Hydrogen bond heat from

The figures in brackets are the increments resulting from the introduction of hydroxyl or carboxyl groups, For these simply related structures it would seem that the sublimation heats are derived addi-lively. Whilst this is not generally so, there are probably many other sets of structures for which this approximation applies. Without going into further examples here, it is obvious that much can be learnt of hydrogen bond contributions from lattice energies. 

Calorimetric measurements (Sturtevant et al., 1955) provide additional evidence that hydrogen bonding is involved in the polymerization. The magnitude and pH dependence of the heat evolved upon polymerization of fibrin monomer can be accounted for by means of the. same theory used to explain the pH changes. The heat evolved per monomer is taken as equal to the heat evolved per link (i.e., per rxij hydrogen bonds) formed. At any pH it arises from the formation of hydrogen bonds and from the polymerization-induced ionization of donors and acceptors. It is given by... 

Fig. 10.13 a Transparency of a heat-jffessed film of CNC-g-P(MMA-r-BMA-r-UPyMA). b Chemical composition of CNC-g-P(MMA-r-BMA-r-UPyMA). c The dimerization of UPy by four hydrogen bonds. Reproduced from Ref. [33] by ptamission of John Wiley Sons Ltd... 

The most common hydrophobic adsorbents are activated carbon and siUcahte. The latter is of particular interest since the affinity for water is very low indeed the heat of adsorption is even smaller than the latent heat of vaporization (3). It seems clear that the channel stmcture of siUcahte must inhibit the hydrogen bonding between occluded water molecules, thus enhancing the hydrophobic nature of the adsorbent. As a result, siUcahte has some potential as a selective adsorbent for the separation of alcohols and other organics from dilute aqueous solutions (4). 

---