Carbonate conversion cascade

Definition

Under acid attack, carbonate is converted stepwise to bicarbonate, then to carbonic acid, and finally released as carbon dioxide gas. This sequence dissolves carbonate scale into solution.

Each protonation step consumes hydrogen ions, which is why pH creeps upward during cleaning as scale dissolves. The final carbon dioxide off-gasses ferociously from the storage tank, removing carbon from the system entirely. Run in reverse at higher pH, the same chemistry re-forms scale, which is the trap behind over-neutralization.

Related concepts

Calcium carbonate solubility · Carbonate system shift with pH · Acid cleaning of scale

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Part of The Blueprint of Water · 🧪 chemistry