Henderson–hasselbalch Buffer Preparation Tool

Henderson–Hasselbalch Buffer Preparation Tool

Calculate acid/base ratio and preparation amounts (moles, grams, and/or stock volumes) for a target pH.

Target Target buffer

Target pH (pH)

Allowed range: 0.0 to 14.0

pKₐ (pKₐ)

Enter the pKₐ at your working temperature/ionic strength.

Total buffer concentration (C_total)

C_total = [HA] + [A⁻]

Final volume (V_final)

Volume for the final buffer solution.

Method Provide reagents (stocks and/or solids)

How will you prepare?

Mix acid and base stock solutions Enter stock concentrations for HA and A⁻ Weigh solid(s) and QS with water Enter molar masses (g/mol) for solids used Acid stock + base solid Stock for HA, solid for A⁻ Base stock + acid solid Stock for A⁻, solid for HA

Acid stock (HA)

Stock concentration (C_stock, HA)

Used for V_HA = n_HA ÷ C_stock_HA

Base stock (A⁻)

Stock concentration (C_stock, A⁻)

Used for V_A = n_A ÷ C_stock_A

Acid solid (HA)

Molar mass (MW, HA)

Unit: g/mol

Account for hydrate/assay factor (HA) grams = (moles × MW) ÷ f

Purity / Factor (f, HA)

Allowed: 0.01 to 1.50

Base solid (A⁻)

Molar mass (MW, A⁻)

Unit: g/mol

Account for hydrate/assay factor (A⁻) grams = (moles × MW) ÷ f

Purity / Factor (f, A⁻)

Allowed: 0.01 to 1.50

Water estimate

Provide available final volume after adding stocks Computes water-to-add: V_water = V_final − (sum of stock volumes). For hybrids, ignores solid volume.

Advanced Rounding • Steps • Graph

Volumes rounding

Applies to displayed stock volumes and water estimate.

Mass rounding

Applies to grams for solids.

Concentrations formatting

Affects displayed [HA], [A⁻], and ratio.

Optional modules

Show calculation steps Show ratio vs pH graph

Graph shows fraction base = R/(1+R) vs pH.

Results

Monoprotic HA ⇄ H⁺ + A⁻

Target composition

Ratio [A⁻]/[HA]

—

[HA]

—

[A⁻]

—

Moles required

n_HA

—

n_A

—

Preparation amounts

—

A⁻

—

Water / QS

—

Notes

Status

Enter inputs and press Calculate

Fraction base vs pH

fraction_base = R/(1+R), pH range: pKₐ ± 2