Gibbs energies of formation for hydrocerussite [Pb(OH){sub 2}{center_dot}(PbCo{sub 3}){sub 2}(s)] and hydrozincite {l_brace}[Zn(OH){sub 2}]{sub 3}{center_dot}(ZnCO{sub 3}){sub 2}(s){r_brace} at 298 K and 1 bar from electrochemical cell measurements
- Univ. of California, Davis, CA (United States)
New values are reported for the Gibbs energies of formation from the elements for hydrocerussite Pb(OH){sub 2}{center_dot}(PbCO{sub 3}){sub 2} and hydrozincite [Zn(OH){sub 2}]{sub 3}{center_dot}(ZnCO{sub 3}){sub 2}. These {Delta}G{sub f}{sup 0} values were obtained from electrochemical cells without liquid junction. The authors determined {Delta}G{sub f}{sup 0} [Pb(OH){sub 2}{center_dot}(PbCO{sub 3}){sub 2}(s)] = {minus}1,699.8 {+-} 1.6 kJ/mol for hydrocerussite and {Delta}G{sub f}{sup 0} {l_brace}[Zn(OH){sub 2}]{sub 3}{center_dot}(ZnCO{sub 3}){sub 2}{r_brace} = {minus}3,163.3 {+-} 4 kJ/mol for hydrozincite. These results allow future electrochemical cell experiments to be performed to determine the {Delta}G{sub f}{sup 0} values of other hydroxycarbonate minerals using either the Pb amalgam-hydrocerussite or the Zn amalgam-hydrozincite as reference electrodes. These reference electrodes provide a strategy for establishing Gibbs energies for phases with two different anions, which are geochemically interesting but difficult to study experimentally.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-92ER14307
- OSTI ID:
- 653506
- Journal Information:
- American Mineralogist, Vol. 83, Issue 7-8; Other Information: PBD: Jul-Aug 1998
- Country of Publication:
- United States
- Language:
- English
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