Potassium hydrogen phthalate
Synonym(s):Potassium hydrogen phthalate;KHP;Potassium biphthalate;buffer solution;Potassium phthalate monobasic
- CAS NO.:877-24-7
- Empirical Formula: C8H5KO4
- Molecular Weight: 204.22
- MDL number: MFCD00146206
- EINECS: 212-889-4
- SAFETY DATA SHEET (SDS)
- Update Date: 2025-01-27 09:38:02

What is Potassium hydrogen phthalate?
Chemical properties
white crystalline powder
The Uses of Potassium hydrogen phthalate
As a primary standard for preparing volumetric alkali solutions and as a buffer in pH determinations. Potassium hydrogen phthalate is used as a primary standard for acid- base titrations as well as for calibrating pH meters. It acts as a buffer in pH determination. It finds application as a useful standard for total organic carbon testing.
The Uses of Potassium hydrogen phthalate
As primary standard for preparing volumetric alkali solutions, also as a buffer in pH determinations.
The Uses of Potassium hydrogen phthalate
Potassium hydrogen phthalate [KHP; pH(S) = 4.005 (25 °C)] is a certified secondary standard reference material used as a calibration buffer standard for pH instruments or pH electrodes.
What are the applications of Application
Potassium phthalate monobasic is a primary acid standard for volumetric preparations
General Description
Flammability and Explosibility
Not classified
Purification Methods
Crystallise it first from a dilute aqueous solution of K2CO3, then H2O (3mL/g) between 100o and 0o. Before being used as a standard in volumetric analysis, analytical grade potassium hydrogen phthalate should be dried at 120o for 2hours, then allowed to cool in a desiccator. [Beilstein 9 IV 3169.]
Properties of Potassium hydrogen phthalate
Melting point: | 295-300 °C (dec.) (lit.) |
Boiling point: | 98.5-99.5 ;°C/740 ;mmHg(lit .) |
Density | 1.006 g/mL at 20 °C |
storage temp. | Store at +5°C to +30°C. |
solubility | H2O: 100 mg/mL, clear, colorless |
form | Solid |
color | White |
Odor | Odorless |
PH | 4.00-4.02 (25.0℃±0.2℃, 0.05M) |
PH Range | 3.8 - 4.0 (5% aq. sol.) |
Water Solubility | 80 G/L (20 ºC) |
Merck | 14,7612 |
BRN | 3637128 |
Stability: | Stable. Incompatible with strong oxidizing agents. |
CAS DataBase Reference | 877-24-7(CAS DataBase Reference) |
EPA Substance Registry System | Monopotassium phthalate (877-24-7) |
Safety information for Potassium hydrogen phthalate
Signal word | Warning |
Pictogram(s) |
![]() Exclamation Mark Irritant GHS07 |
GHS Hazard Statements |
H315:Skin corrosion/irritation H319:Serious eye damage/eye irritation |
Precautionary Statement Codes |
P280:Wear protective gloves/protective clothing/eye protection/face protection. P302+P352:IF ON SKIN: wash with plenty of soap and water. P305+P351+P338:IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P332+P313:IF SKIN irritation occurs: Get medical advice/attention. P337+P313:IF eye irritation persists: Get medical advice/attention. |
Computed Descriptors for Potassium hydrogen phthalate
InChIKey | IWZKICVEHNUQTL-UHFFFAOYSA-M |
Potassium hydrogen phthalate manufacturer
JSK Chemicals
Shri Shanti Laboratories
ARRAKIS INDUSTRIES LLP
Techno Pharmchem
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