A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum ab...A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum absorption peak of Ce(IV)-(TB-ASA)-KBrO3 system is at 510 nm.The amount of Ce(IV) and the difference of absorbance(△A) showed a good linear relationship over the range of 5.7×10-8-5.1×10-7 mol/L.The regression equation is △A=2.3×10-11 C(C:mol/L)+0.0196,with a regression coefficient of 0.9914 at t...展开更多
The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reacti...The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reaction of La^(3+),Gd^(3+)and Ho^(3+)with TBA were studied.It is shown in the study that prerequisites for performing differential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reaction mechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effects could be neglected.展开更多
A new method,dual-series linear regression method,has been used to study the complexation equilibrium of praseodymium(Pr^(3+))with tribromoarsenazo(TBA)without knowing the accurate concentra- tion of the complexing ag...A new method,dual-series linear regression method,has been used to study the complexation equilibrium of praseodymium(Pr^(3+))with tribromoarsenazo(TBA)without knowing the accurate concentra- tion of the complexing agent TBA.In 1.2 mol/L HCl solution, Pr^(3+)reacts with TBA and forms 1:3 com- plex,the conditional stability constant(lgβ_3)of the complex determined is 15.47,and its molar absorptivity(ε_3^(630))is 1.48×10~5 L·mol^(-1)·cm^(-1).展开更多
According to the appearing of isosbestic point in the absorption spectra of Ho/Y-Tribromoarsenazo (TBA)systems,the complexation reaction is considered to be M+nL=ML_n.A method has been proposed based on it for calcula...According to the appearing of isosbestic point in the absorption spectra of Ho/Y-Tribromoarsenazo (TBA)systems,the complexation reaction is considered to be M+nL=ML_n.A method has been proposed based on it for calculating the mole fraction of free complexing agent in the solutions from spectral data.and two linear regression formula have been introduced to determine the composition,the molar absorptivity,the conditional stability constant of the complex and the concentration of the complexing agent. This method has been used in Ho-TBA and Y-TBA systems.Ho^(3+)and Y^(3+)react with TBA and form 1: 2 complexes in HCl-NaAc buffer solution at pH 3.80.Their molar absorptivities determined are 1.03×10~8 and 1.10×10~8 cm^2·mol^(-1),and the conditional stability constants(logβ_2)are 11.37 and 11.15 respectively.After considering the pH effect in TBA complexing,their stability constants(log β_2^(ahs))are 43.23 and 43.01. respectively.The new method is adaptable to such systems where the accurate concentration of the complexing agent can not be known conveniently.展开更多
文摘A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum absorption peak of Ce(IV)-(TB-ASA)-KBrO3 system is at 510 nm.The amount of Ce(IV) and the difference of absorbance(△A) showed a good linear relationship over the range of 5.7×10-8-5.1×10-7 mol/L.The regression equation is △A=2.3×10-11 C(C:mol/L)+0.0196,with a regression coefficient of 0.9914 at t...
基金The Project was supported by the National Natural Science Foundation of China
文摘The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reaction of La^(3+),Gd^(3+)and Ho^(3+)with TBA were studied.It is shown in the study that prerequisites for performing differential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reaction mechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effects could be neglected.
文摘A new method,dual-series linear regression method,has been used to study the complexation equilibrium of praseodymium(Pr^(3+))with tribromoarsenazo(TBA)without knowing the accurate concentra- tion of the complexing agent TBA.In 1.2 mol/L HCl solution, Pr^(3+)reacts with TBA and forms 1:3 com- plex,the conditional stability constant(lgβ_3)of the complex determined is 15.47,and its molar absorptivity(ε_3^(630))is 1.48×10~5 L·mol^(-1)·cm^(-1).
文摘According to the appearing of isosbestic point in the absorption spectra of Ho/Y-Tribromoarsenazo (TBA)systems,the complexation reaction is considered to be M+nL=ML_n.A method has been proposed based on it for calculating the mole fraction of free complexing agent in the solutions from spectral data.and two linear regression formula have been introduced to determine the composition,the molar absorptivity,the conditional stability constant of the complex and the concentration of the complexing agent. This method has been used in Ho-TBA and Y-TBA systems.Ho^(3+)and Y^(3+)react with TBA and form 1: 2 complexes in HCl-NaAc buffer solution at pH 3.80.Their molar absorptivities determined are 1.03×10~8 and 1.10×10~8 cm^2·mol^(-1),and the conditional stability constants(logβ_2)are 11.37 and 11.15 respectively.After considering the pH effect in TBA complexing,their stability constants(log β_2^(ahs))are 43.23 and 43.01. respectively.The new method is adaptable to such systems where the accurate concentration of the complexing agent can not be known conveniently.
