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  • Equilibrium constant  (2)
  • Brassica napus  (1)
  • Springer  (3)
  • American Institute of Physics (AIP)
  • Ovid Technologies
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  • Springer  (3)
  • American Institute of Physics (AIP)
  • Ovid Technologies
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  • 1
    ISSN: 1572-8927
    Keywords: Equilibrium constant ; enthalpy change ; entropy change ; heat capacity change ; capacity change ; flow calorimetry ; high temperature ; hydrochloric acid ; acetic acid ; sodium acetate ; isocoulombic reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The aqueous reactions, {ie865-1} were studied as a function of ionic strength at 275, 300, and 320°C using a flow calorimetric technique. Log K, ΔH and ΔS values were determined from the fits of the calculated and experimental heats while ΔCp values were calculated from the variation of ΔH values with temperature. The log K and ΔH values for the first two reactions agree well with literature values at these temperatures. No previous results have been reported for the third reaction. The use of equations containing identical numbers of positive and identical numbers of negative charges on both sides of the equal sign (isocoulombic reaction principle) was applied to the log K values determined in this study. The resulting plots of log K for the isocoulombic reactions vs. I/T were approximately linear, which demonstrates that the ΔCp values for these reactions are approximately zero.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8927
    Keywords: Equilibrium constant ; enthalpy change ; entropy change ; heat ; capacity change ; flow calorimetry ; high temperature ; hydrogen sulfate ion and sodium sulfate ion formation ; isocoulombic effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The aqueous reactions, $$\begin{gathered} H^ + + SO_4^{2 - } = HSO_4^ - ,Na^ + + SO_4^{2 - } = NaSO_1^ - , \hfill \\ and H^ + + HSO_4^ - = H_2 SO_4 (aq) \hfill \\ \end{gathered} $$ were studied as a function of ionic strength(I) at 150, 175, 200, 250, 300 and 320°C using a flow calorimetric procedure. Log K, ΔH, ΔS and ΔC p values at I=0 were derived from the data at each temperature. Using these experimental values, equations describing log K, ΔH, ΔS and ΔC p at I=0 and temperatures from 150 to 320°C were derived for each system. The use of equations containing identical numbers of positive and identical numbers of negative charges on both sides of the equal sign (isocoulombic reaction principle) was evaluated as a technique for the extrapolation of log K values valid below 100°C to temperatures above 150°C. This evaluation indicated that the principle gives good estimates up to 320°C.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 181 (1996), S. 307-316 
    ISSN: 1573-5036
    Keywords: allelochemicals ; Brassica napus ; germination ; glucosinolates ; isothiocyanates ; rapeseed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Enzymatic hydrolysis of glucosinolates, a class of compounds found in Brassica species, results in a number of products with potential to inhibit seed germination. To investigate the impact of both volatile and water-soluble allelochemicals, germination bioassays using Lactuca sativa seeds were conducted with root and combined leaf and stem tissues of Brassica napus. Tissues in which glucosinolates were hydrolyzed to remove volatile glucosinolate degradation products were compared with intact tissues and water controls. Only tissues containing glucosinolates produced volatiles that inhibited germination. Volatiles were trapped and identified using GC-MS. Volatiles produced in greater quanitity from intact tissues than from tissues without glucosinolates were almost exclusively glucosinolate hydrolysis products. Water-soluble components also inhibited germination. Chemical analysis of extracts confirmed the presence of glucosinolate hydrolysis products, but indicated the involvement of additional allelochemicals, especially in leaf and stem tissues. Results support the proposal that glucosinolate-containing plant tissues may contribute to reductions in synthetic pesticide use if weed seeds are targeted.
    Type of Medium: Electronic Resource
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