Scientists at the University of Chicago have conducted quantum simulations to simulate the behavior of water under extreme conditions found in the Earth's mantle. The researchers' article was published in the journal Proceedings of the National Academy of Sciences. The scientific work is summarized in a press release on EurekAlert !.
At ultra-high temperature and pressure, water begins to exhibit anomalous properties, being simultaneously in different phases. It can be liquid when the temperature of the medium is 10 times higher than the boiling point, and also combine the signs of a liquid and a solid.
Scientists have simulated conditions using a supercomputer, increasing the temperature and pressure of the environment in which water molecules are located, to values that, respectively, are 40 times and 100 thousand times higher than normal conditions. It is impossible to conduct such an experiment in a laboratory, since water begins to enter into chemical reactions with the equipment material. For simplicity, the researchers looked at only a small number of H2O molecules by examining their quantum states under extreme conditions.
Researchers have shown that at a temperature of 1000 Kelvin (726 degrees Celsius) and a pressure of 11-20 gigapascals (GPa), water is in a liquid phase and rapidly dissociates into ions, which immediately recombine. This process is carried out using a bimolecular mechanism, when the kinetic energy of two molecules is so high that they decay upon collision. The resulting short-lived ions play the role of charge carriers, which explains why the electrical conductivity of water in such an extreme environment is 6-7 orders of magnitude higher than under normal conditions. In this case, the hydrogen bonds between the molecules, providing a liquid state, are retained at least at pressures up to 20 gigapascals.