Heats of Formation of Manganomanganic Oxide and Manganese Dioxide¹

Assessment of the Mn-O system

“…44 combustion Ulich and Siemonsen [99] 1388. 55 solution Shomate [47] 1387.09 assessed Mah, [101] Zordan and Hepler [108] 1387. 51 assessed Robie and Waldbaum [104] 1388.…”

“…[20,26,33,36,40,42,44,45] 2.1.3 ␣-, ␤-Hausmannite (Mn 3 O 4 ), Pyrolusite (MnO 2 ), and Bixbyite (Mn 2 O 3 ). The question of the homogeneity range of ␣-and ␤-hausmannite has been investigated by a number of authors, some of whom declare haus- [26,29,[46][47][48] while others find differing degrees of nonstoichiometry. [15,16,27,39,41,[49][50][51][52] The most reliable and most recent investigation seems to be the one from Keller and Dieckmann, [53] who determined the maximum homogeneity range of Mn 3−␦ O 4 to be 0.5710 < x O < 0.5717, i.e., very small.…”

“…[47,90,[94][95][96][97][98][99][100] Additionally, the experimental data have been assessed and tabulated by a number of authors [72,[101][102][103][104][105][106][107][108] (Table 11). The following values, as quoted by Kubaschewski et al, [105] were used in the experimental data file: 384.9 kJ/mol for stoichiometric Mn 1 …”

Thermodynamic Assessment of the Fe-Mn-O System

“…The measured temperatures at which this transformation takes place varies between 1403 and 1473 K in air at 1 atmosphere total pressure, with a larger group between 1443 and 1450 K. [20,[25][26][27][28][29][30][31][32][33][34] The transformation enthalpy has been measured by three authors ranging from 18 to 22.82 kJ/ mole. [26][27][28] The nonstoichiometry of hausmannite has been investigated by a number of authors, some of them find it to be stoichiometric Mn 3 O 4 , [35][36][37][38][39] while others find different degree of nonstoichiometry. [20,30,31,[40][41][42][43][44][45][46] b-Mn 3 O 4 melts according to b-Mn 3 O 4 fi liquid + gas.…”

“…There are many determinations on the enthalpy of formation, D o f H 298 , [25,38,[53][54][55][56][57][58][59][60][61][62] the entropy at 298.15 K, o S 298 , [25,37,59,[62][63][64][65] and heat capacity, c p , [37,64,65] see Table 1. The heat content of a-Mn 3 O 4 has been measured by Southard and Moore [28] and Fritsch and Navrotsky.…”