GIFSQ Tools · Module 11 — Ingredients, Additives & Formulation · Tool 216 of 500
Plan an acid–salt buffer from the Henderson–Hasselbalch equation: the base-to-acid ratio at your target pH, the moles of each part, and the buffer capacity.
Try sample values — fills the form with the worked example below.
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Base : acid ratio
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Acid (mol)
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Base (mol)
Equation: Ratio (base ÷ acid) = 10^(pH − pKa). Acid (mol) = total moles ÷ (1 + ratio). Base (mol) = total moles − acid. Buffer capacity β (mol/L per pH) = 2.303 × concentration × ratio ÷ (1 + ratio)².
Method: Henderson–Hasselbalch buffer planning: pH = pKa + log10(base ÷ acid). The acetic acid / acetate system (pKa 4.76) and the citric acid / citrate system (pKa1 3.13, pKa2 4.76, pKa3 6.40) are the usual food buffers; this tool treats one dissociation step only.
Assumptions: the acid is monoprotic (or one step of a polyprotic acid is used); activity coefficients are taken as 1; temperature is near 25 °C, where the stated pKa applies.
Limitations: real food systems have other acids and salts that shift the pH — always measure the finished pH and adjust; the capacity is highest at pH = pKa.
Rounding: ratio to 2 decimal places; moles to 4 decimal places; buffer capacity to 4 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Henderson–Hasselbalch buffer planning: pH = pKa + log10(base ÷ acid). The acetic acid / acetate system (pKa 4.76) and the citric acid / citrate system (pKa1 3.13, pKa2 4.76, pKa3 6.40) are the usual food buffers; this tool treats one dissociation step only.
Assumptions: the acid is monoprotic (or one step of a polyprotic acid is used); activity coefficients are taken as 1; temperature is near 25 °C, where the stated pKa applies.
Limitations: real food systems have other acids and salts that shift the pH — always measure the finished pH and adjust; the capacity is highest at pH = pKa.
Rounding: ratio to 2 decimal places; moles to 4 decimal places; buffer capacity to 4 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Acetic acid buffer, pKa 4.76, target pH 4.76, 0.10 mol/L, 1 L: ratio = 10^0 = 1.00; acid = 0.10 ÷ 2 = 0.0500 mol, base = 0.0500 mol; capacity β = 2.303 × 0.10 × 1 ÷ 4 = 0.0576 mol/L per pH.
Enter values above to see results.
Buffer capacity is highest when pH equals pKa. A buffer works best within about one pH unit of its pKa. Tool 216 of 500 — GIFSQ
