How soap is made - material, manufacture, making, used, processing, components, procedure, steps Soap Background Soap is a combination of animal fat or plant oil and caustic soda. When dissolved in water, it breaks dirt away from surfaces. Through the ages soap has been used to cleanse, to cure skin sores, to dye hair, and as a salve or skin ointment. But today we generally use soap as a cleanser or perfume. The exact origins of soap are unknown, though Roman sources claim it dates back to at least 600 B.C. , when Phoenicians prepared it from goat's tallow and wood ash. Soap was also made by the Celts, ancient inhabitants of Britain. Soap was used widely throughout the Roman empire, primarily as a medicine. Mention of soap as a cleanser does not appear until the second century A.D. By the eighth century, soap was common in France, Italy, and Spain, but it was rarely used in the rest of Europe until as late as the 17th century. Manufacture of soap began in England around the end of the 12th century. Soap-makers had to pay a heavy tax on all the soap they produced.

The tax collector locked the lids on soap boiling pans every night to prevent illegal soap manufacture after hours. Because of the high tax, soap was a luxury item, and it did not come into common use in England until after the tax was repealed in 1853. In the 19th century, soap was affordable and popular throughout Europe. Early soap manufacturers simply boiled a solution of wood ash and animal fat. A foam substance formed at the top of the pot. When cooled, it hardened into soap. Around 1790, French soapmaker Nicolas Leblanc developed a method of extracting caustic soda (sodium hydroxide) from common table salt (sodium chloride), replacing the wood ash element of soap. The French chemist Eugene-Michel Chevreul put the soap-forming process (called in English saponification) into concrete chemical terms in 1823. In saponification, the animal fat, which is chemically neutral, splits into fatty acids, which react with alkali carbonates to form soap, leaving glycerin as a byproduct.

Soap was made with industrial processes by the end of the 19th century, though people in rural areas, such as the pioneers in the western United States, continued to make soap at home. Raw Materials Soap requires two major raw materials: fat and alkali. The alkali most commonly used today is sodium hydroxide. Potassium hydroxide can also be used. Potassium-based soap creates a more water-soluble product than sodium-based soap, and so it is called "soft soap." Soft soap, alone or in combination with sodium-based soap, is commonly used in shaving products. Animal fat in the past was obtained directly from a slaughterhouse. Modern soapmakers use fat that has been processed into fatty acids. This eliminates many impurities, and it produces as a byproduct water instead of glycerin. Many vegetable fats, including olive oil, palm kernel oil, and coconut oil, are also used in soap making. Additives are used to enhance the color, texture, and scent of soap. Fragrances and perfumes are added to the soap mixture to The above illustrations show the kettle process of making soap. cover the odor of dirt and to leave behind a fresh-smelling scent.

Abrasives to enhance the texture of soap include talc, silica, and marble pumice (volcanic ash). Soap made without dye is a dull grey or brown color, but modern manufacturers color soap to make it more enticing to the consumer. The Manufacturing Process The kettle method of making soap is still used today by small soap manufacturing companies. This process takes from four to eleven days to complete, and the quality of each batch is inconsistent due to the variety of oils used. Around 1940, engineers and scientists developed a more efficient manufacturing process, called the continuous process. This procedure is employed by large soap manufacturing companies all around the world today. Exactly as the name states, in the continuous process soap is produced continuously, rather than one batch at a time. Technicians have more control of the production in the continuous process, and the steps are much quicker than in the kettle method—it takes only about six hours to complete a batch of soap. The Kettle Process Boiling 1 Fats and alkali are melted in a kettle, which is a steel tank that can stand three stories high and hold several thousand pounds of material. Steam coils within the kettle heat the batch and bring it to a boil.

After boiling, the mass thickens as the fat reacts with the alkali, producing soap and glycerin. Salting 2 The soap and glycerin must now be separated. The mixture is treated with salt, causing the soap to rise to the top and the glycerin to settle to the bottom. The glycerin is extracted from the bottom of the kettle. Strong change 3 To remove the small amounts of fat that have not saponified, a strong caustic solution is added to the kettle. This step in the process is called "strong change." The mass is brought to a boil again, and the last of the fat turns to soap. The batch may be given another salt treatment at this time, or the manufacturer may proceed to the next step. Pitching 4 The next step is called "pitching." The soap in the kettle is boiled again with added water. The mass eventually separates into two layers. The top layer is called "neat soap," which is about 70% soap and 30% water. The lower layer, called "nigre," contains most of the impurities in the soap such as dirt and salt, as well as most of the water.

The neat soap is taken off the top. The soap is then cooled. The finishing process is the Developed around 1940 and used by today's major soap-making companies, the above illustrations show the continuous process of making soap. same as for soap made by the continuous process. The Continuous Process Splitting 1 The first step of the continuous process splits natural fat into fatty acids and glycerin. The equipment used is a vertical stainless steel column with the diameter of a barrel called a hydrolizer. It may be as tall as 80 feet (24 m). Pumps and meters attached to the column allow precise measurements and control of the process. Molten fat is pumped into one end of the column, while at the other end water at high temperature (266°F [130°C]) and pressure is introduced. This splits the fat into its two components. The fatty acid and glycerin are pumped out continuously as more fat and water enter. The fatty acids are then distilled for purification. Mixing 2 The purified fatty acids are next mixed with a precise amount of alkali to form soap. Other ingredients such as abrasives and fragrance are also mixed in.

The hot liquid soap may be then whipped to incorporate air. Cooling and finishing 3 The soap may be poured into molds and allowed to harden into a large slab. It may also be cooled in a special freezer. The slab is cut into smaller pieces of bar size, which are then stamped and wrapped. The entire continuous process, from splitting to finishing, can be accomplished in several hours. Milling 4 Most toiletry soap undergoes additional processing called milling. The milled bar lathers up better and has a finer consistency than non-milled soap. The cooled soap is fed through several sets of heavy rollers (mills), which crush and knead it. Perfumes can best be incorporated at this time because their volatile oils do not evaporate in the cold mixture. After the soap emerges from the mills, it is pressed into a smooth cylinder and extruded. The extruded soap is cut into bar size, stamped and wrapped. Byproducts Glycerin is a very useful byproduct of soap manufacture. It is used to make hand lotion, drugs, and nitroglycerin, the main component of explosives such as dynamite.

Where To Learn More Soaps & Detergents: Chemistry | Clean Living | American Cleaning Institute American Cleaning Institute Soaps & Detergents: Chemistry To understand what is needed to achieve effective cleaning, it is helpful to have a basic knowledge of soap and detergent chemistry. Water, the liquid commonly used for cleaning, has a property called surface tension. In the body of the water, each molecule is surrounded and attracted by other water molecules. However, at the surface, those molecules are surrounded by other water molecules only on the water side. A tension is created as the water molecules at the surface are pulled into the body of the water. This tension causes water to bead up on surfaces (glass, fabric), which slows wetting of the surface and inhibits the cleaning process. You can see surface tension at work by placing a drop of water onto a counter top. The drop will hold its shape and will not spread. In the cleaning process, surface tension must be reduced so water can spread and wet surfaces. Chemicals that are able to do this effectively are called surface active agents, or surfactants.

They are said to make water "wetter." Surfactants perform other important functions in cleaning, such as loosening, emulsifying (dispersing in water) and holding soil in suspension until it can be rinsed away. Surfactants can also provide alkalinity, which is useful in removing acidic soils. Surfactants are classified by their ionic (electrical charge) properties in water: anionic (negative charge), nonionic (no charge), cationic (positive charge) and amphoteric (either positive or negative charge). Soap is an anionic surfactant. Other anionic as well as nonionic surfactants are the main ingredients in today's detergents. Now let's look closer at the chemistry of surfactants. Soaps Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali. First let's examine the composition of fats, oils and alkalis; then we'll review the soapmaking process. Fats and Oils The fats and oils used in soapmaking come from animal or plant sources.

Each fat or oil is made up of a distinctive mixture of several different triglycerides. In a triglyceride molecule, three fatty acid molecules are attached to one molecule of glycerine. There are many types of triglycerides; each type consists of its own particular combination of fatty acids. Fatty acids are the components of fats and oils that are used in making soap. They are weak acids composed of two parts: A carboxylic acid group consisting of one hydrogen (H) atom, two oxygen (O) atoms, and one carbon (C) atom, plus a hydrocarbon chain attached to the carboxylic acid group. Generally, it is made up of a long straight chain of carbon (C) atoms each carrying two hydrogen (H) atoms. Alkali An alkali is a soluble salt of an alkali metal like sodium or potassium. Originally, the alkalis used in soapmaking were obtained from the ashes of plants, but they are now made commercially. Today, the term alkali describes a substance that chemically is a base (the opposite of an acid) and that reacts with and neutralizes an acid.

The common alkalis used in soapmaking are sodium hydroxide (NaOH), also called caustic soda; and potassium hydroxide (KOH), also called caustic potash. How Soaps are Made Saponification of fats and oils is the most widely used soapmaking process. This method involves heating fats and oils and reacting them with a liquid alkali to produce soap and water (neat soap) plus glycerine. The other major soapmaking process is the neutralization of fatty acids with an alkali. Fats and oils are hydrolyzed (split) with a high-pressure steam to yield crude fatty acids and glycerine. The fatty acids are then purified by distillation and neutralized with an alkali to produce soap and water (neat soap). When the alkali is sodium hydroxide, a sodium soap is formed. Sodium soaps are "hard" soaps. When the alkali is potassium hydroxide, a potassium soap is formed. Potassium soaps are softer and are found in some liquid hand soaps and shaving creams. The carboxylate end of the soap molecule is attracted to water. It is called the hydrophilic (water-loving) end.

The hydrocarbon chain is attracted to oil and grease and repelled by water. It is known as the hydrophobic (water-hating) end. How Water Hardness Affects Cleaning Action Although soap is a good cleaning agent, its effectiveness is reduced when used in hard water. Hardness in water is caused by the presence of mineral salts - mostly those of calcium (Ca) and magnesium (Mg), but sometimes also iron (Fe) and manganese (Mn). The mineral salts react with soap to form an insoluble precipitate known as soap film or scum. Soap film does not rinse away easily. It tends to remain behind and produces visible deposits on clothing and makes fabrics feel stiff. It also attaches to the insides of bathtubs, sinks and washing machines. Some soap is used up by reacting with hard water minerals to form the film. This reduces the amount of soap available for cleaning. Even when clothes are washed in soft water, some hardness minerals are introduced by the soil on clothes. Soap molecules are not very versatile and cannot be adapted to today's variety of fibers, washing temperatures and water conditions.

Soap - Chemistry Encyclopedia - structure, reaction, water, uses, name, molecule, History of Soap Soap - Chemistry Encyclopedia Soap Photo by: Vladimir Voronin Soaps are cleaning agents that are usually made by reacting alkali (e.g., sodium hydroxide) with naturally occurring fat or fatty acids. The reaction produces sodium salts of these fatty acids, which improve the cleaning process by making water better able to lift away greasy stains from skin, hair, clothes, and just about anything else. As a substance that has helped clean bodies as well as possessions, soap has been remarkably useful. History of Soap The discovery of soap predates recorded history, going back perhaps as far as six thousand years. Excavations of ancient Babylon uncovered cylinders with inscriptions for making soap around 2800 B.C.E. Later records from ancient Egypt (c. 1500 B.C.E. ) describe how animal and vegetable oils were combined with alkaline salts to make soap. According to Roman legend, soap got its name from Mount Sapo, where animals were sacrificed. Rain would wash the fat from the sacrificed animals along with alkaline wooden ashes from the sacrificial fires into the Tiber River, where people found the mixture helped clean clothes.

This recipe for making soap was relatively unchanged for centuries, with American colonists collecting and cooking down animal tallow (rendered fat) and then mixing it with an alkali potash solution obtained from the accumulated hardwood ashes of their winter fires. Similarly, Europeans made something known as castile soap using olive oil. Only since the mid-nineteenth century has the process become commercialized and soap become widely available at the local market. Chemistry of Soap The basic structure of all soaps is essentially the same, consisting of a long hydrophobic (water-fearing) hydrocarbon "tail" and a hydrophilic (waterloving) anionic "head": CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 COO − or CH 3 (CH 2 ) n COO − The length of the hydrocarbon chain ("n") varies with the type of fat or oil but is usually quite long. The anionic charge on the carboxylate head is usually balanced by either a positively charged potassium (K + ) or sodium (Na + ) cation.

In making soap, triglycerides in fat or oils are heated in the presence of a strong alkali base such as sodium hydroxide, producing three molecules of soap for every molecule of glycerol. This process is called saponification and is illustrated in Figure 1. Like synthetic detergents, soaps are "surface active" substances ( surfactants ) and as such make water better at cleaning surfaces. Water, although a good general solvent, is unfortunately also a substance with a very high surface tension. Because of this, water molecules generally prefer to stay together rather than to wet other surfaces. Surfactants work by reducing the surface tension of water, allowing the water molecules to better wet the surface and thus increase water's ability to dissolve dirty, oily stains. Figure 1. In studying how soap works, it is useful to consider a general rule of nature: "like dissolves like." The nonpolar hydrophobic tails of soap are lipophilic ("oil-loving") and so will embed into the grease and oils that help dirt and stains adhere to surfaces. The hydrophilic heads, however, remain surrounded by the water molecules to which they are attracted.

As more and more soap molecules embed into a greasy stain, they eventually surround and isolate little particles of the grease and form structures called micelles that are lifted into solution. In a micelle, the tails of the soap molecules are oriented toward and into the grease, while the heads face outward into the water, resulting in an emulsion of soapy grease particles suspended in the water. With agitation, the micelles are dispersed into the water and removed from the previously dirty surface. In essence, soap molecules partially dissolve the greasy stain to form the emulsion that is kept suspended in water until it can be rinsed away (see Figure 2). As good as soaps are, they are not perfect. For example, they do not work well in hard water containing calcium and magnesium ions, because the calcium and magnesium salts of soap are insoluble; they tend to bind to the calcium and magnesium ions, eventually precipitating and falling out of solution. In doing so, soaps actually dirty the surfaces they were designed to clean. Thus soaps have been largely replaced in modern cleaning solutions by synthetic detergents that have a sulfonate (R-SO 3 − ) group instead of the carboxylate head (R-COO − ).

Sulfonate detergents tend not to precipitate with calcium or magnesium ions and are generally more soluble in water. Uses of Soap Although the popularity of soap has declined due to superior detergents, one of the major uses of animal tallow is still for making soap, just as it was in years past. Beyond its cleaning ability, soap has been used in other applications. For example, certain soaps can be mixed with gasoline to produce gelatinous napalm, a substance that combusts more slowly than pure gasoline when ignited or exploded in warfare. Soaps are also used in "canned heat," a commercialized mixture of soap and alcohol that can be ignited and used to cook foods or provide warmth. Overall, soap is a remarkably useful substance, just as it has been for thousands of years. David A. Dobberpuhl Figure 2. How soap works: The hydrophobic tails of soap molecules embed in grease and oil, breaking it up into particles called micelles that lift off the surface and disperse into water. Bibliography Brady, James E.; Russell, Joel W.; and Holum, John R. (2000). Chemistry: Matter and Its Changes, 3rd edition.

New York: Wiley. Internet Resources "The History and Chemistry of Soaps and Detergents." The Soap and Detergent Association. Available from the SDA Kids Corner at . Also read article about Soap from Wikipedia User Contributions: Soap 101: Making Your Own Shampoo and Soap Normal pH is 7.0 Water should be 7.0 Acids are chemicals with a pH lower than "neutral". An acid may be mild or extremely caustic. Alkaline substances have a pH higher than 7.0. They may be mild or corrosive. The type of acid used to make soap is a fatty acid, either from animal fat or vegetable oil. The alkali used to cause the chemical reaction with the fatty acids is either made from potash (lye water) or sodium hydroxide. Saponification When a base reacts with a fat or oil, fatty acids are separated from the glycerin and the sodium or potassium component of the alkali bonds with the fatty acids. The product formed by the sodium or potassium and the fatty acids is a salt. Technically speaking, soap is a salt. Glycerin (also called glycerol) is a by-product that also has cleansing properties.

It is hydroscopic, i.e. moisturizing because it attracts water from the air. As can be deduced by the notes in the table, soap should have a neutral pH. It should not burn the skin. It should also be made from pure ingredients so let's discuss the ingredients. Animal Fat: Most inexpensive soaps are by-products of the meat packing industry. There are, however, a large number of reasons for preferring vegetable-based soaps over animal ones, not the least of which is that toxins, including synthetic hormones used to bulk up animals, tend to accumulate in fat tissue. If this were not a cogent enough argument, it is fairly easy to demonstrate that animal fats tend to clog pores more than vegetable oils. Even going back many centuries, soaps made from vegetable oils, like Castile soap, were regarded as superior to those made from lard. Animal fat has to be "rendered" or purified. This involves cooking and odor. Meat has to be separated from the fat. This is usually done by heating the fat so that the cracklings separate. The meat looks like it has been cooked, which, of course, it has. The meat must be removed.

Sometimes, water has to be added so that it absorbs the impurities. Then, the "soup" has to cooled, usually slowly, so that the fat separates and rises to the top while the heavier parts sink. The fat is then skimmed off. If the fat still has odor and impurities, the process has to be repeated. Vegetable Oils: In Spain, there was a tradition of fine soap making, called Castile because of the place name. These soaps used mainly olive oil. Today, coconut oil, sometimes called coconut butter, is used in many soaps because it lathers nicely and is almost odorless. However, almost any vegetable oil can be used. The more common ones are almond, avocado, jojoba, palm, and shea butter. Lye Water: As noted, this is made by pouring or dripping water over ashes. Different woods or other organic materials produce variations in color. Soft water, i.e., rain or spring water, should be used. If the solution does not have a high enough pH, it needs to be poured over more ash. If it is too corrosive, more water needs to be added.

This is a time consuming process that requires burning one's own organic materials over an open fire or in a cast iron pot. If a feather dissolves in the lye, the pH is probably about right. Some try floating eggs or potatoes in the brew. These objects should float so that half their mass is below the water line. This kind of base will make a soft soap, not a hard soap. Caustic Soda: Sodium hydroxide is a nasty chemical that requires special handling, like safety goggles and gloves. It was introduced in the 19th century by a French chemist named Nicolas Leblanc (1742-1806) and improved by a Belgian chemist, Ernest Solvay (1836-1922), who changed the nature of the soap and impacted the industry radically. Basically, the newer methods substituted sodium hydroxide for the lye water made from potash. The result was a hard soap that was easy to store and ship. Soap making moved from the farm to industrial manufacturers who realized huge profits from the recycling of animal fats into commercially viable cakes that were easy to sell.

Other Ingredients: As everyone knows, there can be a lot of ingredients in soap: chemical stabilizers, preservatives, fragrances, vitamins, seaweed, corn, oatmeal, pumice, aloe, dyes, milk, fruit or berries, cucumbers or carrots or other vegetables, exotic oils, beeswax, herbs and flowers . . . Each ingredient changes the chemistry of the bar of soap. Let's see how clear I can be. Milk, from goats or other animals, counts towards the acid (and water) component of the soap. Aloe gel counts towards the base component and enhances the disinfecting properties of the soap. Intuitive people as well as those who are cutting edge in new ecological developments must realize that each constituent not only has to go through some process to prepare it for use in the soap but each one changes the pH of the soapand our environmentbecause even if run-off today does not start in a temple where animal sacrifices are performed, it starts with animal sacrifice and ends up laced with antibiotics and derivatives of the petrochemical industry that eventually end up in sewage and septic systems. Commercial Soap Dial is a good example of a commercial soap.

It is produced by Armour, but it is a truly distant cousin of Borax, a cleanser that went into production after the discovery of vast deposits of borax in Death Valley during the Gold Rush in 1880. The Armour family went into the soap business eight years later. Then, it produced a scouring pad for aluminum cookware called Brillo (1913). Purex began in a garage in Los Angeles in 1922. Enter the meatpacking industry: Dial is introduced in 1948 as the first antibacterial soap. The ad campaign was enormous and promised 24-hour protection from bacteria-causing odors. Next comes Vienna sausage in aluminum containers . . . beginning to see a flash back of your childhood? Let me continue. In 1988, while the former host of "Death Valley Days" was sitting in the Oval Office, the rights to market 20-mule team of Boraxo were acquired. Next came the first microwave cup meals. A year later, Liquid Dial is introduced. It rings up a million in sales in the first 10 weeks on the market. The deal with WalMart took another decade to pull together.

In the meantime, the company split and spun off some products and acquired new ones. Soap versus Detergent A detergent is a synthetic imitation of a soap, i.e. a laundering agent made from chemicals. Detergents were developed in Germany in 1916. They are not just "imitation soaps." Detergents are different from soaps in that they do not combine with natural mineral salts in water and do not form scum. Unlike real soap, detergents work in cold water and with salt water. Soap and detergent have similar capacities to emulsify fats and oils and to hold dirt, but from this point on, they are significantly different due to the presence of surfactants and additives, such as whitening agents. The list of the chemicals used to produce these detergent effects is hair raising. Beginning around 1960, it was noted that there was more foam on rivers and that sewage treatment facilities were encountering serious problems, including that water foamed when it came out of the tap, this due to the fact that propylene-based alkyl benzene sulphonates are not completely degraded by the bacteria naturally present in effluents.

It is not for me to try to explain the chemistry of all that started to go wrong, but merely to note that the correction being sought was to increase use of proteolytic enzymes to aid the breakdown of materials that were not readily "bio-degradable." The ramifications of this are almost too far-reaching to imagine. Summary It is not possible to do justice to soap's fascinating history in a single web page, but this overview ought to give many people incentive to reflect on the many, many soap products they use daily: liquid soap, bar soap, shampoo, liquid and powdered dishwasher and laundry detergents, and a host of specialty cleaning products, all of which have a major impact on health and the environment. Fortunately, however, there is a resurgence of interest in cottage industry soap manufacturing in which both the hygienic and aesthetic demands of the most fastidious connoisseur can be satisfied. Copyright by Ingrid Naiman 2004 ELEMENT: SODIUM Spectra of Gas Discharges History (English, soda; Medieval Latin, sodanum, headache remedy) Long recognized in compounds, sodium was first isolated by Davy in 1807 by electrolysis of caustic soda.

Sources Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the fourth most abundant element on earth, comprising about 2.6% of the earth's crust; it is the most abundant of the alkali group of metals. It is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride. This method is much cheaper than that of electrolyzing sodium hydroxide, as was used several years ago. Compounds The most common compound is sodium chloride, but it occurs in many other minerals, such as soda niter, cryolite, amphibole, zeolite, etc. Properties Sodium, like every reactive element, is never found free in nature. Sodium is a soft, bright, silvery metal which floats on water, decomposing it with the evolution of hydrogen and the formation of the hydroxide. It may or may not ignite spontaneously on water, depending on the amount of oxide and metal exposed to the water. It normally does not ignite in air at temperatures below 115oC. Uses Metallic sodium is vital in the manufacture of esters and in the preparation of organic compounds.

The metal may be used to improve the structure of certain alloys, to descale metal, and to purify molten metals. An alloy of sodium with potassium, NaK, is also an important heat transfer agent. Compounds Sodium compounds are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries. Soap is generally a sodium salt of certain fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. Among the many compounds that are of the greatest industrial importance are common salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (hypo, Na2S2O3 . 5H2O), and borax (Na2B4O7 . 10H2O). Isotopes Thirteen isotopes of sodium are recognized. Cost Metallic sodium is priced at about 15 to 20 cents/lb in quantity. Reagent grade (ACS) sodium in January 1990 cost about $35/lb.

On a volume basis, it is the cheapest of all metals. Handling Sodium metal should be handled with great care. It cannot be maintained in an inert atmosphere and contact with water and other substances with which sodium reacts should be avoided. Sources: Los Alamos National Laboratory; CRC Handbook of Chemistry and Physics; American Chemical Society Element image from used with permission Sodium - Element information, properties and uses | Periodic Table Chemistry in its element: sodium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) This week an essential element with a split personality. Here's David Read. David Read Sodium, like most elements in the periodic table could be said to have a dual personality. On one side it is an essential nutrient for most living things, and yet, due to its reactive nature is also capable of wreaking havoc if you happen to combine it with something you shouldn't. As such sodium is found naturally only in compounds and never as the free element. Even so it is highly abundant, accounting for around 2.6 per cent of the earths crust by weight.

Its most common compounds include dissolved sodium chloride (or table salt), its solid form, halite and as a charge balancing cation in zeolites. Aside from being an essential nutrient, the story of man and sodium is said to begin all the way back in the time of the Pharaohs in Ancient Egypt, with the first recorded mention of a sodium compound in the form of hieroglyphics. It is difficult to describe a pictogram through speech but imagine a squiggly line over the top of a hollow eye-shape, over the top of a semicircle, with a left-facing vulture image next to them all. This pictogram meant divine or pure and its name is the root of the word natron, which was used to refer to washing soda, or sodium carbonate decahydrate, as we would know it today. Sodium carbonate was used in soap, and also, in the process of mummification thanks to its water absorbing and bacteria killing pH control properties. In medieval Europe, however, sodium carbonate was also used as a cure for headaches, and so took the name sodanum, from the Arabic suda, meaning headache.

It was this terminology that inspired Sir Humphrey Davy to call the element sodium when he first isolated it by passing an electric current through caustic soda, or sodium hydroxide, in 1807. This process is known as electrolysis and using it Davy went on to isolate elemental potassium, calcium, magnesium and barium by a very similar method. Chemistry teachers often confuse children when they tell them about chemical symbols. Whilst ones like H, N, C and O all seem perfectly logical, abbreviating sodium to Na seems counterintuitive at first. However, if we consider the word natron, we can see where the abbreviated form came from. When isolated in metallic form, silvery white sodium is a violent element, immediately oxidising upon contact with air, and violently producing hydrogen gas which may burst into flame when brought into contact with water. It is one of the highly reactive group one elements that are named the alkali metals. Like the other alkali metals, it has a very distinctive flame test - a bright orange colour, from the D-line emission. This is something you will have seen in all built up areas in the form of street lamps, which use sodium to produce the unnatural yellow light bathing our streets.

This effect was first noted in 1860 by Kirchoff and Bunsen of Bunsen Burner fame. Almost all young chemists will have done a flame test at some point, and sodium chloride is a popular choice. Unfortunately, the intensity of the colour is such that if any of the compound is spilled into the Bunsen burner, it is cursed to burn with a blue and orange speckled flame seemingly forever. The reaction of sodium with water is a favourite demonstration, and clips of it abound on the internet. Sodium and its compounds have applications so diverse it would be impossible to mention them all here, a couple of examples include the fact that sodium is used to cool nuclear reactors, since it won't boil as water would at the high temperatures that are reached. Sodium hydroxide can be used to remove sulfur from petrol and diesel, although the toxic soup of by-products that is formed has led to the process being outlawed in most countries. Sodium hydroxide is also used in biodiesel manufacture, and as a key component in products that remove blockages from drains.

Baking soda actually contains sodium (it's in the name!) and its chemical name is sodium bicarbonate, where I'm sure you've come across it in baking or cooking where it undergoes thermal decomposition at above 70°C to release carbon dioxide - which then makes your dough rise. It is as an ion, however, that sodium really becomes important. An average human being has to take in around two grams of sodium a day - and virtually all of this will be taken in the form of salt in the diet. Sodium ions are used to build up electrical gradients in the firing of neurons in the brain. This involves sodium (and its big brother potassium) diffusing through cell membranes. Sodium diffuses in and is pumped back out, while potassium does the reverse journey. This can take up a huge amount of the body's energy - sometimes as much as 40 per cent. I'd like to end with a brief story which highlights the dual personality of sodium. One man bought three and a half pounds of sodium metal from the internet and spent the evening reacting it with water in various shapes and sizes whilst he and his friends watched from a safe distance. The party was apparently a success, but he doesn't suggest hosting your own.

The following day when the host came outside to check the area where he detonated the sodium was clear, he noticed that it was covered in swarms of yellow butterflies. After doing some research, he found that these butterflies had an interesting habit. The males search for sodium and gradually collect it, presenting it to their mates later as a ritual. So, that sums up the two faces of sodium. Its violent reactive nature contrasted with its use by amorous butterflies. Meera Senthilingam That was Southampton university's David Read with the two faced chemistry of sodium. Now next week, the chemical equivalent of train spotting. Brian Clegg It's easy to accuse the scientists who produce new, very heavy elements of being chemistry's train spotters. Just as train spotters spend hours watching for a particular locomotive so they can underline it in their book, it may seem that these chemists laboriously produce an atom or two of a superheavy element as an exercise in ticking the box. But element 114 has provided more than one surprise, showing why such elements are well worth investigating.

Meera Senthilingam And to find out why element 114 is worth the effort join Brian Clegg in next week's Chemistry in its element. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) salt (NaCl) | sodium chloride | Britannica.com sodium chloride Alternative Titles: common salt, sodium chloride, table salt Related Topics salt Salt (NaCl), sodium chloride, mineral substance of great importance to human and animal health, as well as to industry. The mineral form halite , or rock salt, is sometimes called common salt to distinguish it from a class of chemical compounds called salts . Salt crystal magnified. U.S.Geological Survey Properties of common salt are shown in the table. Salt is essential to the health of both people and animals. Table salt, used universally as a seasoning, is fine-grained and of high purity.

To ensure that this hygroscopic (i.e., water-attracting) substance will remain free-flowing when exposed to the atmosphere, small quantities of sodium aluminosilicate, tricalcium phosphate , or magnesium silicate are added. Iodized salt —that is, salt to which small quantities of potassium iodide have been added—is widely used in areas where iodine is lacking from the diet, a deficiency that can cause swelling of the thyroid gland , commonly called goitre . Livestock also require salt; it is often made available in solid blocks. Learn about salt, including its health effects. Contunico © ZDF Enterprises GmbH, Mainz The meat-packing, sausage-making, fish-curing, and food-processing industries use salt as a preservative or seasoning or both. It is employed for curing and preserving hides and as a brine for refrigeration. In the chemical industry , salt is required in the manufacture of sodium bicarbonate (baking soda), sodium hydroxide (caustic soda), hydrochloric acid , chlorine , and many other chemicals. Salt is also employed in soap , glaze, and porcelain enamel manufacture and enters into metallurgical processes as a flux (a substance promoting fusing of metals).

When applied to snow or ice , salt lowers the melting point of the mixture. Thus, large amounts are used in northern climates to help rid thoroughfares of accumulated snow and ice. Salt is used in water-softening equipment that removes calcium and magnesium compounds from water. An explanation of how salt is used in the winter to melt ice on roadways. © American Chemical Society (A Britannica Publishing Partner) History of use nitrous acid In some parts of the Western Hemisphere and in India, the use of salt was introduced by Europeans, but in parts of central Africa it is still a luxury available only to the rich. Where people live mainly on milk and raw or roasted meat (so that its natural salts are not lost), sodium chloride supplements are unnecessary; nomads with their flocks of sheep or herds of cattle, for example, never eat salt with their food. On the other hand, people who live mostly on cereal, vegetable, or boiled meat diets require supplements of salt. The habitual use of salt is intimately connected with the advance from nomadic to agricultural life, a step in civilization that profoundly influenced the rituals and cults of almost all ancient nations.

The gods were worshipped as the givers of the kindly fruits of the earth, and salt was usually included in sacrificial offerings consisting wholly or partly of cereal elements. Such offerings were prevalent among the Greeks and Romans and among a number of the Semitic peoples. Covenants were ordinarily made over a sacrificial meal, in which salt was a necessary element. The preservative qualities of salt made it a peculiarly fitting symbol of an enduring compact, sealing it with an obligation to fidelity . The word salt thus acquired connotations of high esteem and honour in ancient and modern languages. Examples include the Arab avowal “There is salt between us,” the Hebrew expression “to eat the salt of the palace,” and the modern Persian phrase namak ḥarām, “untrue to salt” (i.e., disloyal or ungrateful). In English the term “salt of the earth” describes a person held in high esteem. Chemistry: Fact or Fiction? Salt contributes greatly to our knowledge of the ancient highways of commerce. One of the oldest roads in Italy is the Via Salaria ( Salt Route) over which Roman salt from Ostia was carried into other parts of Italy.

Herodotus tells of a caravan route that united the salt oases of the Libyan Desert . The ancient trade between the Aegean and the Black Sea coast of southern Russia was largely dependent on the salt pans (ponds for evaporating seawater to obtain salt) at the mouth of the Dnieper River and on the salt fish brought from this district. Britannica Stories Leap Second Cakes of salt have been used as money in Ethiopia and elsewhere in Africa and in Tibet . In the Roman army an allowance of salt was made to officers and men; in imperial times, this salarium (from which the English word salary is derived) was converted into an allowance of money for salt. China, the United States, India, Germany, Canada, and Australia are the world’s largest salt producers in the early 21st century. Occurrence Seawater Though the material that gives seawater its salty flavour is composed of many substances, sodium chloride, or common salt, is by far the predominant compound .

On the assumption that 1 gallon (about 4 litres) of seawater contains 0.231 pound (about 105 grams) of salt and that rock salt on the average is 2.17 times as dense as water, it has been estimated that if the oceans of the world were completely dried up, they would yield at least 4.5 million cubic miles of rock salt, or about 14.5 times the bulk of the entire continent of Europe above the high-water mark. An explanation of why seawater is salty. Contunico © ZDF Enterprises GmbH, Mainz Seawater contains on the average about 3 percent salt, although the actual concentration varies from about 1 percent (in the polar seas) to 5 percent. Enclosed waters such as the Mediterranean and Red seas contain a higher proportion of salt than does the open ocean at the same latitude .

Irrespective of the source of the seawater, salt obtained by the evaporation of seawater has the following composition: sodium chloride 77.76 percent, magnesium chloride 10.88 percent, magnesium sulfate 4.74 percent, calcium sulfate 3.60 percent, potassium chloride 2.46 percent, magnesium bromide 0.22 percent, and calcium carbonate 0.34 percent. The first map of ocean salinity taken by the Aquarius/SAC-D spacecraft, August–September 2011. GSFC—JPL-Caltech/NASA World War II At one time almost all the salt used in commerce was produced from the evaporation of seawater, and sea salt still is a staple commodity in many maritime countries, especially where the climate is dry and the summer is long. Commercial salt is manufactured from rock salt, as well as from seawater and other natural and artificial brines . Most of the artificial brines are obtained by pumping water into underground salt beds. A considerable amount of brine itself is used directly in industrial countries.

Manufacture from rock salt The beds of rock salt are mined or quarried by the usual excavation methods, depending on the depths and thicknesses of the deposits and on local conditions. The mined rock salt sometimes is dissolved and the salt manufactured by treatment of the brine, as described below. The method affords opportunities for purification of the salt. When the rock salt is of a high degree of purity, as in Poland and the United States, the salt may be ground, screened, and marketed without further processing. The salt is mined in large lumps that are first crushed, then more finely ground and screened by size into various grades; the salt is then bulk-loaded into trucks, hoppers, or barges or loaded into bags for further handling. Bulk handling has been greatly facilitated by the use of anticaking agents which allow the salt to be stored uncovered and outdoors without becoming a hard mass again. Manufacture from seawater and brines Only a certain quantity of salt will dissolve in water at any given temperature. Once the solution contains as much salt as it can hold, it is said to be saturated; any further additions of salt will not dissolve. Evaporation is the reverse of this process.

When an aqueous solution of several salts ( seawater , for example) is evaporated, each of the salts precipitates as it reaches its point of saturation in the solution. Thus, the different salts in seawater will precipitate at different times, forming layers on the bottom of the evaporating pond. For seawater and many brines, the order of deposition is calcium carbonate, calcium sulfate, sodium chloride, magnesium sulfate, potassium magnesium chloride, and magnesium chloride. Solar evaporation In maritime countries where there is a negative evaporation rate—i.e., the amount of water evaporating exceeds the amount of rainfall by at least 75 cm (about 30 inches)—salt is produced by solar evaporation from seawater. The processes used are similar in general principle from country to country, but details of equipment vary from sophisticated in the United States to quite primitive in developing nations. Salt drying on red clay. The salt was evaporated from seawater in the town of Guérande in … © Photocomptoir/Fotolia A preliminary concentration is usually accomplished by allowing the seawater to flow through a series of gates constructed of wood or a combination of wood and concrete into a series of shallow ponds separated by dikes.

In these ponds the solution is concentrated to a specific gravity of about 1.22; this means that a given volume of brine is 1.22 times as dense as a given volume of pure water. At this stage, suspended impurities such as sand, clay, and the less soluble salts such as calcium carbonate, or chalk , and calcium sulfate are removed. Solar evaporation of the Dead Sea water is hastened by adding dye to the water. The dye permits more heat to be absorbed from sunlight in thinner layers of brine so that shallow ponds may be used and the penetration of brine into the ground is reduced. Once it has been concentrated, the brine is run through a series of crystallizing pans, usually four in number, where the salt is deposited as evaporation proceeds. In the first crystallizing pan, the brine is concentrated to a specific gravity of 1.23 and remains partly contaminated with calcium sulfate. The specific gravity of the solution in the pan increases slowly during crystallization of the salt, reaching 1.24 in the second pan. In the third pan the specific gravity of the solution reaches 1.25, and the salt deposited there contains small amounts of magnesium sulfate as an impurity.

The final solution, termed bitterns , has a specific gravity of 1.25–1.26 and is used in some countries (United States and Israel) in the manufacture of potash , bromine , epsom salts (magnesium sulfate), and magnesium chloride. In developing countries the salt in each crystallizing pan is raked into rows, where it is allowed to drain for several days. After that it is collected into heaps, drained again, lifted from the pans, and finally dried. In industrial countries the salt is harvested mechanically and washed with saturated brine. It is then dewatered, washed with fresh water, and stored for further processing or direct sale. Use of artificial heat In areas where bedded deposits can be solution-mined, evaporated salt is recovered from these solutions with artificial heat. Some evaporated salt also is made from natural brine or solar salt. Formerly, brine was concentrated in open pans over fire. More recently, steam-jacketed vessels have been used. The largest amount of salt produced in the colder climates is rock salt.

The largest amount of evaporated salt is produced by multiple-effect vacuum evaporators, and an important quantity is made in so-called open crystallizers or grainers that produce a type of crystal preferred for use in some of the food industries. The brine, natural or artificial, is first pumped into settling tanks, where calcium and magnesium compounds may be removed by chemical treatment. In grainer operations the settled and filtered brine is delivered to the grainer, a long open trough heated with steam coils. The brine is fed into the grainer at approximately the same rate at which evaporation is taking place and at a temperature only slightly below that of the brine in the grainer. The residue of brine, or bitterns, may be removed continuously, once a day, or less often. Evaporation occurs at the surface of the liquid, and the crystals originate there. They remain at the surface, held up by the surface tension of the brine. The crystal grows at the top edges, becoming a small inverted hollow pyramid, or hopper. Eventually the hopper sinks and ceases to grow. When the crystals are recovered, the salt is largely in the form of flakes, hence the name flake salt.

When multiple-effect evaporators are used, the vacuum in each vessel is adjusted so that the vapour from the first vessel is hot enough to boil the brine in the second, the vapour from the second supplying the heat to operate the third vessel or effect. The brine is usually sent through the stages or effects in succession, although in the case of salt manufacture fresh brine may be fed to each stage if desired. With open pans, 4,500 to 5,400 kg (10,000 to 12,000 pounds) of steam are required to produce 900 kg (1 ton) of salt. With triple-effect evaporation, 630 kg (1,400 pounds) of steam produce 1 ton of salt. The Alberger process is partially a vacuum-pan and partially a grainer operation in which cubic crystals are formed in the solution fed to the grainer pans by a partial vacuum-pan evaporation. These seed crystals in the grainer produce a salt that is a mixture of the grainer-type flake and the flake grown on seed crystals.

About 1,360 kg (3,000 pounds) of steam are required to produce one ton of salt. Salt from the Alberger process is centrifuged (spun) from the brine and then dried. Table salt may have small amounts of aluminum calcium silicate, calcium silicate, magnesium silicate, tricalcium silicate, magnesium carbonate, or tricalcium phosphate added to keep it free-flowing. Iodized salt has potassium iodide added. In some countries yellow prussiate of soda, to prevent caking, is added in minute amounts as regulated by the government. Sodium, Chemical Element - reaction, water, uses, elements, examples, metal, gas, number PRONUNCIATION SO-dee-um Compounds of sodium have been known, of course, throughout human history. But sodium metal was not prepared until 1807. The reason is that sodium attaches itself very strongly to other elements. Its compounds are very difficult to break apart. It was not until 1807 that English chemist Sir Humphry Davy (1778-1829) found a way to extract sodium from its compounds.

(See sidebar on Davy in the calcium entry in Volume 1.) Sodium metal itself has relatively few uses. It reacts with other substances easily, sometimes explosively. However, many sodium compounds have many uses in industry, medicine, and everyday life. Discovery and naming Sodium carbonate, or soda (Na 2 CO 3 ), was probably the sodium compound best known to ancient peoples. It is the most common ore of sodium found in nature. This explains why glass was one of the first chemical products made by humans. Glass is made by heating sodium carbonate and calcium oxide (lime) together. When the mixture cools, it forms the hard, clear, transparent material called glass. Glass was being manufactured on a large scale in Egypt as early as 1370 B.C. The Egyptians called soda natron. Much later, the Romans used a similar name for the compound, natrium. These names explain the chemical symbol used for sodium, Na. The name sodium probably originated from an Arabic word suda, meaning "headache." Soda was sometimes used as a cure for headaches among early peoples.

The word suda also carried over into Latin to become sodanum, which also means "headache remedy." In the early 1800s, Davy found a way to extract a number of active elements from their compounds. Sodium was one of these elements. Davy's method involved melting a compound of the active element, then passing an electric current through the molten (melted) compound. Davy used sodium hydroxide (NaOH) to make sodium. Physical properties Sodium is a silvery-white metal with a waxy appearance. It is soft enough to be cut with a knife. The surface is bright and shiny when first cut, but quickly becomes dull as sodium reacts with oxygen in the air. A thin film of sodium oxide (Na 2 O) forms that hides the metal itself. Sodium's melting point is 97.82°C (208.1°F) and its boiling point is 881.4°C (1,618°F). Its density is slightly less than that of water, 0.968 grams per cubic centimeter. Sodium is a good conductor of electricity. Chemical properties Sodium is a very active element.

It combines with oxygen at room temperature. When heated, it combines very rapidly, burning with a brilliant golden-yellow flame. Sodium also reacts violently with water. (See accompanying sidebar.) It is so active that it is normally stored under a liquid with which it does not react. Kerosene or naphtha are liquids commonly used for this purpose. Sodium also reacts with most other elements and with many compounds. It reacts with acids to produce hydrogen gas. It also dissolves in mercury to form a sodium amalgam. An amalgam is an alloy of mercury and at least one other metal. Occurrence in nature Sodium never occurs as a free element in nature. It is much too active. It always occurs as part of a compound. The most common source of sodium in the Earth is halite. Halite is nearly pure sodium chloride (NaCl). It is also called rock salt. Halite can be found in underground deposits similar to coal mines. Those deposits were formed when ancient oceans evaporated (dried up), leaving sodium chloride behind. Earth movements eventually buried those deposits. Now they can be mined to remove the sodium chloride. Sodium and water aren't friends O il and vinegar don't mix. But sodium and water really don't mix!

Sodium reacts violently with water. The effect is fascinating. When sodium metal is first placed into water, it floats. But it immediately begins to react with water, releasing hydrogen gas: A great deal of energy is released in this reaction. It is enough to set fire to the hydrogen gas. The sodium metal reacts with water. So much heat is released that the sodium melts. It turns into a tiny ball of liquid sodium. At the same time, the sodium releases hydrogen from water. The hydrogen gas catches fire and causes the ball of sodium to go sizzling across the surface of the water. Sodium reacts violently with water. Sodium chloride can also be obtained from seawater and brine. Brine is similar to seawater, but it contains more dissolved salt. Removing sodium chloride from seawater or brine is easy. Sodium stored in oil to prevent its reaction with the surrounding air. All that is needed is to let the water evaporate. The sodium chloride is left behind. It only needs to be separated from other chemicals that were also dissolved in the water. Isotopes There is only one naturally occurring isotope of sodium, sodium-23. Isotopes are two or more forms of an element.

Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. Six radioactive isotopes of sodium are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. Two radioactive isotopes of sodium—sodium-22 and sodium-24—are used in medicine and other applications. They can be used as tracers to follow sodium in a person's body. A tracer is a radioactive isotope whose presence in a system can easily be detected. The isotope is injected into the system at some point. Inside the system, the isotope gives off radiation. That radiation can be followed by means of detectors placed around the system. Sodium-24 also has non-medical applications.

For example, it is used to test for leaks in oil pipe lines. These pipe lines are usually buried underground. It may be difficult to tell when a pipe begins to leak. One way to locate a leak is to add some sodium-24 to the oil. If oil leaks out of the pipe, so does the sodium-24. The leaking oil may not be visible, but the leaking sodium-24 is easily detected. It is located by instruments that are designed to detect radiation. Extraction One way to obtain pure sodium metal is by passing an electric current through molten (melted) sodium chloride: This method is similar to the one used by Humphry Davy in 1808. But there is not much demand for sodium metal. Sodium compounds are much more common. A second and similar method is used to make a compound known as sodium hydroxide (NaOH). The sodium hydroxide is then used as a starting point for making other sodium compounds. The method for making sodium hydroxide is called the chloralkali process. The name comes from the fact that both chlorine and an alkali metal (sodium) are produced at the same time.

In this case, an electric current is passed through a solution of sodium chloride dissolved in water: Three useful products are obtained from this reaction: chlorine gas (Cl 2 ), hydrogen gas (H 2 ), and sodium hydroxide (NaOH). The chlor-alkali process is one of the most important industrial processes used today. Uses Sodium metal has a relatively small, but important, number of uses. For example, it is sometimes used as a heat exchange medium in nuclear power plants. A heat exchange medium is a material that picks up heat in one place and carries it to another place. Water is a common heat exchange medium. Some home furnaces burn oil or gas to heat water that travels through pipes and radiators in the house. The water gives off its heat through the radiators. Sodium does a similar job in nuclear power plants. Heat is produced by nuclear fission reactions at the core (center) of a nuclear reactor. In a nuclear fission reaction, large atoms break down to form smaller atoms. As they do so, large amounts of heat energy are given off. Liquid sodium is sealed into pipes that surround the core of the reactor. As heat is generated, it is absorbed (taken up) by the sodium.

The sodium is then forced through the pipes into a nearby room. In that room, the sodium pipes are wrapped around pipes filled with water. The heat in the sodium converts the water to steam. The steam is used to operate devices that generate electricity. Another use of sodium metal is in producing other metals. For example, sodium can be combined with titanium tetrachloride (TiCl 4 ) to make titanium metal: Sodium is also used to make artificial rubber. (Real rubber is made from the collected sap of rubber trees and is expensive.) The starting material for artificial rubber is usually a small molecule. The small molecule reacts with itself over and over again. It becomes a much larger molecule called a polymer. The polymer is the material that makes up the artificial rubber. Sodium metal is used as a catalyst in this reaction. A catalyst is a substance used to speed up or slow down a chemical reaction without undergoing any change itself. The combination of an electric current and sodium vapor produces a yellowish glow in street lamps. Sodium is frequently used in making light bulbs. Sodium is first converted to a vapor (gas) and injected into a glass bulb. An electric current is passed through a wire or filament in the gas-filled bulb.

The electric current causes the sodium vapor to give off a yellowish glow. Many street lamps today are sodium vapor lamps. Their advantage is that they do not produce as much glare as do ordinary lights. Compounds Almost all sodium compounds dissolve in water. When it rains, sodium compounds dissolve and are carried into the ground. Eventually, the compounds flow into rivers and then into the oceans. The ocean is salty partly because sodium compounds have been dissolved for many centuries. But that means that finding sodium compounds on land is somewhat unusual. They tend to be more common in desert areas because deserts experience low rainfall. So sodium compounds are less likely to be washed away. Huge beds of salt and sodium carbonate are sometimes found in desert areas. Dozens of sodium compounds are used today in all fields. Some of the most important of these compounds are discussed below. Sodium chloride (NaCl). The most familiar use of sodium chloride is as a flavor enhancer in food. It is best known as table salt. Large amounts of sodium chloride are also added to prepared foods, such as canned, bottled, frozen, and dried foods. One purpose of adding sodium chloride to these foods is to improve their flavors. But another purpose is to prevent them from decaying.

Sodium chloride kills bacteria in foods. It has been used for hundreds of years as a food preservative. The "pickling" or "salting" of a food, for example, means the adding of salt to that food to keep it from spoiling. This process is one reason people eat so much salt in their foods today. Most people eat a lot of prepared foods. Those prepared foods contain a lot of salt. People are often not aware of all the salt they take in when they eat such foods. Sodium chloride is also the starting point for making other sodium compounds. In fact, this application is probably the number one use for sodium chloride. Almost all sodium compounds dissolve in water. They tend to be more common in desert areas because deserts experience low rainfall. Sodium carbonate (Na2CO3). Sodium carbonate is also known by other names, such as soda, soda ash, sal soda, and washing soda. It is also used as the starting point in making other sodium compounds. A growing use is in water purification Sodium chloride (table salt) crystals. and sewage treatment systems. The sodium carbonate is mixed with other chemicals that react to form a thick, gooey solid.

The solid sinks to the bottom of a tank, carrying impurities present in water or waste water. Sodium carbonate is also used to make a very large number of commercial products, such as glass, pulp and paper, soaps and detergents, and textiles. Sodium bicarbonate (NaHCO3). When sodium bicarbonate is dissolved in water, it produces a fizzing reaction. That reaction can be used in many household situations. For example, the fizzy gas can help bread batter rise. The "rising" of the batter is caused by bubbles released when sodium bicarbonate (baking soda) is added to milk in the batter. Certain kinds of medications, such as Alka-Seltzer, also include sodium bicarbonate. The fizzing is one of the effects of taking Alka-Seltzer that helps settle the stomach. Sodium bicarbonate is also used in mouthwashes, cleaning solutions, wool and silk cleaning systems, fire extinguishers, and mold preventatives in the timber industry.

Examples of lesser known compounds are as follows: sodium alginate (NaC 6 H 7 O 6 ): a thickening agent in ice cream and other prepared foods; manufacture of cement; coatings for paper products; water-based paints sodium bifluoride (KHF 2 ): preservative for animal specimens; antiseptic (germ-killer); etching of glass; manufacture of tin plate sodium diuranate, or "uranium yellow" (Na 2 U 2 O 7 ): used to produce yellowish-orange glazes for ceramics sodium fluorosilicate (Na 2 SiF 6 ): used to make "fluoride" toothpastes that protect against cavities; insecticides and rodenticides (rat-killers); moth repellent; wood and leather preservative; manufacture of laundry soaps and "pearl-like" enamels sodium metaborate (NaBO 2 ): herbicide sodium paraperiodate (Na 3 H 2 IO 6 ): helps tobacco to bum more completely and cleanly; helps paper products retain strength when wet sodium stearate (NaOOCC 17 H 35 ): keeps plastics from breaking down; waterproofing agent; additive in toothpastes

 and cosmetics sodium zirconium glycolate (NaZrH 3 (H 2 COCOO) 3 ): deodorant; germicide (germ-killer); fire-retardant A common compound of sodium, sodium bicarbonate, produces a fizzing reaction.

It is an ingredient in such medications as Alka-Seltzer. Health effects Sodium has a number of important functions in plants, humans, and animals. In humans, for example, sodium is involved in controlling the amount of fluid present in cells. An excess or lack of sodium can cause cells to gain or lose water. Either of these changes can prevent cells from carrying out their normal functions. Dietary concerns P eople sometimes talk about the amount of "sodium" in their diet. Or they may refer to the amount of "salt" in their diet. The two terms are similar, but not exactly alike. In the body, sodium occurs most often as sodium chloride. A common name for sodium chloride is salt. The Committee on Dietary Allowance of the U.S. Food and Nutrition Board recommends that a person take in about 1,100 to 3,300 milligrams of sodium per day. The human body actually needs only about 500 milligrams of sodium. Studies show that the average American takes in about 2,300 to 6,900 milligrams of sodium per day. This high level of sodium intake troubles many health experts.

Too much sodium can affect the body's ability to digest fats, for example. The most serious problem, however, may be hypertension. Hypertension is another name for "high blood pressure." A person with high blood pressure may be at risk for stroke, heart attack, or other serious health problems. Sodium is also involved in sending nerve messages to and from cells. These impulses control the way muscles move. Again, an excess or lack of sodium can result in abnormal nerve and muscle behavior. Sodium is also needed to control the digestion of foods in the stomach and intestines. Also read article about Sodium from Wikipedia User Contributions: Chemical risks in detergents production Chemical risks in detergents production What kind of splashes in detergents production? The origins of cleanliness date back to prehistoric times. Since water is essential for life, the earliest people lived near water and knew something about its cleansing properties. Detergents were developed in response to a shortage of animal and vegetable fats and oils during World War I and II. In addition, a substance that was resistant to hard water was needed to make cleaning more effective. At that time petroleum was found to be a plentiful source for the manufacture of detergents.

Today, detergents are mainly made from a variety of petrochemicals and/or oleochemicals (derivated from fats and oils). According to recent trend, liquid cleansing products are outpacing the powder cleaning products. Detergents can be found for example in: Laundry detergents: they are formulated to meet a variety of soil and stail removal, bleaching, fabric softening and conditioning. Dishwashing products: this includes detergents for hands and machine dishwashing as well as some specialty products. Household cleaning: they are used to clean painted, plastic, metal, porcelain, glass and other surfaces. Because no single product can provide optimum performance on all surfaces and soils, a broad range of products has been formulated to clean efficiently and easily. Amongst the different manufacturers companies, we can find: Solvay, Henkel, Procter & Gamble, Unilever Chemical Risk A detergent (or surfactant) is a chemical compound which has surfactant properties that make it capable to remove soils. It also often contains anti-microbial agents. Chemicals used The first step of manufacturing these detergents is the selection of raw materials.

Raw materials are chosen according to the many criteria, including their human and environmental safety, cost, compatibility with other ingredients, and the form and performance characteristics of the finished products. Amongst these different ingredients you can find: Sodium hypochlorite helping whiten, brighten and remove stains. Alkalis (ammonium, sodium hydroxide). Alkalinity is useful in removing acidity, fatty and oil soils. Acids (nitric acid, acetic acid, hydrochloric acid, sulphonic acid) to neutralize or adjust alkalinity of other ingredients and because some specialty cleaners need extra acidity to remove mineral build up. Colouring agent (pigments or dyes). Solvents (ethanol, isopropanol, propylene glycol) to prevent separation or deterioration of ingredients in liquid products and dissolve organic soils.

Question: Na is the chemical substance for which element used in the manufacture of soap?
Answer: SODIUM