Hydrochloric acid is a compound of hydrogen and chlorine, also known as, hydrogen chloride (HCl) which can be found in water. This substance is a highly corrosive, potent, mineral acid which is naturally found in gastric acid which is one of the main components that works in the intestinal tract to break down food and get rid of waste matter. Gastric acid also works in the system as a barrier against bacteria in order to prevent contaminations. The gastric acid consists primarily of hydrochloric acid which break down the stomach contents. Chloride (Cl−) and hydrogen (H+) ions are excreted separately in the stomach region which rest at the top of the stomach by parietal cells of the gastric mucosa into a secretory system called canaliculi before it enters the stomach lumen. After leaving the abdomen, the hydrochloric acid of the chyme is neutralize in the duodenum by sodium bicarbonate. The stomach itself is guarded from the strong acid by the release of a thick, protective mucus layer, and by secretin induced buffering with sodium bicarbonate. If hydrochloride is present in the esophagus, it can aggravate the coating of the esophagus and result in the sensation like peptic ulcers or heartburn.
Outside of being naturally developed in the body, hydrochloric acid is repeatedly used as a potent inorganic acid in many industrial processes. During the Middle Ages, it was used by alchemist in the quest for the philosopher’s stone, and afterwards by European scientists such as Davy, Glauber and Priestley in their scientific studies. Historically it was named ‘muriatic acid’ or ‘spirits of salt’, developed from vitriol and common salt. Hydrochloric acid became popularly used at the beginning of the Industrial Revolution, when it was used in the chemical industry as a chemical agent in the large-scale manufacturing of vinyl chloride used to make PVC plastic, and MDI/TDI for polyurethane.
Hydrochloric acid is mainly used to produce chlorides, for filtering ore in the manufacturing of tin and tantalum, for the storage and cleaning of metal produce, in electroplating, in eliminating scale from boilers, to deactivate basic systems, as a laboratory agent, as a catalyst and solvent in organic syntheses, in the manufacture of fertilizers and dyes, for hydrolyzing starch and proteins in the organization of certain food goods and in the photographic, textile, and rubber business. It is also used in many smaller-scale application, involving household cleaning, production of gelatin and other food preservatives, descaling, and leather processing. About 20 million metric tons of hydrochloric acid is manufactured annually.
Potassium nitrate which is a chemical compound is also utilized to preserve food as a common ingredient of salted meat since the Middle Ages, though its use has been mostly ceased and substituted with sodium nitrate (and nitrite) because they are more reliable in safeguarding food from bacterial infection. However, it is still used in some food applications, such as charcuterie and the brine used to make corned beef. Potassium nitrate was also used long ago for several kinds of burning fuses, including slow matches, stimulant in amateur rocket propellants, and in several fireworks such as smoke bombs. The major commercial source of the nitrate ion from the Late Middle Ages through to the 19th century is composing urine.
As compost, potassium nitrate is used as a contributor of nitrogen and potassium, which is two of the major nutrients for vegetation. Potassium nitrate is also the key ingredient for tree stump remover because it speeds up the natural decomposition of the stump. It is used as a solvent in the heat treatment of metals in the post-wash. It works well as a short-term rust inhibitor because of its capability to oxidize, water contents at a low cost. It has also been used in the production of ice cream and can be identified in some toothpaste particularly created for delicate teeth. Potassium nitrate is also one of the three components of black powder, along with pulverized charcoal and sulfur, where it acts as an oxidizer.