Potassium hydroxide - KOH

What is Potassium Hydroxide?

Potassium hydroxide is an inorganic compound which is denoted by the chemical formula KOH.

Potassium hydroxide is also known as caustic potash, lye, and potash lye. This alkali metal hydroxide is a very powerful base. In its aqueous form, its appearance is that of a clear solution. In its solid form, KOH can exist as white to slightly yellow lumps, flakes, pellets, or rods. No characteristic odor can be attributed to this compound in its solid-state.

Potassium hydroxide is soluble in water, freely soluble in ethanol, methanol, and glycerin. It is slightly soluble in ether. It is non-combustible but highly corrosive. It is widely used in chemical manufacturing, cleaning compounds, and petroleum refining.

Properties of Potassium Hydroxide – KOH

KOH Potassium hydroxide
Molecular weight/molar mass of KOH 56.11 g/mol
Density of Potassium hydroxide 2.044 g/cm3
Boiling Point of Potassium hydroxide 1,327 °C
Melting Point of Potassium hydroxide 360 °C

Potassium hydroxide Structure – KOH


Potassium hydroxide structure

Potassium hydroxide structure

Uses of Potassium Hydroxide

  • Potassium hydroxide solution is more conductive when compared to NaOH and therefore used as an electrolyte in some alkaline batteries.
  • It is used as a pH control agent in the food industry.
  • It is used in the thickening of food.
  • It is used in chip fabrication for semiconductors.
  • It is used in the manufacturing of cuticle removers which is used in manicure treatment.
  • It is used in the identification of species of fungi.
  • It is used in mercerizing cotton.
  • It is used in alkalimetric titrations in analytical chemistry.
  • Used in the manufacturing of liquid fertilizers.

Chemical Reactions Undergone by KOH

1. Saponification of ester

The ester is saponified by heating with a known amount of potassium hydroxide in an organic solvent in a sealed tube. To be useful analytically, this reaction must be quantitative in a reasonable length of time. One condition that favors a rapid and quantitative reaction is the use of as strong a base as possible.


2. Reacts with CO2 to produce bicarbonate

The addition of hydroxide ions by adding lime, sodium hydroxide, or potassium hydroxide, adjusts the pH because the hydroxide ion reacts with carbon dioxide to form bicarbonate alkalinity.


Health Hazards 

The health hazards of potassium hydroxide are similar to those of the other strong alkalies, such as sodium hydroxide. Potash lye and its solution can severely irritate skin, mucous membranes, and eyes. When it comes in contact with water or moisture it can generate heat to instigate combustion. Potassium hydroxide is corrosive to tissues.

Learn more about the Structure, physical and chemical properties of KOH from the experts at BYJU’S.

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