scholarly journals Thermochemistry of Eight Membered Ring Hydrocarbons. The Enthalpy of Formation of Cyclooctane

2001 ◽  
Vol 71 (3) ◽  
pp. 507-515
Author(s):  
Daniela Gheorghe ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Phase ◽  
Phase Change ◽  
Enthalpy Of Formation ◽  
Membered Ring ◽  
Heat Of Combustion ◽  
Enthalpies Of Formation ◽  
Scanning Calorimetry ◽  
Solid Liquid ◽  
The Enthalpy Of Formation

A new value of the enthalpy of formation of cyclooctane (-156.2�1.2 kJ mol-1) based on heat of combustion measurements is reported. Its solid - liquid phase change was investigated by differential scanning calorimetry in both directions revealing an overcooling effect of over 23 K. Our enthalpy of formation of cyclooctane was used together with literature values of heats of hydrogenation of 8 carbon atoms cycloolefins to calculate the enthalpies of formation of the later. The strain energies of the investigated molecules were calculated and discussed.

Solid-liquid phase equilibrium diagrams of binary mixtures containing fatty acids, fatty alcohol compounds and tripalmitin using differential scanning calorimetry

2019 ◽  
Vol 497 ◽  
pp. 19-32 ◽  
Author(s):  
Fernanda Paludetto Pelaquim ◽  
Flávio Cardoso de Matos ◽  
Lisandro Pavie Cardoso ◽  
Eduardo Augusto Caldas Batista ◽  
Antonio José de Almeida Meirelles ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Differential Scanning Calorimetry ◽  
Phase Equilibrium ◽  
Liquid Phase ◽  
Binary Mixtures ◽  
Fatty Alcohol ◽  
Scanning Calorimetry ◽  
Solid Liquid

Mixtures of d- and l-carvone: I. Differential scanning calorimetry and solid-liquid phase diagram

1996 ◽  
Vol 274 ◽  
pp. 231-242 ◽  
Author(s):  
H.E. Gallis ◽  
F. Bougrioua ◽  
H.A.J. Oonk ◽  
P.J. van Ekeren ◽  
J.C. van Miltenburg
Keyword(s):  
Phase Diagram ◽  
Differential Scanning Calorimetry ◽  
Liquid Phase ◽  
Scanning Calorimetry ◽  
Solid Liquid

Heat Capacity of K3LnCl6 Compounds with Ln = La, Ce, Pr, Nd

1999 ◽  
Vol 54 (3-4) ◽  
pp. 229-235 ◽  
Author(s):  
M. Gaune-Escard ◽  
L. Rycerz
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Liquid Phase ◽  
Temperature Dependence ◽  
Heat Capacities ◽  
Scanning Calorimetry ◽  
The Enthalpy Of Formation

The heat capacities of the solid and liquid K3LnCl6 compounds (Ln = La, Ce, Pr, Nd) have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. Their temperature dependence is discussed in terms of the phase transitions of these compounds as reported in literature. The heat capacity increases and decreases strongly in the vicinity of a phase transition but else varies smoothly. The Cp data were fitted by an equation which provides a satisfactory representation up to the temperatures of Cp discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained compare satisfactorily with these experimental data.

scholarly journals Voltammetric monitoring of a solid-liquid phase transition in N,N,N′,N′-tetraoctyl-2,6-diamino-9,10-anthraquinone (TODAQ)

2019 ◽  
Vol 24 (1) ◽  
pp. 11-16
Author(s):  
Sunyhik Ahn ◽  
Thomas R. Forder ◽  
Matthew D. Jones ◽  
Richard A. R. Blackburn ◽  
Paul S. Fordred ◽  
...  
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Liquid Phase ◽  
Apparent Activation Energy ◽  
Electrode Surface ◽  
Scanning Calorimetry ◽  
Liquid Phase Transition ◽  
Midpoint Potential ◽  
Solid Liquid

AbstractExploratory experiments on effects from a phase transition are reported for a low-melting microcrystalline anthraquinone (N,N,N′,N′-tetraoctyl-2,6-diamino-9,10-anthraquinone or TODAQ). Data for the solid-liquid phase transition are obtained by differential scanning calorimetry and then compared to data obtained by voltammetry. In preliminary electrochemical measurements, microcrystal deposits on a basal plane pyrolytic graphite electrode are shown to undergo a solid-state 2-electron 2-proton reduction in contact to aqueous 0.1 M HClO4 with a midpoint potential Emid,solid = − 0.24 V vs. SCE. The reduction mechanism is proposed to be limited mainly by the triple phase boundary line and some transport of TODAQ molecules towards the electrode surface for both solid and melt. A change in the apparent activation energy for this reduction is observed at 69 °C, leading to an enhanced increase in reduction current with midpoint potential Emid,liquid = − 0.36 V vs. SCE. A change of TODAQ transport along the crystal surface for solid microcrystalline material (for the solid) to diffusion within molten microdroplets (for the liquid) is proposed. Upon cooling, a transition at 60 °C back to a higher apparent activation energy is seen consistent with re-solidification of the molten phase at the electrode surface. Differential scanning calorimetry data for solid TODAQ dry and for TODAQ in contact to aqueous 0.1 M HClO4 confirm these transitions.

A low-temperature technique for measuring enthalpies of formation

1996 ◽  
Vol 11 (6) ◽  
pp. 1403-1409 ◽  
Author(s):  
T. P. Weihs ◽  
T. W. Barbee ◽  
M. A. Wall
Keyword(s):  
Low Temperature ◽  
Enthalpy Of Formation ◽  
Enthalpies Of Formation ◽  
Scanning Calorimetry ◽  
Free Standing ◽  
Metal Compounds ◽  
Si Substrates ◽  
Multilayer Foils ◽  
Formation Enthalpies ◽  
The Enthalpy Of Formation

A technique to accurately measure the formation enthalpies of transition metal compounds at relatively low temperatures using thick multilayer foils and differential scanning calorimetry is demonstrated. The enthalpy of formation of Cu51Zr14 was measured using 25 μm thick, free-standing Cu–Zr multilayer foils. The multilayers were deposited onto Si substrates using a planetary, magnetron source sputtering system. They were removed from their substrates, cut into 6 mm diameter specimens, and scanned in temperature from 50 °C to 725 °C in a differential scanning calorimeter. Three distinct exothermic reactions were systematically observed. The heats from the first two reactions were summed and then analyzed using a simple model that accounts for interfacial reactions and heat losses during deposition. The enthalpy of formation for Cu51Zr14 was measured to be 14.3 ± 0.3 kJ/mol. This quantity agrees with the single value of ΔHf = 14.07 ± 1.07 kJ/mol reported in the literature for this Cu–Zr compound. The advantages of measuring formation enthalpies using thick multilayer foils and low temperature calorimetry are discussed.

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