Gibbs Free Energy of Formation of Synthetic Cryptomelane
Cryptomelane with a formal composition of K0.88Mn(III)0.24Mn(IV)7.60O16.00∙0.33H2O was precipitated from a solution of sulfuric acid containing dissolved manganese sulfate. The oxidation state of manganese in solution was controlled by bubbling pure oxygen gas through and the pH was raised from 1.0...
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| Language: | deu |
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Swiss Chemical Society
1984-12-01
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| Series: | CHIMIA |
| Online Access: | https://www.chimia.ch/chimia/article/view/9630 |
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| author | Raphael Hypólito José Vicente Valarelli Rudolf Giovanoli Silvania M. Netto |
| author_facet | Raphael Hypólito José Vicente Valarelli Rudolf Giovanoli Silvania M. Netto |
| author_sort | Raphael Hypólito |
| collection | DOAJ |
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Cryptomelane with a formal composition of K0.88Mn(III)0.24Mn(IV)7.60O16.00∙0.33H2O was precipitated from a solution of sulfuric acid containing dissolved manganese sulfate. The oxidation state of manganese in solution was controlled by bubbling pure oxygen gas through and the pH was raised from 1.00 to 2.90 by addition of KOH.
Measurements of pH and Eh as well as determination of ion activities in equilibrium with the obtained solid led to a pH = f(Eh) curve with an inclination corresponding to the synthesis equation:
(0.88K+) + 7.84Mn2+ + 16.01H2O ⇌ K0.88Mn(III)0.24Mn(IV)7.60O16.00∙0.33H2O + 31.36H+ + 15.68e
By Nernst’s equation an E° value was determined permitting the calculation of Gibbs free energy of reaction, (ΔGR)°298 = 1323.98 ± 3.29 kJ∙mol-1 and formation, ΔG°fCRYP = - 4482.08 ±3.40 kJ∙mol-1 of synthesized cryptomelane.
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| format | Article |
| id | doaj-art-274562e156e64f5096da09eadb2b2dd5 |
| institution | OA Journals |
| issn | 0009-4293 2673-2424 |
| language | deu |
| publishDate | 1984-12-01 |
| publisher | Swiss Chemical Society |
| record_format | Article |
| series | CHIMIA |
| spelling | doaj-art-274562e156e64f5096da09eadb2b2dd52025-08-20T02:29:52ZdeuSwiss Chemical SocietyCHIMIA0009-42932673-24241984-12-01381210.2533/chimia.1984.427Gibbs Free Energy of Formation of Synthetic CryptomelaneRaphael Hypólito0José Vicente Valarelli1Rudolf Giovanoli2Silvania M. Netto3Universidade de Sao Paulo, Institute de Geociencias, Caixa Postal 20’899, BR - 01’000 Sao Paulo, BrasilUniversidade de Sao Paulo, Institute de Geociencias, Caixa Postal 20’899, BR - 01’000 Sao Paulo, BrasilLaboratorium für Elektronenmikroskopie, Institut für anorganische, analytische und physikalische Chemie der Universität Bern, Freiestr. 3, Postfach 140, CH-3000 Bern 9, SchweizUniversidade de Sao Paulo, Institute de Geociencias, Caixa Postal 20’899, BR - 01’000 Sao Paulo, Brasil. Cryptomelane with a formal composition of K0.88Mn(III)0.24Mn(IV)7.60O16.00∙0.33H2O was precipitated from a solution of sulfuric acid containing dissolved manganese sulfate. The oxidation state of manganese in solution was controlled by bubbling pure oxygen gas through and the pH was raised from 1.00 to 2.90 by addition of KOH. Measurements of pH and Eh as well as determination of ion activities in equilibrium with the obtained solid led to a pH = f(Eh) curve with an inclination corresponding to the synthesis equation: (0.88K+) + 7.84Mn2+ + 16.01H2O ⇌ K0.88Mn(III)0.24Mn(IV)7.60O16.00∙0.33H2O + 31.36H+ + 15.68e By Nernst’s equation an E° value was determined permitting the calculation of Gibbs free energy of reaction, (ΔGR)°298 = 1323.98 ± 3.29 kJ∙mol-1 and formation, ΔG°fCRYP = - 4482.08 ±3.40 kJ∙mol-1 of synthesized cryptomelane. https://www.chimia.ch/chimia/article/view/9630 |
| spellingShingle | Raphael Hypólito José Vicente Valarelli Rudolf Giovanoli Silvania M. Netto Gibbs Free Energy of Formation of Synthetic Cryptomelane CHIMIA |
| title | Gibbs Free Energy of Formation of Synthetic Cryptomelane |
| title_full | Gibbs Free Energy of Formation of Synthetic Cryptomelane |
| title_fullStr | Gibbs Free Energy of Formation of Synthetic Cryptomelane |
| title_full_unstemmed | Gibbs Free Energy of Formation of Synthetic Cryptomelane |
| title_short | Gibbs Free Energy of Formation of Synthetic Cryptomelane |
| title_sort | gibbs free energy of formation of synthetic cryptomelane |
| url | https://www.chimia.ch/chimia/article/view/9630 |
| work_keys_str_mv | AT raphaelhypolito gibbsfreeenergyofformationofsyntheticcryptomelane AT josevicentevalarelli gibbsfreeenergyofformationofsyntheticcryptomelane AT rudolfgiovanoli gibbsfreeenergyofformationofsyntheticcryptomelane AT silvaniamnetto gibbsfreeenergyofformationofsyntheticcryptomelane |