Potassium hydrogen phthalate

Potassium hydrogen phthalate

Potassium hydrogen phthalate sample
Names
IUPAC name Potassium hydrogen phthalate
Other names 1,2-Benzenedicarboxylic acid Hydrogen potassium phthalate KHP KHPh Monopotassium phthalate Phthalic acid potassium salt Potassium acid phthalate Potassium biphthalate Potassium biphthalate monopotassium salt
Properties
Chemical formula	C8H5KO4
Molar mass	204.22 g/mol
Appearance	White solid
Odor	Odorless
Density	1.636 g/cm3
Melting point	295–300 °C (563–572 °F; 568–573 K) (decomposes)
Boiling point	Decomposes
Solubility in water	8 g/100 ml (20 °C)
Solubility	Slightly soluble in ethanol, methanol Insoluble in hydrocarbons, halocarbons
Vapor pressure	~0 mmHg
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	3,200 mg/kg (rat, oral)
Related compounds
Related compounds	Phthalic acid Phthalic anhydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium hydrogen phthalate or potassium biphthalate, often called simply KHP, is an acidic salt of phthalic acid. KHP has the chemical formula C₈H₅KO₄.

Properties

Chemical

Potassium hydrogen phthalate is neutralized completely with potassium hydroxide or carbonate to dipotassium phthalate.

Physical

Potassium hydrogen phthalate is a colorless crystalline solid, moderate soluble in water. It is stable in air and is not hygroscopic.

Availability

Potassium hydrogen phthalate is sold by chemical suppliers.

Preparation

Can be prepared by partially neutralizing phthalic acid with potassium hydroxide or potassium bicarbonate.

Projects

• Standard in acid-base titrations and thermogravimetric analysis
• Buffering agent

Handling

Safety

Potassium hydrogen phthalate is irritant and should be handled with care.

Storage

In closed bottles.

Disposal

No special disposal is required, though it's best to neutralize it completely before disposal.