation of Fe(III) complex with cefotaxime has been studied colorimetrically at an absorption maximum of 480 nm at different temperatures. The data showed that Fe(III) and cefotaxime combine in the molar ratio of 1:1  at pH 7.4 with ionic strength maintained using 0.1M KNO3. The stability constants of the complex were calculated to be 1.56 - 1.90 x 104 by continuous variation method and 1.34 - 1.71 x 104 by mole ratio method at 25 and 40 oC respectively. ∆HƟ values for the complex were calculated to be -1.02 x 104 and -1.05 x 104 J by continuous variation method and mole ratio method respectively. ∆GƟ of the complex were calculated to be -2.44 – (-2.51) x 104 J by continuous variation method and -2.41- (- 2.48)  x 104 J by mole ratio method at 25 and 40 oC.  ∆SƟ of the complex were calculated to be 2.44 - 2.51 x 104 J/K by continuous variation method and -2.41 -2.48) x 104 J/K by mole ratio method at 25 and 40 oC respectively. Cefotaxime is a good chelating agent and can be an efficient antidote in the therapy of copper overload or poisoning.  

scholarly journals FORMULA ESTABLISHMENT OF COLORLESS Pb(II) COMPLEX WITH N-BENZOYL-N-PHENYL HYDROXYLAMINE (BPA) USING ATOMIC ABSORPTION SPECTROSCOPY

2012 ◽  
Vol 12 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Dhananjay B Sarode ◽  
Sopan T Ingle ◽  
Sanjay B Attarde
Keyword(s):  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Variation Method ◽  
Ratio Method ◽  
Slope Ratio ◽  
Mole Ratio Method ◽  
Continuous Variation Method ◽  
Slope Ratio Method

A new method for determination of stoichiometry of colorless complexes by using atomic absorption spectrophotometric technique in continuous variation method and slope ratio method was described here. This method can be used in same manner as that of mole ratio method and slope ratio method. In this method atomic absorption spectroscopy was used instead of UV-Vis spectrophotometry. Atomic absorption spectrophotometric technique is superior to UV-Vis spectrophotometry as it can be applied to colorless soluble complexes. Pb(II) and n-benzoyl-n-phenyl hydroxylamine react to form colorless complex at pH 6.5, which can be easily determined by this method. It was found that Pb(II) forms 1:2 complex with n-benzoyl-n-phenyl hydroxylamine and is quantitatively extracted back to aqueous solution for AAS analysis.

scholarly journals Evaluation of Stoichiometry, Stability Constants and Gibbs Free Energies of Acetaminophen-Zn (II) complex at Different Temperatures

2020 ◽  
Vol 24 (7) ◽  
pp. 1137-1143
Author(s):  
O.V. Ikpeazu ◽  
I.E. Otuokere ◽  
K.K. Igwe
Keyword(s):  
Free Energy ◽  
Stability Constant ◽  
Gibbs Free Energy ◽  
Stability Constants ◽  
Continuous Variation ◽  
Variation Method ◽  
Ratio Method ◽  
Free Energies ◽  
Different Temperatures ◽  
Continuous Variation Method

Acetaminophen also known as paracetamol, is a drug used in the treatment of pain and fever. It is essentially used for the relief of mild to moderate pain. The presence of phenol and carbonyl oxygen atom enables acetaminophen to behave as a bidentate ligand. The stoichiometry, stability constants and Gibbs free energies of acetaminophen-Zn (II) were determined colorimetrically at 25 and 40 oC using continuous variation and mole  ratio methods. The formation of Zn (II) complex with acetaminophen was studied colorimetrically at an absorption maximum of 630 nm at different temperatures. The data showed that Zn (II) and acetaminophen combine in the molar ratio of 1:1 at pH 7.4 with ionic strength maintained using 0.1M KNO3. Calculated stability constants values were 2.70 x 103 and 2.20 x 103 using continuous variation method and 7.21 x 103 and 7.21 x 103 using mole ratio methods at 25 and 40 oC respectively. Calculated ΔGƟ for the complex were - 1.96 x 104 and -1.98 x 104 J using continuous variation method and -2.2 x 104 J and - 2.31 x 104 J using mole ratio method at 25 and 40 oC respectively. The stability constant and Gibbs free energy results suggested that acetaminophen used in the study is a good chelating agent and can be an efficient antidote in the therapy of Zn (II) overload or poisoning. Keywords: Acetaminophen, Zinc, complex, stability constant, Gibbs free energy.

Modeling of Electrical Resistivity Evolution Using Free Energy Analysis for NiTi Shape Memory Alloy Wires

2011 ◽  
Vol 311-313 ◽  
pp. 2282-2285
Author(s):  
Jian Jun Zhang
Keyword(s):  
Electrical Resistivity ◽  
Free Energy ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Free Energy Change ◽  
Energy Change ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Proposed Model ◽  
Free Energy Analysis

This paper presents a transformation kinetics model of NiTi shape memory alloy (SMA) wires based on electrical resistivity (ER) derivative study under the assumption that the derivative of electrical resistivity with respect to temperature is in linear relationship with the derivative of free energy change with respect to temperature. Free energy change and electrical resistivity properties of SMA are analyzed based on differential scanning calorimetry (DSC) experiments during phase transformation. The simulated evolution of electrical resistivity during thermomechanical transformation is presented using the proposed model.

Adsorption of Liquids and Swelling of Wood. Part VI. Saturated Amounts and Some Thermodynamic Values of Adsorption

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 91-97
Author(s):  
Kei Morisato ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Molecular Size ◽  
Free Energy Change ◽  
Energy Change ◽  
Multilayer Adsorption ◽  
Monolayer Adsorption ◽  
Wood Part ◽  
Cohesive Interaction

Summary To understand the swelling phenomenon of wood in liquids,the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood,the values of free energy change of adsorption for methanol were lower than the values for acetone,although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity,the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore,the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood.

scholarly journals REMOVAL OF CU (II) FROM DYE EFFLUENT USING NATURAL AND PHOSPHATE-MODIFIED NIGERIAN KAOLINITE CLAY

2019 ◽  
Vol 7 (8) ◽  
pp. 402-414
Author(s):  
S. C. Olu ◽  
P. E. Dim ◽  
J. O. Okafor
Keyword(s):  
Free Energy ◽  
Metal Ion ◽  
Fourier Transforms ◽  
Lattice Structure ◽  
Enthalpy Change ◽  
Free Energy Change ◽  
Energy Change ◽  
Order Model ◽  
Acid Modification ◽  
Kaolinite Clay

This study indicates kaolinite clay as an effective adsorbent for the uptake of Cu (II) from wastewater. The adsorption process was studied with variation of time, temperature and adsorbent dosage at the effluent pH of 6. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer Emmett and Teller (BET) and Scanning electron microscopy (SEM) were used to characterize the adsorbents. XRD spectra showed that modification with KH2PO4 did not significantly change the crystal spacing on the lattice structure of the clay mineral; however, there were shifts in the intensity of the peaks for the modified kaolinite clay. The FTIR spectra showed that certain functional groups are responsible for binding the metal ions from solution. SEM indicated an increase in the porosity of the modified adsorbent as compared with the unmodified kaolinite, which enhances metal ion adsorption on modified kaolinite clay. The BET indicate that acid modification increased the surface area and total pore volume of the kaolinite clay. The kinetic study revealed that the pseudo-first-order model fitted poorly to the equilibrium data, however, the pseudo-second-order model had a good fit for all reaction time at different initial concentrations. The mechanism of the sorption process was evaluated using thermodynamic properties such as enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), which were evaluated using Van’t Hoff equations. The negative values of free energy change (ΔG), suggests spontaneity and feasibility of the process. The positive values of enthalpy change (ΔH) indicate endothermic nature of the process.

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