examples concerning ion association are in Figure 16.9. Most
association constants increase upon cooling, but to a different
extent. The pH ofpurewater is about 8.0 at 208 C.
Uncoupling of consecutive reactions can occur, leading to a changed
product mix. This is discussed in Section 4.4.
Hydrophobic interactions decrease in magnitude and may even
become repulsive below 0 8 C. See Figure 3.4. This may, e.g., cause
dissociation of proteins.FIGURE16.9 The effect of temperature on the change in association constant,
relative to itspKavalue at 30 8 C, of various acids and water. (Mainly after Franks [see
Bibliography].)