NIST185I

Potassium hydrogen phthalate

NIST^® SRM^® 185i, pH standard

• Synonym(s): Potassium phthalate monobasic, KHP, Phthalic acid monopotassium salt, Potassium biphthalate, Potassium hydrogen phthalate
• Linear Formula: HOOCC₆H₄COOK
• CAS Number: 877-24-7
• Molecular Weight: 204.22
• Beilstein: 3637128
• MDL number: MFCD00013070
• UNSPSC Code: 41116107
• PubChem Substance ID: 329818718
• NACRES: NA.24

Properties

• grade: certified reference material
• Quality Level: 100
• Agency: suitable for SM 2310; suitable for SM 2320
• form: crystals
• packaging: pkg of 60 g
• manufacturer/tradename: NIST^®
• mp: 295-300 °C (dec.) (lit.)
• SMILES string: [K+].OC(=O)c1ccccc1C([O-])=O
• InChI: 1S/C8H6O4.K/c9-7(10)5-3-1-2-4-6(5)8(11)12;/h1-4H,(H,9,10)(H,11,12);/q;+1/p-1
• InChI key: IWZKICVEHNUQTL-UHFFFAOYSA-M

Description

General description

SRM 185I is certified as a p^H standard [p^H(S)].   

Each unit of SRM 185I consists of 60 g of potassium hydrogen phthalate.

SRM 185I _SDS

SRM 185I _CoA

Application

Potassium hydrogen phthalate standard reference material (SRM) is intended for use in preparing solutions for calibrating electrodes for p^H measuring systems.

Features and Benefits

• SRM 185I is available with certified p^H(S) values and their expanded uncertainties. 
• Certified values are derived from potential measurements of cells without liquid junction by the primary measurement method. 
• Certified values are metrologically traceable to the International System of Units (SI) of amount-of-substance and mass and to the definition of single ion activity. 
• The NIST certificate is provided with maintenance, storage, handling, and use instructions.

Other Notes

Please download a current certificate at nist.gov/SRM for current analytes and certified values.

Legal Information

NIST is a registered trademark of National Institute of Standards and Technology

SRM is a registered trademark of National Institute of Standards and Technology

Safety Information

• Storage Class Code: 13 - Non Combustible Solids
• WGK: WGK 1
• Flash Point(F): 387.1 °F - Pensky-Martens closed cup
• Flash Point(C): 197.3 °C - Pensky-Martens closed cup