There are very few things that modern science does not understand. One of them is consciousness; the other is water.1 In the case of consciousness, the hard problem is designing good experiments; in the case of water, finding a theory that explains its properties.*Archive.org: The Left Hand of the Electron - Isaac Asimov
Thermodynamic theories assume that any substance may be characterized by its internal energy U(S,V), where S and V are extensive variables, S is a measure of the number of accessible quantum states at a given temperature T, and V is a measure of the spatial extension of the system at a given pressure p. By the first law of thermodynamics dU(S,V) = T·dS – p·dV. Every substance has an equation of state (EoS) p = kBT·[1/V + B2(T)/V2 + …], where kB = 0.0138 zJ·K–1 is a universal constant. B2(T) is negative at low temperature and positive at high temperatures. At B2(T) = 0, attractive and repulsive forces are in balance. For an ideal gas, B2(T) = 0; for a system of hard spheres of diameter σ, B2(T) = 2π·σ3/3; for a van der Waals gas, B2(T) = b – a/kBT, with b and a measuring the repulsive and attractive forces between molecules.
Let MW designate molecular weight. The substance displaying the greatest ratio TB/MW = 80(8) K·Da–1 is water (H2O), followed by hydrogen fluoride (HF), and ammonia (NH3). TB/MW thus corresponds to the density of cohesive energy. The fact that water is an elixir for life is perfectly justified from a thermodynamic point of view. In chemistry, such high densities are usually associated with abnormally high ebullition points.
A phase diagram in the plane represents the domains where a substance may exist as a solid, liquid, or gas. Domain boundaries are marked by coexistence lines. It is there that two phases coexist. Substances undergo first-order transitions at coexistence lines; the system absorbs or releases energy, giving rise to discontinuous changes in volume and density. The sublimation line is the locus of points where a solid coexists with a gas and may extend from zero to the triple-point temperature T3. In the case of water, this triple point is observed at T3 = 0.01°C = 273.16 K and p3 = 611 Pa = 0.006 atm. The melting line is the locus of points from T3 to an infinite temperature. These phases have different symmetries. Full rotational invariance in the liquid phase turns into discrete symmetries in the crystal phase. The condensation line is the locus of points where a gas coexists with a liquid and extends from T3 to a critical point C. Above C, only a single-phase homogenous system exists. In the case of water, this critical point is observed at TC = 373.946°C = 647.096 K and pC = 22.06 MPa = 217.7 atm. This critical point occurs as soon as two phases share the same symmetry group.....MUCH MORE
Sunday, September 1, 2019
Water and Its Mysteries
Isaac Asimov was fascinated with water and among his non-fiction books is The Left Hand of the Electron which references water over 200 times. And via Inference Review someone else with the fascination. Marc Henry, Professor of Chemistry, Materials Science, and Quantum Physics at the University of Strasbourg:
