Manufacture
Historically KOH was made by boiling a solution of potassium carbonate (potash) with calcium hydroxide (slaked lime), leading to a metathesis reaction which caused calcium carbonate to precipitate, leaving potassium hydroxide in solution:
- Ca(OH)2 + K2CO3 → CaCO3 + 2 KOH
Filtering off the precipitated calcium carbonate and boiling down the solution gives potassium hydroxide ("calcinated or caustic potash"). It was the most important method of producing potassium hydroxide until the late 19th century, when it was largely replaced by the current method of electrolysis of potassium chloride solutions, analogous to the method of manufacturing sodium hydroxide (see chloralkali process):
- 2 KCl + 2 H2O → 2 KOH + Cl2 + H2
Hydrogen gas forms as a by-product on the cathode; concurrently, an anodic oxidation of the chloride ion takes place, forming chlorine gas as a byproduct. Separation of the anodic and cathodic spaces in the electrolysis cell is essential for this process.
Read more about this topic: Potassium Hydroxide
Famous quotes containing the word manufacture:
“The profession of magician, is one of the most perilous and arduous specialisations of the imagination. On the one hand there is the hostility of God and the police to be guarded against; on the other it is as difficult as music, as deep as poetry, as ingenious as stage-craft, as nervous as the manufacture of high explosives, and as delicate as the trade in narcotics.”
—William Bolitho (1890–1930)
“I believe that the miseries consequent on the manufacture and sale of intoxicating liquors are so great as imperiously to command the attention of all dedicated lives; and that while the abolition of American slavery was numerically first, the abolition of the liquor traffic is not morally second.”
—Elizabeth Stuart Phelps (1844–1911)
“The great cry that rises from all our manufacturing cities, louder than the furnace blast, is all in very deed for this—that we manufacture everything there except men.”
—John Ruskin (1819–1900)