How do I calculate NaOH concentration from a KHP standardization?

KHP reacts with NaOH 1 : 1, so c(NaOH) = m(KHP) / [M(KHP) × V(NaOH)] with M = 204.22 g/mol and V in litres. For 0.5105 g of KHP and 24.98 mL of NaOH, c = 0.5105 / (204.22 × 0.02498) = 0.1001 mol/L. Run about three replicates, check that the relative average deviation is within 0.2 %, and report the mean.

How is a back titration calculated?

Work out the total excess reagent added (c₁V₁), subtract the amount that reacted with the back-titrant (c₂V₂ times their ratio), and the difference is what reacted with the analyte; then apply the analyte-to-reagent ratio. For CaCO₃ with HCl (1 : 2): n(CaCO₃) = ½ × (0.1000 × 0.05000 − 0.1000 × 0.02000) = 0.001500 mol = 0.1501 g. Back titration suits slow reactions, insoluble samples, or cases with no good indicator for the direct reaction.

What is a gravimetric factor and how is it found?

The gravimetric factor F = a × M(analyte) / [b × M(weighing form)], with a and b chosen so the key element balances. Iron weighed as Fe₂O₃ gives F = 2 × 55.845 / 159.69 = 0.6994; chloride weighed as AgCl gives F = 35.45 / 143.32 = 0.2474. The analyte percentage is then mass of precipitate × F / sample mass × 100 %. The tool sets a and b automatically from the shared element, and you can override them.

How much primary standard should I weigh, and why aim for at least 20 mL?

Each burette reading carries about ±0.01 mL and a titre needs two readings, so ±0.02 mL; keeping the relative error at or below 0.1 % needs at least 20 mL. An analytical balance weighing by difference carries ±0.0002 g, so the mass should be at least 0.2 g. Weigh m = c × V × M ÷ r with V = 20–25 mL. When this is too small — e.g. about 0.12 g of K₂Cr₂O₇ for 0.1 M thiosulfate — weigh about 1.2 g into a 250 mL flask and titrate 25.00 mL aliquots.

🧮

🧮Titration Calculator - Standardization, Back Titration, Titer and Gravimetric Factor

Every titration calculation rests on stoichiometry: moles of analyte = (a/b) × c × V, and the mass fraction w = c·V·(a/b)·M / m_s × 100 %. For example, 0.5105 g of potassium hydrogen phthalate (KHP, 204.22 g/mol) neutralised by 24.98 mL of NaOH gives c(NaOH) = 0.5105 / 204.22 / 0.02498 = 0.1001 mol/L, and 0.1325 g of anhydrous Na₂CO₃ titrated to the methyl orange end point (1 : 2) with 25.00 mL of HCl gives c(HCl) = 0.1000 mol/L. This tool includes the common standardizations — NaOH with KHP or oxalic acid, HCl with Na₂CO₃ or borax, KMnO₄ with Na₂C₂O₄, Na₂S₂O₃ with K₂Cr₂O₇ or KIO₃, EDTA with ZnO or CaCO₃, and AgNO₃ with NaCl — handles replicate titrations (mean, standard deviation, RSD, relative average deviation) and weighing a larger portion into a volumetric flask with aliquots, and tells you how much primary standard to weigh for a 20–25 mL titre. Analyte content can be found by direct, back or indirect titration: in an antacid, 0.2000 g treated with 50.00 mL of 0.1000 M HCl and back-titrated with 20.00 mL of 0.1000 M NaOH contains 75.06 % CaCO₃; calcium precipitated as oxalate and titrated with KMnO₄ uses Ca : MnO₄⁻ = 5 : 2. The ratio can come from a preset, be typed in, or be derived by balancing an equation, and the titer T is shown too. The gravimetric section computes the gravimetric factor from two formulas — Cl/AgCl = 0.2474, Fe/Fe₂O₃ = 0.6994, S/BaSO₄ = 0.1374 — plus the analyte percentage and the sample mass needed. Every step is written out, with tips on burette readings, weighing error and significant figures.

Free · No sign-up · Runs in your browserLast updated: 2026-10-29

Loading tool...

How to use Titrimetric & Gravimetric Calculator

1Choose Standardization, Analyte content or Gravimetric, then pick a preset system or enter your own formulas and ratio
2Enter masses, titre volumes and concentrations — add replicate rows or tick the flask-and-aliquot option
3Read the concentration, content or gravimetric factor with statistics and the full worked calculation, and copy the result

FAQ

How do I calculate NaOH concentration from a KHP standardization?: KHP reacts with NaOH 1 : 1, so c(NaOH) = m(KHP) / [M(KHP) × V(NaOH)] with M = 204.22 g/mol and V in litres. For 0.5105 g of KHP and 24.98 mL of NaOH, c = 0.5105 / (204.22 × 0.02498) = 0.1001 mol/L. Run about three replicates, check that the relative average deviation is within 0.2 %, and report the mean.
How is a back titration calculated?: Work out the total excess reagent added (c₁V₁), subtract the amount that reacted with the back-titrant (c₂V₂ times their ratio), and the difference is what reacted with the analyte; then apply the analyte-to-reagent ratio. For CaCO₃ with HCl (1 : 2): n(CaCO₃) = ½ × (0.1000 × 0.05000 − 0.1000 × 0.02000) = 0.001500 mol = 0.1501 g. Back titration suits slow reactions, insoluble samples, or cases with no good indicator for the direct reaction.
What is a gravimetric factor and how is it found?: The gravimetric factor F = a × M(analyte) / [b × M(weighing form)], with a and b chosen so the key element balances. Iron weighed as Fe₂O₃ gives F = 2 × 55.845 / 159.69 = 0.6994; chloride weighed as AgCl gives F = 35.45 / 143.32 = 0.2474. The analyte percentage is then mass of precipitate × F / sample mass × 100 %. The tool sets a and b automatically from the shared element, and you can override them.
How much primary standard should I weigh, and why aim for at least 20 mL?: Each burette reading carries about ±0.01 mL and a titre needs two readings, so ±0.02 mL; keeping the relative error at or below 0.1 % needs at least 20 mL. An analytical balance weighing by difference carries ±0.0002 g, so the mass should be at least 0.2 g. Weigh m = c × V × M ÷ r with V = 20–25 mL. When this is too small — e.g. about 0.12 g of K₂Cr₂O₇ for 0.1 M thiosulfate — weigh about 1.2 g into a 250 mL flask and titrate 25.00 mL aliquots.

Features

10 standardizations: KHP, oxalic acid, Na₂CO₃, borax, Na₂C₂O₄, K₂Cr₂O₇, KIO₃, ZnO, CaCO₃, NaCl
Replicate statistics: mean concentration, standard deviation, RSD and relative average deviation
Mass of primary standard to weigh, with a warning when it falls below 0.2 g
Direct, back and indirect titrations reported as % (w/w) or g/100 mL
Stoichiometric ratio from a balanced equation, plus titer T in g/mL
Gravimetric factor with automatic coefficients; presets for AgCl, Fe₂O₃, BaSO₄, Ni(DMG)₂, Mg₂P₂O₇ and more
Molar masses computed from formulas with IUPAC atomic weights; results to 4 significant figures
Burette, pipette, balance and significant-figure tips

Related tools

View all 68 Chemistry Tools →