HydraDENT · Dental Unit Waterline Treatment

Free Chlorine Speciation versus pH

Theoretical HOCl / OCl⁻ distribution from the chlorine acid–base equilibrium (pKa = 7.5 at 25 °C). Calculated values, not sensor measurements. Hover or drag across the plot to read values.

HOCl OCl⁻
Fig. 4. Theoretical variation of HOCl and OCl⁻ fractions with pH based on chlorine acid-base equilibrium (pKa = 7.5 at 25°C).

Model

HOCl = 1 / (1 + 10(pH − 7.5))
OCl⁻ = 1 − HOCl

Reading the plot

Below pH 7.5 the more biocidal HOCl dominates; above it, OCl⁻ dominates. At pH 7.5 the two species are equal (50 %).

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PNG is rendered at 2100 px wide (3.5 in single-column at 600 dpi). SVG is vector for camera-ready submission.

Curves computed at 0.01 pH resolution; markers show the tabulated reference points.