Solubility product and heat of formation of lead alkyl xanthates by microcalorimetric titration

• Kso and ΔHo for lead alkyl xanthates were determined by microcalorimetry.
• Lead ions were microcalorimetrically titrated with alkyl xanthate ions.
• A new relationship is given for logKso and carbon atoms in the xanthate alkyl chain.
• A relationship is given between ΔHo and carbon atoms in the xanthate alkyl chain.

Microcalorimetric titration of lead ions with various alkyl xanthate ions was used to determine the solubility product (Kso) and the heat of formation (ΔH0) of lead alkyl xanthates (PbX2). The titration was carried out at 25 °C in a 25 mL size isoperibol reactor containing lead aqueous solutions with an ionic strength of 0.01 M and pH 6. Sodium ethyl xanthate, potassium propyl xanthate, potassium butyl xanthate and potassium amyl xanthate were used in this study. A new relationship was found for the Kso and the number of carbon atoms (N) in the xanthate alkyl chain, namely logKso = − 10.033 − 1.049 N. The relationship between ΔH0 and N was found to be ΔH0 = − 62.29 − 7.218 N, in kJ/mol PbX2. The Kso and ΔH0 values that were determined by microcalorimetry were compared to those theoretically calculated taking into account the transfer of the xanthate alkyl chain from the aqueous solution to the lead xanthate solid phase. There was an excellent agreement between theoretical and calorimetric ΔH0. Low deviation was found between theoretical and calculated Kso.

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