Table 5.
Transformation thermodynamics at bulk and nanoscale at 298 K
| Reactions | Surface area, m2/g (m2/mol) | ΔH°f-ox,nano-pt, kJ/mol | ΔS°298(ox), J/mol⋅K | ΔG°f-ox,nano-pt, kJ/mol | ∆H°f-ox,bulk-pt, kJ/mol | ∆G°f-ox,bulk-pt, kJ/mol |
| Phase-transformation (-pt) reactions | ||||||
| Na0.09·MnO1.815·0.64H2O = Ca0.12·MnO1.825·0.81H2O | 95 (10,000) | −22.14 ± 2.96 | 6.72 ± 0.23 | −20.14 ± 2.96 | −21.86 ± 2.97 | −23.86 ± 2.97 |
| K0.21·MnO1.87·0.49H2O = Ca0.12·MnO1.82·0.66H2O | 35 (3,600) | −13.33 ± 2.51 | 6.71 ± 0.22 | −15.33 ± 2.51 | −13.19 ± 2.52 | −15.19 ± 2.52 |
| Na0.08·MnO1.825·0.54H2O = K0.21·MnO1.90·0.47H2O | 28 (3,000) | −7.78 ± 2.85 | −1.12 ± 0.22 | −7.45 ± 2.85 | −7.36 ± 2.86 | −7.03 ± 2.86 |
| K0.21·MnO1.90·0.47H2O = K0.10·MnO1.965·0.28H2O | 29 (3,000) | −31.71 ± 2.27 | −13.29 ± 0.14 | −27.75 ± 2.27 | −32.37 ± 2.27 | −28.41 ± 2.27 |
| Nanophase transformation (nano,pt), charge-compensated formulas | ||||||
| Na0.09·H0.37MnO2·0.455H2O = Ca0.12H0.35MnO2·0.635H2O | 95 (10,000) | −64.94 ± 3.17 | 32.73 ± 0.71 | −74.69 ± 3.18 | −64.66 ± 3.18 | −74.41 ± 3.18 |
| K0.21H0.26MnO2·0.36H2O = Ca0.12H0.36MnO2·0.48H2O | 35 (3,600) | −25.21 ± 3.16 | 34.58 ± 0.21 | −14.90 ± 3.16 | −35.52 ± 3.17 | −35.38 ± 3.17 |
| Na0.08·H0.35MnO2·0.365H2O = K0.21H0.20MnO2·0.37H2O | 28 (3,000) | −3.98 ± 3.14 | −14.78 ± 0.20 | 0.43 ± 3.14 | −3.56 ± 3.15 | 0.85 ± 3.15 |
| K0.21H0.20MnO2·0.37H2O = K0.10H0.07MnO2·0.245H2O | 29 (3,000) | −30.18 ± 3.14 | −15.82 ± 0.15 | −25.46 ± 3.14 | −30.84 ± 3.16 | −26.12 ± 3.16 |
Standard enthalpies, entropies, and free energies for nanophase and bulk transformations involving solid oxides are ∆H°f-ox,pt, ΔS°298(ox), and ∆G°f-ox,pt, whereas those involving aqueous ion-exchange reactions are ∆H°f,pt, ΔS°298(aq), and ∆G°f,pt.