SS Component

THE HISTORY BEHIND ACIDS AND BASES

Our PBL project discusses the properties of acids and bases. So what is the history behind HCl , NaOH, and pH? Hydrochloric acid was discovered around 800 AD by the alchemist Jabir ibn Hayyan (Geber), by mixing Sodium chloride -common salt- with vitriol (sulfuric acid). Jabir discovered many important chemicals, and recorded his findings in over twenty books, which carried his chemical knowledge of hydrochloric acid and other basic chemicals for hundreds of years. Jabir's invention of the gold-dissolving aqua regia, consisting of hydrochloric acid and nitric acid, was of great interest to alchemists searching for the philosopher's stone. In the Middle Ages, hydrochloric acid was known to European alchemists as spirit of salt or acidum salis. Gaseous HCl was called marine acid air. The old (pre- systematic) name muriatic acid has the same origin (muriatic means "pertaining to brine or salt"), and this name is still sometimes used. Notable production was recorded by Basilius Valentinus, the alchemist- canon of the Benedictine priory Sankt Peter in Erfurt, Germany in the fifteenth century. In the seventeenth century, Johann Rudolf Glauber from Karlstadt am Main, Germany used sodium chloride salt and sulfuric acid for the preparation of sulfate" sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and in 1818 Humphry Davy of Penzance, England proved that the chemical composition included hydrogen and chlorine. During the Industrial Revolution in Europe, demand for alkaline substances such as soda ash increased, and the new industrial soda process by Nicolas Leblanc ( Issoundun, France) enabled cheap large-scale production. In the Leblanc process, salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the Alkali Act of 1863, excess HCl was vented to the air. After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.

Sodium Hydroxide was first prepared by soap makers. A procedure for making sodium hydroxide appeared as part of a recipe for making soap in an Arab book of the late 13th century: Al-mukhtara` fi funun min al-suna` (Inventions from the Various Industrial Arts), which was compiled by al-Muzaffar Yusuf ibn `Umar ibn `Ali ibn Rasul, a king of Yemen.The recipe called for passing water repeatedly through a mixture of alkali (Arabic: al-qily, where qily is ash from saltwort plants, which are rich in sodium ; hence alkali was impure sodium carbonate) and quicklime (calcium oxide, CaO), whereby a solution of sodium hydroxide was obtained. European soap makers also followed this recipe. When in 1791 the French chemist and surgeon Nicolas Leblanc (1742–1806) patented a process for mass-producing sodium carbonate, natural "soda ash" (impure sodium carbonate that was obtained from the ashes of plants that are rich in sodium) was replaced by this artificial version. However, by the 20th century, the electrolysis of sodium chloride had become the primary method for producing sodium hydroxide.

In 1909 Sørensen, a Danish chemist, introduced the concept of pH as a convenient way of expressing acidity. the negative logarithm of hydrogen ion concentration. Sørensen (1868–1939), who held a PhD from the University of Copenhagen, directed the chemical department of the Carlsberg Laboratory. The context for the introduction of the concept of pH was the slow changeover from the old color-change tests for indicating the degree of acidity or basicity to electrical methods. In the latter technique the current generated in an electrochemical cell by ions migrating to oppositely charged electrodes was measured, using a highly sensitive (and delicate) galvanometer. Until Sørensen developed the pH scale, there was no widely accepted way of expressing hydrogen ion concentrations.

Alchemist, Jabir ibn Hayyan Founder of Sodium Hydroxide Sørensen