Different weighting procedures resulted in slightly different K values

Another approach is to use all of our solubility-pH data at each temperature to perform computer calculations, resulting in an overall "best" fit of [7] to obtain the desired K value. Different weighting procedures resulted in slightly different K values, but all K values obtained in this way were in good agreement with those already listed in Table 2. For further calculations and comparisons with earlier investigators' results, we will use the values listed in Table 2 as the best that can be derived from our solubility combined with the activity coefficient that we ignore. zinc hydroxide
Whether or not our K values have the importance we ascribe to them, the use of these K values in [7] does result in calculated solubilities that agree well with the experimental values in Table 1 over the entire temperature and pH range. In this sense, our K value has an uncertainty of a few percent.
Our measurements and calculations give K,, = 1.74 x 10-I7 at 25°C. Since this K,, is estimated based on our solubility in relatively low pH solutions, all of which are quite dilute, it is appropriate to approximate this value with the thermodynamic solubility product, although we ignore the activity coefficient - cients. This value can be compared with the results of previous researchers, as shown below.
Reported solubility products range from 10-l3 to lo-" at or near 25"C. Here, we consider only the best-looking few of these early surveys. Fulton and Swinehart (7) found Ksp = 0.7 x 10-17. Schindler et al. (8) Ksp= 3.39 x 10-17 has been reported. Davies and Staveley (9) reported Ksp.= 3.80 x 10-I 7 . Each of these thermodynamic (activity coefficient taken into account) solubility products applies to the orthorhombic (E) variant of zinc hydroxide and can therefore be compared with our values. Our evaluation of all these investigations led us to consider Ksp = 3.5 x 10-17 to be the "best" value. The difference between this 'best' value and our results corresponds to a difference of 0.4 kcal mol-' in the AGO of [5a]