Sodium fluoride (NaF) is a chemical compound and medication. As a medication it is primarily used to prevent tooth decay in children older than 6 months in areas where the drinking water is low in fluoride. Sodium fluoride is used as a liquid, pill, or paste by mouth with this use being known as fluoride therapy.
Chemistry
Aqua regia (; from Latin, lit. "royal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange fuming liquid, so named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals.
Applications
Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process for refining the highest quality (99.999%) gold.
Limewater is the common name for a diluted solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble in water (1.5 g/L at 25 °C. Pure limewater is clear and colorless, with a slight earthy smell and an alkaline bitter taste of calcium hydroxide. The term lime refers to the alkaline mineral, and is unrelated to the acidic fruit.