Water, boiling point ionic product

Table 12.2 gives the properties of sub- and supercritical water. Subcritical water is the water that is in a state under a pressurized condition at temperatures above its boiling point under ambient pressure and below the critical point Tc = 374°C Pc = 22.1 MPa, pc = 320 kg/cm ). The dielectric constant of liquid water decreases with increasing temperature (Nanda et al., 2014b). At temperatures from 277 to 377°C, the dielectric constant becomes as low as those of polar organic solvents. The ionic product of water is maximized at temperatures between 227 and 372°C depending upon the pressure (Kruse and Dinjus, 2007). Thus, subcritical water acts as acid and/or base catalysts for reactions, such as hydrolysis of ether/ester bonds, and also as a solvent for the extraction of low molecular mass products (Brunner, 2009). 

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