A longstanding mystery about how salt dissolves in water has finally been solved, thanks to machine learning.
Understanding the complete process of how sodium chloride, or salt, dissolves in water is important for a range of scientific disciplines, from accurate climate models to making batteries.
Researchers have tried to work out what happens on a molecular level using computer simulations that start with a configuration of salt crystals in water, but the large number of complex interactions between the salt and water molecules makes it computationally infeasible to go any further than the initial stages.
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Now, at the University of Cambridge and her colleagues have used a machine learning model to better predict these complex interactions, which means the model can peer further ahead in the dissolution process.
Much of the mystery about the later stages of dissolution revolved around whether the salt crystal broke down into smaller and smaller crystals or suddenly dissolved into individual ions all at once 鈥� but O鈥橬eill and her team鈥檚 model have shown it is a sort of crumbling.
鈥淲e initially get some of the ions slowly dissolving off, step by step, and then the crystal gets to some point where it gets quite unstable, and then it just really rapidly disintegrates or crumbles,鈥� says O鈥橬eill.
The neural network was able to predict these complex interactions because it was fed a large data set of smaller examples of how salt ions and water molecules interact and the forces between them, which are easier to calculate accurately, says O鈥橬eill.
, another member of the study team at the University of Cambridge, says this method could be applied to work out how other ionic compounds dissolve, but the model would need significant readjustment for each specific scenario.
Using better-quality data to feed into the model, as well as running a large number of simulations, is the reason for the model鈥檚 success, says at Charles University in Prague, Czech Republic. 鈥淭hese critical unresolved questions [about salt dissolution] were answered by this paper.鈥�
But there are still some hazy aspects of how exactly the crumbling process occurs, says Klimes, which could be an object for more study. 鈥淏etween the steady loss of the ions and the end part where everything is dissolved, there is this sudden crumbling and maybe it鈥檚 a bit hazy how this really happens,鈥� he says.
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