Product Overview

Potassium Hydrogen Phthalate 99.5% AR (CAS No. 877-24-7) is a monoprotic acidic potassium phthalate salt with well-established acid–base and buffer chemistry. The remaining carboxylic-acid proton provides a predictable titration reaction with strong bases, while aqueous potassium hydrogen phthalate solutions occupy a useful mildly acidic pH region. High-purity, specifically certified forms have long-standing roles in acidimetry and pH reference systems.

The AR grade is positioned for conventional titrimetric analysis, buffer preparation, routine pH-related laboratory work and QC where reagent-grade KHP is appropriate. It can also serve as an organic reference substrate in established chemical-oxygen-demand procedures. The catalogue assay does not by itself make this material a certified primary standard or certified pH reference material.

Typical Applications

• Acid–base titration and alkalimetric reagent-standardisation work where suitability is established by the applicable procedure.
• Preparation of phthalate buffer solutions for routine pH measurement and method checks.
• Preparation of potassium hydrogen phthalate solutions used as COD reference substrates in established methods.
• Analytical reagent preparation for acidity and alkalinity procedures.
• Laboratory quality-control and titration-method verification.
• Study of acid–base equilibria and electrode response in mildly acidic buffer media.

Common Synonyms

• Potassium acid phthalate
• Potassium biphthalate
• Hydrogen potassium phthalate
• Potassium hydrogen benzene-1,2-dicarboxylate
• KHP

Storage Conditions

Keep tightly closed, dry and protected from contamination, particularly alkaline residues that could alter its acidimetric behaviour. Analytical weighing should be performed with clean, dry equipment so that reagent composition remains suitable for reproducible solution preparation.