scholarly journals The Identification of Insoluble Adducts of Lewis Acids with Bases by Extension of the Continuous Variation Method to Solid-Liquid Reactions

1987 ◽  
Vol 60 (4) ◽  
pp. 1361-1365
Author(s):  
Goro Hihara ◽  
Kazuhiro Mitani ◽  
Hiroshi Miyamae ◽  
Miharu Nagata
Keyword(s):  
Lewis Acids ◽  
Continuous Variation ◽  
Variation Method ◽  
Continuous Variation Method ◽  
Solid Liquid

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 SPECTROPHOTOMETRIC STUDY ON THE FORMATION AND ANALYTICAL APPLICATION OF THE RHODIUM (III) CHELATE WITH 2-THIOXO-4-THIAZOLIDINONE

2002 ◽  
Vol 10 (11) ◽  
pp. 89-96
Author(s):  
Ion Ganescu ◽  
Vasilica Muresan ◽  
Liana Simona Sbirna ◽  
Anca Ganescu ◽  
Sebastian Sbirna ◽  
...  
Keyword(s):  
Binary System ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Study ◽  
Continuous Variation ◽  
Analytical Application ◽  
Variation Method ◽  
Instability Constant ◽  
Formation Conditions ◽  
Continuous Variation Method

The paper presents a spectrophotometric study of the binary system Rh(III)-2-thioxo-4-thiazolidinone. The formation conditions and the analytical application of the formed complex for spectrophotometric determination of Rh(III) were studied. The composition of the Rh(III) chelate with this particular ligand was determined by the continuous variation method, its instability constant being Kinst = 1,61·10-8 mol2L-2.

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.

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