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What it is. This potassium hydroxide solution is a 0.1 N (0.1 M) volumetric standard base, supplied in a 1 gallon size. It is a clear, colorless titrant for determining acids, acid value, and acidity in routine analysis.
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Molar equals normal. Potassium hydroxide releases one hydroxide ion per formula unit, so 0.1 N equals 0.1 M. Each liter contains about 5.611 g of KOH, and each milliliter neutralizes 0.1 millimole of acid (calculated).
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Why potassium hydroxide. KOH behaves much like sodium hydroxide in titrations but forms more soluble salts with fatty acids and many organic acids. That makes it the preferred base for acid value, free fatty acid, and other titrations of oils, fats, and organic samples.
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Carbon dioxide sensitivity. Hydroxide solutions absorb carbon dioxide from the air, forming carbonate that slowly lowers effective strength and blurs endpoints. Keep the container tightly closed, minimize headspace exposure, and restandardize periodically.
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Standardization. Standardize KOH against a primary standard acid, such as dried potassium hydrogen phthalate, using phenolphthalein or a pH meter. Calculate exact normality from the mass of standard and titrant volume, and use that value in results.
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Calculating acid value. Acid value, in mg KOH per gram, equals the titrant volume in milliliters multiplied by the normality and by 56.1, divided by the sample mass in grams (calculated from the molar mass of KOH). Use the standardized normality for accurate results.
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Indicator choice. Phenolphthalein is the usual indicator for KOH titrations of acids, changing from colorless to pink near pH 8.2 to 10. Lab Pro offers Phenolphthalein Indicator 1% in IPA (1 Pint, 20 L).
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Gallon size for routine testing. The 1 gallon size supports QC labs that titrate daily, providing one consistent lot over an extended period and reducing how often new stock must be standardized.
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Handling at a glance. Even at 0.1 N, potassium hydroxide can irritate eyes and skin. Wear safety glasses and gloves, rinse splashes with water, and keep it away from acids and reactive metals such as aluminum.
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Where it is used. Laboratories use 0.1 N KOH for acid value and free fatty acid testing of oils and fats, total acidity in foods and beverages, acid-base titrations in QC and teaching labs, and pH adjustment in sample preparation.
Technical Specifications
| Chemical Name |
Potassium hydroxide, aqueous volumetric solution |
| CAS Numbers |
1310-58-3 (potassium hydroxide); 7732-18-5 (water) |
| EC Number (KOH) |
215-181-3 |
| Synonyms |
Caustic potash solution, KOH solution |
| Formula (active) |
KOH |
| Molecular Weight (active) |
56.11 g/mol |
| Concentration |
0.1 N (0.1 M) |
| KOH Content |
About 5.611 g/L (calculated) |
| Neutralizing Capacity |
1.00 mL = 0.100 mmol acid (calculated) |
| Typical Indicator |
Phenolphthalein |
| Primary Standard |
Potassium hydrogen phthalate (KHP) |
| Appearance |
Clear, colorless liquid |
| Storage Note |
Absorbs CO2; keep tightly closed |
| Hazard Profile |
Eye and skin irritant at this strength (confirm on SDS) |
| Package Size |
1 gallon |
Applications / Common Uses
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Acid value testing: Titrates free fatty acids in oils and fats.
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Food acidity: Measures total acidity in foods and beverages.
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Acid-base titration: Determines acids in QC and teaching labs.
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HCl cross-checks: Standardizes or verifies standard acids.
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pH adjustment: Raises pH in sample preparation.
Storage, Handling & Shipping
Store tightly closed at room temperature, away from acids and reactive metals. Hydroxide solutions absorb carbon dioxide from the air, so keep the container sealed between uses and restandardize when results depend on exact normality.
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Incompatible materials: Acids, aluminum, zinc, tin, and other reactive metals, and organic halogen compounds.
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Exposure limit (potassium hydroxide): NIOSH REL 2 mg/m³ ceiling.
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Spill response: Contain with inert absorbent, neutralize cautiously with a weak acid, and rinse with water.
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First aid: Skin or eyes: flush with water for at least 15 minutes and seek immediate medical attention.
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GHS signal word: .
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DOT / shipping: ; dilute solutions may not be regulated.
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