The exothermic phenomena in the mixture of sodium sulfide, carbon black, calcium oxide and iron powder in the air were investigated by means of x-ray diffraction, calorimetry, thermogravimetry and gas chromatography.
On the basis of these experimental results, the mechanism of the exothermic reaction in the mixture can be assumed as follows.
The oxidation of sodium sulfide was at first begun by air in the presence of carbon black and then, the water of crystallization in the compound was dehydrated at about 353K. The dehydrated water reacted with calcium oxide to form calcium hydroxide and the heat of reaction raised the temperature of the mixture. Iron powder reached to the combustible state at about 643K and successively changed to Fe₃O₄ and Fe₂O₃ while the exothermic reaction. Carbon black partly ignited and formed carbon monoxide and carbon dioxide. The carbon dioxide reacted to calcium oxide and formed calcium carbonate.
The mixture which consists of 18% sodium sulfide, 18% carbon black, 22% calcium oxide and 42% iron powder generated heat about 2.63kJg^-1.

View full abstract

The molar excess Gibbs energies G^E and molar excess volumes V^E for aqueous solutions of piperidine and pipecoline (2-methyl-piperidine) have been measured at 298.15K and 308.15K (G^E only) for the whole composition range by static and pyknometric methods. All the solutions exhibit positive deviation from ideality and volume contraction. An anomaly in vapor pressure (and G^E) vs. molar composition relation and a rapid decrease of partial molar volume of piperidines in dilute aqueous solution have been found and interpreted in terms of the dissociation of piperidines as weak organic electrolytes.

View full abstract

The recent basic studies by means of heat of solution measurement are reviewed. In this review, the solute-solvent interactions in organic non-electrolyte system under the normal pressure and temperature are mainly described. Contents are follows: 1. accuracy and standard systems, 2. the heat of solution of low molecular weight organic compounds, 3. the heat of solution of polymer liquids, 4. contribution terms in the heat of solution datum, 5. relation between direct and indirect measurements and 6. recent solution calorimeters.

View full abstract