Grotthuss proton hopping

Definition

Hydrogen and hydroxide move through water by passing a proton from molecule to molecule rather than physically drifting through the liquid. This hand-off through the hydrogen-bond network lets them race far faster than ordinary ions.

An extra positive charge passes through water as hydronium hands its proton to a neighbor, while hydroxide moves the opposite way by accepting and passing proton holes. Sodium, calcium, and chloride merely drift, but hydrogen and hydroxide race. This is why the recombination reaction H+ plus OH- gives H2O is nearly instantaneous.

Related concepts

Hydrogen ion as bare proton · Hydronium ion formation · Hydrogen-Bond Network

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Part of The Blueprint of Water · 🧪 chemistry