The nitrogen pentoxide dissociation equilibrium

1994 ◽  
Vol 26 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Huw O. Pritchard
Keyword(s):  
Dissociation Equilibrium ◽  
Nitrogen Pentoxide

Optimal Duration of the Preincubation Phase in Enzyme Inhibition Experiments

2020 ◽  
Author(s):  
Petr Kuzmic
Keyword(s):  
Enzyme Inhibition ◽  
Dose Response ◽  
Enzyme Inhibitor ◽  
Single Point ◽  
Association Rate ◽  
Weakly Bound ◽  
Inhibitor Complex ◽  
Dissociation Equilibrium ◽  
Optimal Duration ◽  
Algebraic Formula

This report describes an algebraic formula to calculate the optimal duration of the pre-incubation phase in enzyme-inhibition experiments, based on the assumed range of expected values for the dissociation equilibrium constant of the enzyme–inhibitor complex and for the bimolecular association rate constant. Three typical experimental scenarios are treated, namely, (1) single-point primary screening at relatively high inhibitor concentrations; (2) dose-response secondary screening of relatively weakly bound inhibitors; (3) dose-response screening of tightly-bound inhibitors.

THE DECOMPOSITION OF NITROGEN PENTOXIDE IN THE PRESENCE OF FOREIGN GASES

1927 ◽  
Vol 49 (5) ◽  
pp. 1257-1269 ◽  
Author(s):  
Warren F. Busse ◽  
Farrington Daniels
Keyword(s):  
Nitrogen Pentoxide

Four Mechanisms Involving Nitrogen Pentoxide

1951 ◽  
Vol 73 (10) ◽  
pp. 4542-4546 ◽  
Author(s):  
Harold S. Johnston
Keyword(s):  
Nitrogen Pentoxide

Mucosal gastrin receptor. III. Regulation by gastrin

1980 ◽  
Vol 238 (2) ◽  
pp. G135-G140 ◽  
Author(s):  
K. Takeuchi ◽  
G. R. Speir ◽  
L. R. Johnson
Keyword(s):  
Serum Gastrin ◽  
Binding Capacity ◽  
Specific Binding ◽  
Equilibrium Constants ◽  
Biological Response ◽  
Liquid Diet ◽  
Regulatory Process ◽  
Membrane Preparation ◽  
Gastrin Receptor ◽  
Dissociation Equilibrium

Specific binding of 125I-labeled gastrin to rat gastric mucosal membranes was found to vary with serum gastrin levels. The dissociation equilibrium constants were not significantly different between receptor preparations. However, the binding capacities of the membrane preparations were directly correlated with serum gastrin levels. Fasting, feeding a liquid diet, and antrectomy significantly decreased serum gastrin and the concentrations of the gastrin receptor. Treatment of fasted and liquid-fed animals with pentagastrin prevented the decrease in receptors. Vagotomy increased both binding capacity and serum gastrin levels. These data indicate that gastrin stimulates the production of its own receptor. The upregulation of the gastrin receptor was evident if the binding capacity was expressed per milligram of protein, per microgram of DNA, or per amount of 125I-labeled choleragen bound to the same membrane preparation. This indicates that the biological response to gastrin is controlled in part by the regulation of the number of gastrin receptors present and that gastrin plays a role in this regulatory process.

TITRATIONS OF ORGANIC SOILS WITH STANDARD BASE: SOLUBILITY OF IONIZABLE FUNCTIONAL GROUPS AT 25 °C

1989 ◽  
Vol 69 (2) ◽  
pp. 313-325 ◽  
Author(s):  
DONALD S. GAMBLE
Keyword(s):  
Functional Groups ◽  
External Solution ◽  
Organic Soil ◽  
Organic Soils ◽  
Total Acid ◽  
Dissociation Equilibrium ◽  
Carboxylate Anions ◽  
Data Production ◽  
Standard Base ◽  
Automatic Titrator

The conversion of undissolved acidic functional groups into dissolved carboxylate anions has been monitored during potentiometric titration of a Typic Mesisol Peat at 25 °C. The analytical chemical calculations of total acid functional groups and of H+ dissociation equilibrium functions take the dissolution process into account. With 0.05 g of sample suspended in 20 mL of 0.1 N NaCl, the molarity of carboxylate anions in the external solution ranged from 4.3 × 10−4 M at 1 mL g−1 0.1 N NaOH, to 1.5 × 10−3 M at 6 mL g−1 0.1 N NaOH. The corresponding amounts of undissolved carboxyl groups were 5.2 × 10−4 and 1.0 × 10−4 mol g−1. Differential acid constants (KGA) for the undissolved carboxyls were 7.6 × 10−4 (σ 1.4 × 10−4) for αG < 0.02 (0.016 – 0.02) and 1.4 × 10−5 (σ 0.04 × 10−5) for αG > 0.026 (0.026 – 0.60). A substantial increase in productivity was achieved by means of an automatic titrator and a microcomputer with spreadsheet software. Types of data production and processing that were previously labor intensive have now become much more practical. Key words: Organic soils, organic matter solubility, organic soil carboxyls, organic soil ion exchange, organic soil titration, pH dependent solubility

scholarly journals The thermal decomposition of nitrogen pentoxide at low pressures

1925 ◽  
Vol 109 (751) ◽  
pp. 526-540 ◽  
Keyword(s):  
Thermal Decomposition ◽  
The Other ◽  
Nitrogen Tetroxide ◽  
Nitrogen Pentoxide ◽  
Other Hand ◽  
Rate Of Reaction ◽  
Reaction Proceeds ◽  
Products Of Reaction ◽  
Glass Surfaces ◽  
Low Pressures

Unimolecular reactions possess a unique interest in that, as Perrin (‘Ann. Physique,’ vol. 11, p. 5, 1919) first pointed out, for the occurrence of such, some type of interaction between radiation and matter must take place. Although such reactions appear to be extremely rare, many physical processes such as evaporation, ionisation in gases at high temperatures and radio-active decay, proceed at rates conforming to a unimolecular law; true chemical reactions which are definitely unimolecular and not pseudo-unimolecular in character are, on the other hand, stated by many ( e. g ., Lowry, ‘Trans. Farad. Soc.,’ vol. 17, p. 596 (1922) ) to be non-existent. In order to substantiate this statement, it is clearly necessary to prove the more complex character of any reaction which satisfies the usual criteria of unimolecular change. The thermal decomposition of gaseous nitrogen pentoxide apparently fulfils these conditions, for Daniels and Johnston (‘J. Am. C. S.,’ vol. 43, p. 53 (1921)) showed that the reaction proceeded according to a unimolecular law over wide ranges of variation of pressure, and Lueck ( ibid ., vol. 44, p. 757 (1922)) obtained practically identical unimolecular constants for the decomposition in solution in carbon tetrachloride and chloroform. On the other hand, Daniels, Wulf and Karrer ( ibid ., vol. 44, p. 2402 (1922) ) suspected the reaction to be autocatalytic, owing to the apparent retardation of the reaction velocity in the presence of ozone, but the experiments of one of us (Hirst, ‘J. C. S.,’ vol. 127, p. 657 (1925), and of White and Tolman (‘J. Am. C. S.’ vol. 47, p. 1,240 (1925)) proved this to be erroneous. In addition, it has been shown that the reaction proceeds uniformly according to the unimolecular law even in the presence of extensive glass surfaces, or of gases which may be either indifferent, such as argon and nitrogen, or the products of reaction, such as nitrogen tetroxide or dioxide or oxygen. The rate of reaction may be expressed in the form - d C/ dt = 4·98 × 10 13 e -24.700/RT . C. Attempts have been made to interpret the experimental results on the hypothesis that the reaction is in reality bimolecular, and only apparently unimolecular in character; but owing to the abnormally large value of the energy of activation, namely, 24,700 calories per gram. molecule, the number of molecules which could be activated per second by inelastic collision, calculated according to the kinetic theory, falls far short of the observed reaction rate, being, in fact, some 10 5 times smaller.

Correlation Between Reduced Mass and Gibbs Energy Change of Reaction

2021 ◽  
Author(s):  
Masatoshi Kawashima
Keyword(s):  
Gibbs Energy ◽  
Bond Formation ◽  
Energy Change ◽  
Gibbs Energy Change ◽  
Positive Direction ◽  
Dissociation Equilibrium ◽  
Equilibrium Reactions ◽  
The Relationship ◽  
Good Agreement ◽  
Bond Formation Reactions

<p>The correlation between the Gibbs free energy change of reaction and the reduced mass was clarified. In the case of bond formation reactions, the computed Gibbs energy change of reaction increased in the positive direction as the reduced mass increased. In the case of dissociation equilibrium reactions, such as the dissociation of tetrahedral carbonyl addition compound, the computed Gibbs energy change of reaction also increased in the positive direction as the reducing mass increased, but the extent of the change was smaller than in the case of bond formation reactions. The results were in good agreement with those derived from the relationship between yield and reduced mass, indicating that was originated from the correlation between the Gibbs energy change and the reduced mass.</p>

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