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1986 Volume 2 Issue 4
1986, 2(04): 288-288
doi: 10.3866/PKU.WHXB19860401
Abstract:
1986, 2(04): 289-290
doi: 10.3866/PKU.WHXB19860402
Abstract:
1986, 2(04): 291-292
doi: 10.3866/PKU.WHXB19860403
Abstract:
1986, 2(04): 293-294
doi: 10.3866/PKU.WHXB19860404
Abstract:
1986, 2(04): 295-296
doi: 10.3866/PKU.WHXB19860405
Abstract:
1986, 2(04): 297-301
doi: 10.3866/PKU.WHXB19860406
Abstract:
The film pressure vs. area curves of the surface films of Triton X-100 and Triton X-305 have been determined on a 46.6% NANO_3 substrates at 25 ℃. The results suggest that the area per molecule on the surface at constant film pressure is a linear function of ethylene oxide chain length. It is proposed that the amphipathic molecule orients at the air/water interface with the hydrophobic group above the interface and the ethylene oxide chain partly lies in the interface and partly penetrates the water phase. Although the fraction of the number of ethylene oxide unit lain in the interface, f, increase progressively with film pressure, is independent of n, the ethylene oxide chain length. With this model, the experimental results can be explained.
The film pressure vs. area curves of the surface films of Triton X-100 and Triton X-305 have been determined on a 46.6% NANO_3 substrates at 25 ℃. The results suggest that the area per molecule on the surface at constant film pressure is a linear function of ethylene oxide chain length. It is proposed that the amphipathic molecule orients at the air/water interface with the hydrophobic group above the interface and the ethylene oxide chain partly lies in the interface and partly penetrates the water phase. Although the fraction of the number of ethylene oxide unit lain in the interface, f, increase progressively with film pressure, is independent of n, the ethylene oxide chain length. With this model, the experimental results can be explained.
1986, 2(04): 302-309
doi: 10.3866/PKU.WHXB19860407
Abstract:
This paper reports the effect of seven salts, namely sodium formate (C_1), sodium acetate(C_2), sodium propionate(C_3), sodium butyrate(C_4), sodium pentanoate(C_5), sodium caproate (C_6) and sodium heptylate(C_7), on the activity coefficients of three solutes, namely ethanol, acetone and acetonitrile, in aqueous solution at 298.1 K. Adopted method is to measure the variation of partial pressure of solute in the equilibrium vapor phase with the concentration of the salt at fixed composition of aqueous solution of solute by gas chromatography, thus to calculate the salt effect activity coefficient of the nonaqueous component in solution.
A design of vapor-liquid equilibrium apparatus for sequential sampling is described in detail.
According to the experimental result, it can be considered that the mechenism of salt effect changes dramatically as the num ber of carbon in the chain of anion increases. Electrostatic in teraction contributes to salt effect mainly for C_1 and C_2 salts. In addition to electrostatic, interaction between the hydrophobic group of C_3 and C_4 anion and that of solute raises a considerable contribution to it. The salt effects for C_5, C_6 and C_7 salts characterize the hydrophobic ions that the hydrophobic hydration, the hydrophobic interaction and the special interaction between the aggregation of hydrophobic ions and the various functional group cause the differentiation of salt effect o three solutes.
This paper reports the effect of seven salts, namely sodium formate (C_1), sodium acetate(C_2), sodium propionate(C_3), sodium butyrate(C_4), sodium pentanoate(C_5), sodium caproate (C_6) and sodium heptylate(C_7), on the activity coefficients of three solutes, namely ethanol, acetone and acetonitrile, in aqueous solution at 298.1 K. Adopted method is to measure the variation of partial pressure of solute in the equilibrium vapor phase with the concentration of the salt at fixed composition of aqueous solution of solute by gas chromatography, thus to calculate the salt effect activity coefficient of the nonaqueous component in solution.
A design of vapor-liquid equilibrium apparatus for sequential sampling is described in detail.
According to the experimental result, it can be considered that the mechenism of salt effect changes dramatically as the num ber of carbon in the chain of anion increases. Electrostatic in teraction contributes to salt effect mainly for C_1 and C_2 salts. In addition to electrostatic, interaction between the hydrophobic group of C_3 and C_4 anion and that of solute raises a considerable contribution to it. The salt effects for C_5, C_6 and C_7 salts characterize the hydrophobic ions that the hydrophobic hydration, the hydrophobic interaction and the special interaction between the aggregation of hydrophobic ions and the various functional group cause the differentiation of salt effect o three solutes.
1986, 2(04): 310-313
doi: 10.3866/PKU.WHXB19860408
Abstract:
In this paper, a comparison has been made of the absorption spectra of nine aromatic monoketones in acetone. It can be seen from our results that the dispersiveness of aromatic monoketones is inhomogeneous in solution. The equilibrium between monomers and dimers shifts to the side of the latter with increasing the concentration of monoketones. A number of factors have been suggested as promotion for the aggregation of aromatic monoketones. This red-shifted absorption was assigned by the method of Davydov-Kasha as the allowed exciton dimer transitin. Furthermore, the geometry of dimer is “face to face”.
In this paper, a comparison has been made of the absorption spectra of nine aromatic monoketones in acetone. It can be seen from our results that the dispersiveness of aromatic monoketones is inhomogeneous in solution. The equilibrium between monomers and dimers shifts to the side of the latter with increasing the concentration of monoketones. A number of factors have been suggested as promotion for the aggregation of aromatic monoketones. This red-shifted absorption was assigned by the method of Davydov-Kasha as the allowed exciton dimer transitin. Furthermore, the geometry of dimer is “face to face”.
1986, 2(04): 314-320
doi: 10.3866/PKU.WHXB19860409
Abstract:
In this paper the polarized Iumminesence spectra are reported for TbP_5O_(14). These spectra were obtained at 77 k. The polarization of each line was measured by the ratio (I_(//)-I_⊥)/(I_(//)+I_⊥), where I_(11)(I_⊥) is the intensity of this line when polarized direction and the analyser is parallel (perpendicular). In according to the polarized ratio the stark levels of ~5D_4 and ~7F_J can be assigned. First, on the basis of the polarized character of spectra of ~5D_4—~7D_0(A_1) transition the level's name of ~5D_4 stark levels are assigned. Second, on the basis of the polarized character of ~5D_4—~7F_J transition the level's name of ~7F_J stark levels are assigned. The polarized character of the line of ~5D_4—A_2, ~5D_4—B_1, ~5D_4—B_2 and ~5D_4—E transition aren't regular and their assignment is complicated.
In this paper the polarized Iumminesence spectra are reported for TbP_5O_(14). These spectra were obtained at 77 k. The polarization of each line was measured by the ratio (I_(//)-I_⊥)/(I_(//)+I_⊥), where I_(11)(I_⊥) is the intensity of this line when polarized direction and the analyser is parallel (perpendicular). In according to the polarized ratio the stark levels of ~5D_4 and ~7F_J can be assigned. First, on the basis of the polarized character of spectra of ~5D_4—~7D_0(A_1) transition the level's name of ~5D_4 stark levels are assigned. Second, on the basis of the polarized character of ~5D_4—~7F_J transition the level's name of ~7F_J stark levels are assigned. The polarized character of the line of ~5D_4—A_2, ~5D_4—B_1, ~5D_4—B_2 and ~5D_4—E transition aren't regular and their assignment is complicated.
1986, 2(04): 321-327
doi: 10.3866/PKU.WHXB19860410
Abstract:
Fourteen dimethyl sulfoxide complexes of lanthanide and yttrium nitrates were prepared and analysed. The IR and Raman spectra of the complexes were studied systematically. The bands have been assigned and discussed. The S=O and Ln—O stretching vibration modes split in the heavy lanthanide complexes, which was attributed to the resonance coupling of same groups. The group symmetry changing causes the split of nitrate combination frequency 1775 cm~(-1). The coordination mode of nitrate can be identified in the complexes. The Ln—O stretching mode was suggested. The generic form of “inclined W” between the Ln—O stretching frequency and the L-value of rare earthes was discovered.
Fourteen dimethyl sulfoxide complexes of lanthanide and yttrium nitrates were prepared and analysed. The IR and Raman spectra of the complexes were studied systematically. The bands have been assigned and discussed. The S=O and Ln—O stretching vibration modes split in the heavy lanthanide complexes, which was attributed to the resonance coupling of same groups. The group symmetry changing causes the split of nitrate combination frequency 1775 cm~(-1). The coordination mode of nitrate can be identified in the complexes. The Ln—O stretching mode was suggested. The generic form of “inclined W” between the Ln—O stretching frequency and the L-value of rare earthes was discovered.
1986, 2(04): 328-334
doi: 10.3866/PKU.WHXB19860411
Abstract:
Surface tension[γ] of aqueous solutions of C_8H_(17)SO_4Na, C_8H_(17)N(CH_3)_3Br and the 1:1 mixture of them have been measured by drop volume method, and their contact angles [θ] on paraffin wax by a microseopefitted with a niometer. According to Young equation, the L/S interface pressures were obtained from γ and θ data. Gibbs adsorption equation was applied for L/S interface to work out the adsorstion isotherms It is seen that the adsorption isotherms are of Langmuir type.
It would be the first time to calculate the molecular interacion parameter of mixed surfactants adsorption layer at L/S interface and to give β~σ values of the same pair of surfactants in A/L, L/L, L/S interface layers.
It has been pointed out that this method is simple, convenient and only a few ml solution is needed for obtaining more than ten different surface properties: surface tension of solution, adsorption at A/L interface, composition of the adsorbed layer at A/L interface, critical micelle concentration, contact angle, critical surface tension of solid, L/S interface pressure, adsorption at L/S interface, composition of the adsorbed layer at L/S interface, molecular interaction parameter in A/L and L/S interface adsorbed layer and in micelle, etc.
Surface tension[γ] of aqueous solutions of C_8H_(17)SO_4Na, C_8H_(17)N(CH_3)_3Br and the 1:1 mixture of them have been measured by drop volume method, and their contact angles [θ] on paraffin wax by a microseopefitted with a niometer. According to Young equation, the L/S interface pressures were obtained from γ and θ data. Gibbs adsorption equation was applied for L/S interface to work out the adsorstion isotherms It is seen that the adsorption isotherms are of Langmuir type.
It would be the first time to calculate the molecular interacion parameter of mixed surfactants adsorption layer at L/S interface and to give β~σ values of the same pair of surfactants in A/L, L/L, L/S interface layers.
It has been pointed out that this method is simple, convenient and only a few ml solution is needed for obtaining more than ten different surface properties: surface tension of solution, adsorption at A/L interface, composition of the adsorbed layer at A/L interface, critical micelle concentration, contact angle, critical surface tension of solid, L/S interface pressure, adsorption at L/S interface, composition of the adsorbed layer at L/S interface, molecular interaction parameter in A/L and L/S interface adsorbed layer and in micelle, etc.
1986, 2(04): 335-341
doi: 10.3866/PKU.WHXB19860412
Abstract:
In this paper, the kinetics and mechanism of the copper( Ⅱ )-catalysed oxidation of ascorbic acid(vitamine C, H2A) by molecular oxygen have been analyzed in detail, and the oscillatory phenomenon of this reaction was discussed.
Young et al~[9] found chemical oscillatory phonomenon of this reaction. In this paper, the oscillatory phonomenon was studied at pH 6-8, The oscillatory phonomenon take place easily in the range of such pH value(as Fig.1). However, the exact number andamplitude of the oscillations could not be exactly duplicated.
The kinetics and mechanism of the reaction on nonoscillatory condition vere studied in detail.
Experimental condition: Phosphate buffer pH=6.0—7.5.......
In this paper, the kinetics and mechanism of the copper( Ⅱ )-catalysed oxidation of ascorbic acid(vitamine C, H2A) by molecular oxygen have been analyzed in detail, and the oscillatory phenomenon of this reaction was discussed.
Young et al~[9] found chemical oscillatory phonomenon of this reaction. In this paper, the oscillatory phonomenon was studied at pH 6-8, The oscillatory phonomenon take place easily in the range of such pH value(as Fig.1). However, the exact number andamplitude of the oscillations could not be exactly duplicated.
The kinetics and mechanism of the reaction on nonoscillatory condition vere studied in detail.
Experimental condition: Phosphate buffer pH=6.0—7.5.......
1986, 2(04): 342-349
doi: 10.3866/PKU.WHXB19860413
Abstract:
The possible effect of catalyst on the kinetics of photoelectroehemieal (PEC) reactions taking place at the surface of semiconductor (SC) electrodes was analysed mainly by considering the nature of junction between SC and catalyst particles. Result of analysis showed that in many cases catalyst could only eatalyse dark reactions. Prerequisite for catalysis of PEC reactions would be sufficiently strong interaction of catalyst particles with the SC/solution junction("liquid junction"), so that the Fermi level of electron system within catalyst particles could approach the quasi-Fermi level of photo-generated minority carriers. Experimental results of investigation of the effects of deposited Au, Ir, Pd and Pt on the kinetics of Ce~(3+)→Ce~(4+) and other reactions taking place on monocrystalline n-TiO2 electrode strongly supported such a model. Technique of RRDE with inter-changeable SC disks was empolyed in investigating catalysis of PEC reactions.
The possible effect of catalyst on the kinetics of photoelectroehemieal (PEC) reactions taking place at the surface of semiconductor (SC) electrodes was analysed mainly by considering the nature of junction between SC and catalyst particles. Result of analysis showed that in many cases catalyst could only eatalyse dark reactions. Prerequisite for catalysis of PEC reactions would be sufficiently strong interaction of catalyst particles with the SC/solution junction("liquid junction"), so that the Fermi level of electron system within catalyst particles could approach the quasi-Fermi level of photo-generated minority carriers. Experimental results of investigation of the effects of deposited Au, Ir, Pd and Pt on the kinetics of Ce~(3+)→Ce~(4+) and other reactions taking place on monocrystalline n-TiO2 electrode strongly supported such a model. Technique of RRDE with inter-changeable SC disks was empolyed in investigating catalysis of PEC reactions.
1986, 2(04): 350-355
doi: 10.3866/PKU.WHXB19860414
Abstract:
The kinetic energy loss and drainage effect of glass capillary viscometer are treated theoretically. These two correction factors interrelate closely and can not be separated with each other. The representative equation of glass capillary viscometer for measuring liquid viscosity may be written as
η/ρt=A~*-(B~*/t~2)-(C~*/t~4)
in which A*, B* and C* are instrumental constants. The numerical factor m of the kinetic energy correction term in the Poiseuille-Hagenbach equation is raised from the effect of adhering of liquids on the wall of the viscometer and may be represented by
m=1+(C~*/B~*t~2)
Therefore, the fact of ascending m with increasing Reynold number will be explained. Equations for calculating the relative viscosity of polymer solution and method for determining the instrumental constants are given.
The kinetic energy loss and drainage effect of glass capillary viscometer are treated theoretically. These two correction factors interrelate closely and can not be separated with each other. The representative equation of glass capillary viscometer for measuring liquid viscosity may be written as
η/ρt=A~*-(B~*/t~2)-(C~*/t~4)
in which A*, B* and C* are instrumental constants. The numerical factor m of the kinetic energy correction term in the Poiseuille-Hagenbach equation is raised from the effect of adhering of liquids on the wall of the viscometer and may be represented by
m=1+(C~*/B~*t~2)
Therefore, the fact of ascending m with increasing Reynold number will be explained. Equations for calculating the relative viscosity of polymer solution and method for determining the instrumental constants are given.
1986, 2(04): 356-362
doi: 10.3866/PKU.WHXB19860415
Abstract:
Influence of added salts on the conformation of 6,10 Br ionene polymer has been examined by viscometry. Molecular dimensions of 6,10 Br in aqueous KBr solutions for the range between 0 to 0.4 mol L~(-1) were calculated. Results showed that corresponding changes had taken placed in four parameters which indicated the long-range interactions: the Huggins constant K' increased the Mark-Houwink exponent a decreased until approximated to 0.5, the solvent-polymer interaction parameter B reduced nearly to zero, and the expansion factor a decreased until approximated to unity when the concentration of KBr increased. These results showed that the 0.4 mol L~(-1) KBr aqueous solution was close to θ-condition. However, the parameters which related to the short-range effects (K_0 and the steric factor σ) did not appear to be affected by the concentration of added salt.
A conformational change was observed for 6,10Br from a swollen random coil in medium of low ionic strength to a compact random coil in medium of high ionic strength. The transition was interpreted in terms of simultaneous decrease in electrostatic repulsion and an increase in hydrophobic attraction among the methyl groups. Since the former interaction was more sensitive to salts than the latter did, a break appeared in the curve of log [η] plotted against the salt concentration C_s....
Influence of added salts on the conformation of 6,10 Br ionene polymer has been examined by viscometry. Molecular dimensions of 6,10 Br in aqueous KBr solutions for the range between 0 to 0.4 mol L~(-1) were calculated. Results showed that corresponding changes had taken placed in four parameters which indicated the long-range interactions: the Huggins constant K' increased the Mark-Houwink exponent a decreased until approximated to 0.5, the solvent-polymer interaction parameter B reduced nearly to zero, and the expansion factor a decreased until approximated to unity when the concentration of KBr increased. These results showed that the 0.4 mol L~(-1) KBr aqueous solution was close to θ-condition. However, the parameters which related to the short-range effects (K_0 and the steric factor σ) did not appear to be affected by the concentration of added salt.
A conformational change was observed for 6,10Br from a swollen random coil in medium of low ionic strength to a compact random coil in medium of high ionic strength. The transition was interpreted in terms of simultaneous decrease in electrostatic repulsion and an increase in hydrophobic attraction among the methyl groups. Since the former interaction was more sensitive to salts than the latter did, a break appeared in the curve of log [η] plotted against the salt concentration C_s....
1986, 2(04): 363-370
doi: 10.3866/PKU.WHXB19860416
Abstract:
The esterification rate constants of the acetic acid with the methanol and ethanol at various temperatures were determined by the flow microcalorimetry, while with the help of Arrhenius relation the activation energies of these reactions were determined.
In order to check the reliability of method, the hydrolysis (reversal reaction of esterification) rate constants of methyl and ethyl acetates were determined, the results of experiments are consistent with results of calculation from the data of esterification experiments.
The esterification rate constants of the acetic acid with the methanol and ethanol at various temperatures were determined by the flow microcalorimetry, while with the help of Arrhenius relation the activation energies of these reactions were determined.
In order to check the reliability of method, the hydrolysis (reversal reaction of esterification) rate constants of methyl and ethyl acetates were determined, the results of experiments are consistent with results of calculation from the data of esterification experiments.
1986, 2(04): 371-381
doi: 10.3866/PKU.WHXB19860417
Abstract:
Ion dip spectroscopy, a folded OODR process with ion detection, has hitherto only been applied to the study of high-lying vibrational levels of ground state polyatomics. We have succeeded in employing this technique to obtain rotationally resolved spectra of NH_3Ã_1A_2″, a fast predissociating species. Conceivably, the method can be generalized to deal with a large number of other predissociating species.
We first obtain high resolution REMPI spectra of C′←X transition via a 3+1 photon scheme by scanning a pulsed dye laser in the 430—480 nm. A sample spectrum of the 0-0 band is shown in Fig.1. Rotational constants B_0=10.80±0.01 cm~(-1) and C_0=5.23±0.01 cm~(-1) are obtained for the C′~A_1′v_2=0 level predissociation lifetimes are inferred from the rotational linewidth for the C′v_2′=0,1,2 levels. We then induce the C′→Ã stimulated emission by scanning a second dye laser from 560—580 nm while holding the first laser to a specific C′←X rovibronic transition. The competition between C′→A and the ionization process from C′ state results in the ion dip spectra shown in Fig.2. The rotational lines of C′→A 0-0, 1-1 and 2-2 bands are listed in Table 3. While selection rules allow Δv_2=0,±2,±4... transition, Franck-Condon factor favors Δv_2=0 only.
....
Ion dip spectroscopy, a folded OODR process with ion detection, has hitherto only been applied to the study of high-lying vibrational levels of ground state polyatomics. We have succeeded in employing this technique to obtain rotationally resolved spectra of NH_3Ã_1A_2″, a fast predissociating species. Conceivably, the method can be generalized to deal with a large number of other predissociating species.
We first obtain high resolution REMPI spectra of C′←X transition via a 3+1 photon scheme by scanning a pulsed dye laser in the 430—480 nm. A sample spectrum of the 0-0 band is shown in Fig.1. Rotational constants B_0=10.80±0.01 cm~(-1) and C_0=5.23±0.01 cm~(-1) are obtained for the C′~A_1′v_2=0 level predissociation lifetimes are inferred from the rotational linewidth for the C′v_2′=0,1,2 levels. We then induce the C′→Ã stimulated emission by scanning a second dye laser from 560—580 nm while holding the first laser to a specific C′←X rovibronic transition. The competition between C′→A and the ionization process from C′ state results in the ion dip spectra shown in Fig.2. The rotational lines of C′→A 0-0, 1-1 and 2-2 bands are listed in Table 3. While selection rules allow Δv_2=0,±2,±4... transition, Franck-Condon factor favors Δv_2=0 only.
....
