Although potassium hydroxide and sodium hydroxide have almost similar properties, one cannot replace the other in certain applications. This ScienceStruck article describes the slight differences between these two compounds.
|Did You Know?
As sodium hydroxide dissolves oils and fats in skin and flesh, animal disposal contractors use it to dispose off animals that are struck and killed by motor vehicles. It is also an inexpensive and easily available compound.
Potassium hydroxide and sodium hydroxide, common inorganic compounds, are used in various industries to produce their salts (like carbonates and phosphates) and a number of useful chemical compounds. They are hygroscopic and deliquescent, which means, they absorb water from the environment and dissolve in it. When added to water, they generate heat. Both are highly corrosive by nature, and need to be handled carefully.
Being alkaline, they are used to neutralize acids. Both are widely used in the paper industry, petrochemical industry, and food industry (in washing or chemical peeling of fruits and vegetables, and in other food processing techniques). They act as food thickeners and are used as additives; for example, in ice creams. As cleaning agents, they are used to produce detergents and other cleaning solutions (for example, drain cleaners). They are used to dissolve carcasses. Because of the similar properties, they have similar uses, but in certain applications manufacturers have to use only KOH or only NaOH. The potassium hydroxide vs. sodium hydroxide analysis given below serves to elaborate on their differences.
Potassium Hydroxide vs. Sodium Hydroxide
|Molar Mass||56.1056 g/mol||39.997 g/mol|
|Density||2.04 g/cm3||2.13 g/cm3|
|Boiling Point||2,421°F (1,327°C)||2,530°F (1,388°C)|
|Melting Point||762.8°F (406°C)||604.4°F (318°C)|
|Common Name||Caustic Potash||Caustic Soda or Lye|
|Production||Relatively less produced.||
Its annual production is about 100 times more than KOH.
|Way of Production||It is obtained through the electrolysis of its chloride.||It is obtained through the electrolysis of sodium chloride.|
|Conductivity||It is more conductive than NaOH.||It is less conductive than KOH.|
|Exothermic||KOH and water reaction is slightly less exothermic.||NaOH and water reaction is slightly more exothermic.|
|More soluble in water, methanol, and ethanol than NaOH. 100 g of NaOH dissolves in 100 ml of water.||It is soluble in water, methanol, and ethanol. It is insoluble in ether and other non-polar solvents. 121 g of KOH dissolves in 100 ml of water.|
|Potassium has an atomic weight of 39.10 and has 19 protons. This makes the metal in potassium hydroxide heavier than the metal in sodium hydroxide.||Sodium has an atomic weight of 22.99, and has only 11 protons. The metal in sodium hydroxide is lighter than the metal in potassium hydroxide.|
|Color and Form|
|It comes in the form of white powder or translucent pellets, which become tacky in air because of its water absorbing property (hygroscopic nature). KOH solutions leave a white or translucent stain.||It comes in the form of whitish pellets, flakes, granules, and liquid. NaOH solutions leave a yellow stain.|
Manufacturers usually prefer sodium hydroxide over potassium hydroxide because it is cheaper. Sometimes, NaOH is preferred because a smaller quantity (as compared to KOH) serves the purpose. The biggest difference between them is the cost, because the cost of NaOH production (from sodium chloride, common salt, which is quite inexpensive) can be around ⅓ of the cost of KOH production.