Potassium Hydrogen Phthalate AR is a high-purity analytical reagent commonly used as a primary standard in analytical chemistry laboratories. It is a white crystalline powder with excellent stability, making it ideal for accurate acid-base titrations and pH calibration applications.

Key Information

Chemical Name: Potassium Hydrogen Phthalate

Synonyms: Potassium Biphthalate, KHP, Potassium Acid Phthalate

Chemical Formula: C₈H₅KO₄

Molecular Weight: 204.22 g/mol

CAS Number: 877-24-7

Appearance: White crystalline powder

Grade: Analytical Reagent (AR)

Purity/Assay: Typically 99.5–100.1%

Uses and Application:

Primary standard for standardisation of Sodium Hydroxide (NaOH)

Acid-base titration analysis

Preparation of buffer solutions

pH meter calibration

Analytical laboratory reagent

TOC calibration standard

Storage:

Store in a cool, dry and well-ventilated area

Keep container tightly closed when not in use

Protect from moisture and direct sunlight

Store away from incompatible materials

Physical Properties

Solubility in Water: Approx. 80–93 g/L

pH (0.05M solution): About 4.0

Melting Point: Approx. 295–300°C (decomposes)

Hazardous Information:

Generally classified as Non-Dangerous Goods

May cause mild irritation to eyes, skin and respiratory tract

Avoid generating or inhaling dust

Not classified as hazardous under normal laboratory handling conditions

Safety Measures:

Wear suitable protective gloves, safety glasses and laboratory clothing

Avoid contact with eyes and skin

Use in a well-ventilated area

Wash hands thoroughly after handling

In case of eye contact, rinse immediately with plenty of water

If inhaled, move the person to fresh air

Keep out of reach of children and unauthorised personnel