Sodium sesquicarbonate

Sodium sesquicarbonate (systematic name: trisodium hydrogendicarbonate) Na3H(CO3)2 is a double salt of sodium bicarbonate and sodium carbonate (NaHCO3 · Na2CO3), and has a needle-like crystal structure. However, the term is also applied to an equimolar mixture of those two salts, with whatever water of hydration the sodium carbonate includes, supplied as a powder.

The dihydrate, Na3H(CO3)2 · 2H2O, occurs in nature as the evaporite mineral trona.

Due to concerns about the toxicity of borax which was withdrawn as a cleaning and laundry product, sodium sesquicarbonate is sold in the European Union (EU) as "Borax substitute".[1] It is also known as one of the E number food additives E500.

Sodium sesquicarbonate
Sodium sesquicarbonate
Identifiers
3D model (JSmol)
ECHA InfoCard 100.007.802
EC Number
  • 208-580-9
Properties
Na3H(CO3)2·2H2O
Appearance white, needle-like
Density 2.112 g/cm3 (dihydrate)
dihydrate
13 g/100 mL (0 °C)
42 g/100 mL (100 °C)
1.5073 (dihydrate)
Structure
monoclinic (dihydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Uses

Sodium sesquicarbonate is used in bath salts, swimming pools, as an alkalinity source for water treatment, and as a phosphate-free product replacing the trisodium phosphate for heavy duty cleaning.

Sodium sesquicarbonate is used in the conservation of copper and copper alloy artifacts that corrode due to contact with salt (called "bronze disease" due to its effect on bronze). The chloride from salt forms copper(I) chloride. In the presence of oxygen and water, even the small amount of moisture in the atmosphere, the cuprous chloride forms copper(II) chloride and hydrochloric acid, the latter of which dissolves the metal and forms more cuprous chloride in a self-sustaining reaction that leads to the entire destruction of the object. Treatment with sodium sesquicarbonate removes copper(II) chlorides from the corroded layer.

It is also used as a precipitating water softener, which combines with hard water minerals (calcium- and magnesium-based minerals) to form an insoluble precipitate, removing these hardness minerals from the water.[2] It is the carbonate moiety which forms the precipitate, the bicarbonate being included to moderate the material's alkalinity.

References

  1. ^ "Borax substitute – laundry booster, multi purpose cleaner, bath soak". Dri-Pak. Retrieved 28 May 2017.
  2. ^ According to cleaning101.com Archived 2007-10-15 at the Wayback Machine
Bath salts

Bath salts are water-soluble, pulverized minerals that are added to water to be used for bathing. They are said to improve cleaning, enhance the enjoyment of bathing, and serve as a vehicle for cosmetic agents. Bath salts have been developed which mimic the properties of natural mineral baths or hot springs. Some bath salts contain glycerine so the product will act as an emollient, humectant or lubricant. Fragrances and colors are often added to bath salts; the fragrances are used to increase users' enjoyment of the bathing experience.

Bronze disease

Bronze disease is the irreversible and nearly inexorable corrosion process occurring when chlorides come into contact with bronze or other copper-bearing alloys. It occurs as a dark green or a lighter fuzzy green coating on copper, bronze, and other copper-bearing alloys generally due either to contamination by salt water or after burial in dirt (as chloride salts are generally present in soil to some degree). If not treated, complete destruction of the affected artefact is possible. Transfer of chlorides from the contaminated artefact to other artefacts can spread the condition.

Chalconatronite

Chalconatronite is a carbonate mineral and rare secondary copper mineral that contains copper, sodium, carbon, oxygen, and hydrogen, its chemical formula is Na2Cu(CO3)2•3(H2O). Chalconatronite is partially soluble in water, and only decomposes, although chalconatronite is soluble while cold, in dilute acids. The name comes from the mineral's compounds, copper ("chalcos" in Greek) and natron, naturally forming sodium carbonate. The mineral is thought to be formed by water carrying alkali carbonates (possibly from soil) reacting with bronze. Similar minerals include malachite, azurite, and other copper carbonates. Chalconatronite has also been found and recorded in Australia, Germany, and Colorado.

Conservation and restoration of copper-based objects

The conservation and restoration of copper and copper-alloy objects is the preservation and protection of objects of historical and personal value made from copper or copper alloy. When applied to items of cultural heritage, this activity is generally undertaken by a conservator-restorer.

Historically, objects made from copper or copper alloy were created for religious, artistic, technical, military, and domestic uses. The act of conservation and restoration strives to prevent and slow the deterioration of the object as well as protecting the object for future use. The prevention and removal of surface dirt and corrosion products are the primary concerns of conservator-restorers when dealing with copper or copper-alloy objects.

Conservation and restoration of metals

Conservation and restoration of metals is the activity devoted to the protection and preservation of historical (religious, artistic, technical and ethnographic) and archaeological objects made partly or entirely of metal. In it are included all activities aimed at preventing or slowing deterioration of items, as well as improving accessibility and readability of them as objects of cultural heritage. Despite the fact that metals are generally considered as the relatively permanent and stable materials, in contact with the environment they deteriorate gradually, some faster and some much slower. This applies especially to archaeological finds.

It is very important that a conservator of metals has knowledge of basic metalworking techniques, history of metalwork, history of art, archaeology, corrosion of metals, scientific research methods, theory and ethics of conservation-restoration.

E number

E numbers ("E" stands for "Europe") are codes for substances that are permitted to be used as food additives for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly found on food labels, their safety assessment and approval are the responsibility of the European Food Safety Authority (EFSA).Having a single unified list for food additives was first agreed upon in 1962 with food colouring. In 1964, the directives for preservatives were added, 1970 for antioxidants and 1974 for the emulsifiers, stabilisers, thickeners and gelling agents.

Imperial Chemical Industries

Imperial Chemical Industries (ICI) was a British chemical company and was, for much of its history, the largest manufacturer in Britain.

It was formed by the merger of leading British chemical companies in 1926.

Its headquarters were at Millbank in London, and it was a constituent of the FT 30 and later the FTSE 100 indices.

ICI made paints and speciality products, including food ingredients, speciality polymers, electronic materials, fragrances and flavourings.

In 2008, it was acquired by AkzoNobel,

which immediately sold parts of ICI to Henkel, and integrated ICI's remaining operations within its existing organisation.

Lake Magadi

Lake Magadi is the southernmost lake in the Kenyan Rift Valley, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron. During the dry season, it is 80% covered by soda and is well known for its wading birds, including flamingos.

Lake Magadi is a saline, alkaline lake, approximately 100 square kilometers in size, that lies in an endorheic basin formed by a graben. The lake is an example of a "saline pan". The lake water, which is a dense sodium carbonate brine, precipitates vast quantities of the mineral trona (sodium sesquicarbonate). In places, the salt is up to 40 m thick. The lake is recharged mainly by saline hot springs (temperatures up to 86 °C) that discharge into alkaline "lagoons" around the lake margins, there being little surface runoff in this arid region. Most hot springs lie along the northwestern and southern shorelines of the lake. During the rainy season, a thin (less than 1 m) layer of brine covers much of the saline pan, but this evaporates rapidly leaving a vast expanse of white salt that cracks to produce large polygons. A single species of fish, a cichlid Alcolapia grahami, inhabits the hot, highly alkaline waters of this lake basin and is commonly seen in some of the hot spring pools around the shoreline, where the water temperature is less than 45 °C.

Lake Magadi was not always so saline. Several thousand years ago (during the late Pleistocene to mid-Holocene in the African humid period), the Magadi basin held a freshwater lake with many fish, whose remains are preserved in the High Magadi Beds, a series of lacustrine and volcaniclastic sediments preserved in various locations around the present shoreline. Evidence also exists for several older Pleistocene precursor lakes that were much larger than present Lake Magadi. At times, Lake Magadi and Lake Natron were united as a single larger lake.

Lake Magadi is also well known for its extensive deposits of siliceous chert. There are many varieties including bedded cherts that formed in the lake and intrusive dike-like bodies that penetrated through overlying sediments while the silica was soft. Most famous is "Magadi-type chert", which formed from a sodium silicate mineral precursor magadiite that was discovered at Lake Magadi in 1967.

Magadi township lies on the lake's east shore, and is home to the Magadi Soda factory, owned by Tata India since December 2005. This factory produces soda ash, which has a range of industrial uses.

The lake is featured in Fernando Meirelles's film The Constant Gardener, which is based on the book of the same name by John le Carré, although in the film the shots are supposed to be at Lake Turkana.

A causeway that crosses the lake provides access to the area west of the lake (Nguruman Escarpment). Recently accommodation for tourists is provided in air conditioned canvas tents.

Lake Natron

Lake Natron is a salt or soda lake in Arusha Region in Tanzania. It is in the Gregory Rift, which is the eastern branch of the East African Rift. The lake is within the Lake Natron Basin, a Ramsar Site wetland of international significance.

The lake is fed principally by the Southern Ewaso Ng'iro River, which rises in central Kenya, and by mineral-rich hot springs. It is quite shallow, less than three metres (9.8 ft) deep, and varies in width depending on its water level. The lake is a maximum of 57 kilometres (35 mi) long and 22 kilometres (14 mi) wide. The surrounding area receives irregular seasonal rainfall, mainly between December and May totalling 800 millimetres (31 in) per year. Temperatures at the lake are frequently above 40 °C (104 °F).High levels of evaporation have left behind natron (sodium carbonate decahydrate) and trona (sodium sesquicarbonate dihydrate). The alkalinity of the lake can reach a pH of greater than 12. The surrounding bedrock is composed of alkaline, sodium-dominated trachyte lavas that were laid down during the Pleistocene period. The lavas have significant amounts of carbonate but very low calcium and magnesium levels. This has allowed the lake to concentrate into a caustic alkaline brine.

Mary Rose

The Mary Rose is a carrack-type warship of the English Tudor navy of King Henry VIII. She served for 33 years in several wars against France, Scotland, and Brittany, then was substantially rebuilt in 1536. She saw her last action on 19 July 1545. She led the attack on the galleys of a French invasion fleet, but she sank in the Solent, the straits north of the Isle of Wight.

The wreck of the Mary Rose was discovered in 1971 and was raised on 11 October 1982 by the Mary Rose Trust in one of the most complex and expensive maritime salvage projects in history. The surviving section of the ship and thousands of recovered artefacts are of great value as a Tudor-era time capsule. The excavation and raising of the Mary Rose was a milestone in the field of maritime archaeology, comparable in complexity and cost to the raising of the 17th-century Swedish warship Vasa in 1961.

The finds include weapons, sailing equipment, naval supplies, and a wide array of objects used by the crew. Many of the artefacts are unique to the Mary Rose and have provided insights into topics ranging from naval warfare to the history of musical instruments. The remains of the hull have been on display at the Portsmouth Historic Dockyard since the mid-1980s while undergoing restoration. An extensive collection of well-preserved artefacts is on display at the Mary Rose Museum, built to display the remains of the ship and its artefacts.

The Mary Rose was one of the largest ships in the English navy through more than three decades of intermittent war, and she was one of the earliest examples of a purpose-built sailing warship. She was armed with new types of heavy guns that could fire through the recently invented gun-ports. She was substantially rebuilt in 1536 and was also one of the earliest ships that could fire a broadside, although the line of battle tactics had not yet been developed. Several theories have sought to explain the demise of the Mary Rose, based on historical records, knowledge of 16th-century shipbuilding, and modern experiments. The precise cause of her sinking is still unclear because of conflicting testimonies and a lack of conclusive physical evidence.

Natron

Natron is a naturally occurring mixture of sodium carbonate decahydrate (Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and sodium sulfate. Natron is white to colourless when pure, varying to gray or yellow with impurities. Natron deposits are sometimes found in saline lake beds which arose in arid environments. Throughout history natron has had many practical applications that continue today in the wide range of modern uses of its constituent mineral components.

In modern mineralogy the term natron has come to mean only the sodium carbonate decahydrate (hydrated soda ash) that makes up most of the historical salt.

Sesqui

Sesqui, Latin for one-and-one-half times, may refer to:

Sodium sesquicarbonate, a double salt of sodium bicarbonate and sodium carbonate

Sesqui 1990, a 1990 festival in the city of Wellington, New Zealand

Sesquicentennial Exposition, a 1926 world's fair hosted in Philadelphia

Sesquilinear, a property of the dot product in complex, multi-dimensional spaces

Sodium carbonate

Sodium carbonate, Na2CO3, (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, water-soluble salts. All forms have a strongly alkaline taste and give moderately alkaline solutions in water. Historically it was extracted from the ashes of plants growing in sodium-rich soils. Because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process.

Tata Chemicals Europe

Tata Chemicals Europe (formerly Brunner Mond (UK) Limited) is a UK-based chemicals company that is a subsidiary of Tata Chemicals Limited, itself a part of the India-based Tata Group. Its principal products are soda ash, sodium bicarbonate, calcium chloride and associated alkaline chemicals.

Trona

Trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, Na2CO3•NaHCO3•2H2O) is a non-marine evaporite mineral. It is mined as the primary source of sodium carbonate in the United States, where it has replaced the Solvay process used in most of the rest of the world for sodium carbonate production.

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