• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.273-279
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• 2016

This paper deals with a control system with a concentration sensor for Ni-W alloy plating solutions. The printed circuit board market has increased with the development of the electronics industry. Gold consumption has also increased dramatically. Various studies of composite plating solutions have been conducted because of the expense of gold. In comparison, the development of sensors capable of measuring a composite plating solution in real-time is still insufficient. Furthermore, there are few systems that can measure and control the concentration of the solution precisely. This study developed a sensor and system to control the concentration of composite plating solution accurately. The sensors were developed based on a spectrophotometric method and a feedback control method was applied in this system.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.307-311
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• 1986

The rates of hydrolysis of the complex, $trans^-[Cr(en)_2F(H_2O)]^{2+}$, have been investigated using spectrophotometric method at various temperatures and pressure. Temperature was 30${\circ}C$ to 50${\circ}C$ and pressure was varied up to 1500bar. The rate constant measured at 30${\circ}C$ is $2.632{\times}10^{-5}sec^{-1}$. The rate constants are decrease with increasing pressure at constants temperature. Activation volume and other activation parameters are calculated from these rate constants. The activation volumes are all positive and lie in the limited range 0.447 ∼ 3.152$cm^3$/mol and the activation entropies are small values. From the results, it was found that this reaction was endothermic and enthalphy controlled reaction in the experimental temperature.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.274-281
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• 1982

Ultraviolet spectrophotometric investigation have been carried out on the systems of pentamethylbenzene and hexamethylbenzene with iodine and iodine monochloride in carbon tetrachloride. The results reveal the formation of the one to one molecular complexes. The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperature. Thermodynamic parameters for the formation of the charge transfer complexes were calculated from these values. These results indicate that the complex formed between polymethylbenzene and iodine monochloride is more stable than that in the case of iodine. This may be a measure of their relative acidities toward polymethylbenzene, which is explained in terms of the relative electronegativities of halogen atoms. These results combined with previous studies of this series indicated that ${\lambda}_{max}$ shift to red with the increasing number of methyl groups on benezene ring and that the relative stabilities of these complexes increase in the order, Benzene < Toluene < Xylene < Durene < Mesitylene < Pentamethylbenzene < Hexamethylbenzene. The reason for the order found is thus additionally discussed.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.326-332
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• 1982

The structure of the complex extracted from an aqueous solution containing methylene blue and tetrafluoroborate with 1,2-dichloroethane has been investigated by comparing IR spectrum of the extract with those of pure components and appeared to be an 1 : 1 contact ion-pair between monovalent ions of opposite charge. The extraction constant obtained from the absorbance data measured at 658nm in 1,2-dichlorethane has a value of 1.1${\times}$at$10^4M{-1}$ 25$^{\circ}$C in the range from 1.43${\times}10^{-2}$ to 2.86${\times}10^{-1}$M HF. In the solvent extraction with nitrobenzene, the identical experiments show that extraction constants are increased with HF concentration possibly due to dissociation of the ion-pair in nitrobenzene.

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.123-129
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• 1990

The rate constants for the solvolysis of $trans-[Cr(en)_2Br_2]^+$ ion were determined by the spectrophotometric method in methanol-, ethanol-, acetone-, and acetonitrile-water mixtures, at 20, 25, 30, and 35$^{\circ}C$, respectively. The rate constants increased with increasing co-solvent compositions. The rate constant did not show any relation with the reciprocal of dielectric constant of the solvent-mixtures. The m values of Grunwald-Winstein equation for methanol-, ethanol-, acetonitrile-, and acetone-water mixtures are 0.109, 0.103, 0.101, and 0.095, respectively. A free energy cycle for the process from the initial state to the transition state in water and water + co-solvent mixtures shows that the change in solvation at the transition state has a dominant effect on the rate. From the above results, it is believed that the mechanism for the aquation of this complex is the Id mechanism.

• Journal of the Korean Chemical Society
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• v.38 no.10
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• pp.705-709
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• 1994

The kinetics of the oxidation reaction of malonic acid by ceric ion in 1 M sulfuric acid solution at $20^{\circ}C$ have been investigated by spectrophotometric method. The reaction rate at a large excess of malonic acid was found to be pseudo-first order. The observed pseudo-first order rate constants, $k_{obs}$, are dependent on the concentration of malonic acid, [MA], of which relationship has been found to be $k_{obs}$ = (0.592[MA])/(1+14.5[MA]$^2$). A mechanism for the reaction has been suggested on the basis of the above rate equation. The rate determining step may be the electron transfer reaction between enolate type malonate anion, which is formed by the acid dissociation reaction of malonic acid, and Ce(IV). The rate depression in the range of high concentration of MA has been explained by the formation of 1 : 2 chelate between Ce(IV) and malonate. According to the mechanism, the pH dependence of the rate, which was studied by Sengupta et al., has also been explained.

• Journal of the Korean Chemical Society
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• v.41 no.6
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• pp.284-291
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• 1997

The critical micelle concentrations($CMC^*$) of a cationic surfactant cetylpyridinium chloride (CPC) and a nonionic surfactant triton X-100(TX-100) in aqueous solutions of n-alcohols(methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol) were determined by UV spectroscopic method at 25$^{\circ}C$. The various thermodynamic values in 0.1 M n-alcohols were calculated by means of the equation derived from the pseudo-phase separation model and compared with the values in the absence of n-alcohols. The results were a good agreement with the nonideal mixed micelle model, and they showed negative deviation from the ideal behavior.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.607-611
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• 1991

The stereochemical ratio cis and trans isomer of the hydration reaction of trans-$[Co(en)(tmd)Cl_2]^+$ complex ion were studied with varing temperature by the spectrophotometric method. It was observed that the ratio of cis-isomer was about 30%, and the intermediate was rearranged. And in order to investigate this mechanism more clearly, stability energy profile, interaction diagram and orbital correlation diagram were calculated by the EHT method. By the calculation, the mechanism of cis-isomer was in good agreement with the experimental results, and it was estimated that the hydration reaction was carried through some distorted square pyramid (sp).

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.375-381
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• 1987

Rates for the aquation of trans-[Cr(tn)$_2Cl_2]^+$ and trans-[Cr(en)(tn)Cl$_2$]^+$ ions in aqueous acidic solution have been measured by spectrophotometric method at various temperatures and pressures. Activation volumes are negative and lie in the limited range -1.7 ∼ -2.9cm$^3$mol$^{-1}$ or the complex ions. Activation entropies and activation compressibility coefficients are small negative values. From the results of thermodynamic parameters, it can be inferred that the aquation of the complex ions proceed through an associative interchange(Ia) mechanism. Furthermore, the information on possible transition state structure and reaction paths can be obtained by considering total stabilization energy of the hypothetical intermediates within the framework of angular overlap model. It is found that the theoretically predicted mechanism is consistent with the experimentally observed results.

• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.50-54
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• 1994

Spectrophotometric determination of some light lanthanide ions by flow injection method is described. Chromeazurol S forms water soluble complex with lanthanide ions in the presence of DTAB. The absorption maximum of the complexes are from 650 nm to 655 nm and the molar absorptivities were ca. $1.8{\times}10^5\;L mol^{-1}cm^{-1}$ on Tris buffer (pH 10.5). The calibration curves for Nd(III), Eu(III) and Sm(III) obtained by FIA are over the range of 0.1 to 0.6 ppm and the correlation coefficient were ca. 0.9993. The detection limits (S/N) were from 10 ppb for Nd(III) and Eu(III) to 20 ppb for Sm(III). The relative standard deviations was ${\pm}$.2% for 0.4 ppm sample. The samples throughput was ca. $50\;cm^{-1}$.