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Alkalis (bases) are all compounds that are able to form hydroxide ions (OH-) in an aqueous solution, i.e. to increase the pH value of a solution (>7). These so-called alkali hydroxides, for example sodium hydroxide (NaOH) or potassium hydroxide (KOH), usually have a good to very good conductivity and are used like acids in surface technology in the most diverse areas.
Alkalis with indicators produce characteristic colourings and feel slippery on the skin. The solutions are corrosive, therefore protective glasses must always be worn when working with alkaline solutions.
Alkaline solutions are used in surface technology in cleaning solutions, alkaline electrolytes, stripper solutions (e.g. for paints), alkaline pickling solutions (e.g. for aluminium), in sewage technology and in the laboratory.
List of common alkalis:
Ammonia solution, NH3
Calcium hydroxide, Ca(OH)3
Potassium hydroxide, KOH
Sodium hydroxide, NaOH