Thermodynamic Measurements in Solution

Various thermodynamic approaches have been used to probe acidity and basicity in solutions. The impact of solvation effects must always be considered when designing these experiments. 

A defining property for any acid is its strength. One way to assess the strengths of aqueous acids is to quantify the enthalpy change of 

This strategy is not straightforward since HA is partly ionized before OH is added, complicating A i determination, but this approach is an acceptable starting point. It is also possible to measure (via titration curves) at different temperatures and use the van t Hoff equation 

Use the data in Table 6.4 to calculate the enthalpy and entropy changes associated with aqueous acetic acid ionization (the third equation in the table), and examine the 

NOTE A/T and AS° for these reactions change rapidly with temperature. Calculations based on these data are valid only over the limited temperature range given above. 

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