Elektrometrische Untersuchungen über die Geschwindigkeit der Bildung von Cu2S in ammoniakalischen Lösungen von Cu+-Ionen mittels Thioacetamid, 4. Mitt.

Quantitative studies of the rate of Cu₂S-formation by thioacetamide (TAA) were made with the help of the polarographic method of continuous registration at constant potential, and the following equation for the reaction rate between Cu⁺-ions andTAA in ammoniacal solutions was derived: 1 $$ - \frac{{d[Cu^I ]}}{{dt}} = k \cdot \frac{{[Cu^I ] \cdot [CH_3 CSNH_2 ]}}{{[NH_3 H_2 O]^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}} \cdot [H^ + ]}}\frac{{^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 4}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$4$}}} }}{{^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 {10}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${10}$}}} }} \cdot \frac{{f_{Cu} }}{{f_{H^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 {10}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${10}$}}} } }}$$ The value at 25.0° of the rate constantk is (1.6±0.2)·10^?2 mole^7/20·litre^?7/20·sec^?1. The validity of equation (1) has been proved over the pH range 8.5–9.5 and the ammonia concentration of 4.0·10^?2–4.0·10^?1 mole per litre, by only a small excess ofTAA and moderate reaction rates.     

Kinetik und Mechanismus der Oxydation von 1,2,4,5-Tetramethylbenzol in essigsaurem Medium

The liquid phase oxidation of 1.2.4.5-tetramethylbenzene catalysed by cobaltous acetate and promoted by KBr in acetic acid was kinetically studied. In view of deriving the kinetic equation for the absorption of oxygen, a number of experiments were carried out. The values of the activation energy and of the preexponentA=10¹⁴ were determined as well. The resulting kinetic equation: $$ - \frac{{d\left[ {O_2 } \right]}}{{d\tau }} = 10^{14} \cdot \exp \left( { - \frac{{84,460 \times 10^3 }}{{RT}}} \right) \cdot C_{C_6 H_2 (CH_3 )_4 }^{0,5} \cdot C_{Co(OAc)_2 }^{0,5} \cdot C_{KBr}^{0,5} $$ is in accordance with the theoretically derived expression of this type.     

Elektrometrische Untersuchungen über die Ag2S-Bildungsgeschwindigkeit in ammoniakalischen Lösungen von Ag+-Ionen mittels Thioacetamid, 5. Mitt.

On basis of polarographic method of continuous registration at constant potential, the quantitative investigation of the rate of Ag₂S formation by thioacetamide (TAA) was performed and, the following equation for the reaction rate between Ag⁺-ions andTAA in ammoniacal solutions has been derived: 1 $$ - \frac{{d[Ag^I ]}}{{d t}} = k \cdot \frac{{[Ag^I ] \cdot [CH_3 CSNH_2 ]^{1/4} }}{{[H^ + ]^{1/10} }} \cdot \frac{{fAg}}{{f_H^{1/10} }}$$ The value, at 25.0^o, of the rate constantk is (6.8±0.4)· ·10^?2 mole^?3/20·litre^3/20·sec^?1. The validity of equation (1) has been proved over the pH range 8.3–10.8 and the ammonia concentration of 5.6·10^?2–1.0 mole per litre, by only a small excess ofTAA and moderate reaction rates.     

Electron capture by protons from theK-shell of H and Ar

Whenever a collision takes place between charged particles, the first Born approximation for electron capture from hydrogenlike ions (Z _T ,e) by a bare nucleusZ _P , must be modified in order to account for the long-range Coulomb effects. One of the simplest ways to fulfill this requirement is provided by theT-matrix of the following form: $$T_{if}^{(1)} = \left\langle {\Phi _f exp\left\{ { - i\frac{{Z_T (Z_p - 1)}}{\upsilon } ln (\upsilon R + v \cdot R)} \right\}\left| {\frac{{Z_P }}{R} - \frac{{Z_P }}{{r_P }}} \right| exp\left\{ {i\frac{{Z_P (Z_T - 1)}}{\upsilon } ln (\upsilon R + v \cdot R)} \right\}\Phi _i } \right\rangle $$ where Φ's are the usual unperturbed channel states andZ's are the nuclear charges. In this transition amplitude, both initial and final scattering states satisfy the correct asymptotic boundary conditions in their respective channels. In the present paper, detailed computation of theK-shell cross sections is carried out for charge exchange in H⁺-H and H⁺-Ar collisions. The results are in good agreement with experimental data.     

Bemerkung zur Rayleigh-Schrödinger-Störungstheorie

The time-independent Hamiltonians ? ₀ and ?=? ₀ + V have a discrete spectrum, eigenvalues, and eigenvectors E _s ^(o) , ¦s〉^(o) resp. E _s, ¦s〉. If the RS perturbation theory can be applied here then an operator \(\mathfrak{p}\) with the property $$\left| s \right\rangle ^{(n + 1)} = \frac{1}{{n + 1}}\mathfrak{p}\left| s \right\rangle ^{(n)} , E_s^{(n + 1)} = \frac{1}{{n + 1}}\mathfrak{p}E_s^{(n)} $$ exists where ¦s〉⁽ⁿ⁾ and E _s ⁽ⁿ⁾ denote the n-th order corrections of perturbation theory if E _s ^(o) is nondegenerate. In the case of degeneracy the operation \(\mathfrak{p}\) remains defined and can always be used todetermine perturbation corrections of quantum mechanical expressions which are invariant in zerothorder under transformations of the basis in degenerate subspaces of ? ₀. The equations $$\left| s \right\rangle = \sum\limits_n^{0,\infty } {\left| s \right\rangle ^{(n)} = e^\mathfrak{p} \left| s \right\rangle ^{(0)} } , E_s = \sum\limits_n^{0,\infty } {E_s^{(n)} } = e^\mathfrak{p} E_s^{(0)} $$ correspond to a basis transformation where nondegenerate eigenvectors ¦s∝> ^(o) and eigenvalues E _s ^(o) of ? ₀ transform into eigenvectors ¦s∝> and eigenvalues E _s of ?. Examples show the usefulness of this formulation.     

Phase transitions and thermodynamic properties of anhydrous caffeine

Caffeine has been found to display a low-temperatureβ- and a high-temperatureα-modification. By quantitative DTA the following data were determined: transformation temperature 141±2°; enthalpy of transition 4.03±0.1 kJ·mole^?1; enthalpy of fusion 21.6±0.5 kJ·mole^?1; molar heat capacity $$\begin{array}{*{20}c} {{\vartheta \mathord{\left/ {\vphantom {\vartheta {^\circ C}}} \right. \kern-\nulldelimiterspace} {^\circ C}}} & {100(\beta )} & {100(\alpha )} & {150(\alpha )} & {100(\alpha )} \\ {{{C^\circ _\mathfrak{p} } \mathord{\left/ {\vphantom {{C^\circ _\mathfrak{p} } {J \cdot K^{ - 1} \cdot mole^{ - 1} }}} \right. \kern-\nulldelimiterspace} {J \cdot K^{ - 1} \cdot mole^{ - 1} }}} & {271 \pm 9} & {287 \pm 10} & {309 \pm 11} & {338 \pm 10} \\ \end{array} $$ in good accord with drop-calorimetric data. For the constants of the equation log (p/Pa)=?A/T+B, static vapour pressure measurements on liquid and solidα-caffeine, and effusion measurements on solidβ-caffeine yielded: $$\begin{array}{*{20}c} {A = 3918 \pm 37; 5223 \pm 28; 5781 \pm 35K^{ - 1} } \\ {B = 11.143 \pm 0.072; 13.697 \pm 0.057; 15.031 \pm 0.113} \\ \end{array} $$ . The evaporation coefficient ofβ-caffeine is 0.17±0.03.     

Auswertung von EMK-Messungen zur Bestimmung thermodynamischer Exzeßgrößen im System Silberchlorid—Lithiumchlorid

The partial molar excessGibbs energies \(\Delta \overline G _{AgCl}^E \) of AgCl in the binary system AgCl?LiCl have been measured over the entire composition range at temperatures between 923.15K and 1175.15K in steps of 50K, using the reversible formation cell $${{Ag\left( s \right)} \mathord{\left/ {\vphantom {{Ag\left( s \right)} {AgCl\left( l \right)}}} \right. \kern-\nulldelimiterspace} {AgCl\left( l \right)}}---LiCl\left( l \right)/C,Cl_2 $$ The measured \(\Delta \overline G _{AgCl}^E \) values were fitted by the use of theRedlich-Kister-Ansatz for thermodynamic excess functions. The evaluatedRedlich-Kister parameters have been used to calculate the molar excessGibbs energies ΔG ^E and the partial molar excessGibbs energies \(\Delta \overline G _{LiCl}^E \) of LiCl. From the temperature dependence of theRedlich-Kister parameters for ΔG ^E the partial and integral molar heats of mixing and excess entropies were calculated. For 1073 K and the mole fractionx=0.5 the following values were obtained: $$\Delta G^E = 2130\left[ {J mol^{ - 1} } \right], \Delta H^E = 1994\left[ {J mol^{ - 1} } \right], \Delta S^E = 0.127 \left[ {J mol^{ - 1} K^{ - 1} } \right]$$      

The mechanism of thermal decomposition of ionic oxalates

A mechanism for the thermal decomposition of ionic oxalates has been proposed on the basis of three quantitative relationships linking the quantitiesr _c/r _i (the ratio of the Pauling covalent radius and the cation radius of the metal atom in hexacoordination) andΣI _i (the sum of the ionization potentials of the metal atom in kJ mol^?1) with the onset oxalate decomposition temperature (T _d) (Eq. 1) the average C-C bond distance (¯d) (Eq. 2), and the activation energy of oxalate decomposition (E _a) (Eq. 3): (1) $$T_d = 516 - 1.4006\frac{{r_c }}{{r_i }}(\sum I_i )^{\frac{1}{2}}$$ (2) $$\bar d = 1.527 + 5.553 \times 10^{ - 6} \left( {122 - \frac{{r_c }}{{r_i }}(\sum I_i )^{\frac{1}{2}} } \right)^2$$ (3) $$E_a = 127 + 1.4853 \times 10^{ - 6} \left( {\left( {\frac{{r_c }}{{r_i }}} \right)^2 \sum I_i - 9800} \right)^2$$ On the basis of these results it is proposed that the thermal decomposition of ionic oxalates follows a mechanism in which the C-O bond ruptures first. From Eq. 3 it is further proposed that strong mutual electronic interactions between the oxalate and the cations restrict the essential electronic reorganization leading to the products, thereby increasingE _a.     

Stable-isotope dilution activation analysis,and determination of Ca,Zn and Ce by means of photon activation

As a new method, stable-isotope dilution activation analysis has been developed. When an element consists of at least two stable isotopes which are converted easily to the radioactive nuclides through nuclear reactions, the total amount of the element (xg) can be determined by irradiating simultaneously the duplicated sample containing small amounts of either enriched isotope (y g), and by using the following equation. $${{x = y\left( {{M \mathord{\left/ {\vphantom {M {M*}}} \right. \kern-\nulldelimiterspace} {M*}}} \right)\left[ {\left( {{{R*} \mathord{\left/ {\vphantom {{R*} R}} \right. \kern-\nulldelimiterspace} R}} \right)\left( {{{\theta _2^* } \mathord{\left/ {\vphantom {{\theta _2^* } {\theta _2 }}} \right. \kern-\nulldelimiterspace} {\theta _2 }}} \right) - \left( {{{\theta _1^* } \mathord{\left/ {\vphantom {{\theta _1^* } {\theta _1 }}} \right. \kern-\nulldelimiterspace} {\theta _1 }}} \right)} \right]} \mathord{\left/ {\vphantom {{x = y\left( {{M \mathord{\left/ {\vphantom {M {M*}}} \right. \kern-\nulldelimiterspace} {M*}}} \right)\left[ {\left( {{{R*} \mathord{\left/ {\vphantom {{R*} R}} \right. \kern-\nulldelimiterspace} R}} \right)\left( {{{\theta _2^* } \mathord{\left/ {\vphantom {{\theta _2^* } {\theta _2 }}} \right. \kern-\nulldelimiterspace} {\theta _2 }}} \right) - \left( {{{\theta _1^* } \mathord{\left/ {\vphantom {{\theta _1^* } {\theta _1 }}} \right. \kern-\nulldelimiterspace} {\theta _1 }}} \right)} \right]} {\left[ {1 - \left( {{{R*} \mathord{\left/ {\vphantom {{R*} R}} \right. \kern-\nulldelimiterspace} R}} \right)} \right]}}} \right. \kern-\nulldelimiterspace} {\left[ {1 - \left( {{{R*} \mathord{\left/ {\vphantom {{R*} R}} \right. \kern-\nulldelimiterspace} R}} \right)} \right]}}$$ Where M and M^* are atomic weights of the element to be determined and the enriched isotope used as a spike,θ ₁ andθ ₂ are natural abundances of two stable isotopes in the element,θ ₁ ^* andθ ₂ ^* are isotopic compositions of the above isotopes in the enriched isotope, and R and R^* are counting ratios of gamma-rays emitted by two radionuclides produced in the sample and the isotopic mixture. Neither calibration standard nor correction of irradiation conditions are necessary for this method. Usefulness of the present method was verified by photon activations of Ca, Zn and Ce using isotopically enriched⁴⁸ca,⁶⁸Zn and¹⁴²Ce.     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The solvent extraction of Yb(III) and Ho(III) by 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous-methanol phase has been studied as a function ofpH ^× and the concentration ofPAN or methanol (MeOH) in the organic phase. When the aqueous phase contains above ～25%v/v of methanol the synergistic effect was increased. The equation for the extraction reaction has been suggested as: $$\begin{gathered} Ln(H_2 0)_{m(p)}^{3 + } + 3 HL_{(o)} + t MeOH_{(o)} \mathop \rightleftharpoons \limits^{K_{ex} } \hfill \\ LnL_3 (MeOH)_{t(o)} + 3 H_{(p)}^ + + m H_2 0 \hfill \\ \end{gathered} $$ where:Ln ³⁺=Yb, Ho; $$\begin{gathered} t = 3 for C_{MeOH in.} \varepsilon \left( { \sim 25 - 50} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon }; \hfill \\ t = 0 for C_{MeOH in.} \varepsilon \left( { \sim 5 - 25} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon } \hfill \\ \end{gathered} $$ . The extraction equilibrium constants (K _ex ) and the two-phase stability constants (β ₃ ^× ) for theLnL ₃(MeOH)₃ complexes have been evaluated.     

Kinetic studies on the formation ofN-nitroso compounds. IV. Formation of mononitrosopiperazine and general discussion ofN-nitrosation mechanisms in aqueous perchloric solution

The mechanism of formation ofN-nitroso compounds, which are considered as potential chemical carcinogens was studied. The kinetics of nitrosation of piperazine (PIP) in aqueous solution of perchloric acid have been investigated using a differential spectrophotometric technique. Based on our experimental results, the following rate law, in thepH-range 0.85 4.36, is proposed: $$v_0 = \left[ {nitrite} \right]_0 2 \left[ {PIP} \right]_0 /\left( {1 + f/\left[ {H^ + } \right]} \right)^2 \left( {g \left[ {PIP} \right]_0 + h + j\left[ {H^ \div } \right]} \right)$$ where [nitrite]₀ and [PIP]₀ represent initial stoichiometric concentrations. At 298.2K and μ=1.0M,f=(1.17±0.11) 10^?3 M,g=(3.5±0.7) 10^?2 M s,h=2.6×10^?6 M ² s andj=(0.95±0.04)M s. When the acidity is increased ([HClO₄]≥1M), a new kinetic term comes into play: $$v_0 ' = p\left[ {nitrite} \right]_0 \left[ {PIP} \right]_0 $$ At 298.2 K and μ=3.0M,p=(1.9±0.2) 10^?3 M ^?1 s^?1. A general mechanism for the nitrosation of anyN-nitrosable substrate in aqueous perchloric solution in which the only nitrosating agents are N₂O₃ and H₂NO₂ ⁺/NO⁺ is proposed. Also, the various particularities of this mechanism, according to thepK of theN-nitrosable substrate, are discussed.     

Berechnung der Madelungkonstante von Aragonit

Madelung's coefficientM _a of aragonite has been calculated considering the non-spherical shape of the CO ₃ ^2? -ions. As a result of the multipole expansionM _a has been found as a function of the C?O-distanced and the charge on the oxygen atomq _o to:

$$\begin{gathered} M_a = \frac{1}{4}\left\{ {10,4446---\left[ {0,65849 + \sum\limits_{n = 1}^{10} {A_n \left( {\frac{{d---0,8}}{a}} \right)^n } } \right]} \right\} \cdot q_o \hfill \\ \left. \begin{gathered} \hfill \\ ---\left[ {0,11066 + \sum\limits_{n = 1}^{12} {B_n \left( {\frac{{d---0,8}}{a}} \right)} ^n } \right] \cdot q_o^2 \hfill \\ \end{gathered} \right\}. \hfill \\ \end{gathered}$$     

Half-width and asymmetry of glow peaks and their consistent analytical representation

The kinetic equation which describes many electronic as well as atomic or chemical reactions under the condition of a steadily linear raise of the temperature, is considered in a mathematically exact and straightforward way. Therefore, the equation has been transformed into a dimensionsless form, using with profit the maximum condition for the intensity peak. The two temperatures T₁ and T₂, corresponding to the half-height of the intensity peak, are found as unique polynomials of the small argument \(\bar y \equiv {{k\bar T} \mathord{\left/ {\vphantom {{k\bar T} E}} \right. \kern-0em} E}\) only ( \(\bar T\) =temperature of peak maximum). Thereupon, further combinations give half-widthδ, peak asymmetryA=δ₂/δ₁ or \(\tilde A = {{\bar C} \mathord{\left/ {\vphantom {{\bar C} {(1 - \bar C)}}} \right. \kern-0em} {(1 - \bar C)}}\) and the maximum of the intensity peakJ; they again all depend only on¯y. In some cases this dependence is weak, so that e.g. it is deduced that the half-width energy product divided by \(\bar T^2 \) is an invariant, different for every kinetic orderπ: $$\frac{{\delta \cdot E[eV]}}{{\bar T^2 }} = \left\{ {\begin{array}{*{20}c} {{1 \mathord{\left/ {\vphantom {1 {4998 K for monomolecular process}}} \right. \kern-\nulldelimiterspace} {4998 K for monomolecular process}}} \\ {{1 \mathord{\left/ {\vphantom {1 {3542 K for bimolecular process}}} \right. \kern-\nulldelimiterspace} {3542 K for bimolecular process}}} \\ {{1 \mathord{\left/ {\vphantom {1 {2872 K for trimolecular process}}} \right. \kern-\nulldelimiterspace} {2872 K for trimolecular process}}} \\ \end{array} } \right.$$ By means of these correlations, activation energy valuesE [eV] can be determined accurately to within 0.5 %, so that for most experiments the inaccuracy of theδ values becomes dominant and limiting. A special nomogram for the express estimation ofE from experimentally observedδ and \(\bar T\) is demonstrated.     

Relation générale entre l'indice de liaison et la distance interatomique dans les molécules conjuguées,planes et linéaires

Two general relation between bond orderl and bond distance d (Å) are proposed:

1. between atomssp ₂-hybridised of second and third row: $$d_{PQ} = \left[ {0,731 + 0,3181\left( {n_P + n_Q } \right) - 0,1477\left( {\zeta _P + \zeta _Q } \right)} \right] - 0,020 + 0,0523\left( {\zeta _P + \zeta _Q } \right)l_{PQ} $$ ,ζ=Z/n,Z=Slater's effective nuclear charge of theπ-orbital).
2. between atomssp-hybridised of the second row: $$d_{PQ} = \left[ {1,904 - 0,123\left( {\zeta _P + \zeta _Q } \right)} \right] - \left[ {0,075 + 0,023\left( {\zeta _P + \zeta _Q } \right)} \right]l_{PQ} $$ (l=total bond orderπ+π′).

     

Löslichkeit von Nickel-Zink-Ferriten in Säuren

Dissolution of zinc and nickel ferrites were previously found^2,3 to conform to the equations: $$\frac{{dx}}{{dt}} = ks_0 \left( {1 - x} \right)^3 K = \frac{1}{t}\left[ {\frac{1}{{\left( {1 - x} \right)^2 }} - 1} \right]$$ x-solubility (%),t=time (min),s ₀=initial specific surface (m ²·g^?1),k-rate constant independent of specific surface,K=apparent rate constant dependent on specific surface (min^?1). The aim of this work was to check the applicability of these equations to the dissolution of nickel—zinc ferrites. The experimental results obtained for 3 mixed ferrites (Ni_0.3Zn_0.7Fe₂O₄, Ni_0.5Zn_0.5Fe₂O₄, Ni_0.7Zn_0.3Fe₂O₄) revealed that kinetics of their dissolution in HCl, HNO₃ and their mixtures also conform to the equations stated above.     

On some multiplicative product of kth derivative of Dirac's delta in x0+|x| and x0−|x|

In this paper we give a sense to the products $${{\left| x \right|^{(n - 2)/2} }} \cdot \frac{{\delta ^{(k - 1)} (x_0 + \left| x \right|)}} {{\left| x \right|^{(n - 2)/2} }}$$ and $\delta ^{(k - 1)} (x_0 - \left| x \right|) \cdot \delta ^{(k - 1)} (x_0 + \left| x \right|)$ . The first of them is a generalization of the product $${{\left| x \right|^{(n - 2)/2} }} \cdot \frac{{\delta (x_0 + \left| x \right|)}} {{\left| x \right|^{(n - 2)/2} }}{\text{ }}$$ given in [1, p. 158].     

Thermal analysis and kinetics of oxidation of molybdenum sulfides

The thermal oxidation process of stoichiometric MoS₂ and nonstoichiometric “Mo₂S₃”, together with the kinetics of oxidation of MoS₂, were studied by using TG and DTA techniques in the Po₂ range 1-0.0890 atm. MoS₂ was oxidized completely to MoO₃ in one step: $$MoS_2 + 7/2O_2 \to MoO_3 + 2SO_2 $$ Irrespective of Po₂ and the heating rate, “Mo₂S₃” was oxidized finally to MoO₃, via the following four steps: $$\begin{gathered} ''Mo_2 S_3 ''\xrightarrow{I}\gamma - Mo_4 O_{11(sur)} + ''Mo_2 S_3 ''\xrightarrow{{II}} \hfill \\ MoO_{2(sur)} + ''Mo_2 S_3 ''\xrightarrow{{III}}MoO_2 \xrightarrow{{IV}}MoO_3 \hfill \\ \end{gathered} $$ where (sur) refers to the surface layer. The kinetic study revealed that the oxidation (α=0.01?0.90) of MoS₂ to MoO₂ was controlled by the kinetics $$1 - (1 - \alpha )^{1/3} = kt$$ and that the apparent activation energies determined with the isothermal and the nonisothermal (10 deg min^?1) method were 98.1±2.2 and 93.5±3.0 kJ mol^?1, respectively, over the temperature range 540–625? and the Po₂ range 0.612-0.129 atm. The relationship between the rate constantk and Po₂ was determined.     

Thermodynamic studies on Pr2TeO6

The standard Gibbs energy of formation of Pr₂TeO₆ $ (\Updelta_{\text{f}} G^{^\circ } \left( {{ \Pr }_{ 2} {\text{TeO}}_{ 6} ,\;{\text{s}}} \right)) $ was derived from its vapour pressure in the temperature range of 1,400–1,480 K. The vapour pressure of TeO₂ (g) was measured by employing a thermogravimetry-based transpiration method. The temperature dependence of the vapour pressure of TeO₂ over the mixture Pr₂TeO₆ (s) + Pr₂O₃ (s) generated by the incongruent vapourization reaction, Pr₂TeO₆ (s) = Pr₂O₃ (s) + TeO₂ (g) + ½ O₂ (g) could be represented as: $ { \log }\left\{ {{{p\left( {{\text{TeO}}_{ 2} ,\;{\text{g}}} \right)} \mathord{\left/ {\vphantom {{p\left( {{\text{TeO}}_{ 2} ,\;{\text{g}}} \right)} {{\text{Pa}} \pm 0.0 4}}} \right. \kern-0em} {{\text{Pa}} \pm 0.0 4}}} \right\} = 19. 12- 27132\; \left({\rm{{{\text{K}}}}/T} \right) $ . The $ \Updelta_{\text{f}} G^{^\circ } \;\left( {{ \Pr }_{ 2} {\text{TeO}}_{ 6} } \right) $ could be represented by the relation $ \left\{ {{{\Updelta_{\text{f}} G^{^\circ } \left( {{ \Pr }_{ 2} {\text{TeO}}_{ 6} ,\;{\text{s}}} \right)} \mathord{\left/ {\vphantom {{\Updelta_{\text{f}} G^{^\circ } \left( {{ \Pr }_{ 2} {\text{TeO}}_{ 6} ,\;{\text{s}}} \right)} {\left( {{\text{kJ}}\,{\text{mol}}^{ - 1} } \right)}}} \right. \kern-0em} {\left( {{\text{kJ}}\,{\text{mol}}^{ - 1} } \right)}} \pm 5.0} \right\} = - 2 4 1 5. 1+ 0. 5 7 9 3\;\left(T/{\text{K}}\right) .$ Enthalpy increments of Pr₂TeO₆ were measured by drop calorimetry in the temperature range of 573–1,273 K and heat capacity, entropy and Gibbs energy functions were derived. The $ \Updelta_{\text{f}} H_{{298\;{\text{K}}}}^{^\circ } \;\left( {{ \Pr }_{ 2} {\text{TeO}}_{ 6} } \right) $ was found to be $ {{ - 2, 40 7. 8 \pm 2.0} \mathord{\left/ {\vphantom {{ - 2, 40 7. 8 \pm 2.0} {\left( {{\text{kJ}}\,{\text{mol}}^{ - 1} } \right)}}} \right. \kern-0em} {\left( {{\text{kJ}}\,{\text{mol}}^{ - 1} } \right)}} $ .     

Kinetic isotope effects for oxidation reaction of olefins by p-quinones in water-acetonitrile solutions of cationic and chloride anionic palladium complexes

Kinetic isotope effects for oxidation reactions of ethylene and cyclohexene in solutions of cationic palladium(ii) complexes in MeCN-H₂O(D₂O) systems, were measured. It was established that the ratio of the initial reaction rates ${{R_0^{H_2 O} } \mathord{\left/ {\vphantom {{R_0^{H_2 O} } {R_0^{D_2 O} }}} \right. \kern-0em} {R_0^{D_2 O} }} $ is equal to 1 for both reactions with the use of cationic complexes of the type Pd(MeCN) _x (H₂O)_4?x ²⁺, which differs from oxidation reactions catalyzed by chloride palladium complexes in the same solutions, where the ratio ${{R_0^{H_2 O} } \mathord{\left/ {\vphantom {{R_0^{H_2 O} } {R_0^{D_2 O} }}} \right. \kern-0em} {R_0^{D_2 O} }} $ = 5.0±0.16 and 4.73±0.14 at H⁺ molar fraction of 0.48 and 0.16, respectively (H⁺ molar fraction was calculated based on the sum of [H⁺] and [D⁺]).     

Dampfdruckmessungen an festem β-Mn und ZrMn2

Using theTorker-technique, the vapour pressures of β-Mn in the temperature range 1230–1370° K have been determined. From these measurements the heat of sublimation of α-Mn at 0° K has been obtained ΔH ₀ ^o=67800±800 cal/g-atom. From measurements of the dissociation pressures of ZrMn₂ the enthalpy ΔH ₀ ^o of the reaction. $${1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3} Zr (s) + {2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}Mn (g) = Zr_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}} Mn_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}} (s)$$ has been evaluated. ΔH ₀ ^o=?49150±700 cal/GFW. Combining this value with the heat of sublimation of α-Mn leads to the heat of formation of Zr_1/3Mn_2/3 ΔH ₀ ^o=?3900±1200 cal/GFW.