Popular LabKit
Volumetric Solution Factor Calculator
Work out the actual strength and factor of a volumetric solution from its standardisation – NaOH, HCl, H₂SO₄, KMnO₄, sodium thiosulphate, EDTA, silver nitrate and perchloric acid – with up to three titrations, blank correction, standard purity and %RSD.
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How it works
Actual normality = actual molarity × n-factor of the solution
Factor = actual strength ÷ nominal strength
W is the weight of primary standard in g, P its purity, V the titre in mL and the ratio the moles of solution that react with one mole of standard.
| Solution | Primary standard | Ratio (solution : standard) |
|---|---|---|
| Sodium hydroxide, perchloric acid | Potassium hydrogen phthalate (204.22) | 1 : 1 |
| Hydrochloric acid | Sodium carbonate (105.99) / borax (381.36) | 2 : 1 |
| Sulphuric acid | Sodium carbonate (105.99) | 1 : 1 |
| Potassium permanganate | Sodium oxalate (134.00) / oxalic acid dihydrate (126.06) | 2 : 5 |
| Sodium thiosulphate | Potassium dichromate (294.18) / potassium iodate (214.00) | 6 : 1 |
| Disodium edetate (EDTA) | Zinc (65.38) / calcium carbonate (100.09) | 1 : 1 |
| Silver nitrate | Sodium chloride (58.44) | 1 : 1 |
Worked example
0.1 M sodium hydroxide against KHP
0.5106 g KHP (100 %) needed 25.00 mL NaOH. Molarity = (0.5106 ÷ 204.22) ÷ 0.02500 = 0.10001 M, so the factor is 1.0001. With three titrations the calculator also gives the mean factor and %RSD.
Verified against the Indian Pharmacopoeia’s worked example
The standardisation example in the Indian Pharmacopoeia Commission’s guidance document on calculations (IPC/GD/10, Calculations in IP) – 0.1 M perchloric acid against 0.3505 g potassium hydrogen phthalate (purity 99.96 %), titre 17.2 mL, blank 0.2 mL – gives the same answer by both routes in this calculator.
| Calculation | Reference answer | LabKit result |
|---|---|---|
| By molecular weight (“Against a primary standard” tab) | 0.101 M | 0.1009 M |
| By the monograph equivalent, 0.02042 g per mL (“Using the monograph equivalent” tab) | 0.101 M | 0.1009 M |
This check is our own; it is not an endorsement by the Indian Pharmacopoeia Commission.
Good practice
- Dry the primary standard as your method specifies and cool it in a desiccator before weighing.
- Run at least three titrations and check that the %RSD meets your SOP.
- Use the blank only when your method calls for one.
- Record the factor and the date on the bottle and re-standardise as often as your SOP requires.
Step-by-step preparation guides
Frequently asked questions
What is a factor?
The factor tells you how far the real strength is from the label. A 0.1 M solution with factor 1.0120 is actually 0.1012 M; multiply titration results by the factor.
Molarity or normality?
The Indian Pharmacopoeia and most modern methods use molarity. Choose N only if your method is written in normality; EDTA is used in molarity only.
Why is KMnO₄ ratio 2 : 5?
In acid solution 2 mol of permanganate react with 5 mol of oxalate (5 electrons per permanganate, 2 per oxalate).
Can I standardise against another standardised solution?
Yes – use the second tab and enter the actual strength of that solution and the volumes used.
Related calculators
Results are for guidance. Follow the standardisation procedure in your pharmacopoeia or SOP and verify calculations before entering them in GMP records.