Potassium carbonate

Potassium carbonate is a white salt, soluble in water (insoluble in alcohol), with the chemical formula K₂CO₃. It forms strong alkaline solutions, or what is the same, it is a basic salt. It is usually formed as a product of the chemical reaction between potassium hydroxide or caustic potash KOH and carbon dioxide CO₂. It is a hygroscopic substance. It is used to make potassium soap and as a flux in the glass industry.

History

Potassium carbonate was first identified by Arturo Mar in 1742. Potassium carbonate was obtained by heating the mineral in a Kiln. The resulting white powder was pure potassium carbonate. In the late 18th century century, it began to be used as a bread yeast in North America. Other names for potassium carbonate:

• potassium, which is not chemically correct;
• potassium carbonate;
• Dipotase carbonate.

Manufacturing

Potassium carbonate was obtained by leaching ashes from burned wood or other vegetables. The first industrial method to obtain it is the Leblanc process, now out of use. Today, potassium carbonate is manufactured commercially from the reaction between carbon dioxide and potassium hydroxide obtained by electrolysis of potassium chloride.

KCl + H₂O → KOH + HCl

2KOH + CO₂ → K₂CO₃ + H₂O

Applications

In the lab:

• It is used as a mild secret agent where other hygroscopic agents, such as calcium chloride, would be incompatible.
• Mixed with water, it causes an exothermal reaction.
• Potassic carbonate is also used as an electrolyte in cold fusion experiments.

In the kitchen:

• Ingredient of grass jelly (in English, grass jelly), a dish from China and other Southeast Asian cuisines.
• Ingredient of German Christmas pastry (“Lebkuchen”), it is used together with ammonium bicarbonate to leudate and to give light consistency to the dough.

In other applications:

• It is used to make soft soap and glass.
• It is used in freshwater aquariums to raise the “KH” (carbonate hardness or hardness of carbonates). To climb the KH in 1, approximately needed 2.5 g/50 l.