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  • 1 St. Petersburg State Polytechnic University Department of Analytical Chemistry St. Petersburg 195251 Russia
  • | 2 Institute of Silicate Chemistry Laboratory of Physics and Chemistry of Nanosized Systems St. Petersburg 199155 Russia
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Abstract  

It has been shown that the exothermic decomposition of KMnO4 in vacuum is accompanied by a significant self-heating effect. It manifests itself in the reduction of the molar enthalpy of the reaction, determined by the third-law method. In comparison with the value 138.3±0.6 kJ mol−1 that is valid for the decomposition of KMnO4 under atmospheric pressure at 493–553 K, the molar enthalpy in vacuum (10−4-10−7 bar) at 484–511 K varies in the range of 136 to 126 kJ mol−1. This is related to the reduction of the thermal conductivity of residual air in the furnace and, as a result, to the self-heating of the reactant, that accelerates the exothermic reaction. A simple method of evaluation of the self-heating effect has been developed. By analogy with the known method for evaluation of the self-cooling effect, it is based on the determination of the molar enthalpy by the third-law method at two different temperatures. The increase of sample temperature above the furnace temperature Tf in the case of the exothermic decomposition of KMnO4 in a high vacuum and Tf≥490 K reaches a few tens of degrees.

Manuscript Submission: HERE

  • Impact Factor (2019): 2.731
  • Scimago Journal Rank (2019): 0.415
  • SJR Hirsch-Index (2019): 87
  • SJR Quartile Score (2019): Q3 Condensed Matter Physics
  • SJR Quartile Score (2019): Q3 Physical and Theoretical Chemistry
  • Impact Factor (2018): 2.471
  • Scimago Journal Rank (2018): 0.634
  • SJR Hirsch-Index (2018): 78
  • SJR Quartile Score (2018): Q2 Condensed Matter Physics
  • SJR Quartile Score (2018): Q2 Physical and Theoretical Chemistry

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Journal of Thermal Analysis and Calorimetry
Language English
Size A4
Year of
Foundation
1969
Volumes
per Year
4
Issues
per Year
24
Founder Akadémiai Kiadó
Founder's
Address
H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address
H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher
Chief Executive Officer, Akadémiai Kiadó
ISSN 1388-6150 (Print)
ISSN 1588-2926 (Online)