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Title: Do stable prenucleation clusters exist in calcium carbonate solutions
Plain: Experiments reported small, stable ion clusters in calcium carbonate solutions even before the solution is saturated, which classical theory forbids. Whether these clusters are truly stable or are short-lived precursors of a dense liquid phase is disputed.
Precise: Clusters of about $20\ \mathrm{Angstrom}$ were reported in 2008 in undersaturated and supersaturated CaCO3 solutions, with properties inconsistent with CNT. Determine whether they are thermodynamically stable solute species (negative formation free energy over a range of concentrations) or kinetically persistent ion associates or droplets of a dense liquid formed by liquid-liquid separation, from measured cluster size distributions and formation free energies versus concentration and pH.
Settled by: Quantitative measurement of the cluster size distribution and its concentration dependence, compared with free-energy calculations, showing stable solutes or metastable dense-liquid droplets.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: 2008