Computer simulations reveal in the most exquisite detail how salt crystals dissolve in water.
Salt dissolution has a resonance with scientists and non-scientists alike being a piece of "chemistry" exploited daily to inhibit the freezing or accelerate the boiling of water. Despite this key role and increased contemporary drivers from e.g. nanotechnology and the desalination industry, the mechanism of salt dissolution has however remained elusive.
To address this longstanding problem a team of researchers from the Thomas Young Centre, the London Centre for Nanotechnology, UCL Chemistry Department and SISSA, Trieste used a combination of highly accurate quantum mechanics based computer simulation approaches, sophisticated free energy sampling techniques, and some of the most powerful computers in the UK (the HECToR and Legion Supercomputers).
In stark contrast to the qualitative textbook model of salt dissolution, the mechanism arrived at from these studies is surprisingly complex, involving multiple steps and a well-defined intermediate state in which the leaving ions are partially solvated and still retain contact with the crystal. The mechanism predicted by the computer simulations can be seen at:
http://www.youtube.com/watch?v=dr4sFNzUVzI
The results of this study may prove crucial to diverse fields such as the atmospheric sciences in better understanding the desalting of aerosol solutions during freezing.
For more information see the article by Liu et al. in PCCP or www.chem.ucl.ac.uk/ice
Journal link - http://pubs.rsc.org/en/content/articlelanding/2011/cp/c1cp21077g
