Potassium hydrogen phthalate

  • Kaliumsäurephthalat
  • 1,2- Benzoldikarbonsäure, monopotassium salt

Colorless solid

Fixed

1.636 g · cm -3

295 ° C ( decomposition)

  • Moderately in water ( 80 g · l-1 at 20 ° C)

> 3200 mg · kg -1 ( LD50, rat, oral)

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(Also called Kaliumsäurephthalat ) Potassium is a salt of o- phthalic acid. The colorless, crystalline solid is soluble in water.

Properties

Potassium completely dissociated in water to produce a potassium cation ( K ) and an anion hydrogenphthalate (HP ). As a weak acid hydrogen phthalate reacts to a small extent reversibly with water to form hydronium ( H3O ) and a doubly negatively charged phthalate ion ( P2 ).

Use

Potassium is used as a standard reference material for pH measurement ( pH 4.01 ) and as a buffering agent (in combination with hydrochloric acid or sodium hydroxide). Similarly, it is used as a concentration standard for measurements of total organic carbon ( TOC) and related parameters of the total organic load of water.

CAS registry number
461092
de