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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Niel Plummer</dc:contributor>
  <dc:creator>Eurybiades Busenberg</dc:creator>
  <dc:date>1986</dc:date>
  <dc:description>&lt;p id=""&gt;One hundred and fifty new measurements of the solubility of witherite were used to evaluate the equilibrium constant of the reaction&amp;nbsp;&lt;i&gt;BaCO&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;(&lt;i&gt;cr&lt;/i&gt;) =&amp;nbsp;&lt;i&gt;Ba&lt;/i&gt;&lt;sup&gt;2+&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) +&amp;nbsp;&lt;i&gt;CO&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2&amp;minus;&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) between 0 and 90&amp;deg;C and 1 atm total pressure. The temperature dependence of the equilibrium constant is given by&amp;nbsp;&lt;i&gt;log&lt;/i&gt;&lt;i&gt;K&lt;/i&gt;&amp;nbsp;= 607.642 + 0.121098&lt;i&gt;T&lt;/i&gt;&amp;nbsp;&amp;minus; 20011.25/&lt;i&gt;T&lt;/i&gt;&amp;nbsp;&amp;minus; 236.4948&amp;nbsp;&lt;i&gt;log&lt;/i&gt;&lt;i&gt;T&lt;/i&gt;&amp;nbsp;where&amp;nbsp;&lt;i&gt;T&lt;/i&gt;&amp;nbsp;is in degrees Kelvin. The&amp;nbsp;&lt;i&gt;log&lt;/i&gt;&lt;i&gt;K&lt;/i&gt;&amp;nbsp;of BaCO&lt;sub&gt;3&lt;/sub&gt;(cr), the Gibbs energy, the enthalpy and entropy of the reaction at 298.15 K are &amp;minus;8.562, 48.87 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, 2.94 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;and &amp;minus;154.0 J &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;&amp;nbsp;&amp;middot; K&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, respectively. The equilibrium constants are consistent with an aqueous model that includes the ion pairs BaHCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;(aq) and BaCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt;(aq) Three different methods were used to evaluate the association constant of BaHCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;(aq), and all yielded similar results. The temperature dependence of the association constant for the reaction&amp;nbsp;&lt;i&gt;Ba&lt;/i&gt;&lt;sup&gt;2+&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) +&amp;nbsp;&lt;i&gt;HCO&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) =&amp;nbsp;&lt;i&gt;BaHCO&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) is given by&amp;nbsp;&lt;i&gt;log&lt;/i&gt;&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;&lt;i&gt;BaHCO&lt;/i&gt;3&lt;sup&gt;+&lt;/sup&gt;&lt;/sub&gt;&amp;nbsp;= &amp;minus;3.0938 + 0.013669&lt;i&gt;T&lt;/i&gt;.&lt;/p&gt;
&lt;p id=""&gt;The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15&amp;deg;K are 0.982, &amp;minus;5.606 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, 23.26 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;&amp;nbsp;and 96.8 J &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;&amp;nbsp;&amp;middot; K&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, respectively. The temperature dependence of the equilibrium constant for the reaction&amp;nbsp;&lt;i&gt;Ba&lt;/i&gt;&lt;sup&gt;2+&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) +&amp;nbsp;&lt;i&gt;CO&lt;/i&gt;&lt;sup&gt;2&amp;minus;&lt;/sup&gt;&lt;sub&gt;3&lt;/sub&gt;(&lt;i&gt;aq&lt;/i&gt;) =&amp;nbsp;&lt;i&gt;BaCO&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;sup&gt;3&lt;/sup&gt;(&lt;i&gt;aq&lt;/i&gt;) is given by&lt;i&gt;log&lt;/i&gt;&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;&lt;i&gt;BaCO&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt;&lt;/sub&gt;&amp;nbsp;= 0.113 + 0.008721&lt;i&gt;T&lt;/i&gt;.&lt;/p&gt;
&lt;p id=""&gt;The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15&amp;deg; K are 2.71, &amp;minus;15.49 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, 14.84 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;&amp;nbsp;and 101.7 J&amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;&amp;nbsp;&amp;middot; K&lt;sup&gt;&amp;minus;1&lt;/sup&gt;.&lt;/p&gt;
&lt;p id=""&gt;The above model leads to reliable calculations of the aqueous speciation and solubility of witherite in the system BaCO&lt;sub&gt;3&lt;/sub&gt;-CO&lt;sub&gt;2&lt;/sub&gt;-H&lt;sub&gt;2&lt;/sub&gt;O from 0 to more than 90&amp;deg;C. Literature data on witherite solubility were re-evaluated and compared with the results of this study.&lt;/p&gt;
&lt;p id=""&gt;Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of &amp;Delta;&lt;sub&gt;f&lt;/sub&gt;H&amp;deg; and &amp;Delta;&lt;sub&gt;f&lt;/sub&gt;G&amp;deg; of Ba&lt;sup&gt;2+&lt;/sup&gt;(aq) to &amp;minus;532.5 and &amp;minus;555.36 kJ &amp;middot; mol&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, respectively, for agreement with solubility data.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/0016-7037(86)90077-3</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>The solubility of BaCO&lt;sub&gt;3&lt;/sub&gt;(cr) (witherite) in CO&lt;sub&gt;2&lt;/sub&gt;-H&lt;sub&gt;2&lt;/sub&gt;O solutions between 0 and 90°C, evaluation of the association constants of BaHCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;(aq) and BaCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt;(aq) between 5 and 80°C, and a preliminary evaluation of the thermodynamic properties of Ba&lt;sup&gt;2+&lt;/sup&gt;(aq)</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>