Potassium hydrogen phthalate

white crystalline powder

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.

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.

As primary standard for preparing volumetric alkali solutions, also as a buffer in pH determinations.

Not classified

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.]