ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of the Enthalpy and Entropy of Peritectic Reaction in the CaO Si0₂(CS)—2CaO Si0₂(C₂S)—2CaO Al₂0₃ Si0₂(C₂AS) System at the Equilibrium Temperature 1588 К

L. Kosa, I. Nerád, K. Adamkovičová, and E. Mikšíková

Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-842 36 Bratislava

Abstract: Inverse drop calorimetry performed in a SETARAM HTC 1800 K was used to measure the relative enthalpy value of the ternary peritectic melt (p.m.) in the CS-C₂S-C₂AS system at the temperature 1754 K with regard to the reference state of a mechanical mixture of β-C₂S, CS, and C₂AS crystals of corresponding composition at 298 K. The same method was applied to measure the relative enthalpy values of peritectic melt in the temperature interval 1624 K-1775 K with regard to the reference state of its glass at 298 K. From these data the temperature-independent value of specific heat capacity of the peritectic melt was determined: c_p(p.m.) = (1.8213 +/- 0.1318) J g^-1 K^-1. Using these quantities and the literature data of some enthalpic quantities for crystalline phases of compounds in the CS-C₂S-C₂AS system, the specific enthalpy of peritectic reaction (p.r.) in this system at equilibrium temperature 1588 K was determined: ∆_p.r.h(1588K) = (231 +/- 33) J g^-1. For determination of this quantity the material balance of peritectic reaction and the material balance of dissociation of C₃S₂ to β-C₂S and CS were also used.

Full paper in Portable Document Format: 526a725.pdf

Chemical Papers 52 (6) 725–730 (1998)