SINGAPORE: Hydrochloric acid is a colourless and odourless solution of hydrogen chloride and water; with chemical formula HCl. Once commonly referred to as muriatic acid or spirit of salt, this acid is a highly corrosive chemical compound with several applications in industry. Here are some of the interesting properties of HCl –
Chemical properties of HCl: Hydrochloric acid is a clear, colourless, highly pungent solution of hydrogen chloride (HCl) in water. It is a highly corrosive, strong mineral acid with many industrial uses. The molar mass being 36.46 g/mol, compound has a density of 1.18 g/cm3 .
HCl can dissociate (ionize) only once to give up one H+ ion (a single proton). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O+.The other ion formed is Cl−, the chloride ion. Hydrochloric acid can therefore be used to prepare salts called chlorides, such as sodium chloride. Hydrochloric acid is a strong acid, since it is essentially completely dissociated in water.
Present in digestive acids: HCl exists naturally within gastric acid which is one of the main elements that works in the intestinal tract to digest food and get rid of secretions in human beings. The gastric acid comprises primarily of hydrochloric acid which acidifies the stomach contents. Chloride and hydrogen ions are secreted separately in the stomach section which sits at the top of the stomach by parietal cells of the gastric mucosa into a secretory network known as canaliculi prior to entering the stomach lumen. After exiting the stomach, the hydrochloric acid of the chyme is dissolved in the duodenum by sodium bicarbonate. The intestinal tract is protected from the strong acid by the secretion of a thick, protective mucus layer, and by secretin induced buffering with sodium bicarbonate. If hydrochloride is sent to the oesophagus, it can aggravate the lining of the oesophagus and lead to the sensation like peptic ulcers or heartburn.
Fatal at certain concentrations (HCl hazards): concentration of 600 molar of HCl can kill a person. The concentration of 50 – 150 molar can make a person blind.
Used in activating oil wells: HCl is used in a process known as oil-well acidization. This process involves injecting the acid into the cavities of oil wells to dissolve away sections of rock, leaving an open column behind. Ultimately, the method serves to accelerate oil production from the well.
HCl as cleaning agent: One of the strongest commercially available cleaners today is hydrochloric acid. Hydrochloric acid is extremely powerful and is recommended as a cleaner. Industrial strength hydrochloric acid, is commonly used on masonry; however, the acid can be used to clean any product that can withstand its effects.
Hydrochloric acid safety: Concentrated HCl is highly corrosive. In laboratories, it is advisable to apply a barrier cream to the hands prior to use. Keep it away from any heat source such as burners, ovens, sunlight etc. Keep containers closed and in an upright position when not in use. For dilute HCl add the acid to water and store the diluted acid solution in a reagent bottle (never add the water to the acid). On industrial scale, label the product, chemical name and chemical formula. Name the ingredients and formulation details where relevant. Follow the first aid and emergency procedures. Provide the details of manufacturer, reference to MSDS and expiry date.