Enthalpy of Formation, Heat Capacity and Entropy of Melamine

Abstract

驻 c H 苓 m = (-2455.17依4.65)kJ•mol-1 ; 驻 f H 苓 m =(-763.38依5.16)kJ•mol-1 .ThebondenthalpyofC抑 N(betweensinglebondand doublebond)inmelaminewasthenestimatedtobe458.30kJ•mol-1 accordingtotheralationshipbetweenbond enthalpyandcombustionenthalpy.ThisvalueislargerthanthatofC-NbutsmallerthanthatofC襒N.Heatcapacity measurementswerecarriedoutinasmallsampleadiabaticcalorimeterfrom80to385K.Weobtained 驻 f H 苓 m at differenttemperaturesbetween80and385Kusingtheheatcapacitydata.Throughcalculationwiththevaluesofheat capacity,therelationshipbetweenthestandardmolarenthalpyofformationandtemperatureisalsopresentedasa functionalequation.Wealsomeasuredthethermolstabilityofmelaminebythethermogravimetry鄄differentialscanning calorimetry(TG鄄DSC)technique,whichshowedathermaldecompositionpeakat603.37KfortheDSCcurve.

Thermoelastic properties of deuterated melamine, C3N6D6, between 4.2–320 K at 5 kPa and between 0.1–5.0 GPa at 295 K from neutron powder diffraction and DFT calculations

“…S1 were implemented. In the first, Debye temperatures were obtained from fitting the measured specific heat of protiated melamine (Stephenson & Berets, 1952: Peng et al, 2009, yielding  D1 = 166 ± 5 K,  D2 = 413 ± 18 and  D3 = 1487 ± 11 K; these correspond to cut-off frequencies in the VDOS of 115 ± 4 cm −1 , 291 ± 12 cm −1 and 1034 ± 7 cm −1 respectively. Although the vibrational spectrum measured at 20 K by inelastic neutron spectroscopy (Fernández-Liencres et al, 2001) is more structured, one can discern groups of modes that correspond roughly with the cut-offs determined from the fitting…”

Calculation and Optimization of Molten Salt for Solar High Temperature Heat Storage

“…Ternary nitrate mixture (53%KNO 3 , 40%NaNO 2 , 7%NaNO 3 ) is used as major heat transfer and thermal storage material in temperature interval 180-500˚C. When the temperature is higher than 500˚C, the content of nitrite component will decrease because of oxidation of the salt in the air, which will lead to higher melting temperature and all kinds of operation faults [1]. The solar power generation and solar thermal chemical reaction need temperature as high as 600-800˚C [2].…”