Half-Carbonate Behavior

Definition

The fact that the P-alkalinity titration converts carbonate only to bicarbonate, so it captures just half of carbonate’s total acid-neutralizing capacity.

Because the P endpoint at pH 8.3 stops after CO3 2- plus H+ becomes HCO3- but before bicarbonate is further neutralized, P includes only half the carbonate. This is why P-alkalinity counts all hydroxide and half the carbonate but no bicarbonate. It is the mechanistic reason the P-to-M comparison can resolve the three alkalinity species.

Related concepts

P- and M-alkalinity Titration · P or M Speciation Relationships · P-alkalinity

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Part of The Blueprint of Water · 📏 measurement