SODIUM HYDROXIDE

Sodium hydroxide = NaOH

EC Number: 215.185.5
E number: E524 (acidity regulators, ...)
CAS Registry No.: 1310.73.2

Other Names: Caustic soda, Lye
Main Uses: Manufacture of other chemicals, and used in many manufacturing processes.
Appearance: Colourless .white solid.
Odour: Odourless

Sodium hydroxide is used to extract alumina from naturally occurring minerals. 
Alumina is used to make aluminum and a variety of products including foil, cans, kitchen utensils, beer kegs and airplane parts. 
Sodium Hydroxide in Other Industrial Manufacturing Uses
Sodium hydroxide is used in many other industrial and manufacturing processes. 

Sodium hydroxide is used to manufacture rayon, spandex, explosives, epoxy resins, paints, glass and ceramics. 
Sodium hydroxide is also used in the textile industry to make dyes, process cotton fabric and in laundering and bleaching, as well as in metal cleaning and processing, oxide coating, electroplating and electrolytic extracting.
Sodium hydroxide is used for making soaps and detergents. 

Sodium hydroxide is used for hard bar soap while potassium hydroxide is used for liquid soaps.
sodium hydroxide is used more often than potassium hydroxide because Sodium hydroxide is cheaper and a smaller quantity is needed.
Sodium hydroxide is used as drain cleaners that contain sodium hydroxide convert fats and grease that can clog pipes into soap, which dissolves in water. (see cleaning agent)
Sodium hydroxide is used for making artificial textile fibres (such as Rayon).

Saponification
Sodium hydroxide can be used for the base.driven hydrolysis of esters (as in saponification), amides and alkyl halides.
However, the limited solubility of sodium hydroxide in organic solvents means that the more soluble potassium hydroxide (KOH) is often preferred. 
Touching sodium hydroxide solution with the bare hands, while not recommended, produces a slippery feeling. 
This happens because oils on the skin such as sebum are converted to soap. 

SODIUM HYDROXIDE
Caustic soda
1310.73.2
Sodium hydrate
Soda lye
White caustic
Sodium hydroxide (Na(OH))
Aetznatron
Ascarite
Sodium hydroxide solution

Dissolving amphoteric metals and compounds
Strong bases attack aluminium. 
Sodium hydroxide reacts with aluminium and water to release hydrogen gas. 
The aluminium takes the oxygen atom from sodium hydroxide, which in turn takes the oxygen atom from the water, and releases the two hydrogen atoms, The reaction thus produces hydrogen gas and sodium aluminate. 
In this reaction, sodium hydroxide acts as an agent to make the solution alkaline, which aluminium can dissolve in.
2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3H2
Sodium aluminate is an inorganic chemical that is used as an effective source of Aluminium hydroxide for many industrial and technical applications. 
Pure sodium aluminate (anhydrous) is a white crystalline solid having a formula variously given as NaAlO2, NaAl(OH)4< (hydrated), Na2O.Al2O3, or Na2Al2O
Formation of sodium tetrahydroxoaluminate(III) or hydrated sodium aluminate is given by:
2Al + 2NaOH + 6H2O → 2 NaAl(OH)4 + 3 H2
This reaction can be useful in etching, removing anodizing, or converting a polished surface to a satin.like finish, but without further passivation such as anodizing or alodining the surface may become degraded, either under normal use or in severe atmospheric conditions.

Sodium hydroxide is used in the manufacture of paper. 
Around 56% of sodium hydroxide produced is used by industry, 25% of which is used in the paper industry. (see chemical pulping)
Sodium hydroxide is used in purifying bauxite ore from which aluminium metal is extracted. 
This is known as Bayer process. (see dissolving amphoteric metals and compounds)
Sodium hydroxide is used in de.greasing metals, oil refining, and making dyes and bleaches.
Sodium hydroxide (NaOH) has no smell. 

Sodium hydroxide is made of solid white crystals that absorb water from the air. 
Sodium hydroxide is caustic. 
Workers who come in contact with sodium hydroxide can be harmed. 
The level of harm depends upon the amount, duration, and activity. 
Sodium hydroxide can burn the eyes, skin, and inner membranes, and cause temporary hair loss.
Sodium hydroxide is used to produce soaps, rayon, paper, products that explode, dyes, and petroleum products. 
Drain cleaners that contain sodium hydroxide convert fats and grease that can clog pipes into soap, which dissolves in water.

Sodium Hydroxide in Pharmaceuticals & Medicine
Sodium hydroxide is used to help manufacture a variety of medicines and pharmaceutical products, from common pain relievers like aspirin, to anticoagulants that can help to prevent blood clots, to cholesterol.reducing medications.

Sodium Hydroxide in Energy
In the energy sector, sodium hydroxide is used in fuel cell production. 
Fuel cells work like batteries to cleanly and efficiently produce electricity for a range of applications, including transportation; materials handling; and stationary, portable and emergency backup power applications. 
Epoxy resins, manufactured with sodium hydroxide, are used in wind turbines.

Sodium Hydroxide in Water Treatment
Municipal water treatment facilities use sodium hydroxide to control water acidity and to help remove heavy metals from water. 
Sodium hydroxide is also used to produce sodium hypochlorite, a water disinfectant.

Sodium Hydroxide in Food Production
Sodium hydroxide is used in several food processing applications, such as curing foods like olives or helping to brown Bavarian.style pretzels, giving them their characteristic crunch. 
Sodium hydroxide is used to remove skins from tomatoes, potatoes and other fruits and vegetables for canning and also as an ingredient in food preservatives that help prevent mold and bacteria from growing in food.

Sodium Hydroxide in Wood & Paper Products
In many paper making processes, wood is treated with a solution containing sodium sulfide and sodium hydroxide.  
This helps dissolve most of the unwanted material in the wood, leaving relatively pure cellulose, which forms the basis of paper. 
In the paper recycling process, sodium hydroxide is used to separate the ink from the paper fibers allowing the paper fibers to be reused again.

Sodium hydroxide is also used to refine raw materials for wood products such as cabinets and furniture and in wood bleaching and cleaning.

Sodium Hydroxide in Aluminum Ore Processing

Properties
Physical properties
Pure sodium hydroxide is a colorless crystalline solid that melts at 318 °C (604 °F) without decomposition, and with a boiling point of 1,388 °C (2,530 °F). 
Sodium hydroxide is highly soluble in water, with a lower solubility in polar solvents such as ethanol and methanol.
NaOH is insoluble in ether and other non.polar solvents.

Similar to the hydration of sulfuric acid, dissolution of solid sodium hydroxide in water is a highly exothermic reaction where a large amount of heat is liberated, posing a threat to safety through the possibility of splashing. 
The resulting solution is usually colorless and odorless. 
As with other alkaline solutions, it feels slippery with skin contact due to the process of saponification that occurs between NaOH and natural skin oils.

Viscosity
Concentrated (50%) aqueous solutions of sodium hydroxide have a characteristic viscosity, 78 mPa·s, that is much greater than that of water (1.0 mPa·s) and near that of olive oil (85 mPa·s) at room temperature. 
The viscosity of aqueous NaOH, as with any liquid chemical, is inversely related to its service temperature, i.e., its viscosity decreases as temperature increases, and vice versa. 
The viscosity of sodium hydroxide solutions plays a direct role in Sodium hydroxides application as well as its storage.

Sodium hydroxide (NaOH), also known as caustic soda or lye, is a highly versatile substance used in a variety of manufacturing processes. 
Sodium hydroxide is a co.product of chlorine production.

Sodium hydroxide is also widely used in pulping of wood for making paper or regenerated fibers. 
Along with sodium sulfide, sodium hydroxide is a key component of the white liquor solution used to separate lignin from cellulose fibers in the kraft process. 
Sodium hydroxide also plays a key role in several later stages of the process of bleaching the brown pulp resulting from the pulping process. 
These stages include oxygen delignification, oxidative extraction, and simple extraction, all of which require a strong alkaline environment with a pH > 10.5 at the end of the stages.

In a similar fashion, sodium hydroxide is used to digest tissues, as in a process that was used with farm animals at one time. 
This process involved placing a carcass into a sealed chamber, then adding a mixture of sodium hydroxide and water (which breaks the chemical bonds that keep the flesh intact). 
This eventually turns the body into a liquid with coffee.like appearance, and the only solid that remains are bone hulls, which could be crushed between one's fingertips.
Sodium hydroxide is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors.

Due to its availability and low cost, Sodium hydroxide has been used by criminals to dispose of corpses. 
Italian serial killer Leonarda Cianciulli used this chemical to turn dead bodies into soap.
In Mexico, a man who worked for drug cartels admitted disposing of over 300 bodies with Sodium hydroxide.
Sodium hydroxide is a dangerous chemical due to Sodium hydroxides ability to hydrolyze protein. 
If a dilute solution is spilled on the skin, burns may result if the area is not washed thoroughly and for several minutes with running water. 
Splashes in the eye can be more serious and can lead to blindness.

In the Bayer process, sodium hydroxide is used in the refining of alumina containing ores (bauxite) to produce alumina (aluminium oxide) which is the raw material used to produce aluminium metal via the electrolytic Hall.Héroult process. 
Since the alumina is amphoteric, Sodium hydroxide dissolves in the sodium hydroxide, leaving impurities less soluble at high pH such as iron oxides behind in the form of a highly alkaline red mud.
Other amphoteric metals are zinc and lead which dissolve in concentrated sodium hydroxide solutions to give sodium zincate and sodium plumbate respectively.

Esterification and transesterification reagent
Sodium hydroxide is traditionally used in soap making (cold process soap, saponification).
Sodium hydroxide was made in the nineteenth century for a hard surface rather than liquid product because Sodium hydroxide was easier to store and transport.
For the manufacture of biodiesel, sodium hydroxide is used as a catalyst for the transesterification of methanol and triglycerides. 
This only works with anhydrous sodium hydroxide, because combined with water the fat would turn into soap, which would be tainted with methanol. 
NaOH is used more often than potassium hydroxide because Sodium hydroxide is cheaper and a smaller quantity is needed.
Due to production costs, NaOH, which is produced using common salt is cheaper than potassium hydroxide.

Food preparation
Food uses of sodium hydroxide include washing or chemical peeling of fruits and vegetables, chocolate and cocoa processing, caramel coloring production, poultry scalding, soft drink processing, and thickening ice cream.
Olives are often soaked in sodium hydroxide for softening; Pretzels and German lye rolls are glazed with a sodium hydroxide solution before baking to make them crisp. 
Owing to the difficulty in obtaining food grade sodium hydroxide in small quantities for home use, sodium carbonate is often used in place of sodium hydroxide.
Sodium hydroxide is known as E number E524.

Specific foods processed with sodium hydroxide include:
German pretzels are poached in a boiling sodium carbonate solution or cold sodium hydroxide solution before baking, which contributes to their unique crust.
Lye.water is an essential ingredient in the crust of the traditional baked Chinese moon cakes.
Most yellow coloured Chinese noodles are made with lye.water but are commonly mistaken for containing egg.
One variety of zongzi uses lye water to impart a sweet flavor.
Sodium hydroxide is also the chemical that causes gelling of egg whites in the production of Century eggs.
Some methods of preparing olives involve subjecting them to a lye.based brine.

The Filipino dessert (kakanin) called kutsinta uses a small quantity of lye water to help give the rice flour batter a jelly like consistency. 
A similar process is also used in the kakanin known as pitsi.pitsi or pichi.pichi except that the mixture uses grated cassava instead of rice flour.
The Norwegian dish known as lutefisk (from lutfisk, "lye fish").

Bagels are often boiled in a lye solution before baking, contributing to their shiny crust.
Hominy is dried maize (corn) kernels reconstituted by soaking in lye.water. 
These expand considerably in size and may be further processed by frying to make corn nuts or by drying and grinding to make grits. 
Hominy is used to create Masa, a popular flour used in Mexican cuisine to make Corn tortillas and tamales. 
Nixtamal is similar, but uses calcium hydroxide instead of sodium hydroxide.

Cleaning agent
Sodium hydroxide is frequently used as an industrial cleaning agent where Sodium hydroxide is often called "caustic". 
Sodium hydroxide is added to water, heated, and then used to clean process equipment, storage tanks, etc. 
Sodium hydroxide can dissolve grease, oils, fats and protein.based deposits. 

Sodium hydroxide is also used for cleaning waste discharge pipes under sinks and drains in domestic properties. 
Surfactants can be added to the sodium hydroxide solution in order to stabilize dissolved substances and thus prevent redeposition. 
A sodium hydroxide soak solution is used as a powerful degreaser on stainless steel and glass bakeware. 
Sodium hydroxide is also a common ingredient in oven cleaners.

A common use of sodium hydroxide is in the production of parts washer detergents. 
Parts washer detergents based on sodium hydroxide are some of the most aggressive parts washer cleaning chemicals. 
The sodium hydroxide.based detergents include surfactants, rust inhibitors and defoamers. 
A parts washer heats water and the detergent in a closed cabinet and then sprays the heated sodium hydroxide and hot water at pressure against dirty parts for degreasing applications. 
Sodium hydroxide used in this manner replaced many solvent.based systems in the early 1990s when trichloroethane was outlawed by the Montreal Protocol.
Water and sodium hydroxide detergent.based parts washers are considered to be an environmental improvement over the solvent.based cleaning methods.

Sodium hydroxide is used in the home as a type of drain opener to unblock clogged drains, usually in the form of a dry crystal or as a thick liquid gel. 
The alkali dissolves greases to produce water soluble products. 
Sodium hydroxide also hydrolyzes the proteins such as those found in hair which may block water pipes. 
These reactions are sped by the heat generated when sodium hydroxide and the other chemical components of the cleaner dissolve in water. 
Such alkaline drain cleaners and their acidic versions are highly corrosive and should be handled with great caution.
Sodium hydroxide is used in some relaxers to straighten hair. 
However, because of the high incidence and intensity of chemical burns, manufacturers of chemical relaxers use other alkaline chemicals in preparations available to average consumers. 
Sodium hydroxide relaxers are still available, but they are used mostly by professionals.
A solution of sodium hydroxide in water was traditionally used as the most common paint stripper on wooden objects. 
Sodium hydroxides use has become less common, because it can damage the wood surface, raising the grain and staining the colour.
Water supplies from acidic formations contain sodium but very little hydroxide. 

WHAT ARE TYPICAL LEVELS OF SODIUM AND HYDROXIDE IN FOOD PRODUCTS?
Sodium levels in foods vary enormously. 
High sodium foods such as pickles, salted meats, and potato chips contain sodium levels of 600 to several thousand parts per million. 
Bottled soft drinks contain from 80 to 250 ppm sodium.
Hydroxide levels in food and beverages are very low. 
The most alkaline foods (those having the highest pH) seldom have more than about 2 ppm hydroxide.

IUPAC name
Sodium hydroxide
Other names
Caustic soda
Lye
Ascarite
White caustic
Sodium hydrate

Historical uses
Sodium hydroxide has been used for detection of carbon monoxide poisoning, with blood samples of such patients turning to a vermilion color upon the addition of a few drops of sodium hydroxide.
Today, carbon monoxide poisoning can be detected by CO oximetry.

In cement mixes, mortars, concrete, grouts
Sodium hydroxide is used in some cement mix plasticisers. 
This helps homogenise cement mixes, preventing segregation of sands and cement, decreases the amount of water required in a mix and increases workability of the cement product, be it mortar, render or concrete.

Summer.winter heat storage
EMPA researchers are experimenting with concentrated sodium hydroxide (NaOH) as the thermal storage or seasonal reservoir medium for domestic space.heating. 
If water is added to solid or concentrated sodium hydroxide (NaOH), heat is released. 
The dilution is exothermic – chemical energy is released in the form of heat. 
Conversely, by applying heat energy into a dilute sodium hydroxide solution the water will evaporate so that the solution becomes more concentrated and thus stores the supplied heat as latent chemical energy.

Neutron Moderator
Seaborg Technologies is working on a reactor design in which NaOH is used as a neutron moderator.

The only hydrates with stable melting points are NaOH·H2O (65.10 °C) and NaOH·3.5H2O (15.38 °C). 
The other hydrates, except the metastable ones NaOH·3H2O and NaOH·4H2O (β) can be crystallized from solutions of the proper composition, as listed above. 
However, solutions of NaOH can be easily supercooled by many degrees, which allows the formation of hydrates (including the metastable ones) from solutions with different concentrations.

For example, when a solution of NaOH and water with 1:2 mole ratio (52.6% NaOH by mass) is cooled, the monohydrate normally starts to crystallize (at about 22 °C) before the dihydrate. 
However, the solution can easily be supercooled down to −15 °C, at which point Sodium hydroxide may quickly crystallize as the dihydrate. 
When heated, the solid dihydrate might melt directly into a solution at 13.35 °C; however, once the temperature exceeds 12.58 °C. 

SODIUM HYDROXIDE BEADS RGT GRADE 1KG
Sodium hydroxide, 20% w/v aqueous solution
Sodium hydroxide, 25% w/v aqueous solution

Soda, caustic
Natriumhydroxid
Rohrputz
Plung
Collo.Grillrein
Liquid.plumr
Caustic soda solution
Collo.Tapetta
Fuers Rohr
Rohrreiniger Rofix

Sodium hydroxide, 30% w/w aqueous solution
Sodium hydroxide, 40% w/v aqueous solution
Sodium hydroxide, 50% w/w aqueous solution
Sodium hydroxide, 0.1N Standardized Solution

Sodium hydroxide often decomposes into solid monohydrate and a liquid solution. 
Even the n = 3.5 hydrate is difficult to crystallize, because the solution supercools so much that other hydrates become more stable.
A hot water solution containing 73.1% (mass) of NaOH is an eutectic that solidifies at about 62.63 °C as an intimate mix of anhydrous and monohydrate crystals.
A second stable eutectic composition is 45.4% (mass) of NaOH, that solidifies at about 4.9 °C into a mixture of crystals of the dihydrate and of the 3.5.hydrate.

Sodium hydroxide, 0.5N Standardized Solution
Sodium hydroxide, 1.0N Standardized Solution
Sodium hydroxide, 2.0N Standardized Solution
Sodium hydroxide, 5.0N Standardized Solution

The third stable eutectic has 18.4% (mass) of NaOH. 
Sodium hydroxide solidifies at about −28.7 °C as a mixture of water ice and the heptahydrate NaOH·7H2O.
When solutions with less than 18.4% NaOH are cooled, water ice crystallizes first, leaving the NaOH in solution.

The α form of the tetrahydrate has density 1.33 g/cm3. 
Sodium hydroxide melts congruously at 7.55 °C into a liquid with 35.7% NaOH and density 1.392 g/cm3, and therefore floats on it like ice on water. 
However, at about 4.9 °C Sodium hydroxide may instead melt incongruously into a mixture of solid NaOH·3.5H2O and a liquid solution.
The β form of the tetrahydrate is metastable, and often transforms spontaneously to the α form when cooled below −20 °C.
Once initiated, the exothermic transformation is complete in a few minutes, with a 6.5% increase in volume of the solid. 
The β form can be crystallized from supercooled solutions at −26 °C, and melts partially at −1.83 °C.
The "sodium hydroxide" of commerce is often the monohydrate (density 1.829 g/cm3). 
Physical data in technical literature may refer to this form, rather than the anhydrous compound.
Adjacent O layers are held together by hydrogen bonds between water molecules.

Chemical properties
Reaction with acids
Sodium hydroxide reacts with protic acids to produce water and the corresponding salts. 
For example, when sodium hydroxide reacts with hydrochloric acid, sodium chloride is formed:
NaOH(aq) + HCl(aq) → NaCl(aq) +H2O(l)
In general, such neutralization reactions are represented by one simple net ionic equation:
OH−(aq) + H+(aq) → H2O(l)
This type of reaction with a strong acid releases heat, and hence is exothermic. 
Such acid–base reactions can also be used for titrations. 
However, sodium hydroxide is not used as a primary standard because Sodium hydroxide is hygroscopic and absorbs carbon dioxide from air.

Reaction with acidic oxides
Sodium hydroxide also reacts with acidic oxides, such as sulfur dioxide. 
Such reactions are often used to "scrub" harmful acidic gases (like SO2 and H2S) produced in the burning of coal and thus prevent their release into the atmosphere. 
For example,
2 NaOH + SO2 → Na2SO3 + H2O

CAS Number: 1310.73.2 
CHEBI: 32145
ChemSpider: 14114
ECHA InfoCard: 100.013.805 
EC Number: 215.185.5
E number: E524 (acidity regulators, ...)
Gmelin Reference: 68430
KEGG: D01169 
MeSH: Sodium+Hydroxide
PubChem CID: 14798
RTECS number: WB4900000
UNII: 55X04QC32I 
UN number: 1824, 1823
CompTox Dashboard (EPA): DTXSID0029634

Reaction with metals and oxides
Glass reacts slowly with aqueous sodium hydroxide solutions at ambient temperatures to form soluble silicates. 
Because of this, glass joints and stopcocks exposed to sodium hydroxide have a tendency to "freeze". 
Flasks and glass.lined chemical reactors are damaged by long exposure to hot sodium hydroxide, which also frosts the glass. 

Crystal structure
NaOH and its monohydrate form orthorhombic crystals with the space groups Cmcm (oS8) and Pbca (oP24), respectively. 
The monohydrate cell dimensions are a = 1.1825, b = 0.6213, c = 0.6069 nm. 
The atoms are arranged in a hydrargillite.like layer structure /O Na O O Na O/. 
Each sodium atom is surrounded by six oxygen atoms, three each from hydroxyl anions HO− and three from water molecules. 
The hydrogen atoms of the hydroxyls form strong bonds with oxygen atoms within each O layer. 

Sodium hydroxide does not attack iron at room temperatures, since iron does not have amphoteric properties (i.e., it only dissolves in acid, not base). 
Nevertheless, at high temperatures (e.g. above 500 °C), iron can react endothermically with sodium hydroxide to form iron(III) oxide, sodium metal, and hydrogen gas.
This is due to the lower enthalpy of formation of iron(III) oxide (−824.2 kJ/mol compared to sodium hydroxide (.500 kJ/mol), thus the reaction is thermodynamically favorable, although its endothermic nature indicates non.spontaneity. 
Consider the following reaction between molten sodium hydroxide and finely divided iron filings:
4 Fe + 6 NaOH → 2 Fe2O3 + 6 Na + 3 H2
A few transition metals, however, may react vigorously with sodium hydroxide.

In 1986, an aluminium road tanker in the UK was mistakenly used to transport 25% sodium hydroxide solution, causing pressurization of the contents and damage to the tanker. 
The pressurization was due to the hydrogen gas which is produced in the reaction between sodium hydroxide and aluminium:
2 Al + 2 NaOH + 6 H2O → 2 NaAl(OH)4 + 3 H2

Precipitant
Unlike sodium hydroxide, which is soluble, the hydroxides of most transition metals are insoluble, and therefore sodium hydroxide can be used to precipitate transition metal hydroxides. 
The following colours are observed:
Copper .blue
Iron(II) .green
Iron(III) .yellow / brown
Zinc and lead salts dissolve in excess sodium hydroxide to give a clear solution of Na2ZnO2 or Na2PbO2.
Aluminium hydroxide is used as a gelatinous flocculant to filter out particulate matter in water treatment. 
Aluminium hydroxide is prepared at the treatment plant from aluminium sulfate by reacting it with sodium hydroxide or bicarbonate.
Al2(SO4)3 + 6 NaOH → 2 Al(OH)3 + 3 Na2SO4Al2(SO4)3 + 6 NaHCO3 → 2 Al(OH)3 + 3 Na2SO4 + 6 CO2
Despite solubility in propylene glycol it is unlikely to replace water in saponification due to propylene glycol primary reaction with fat before reaction between sodium hydroxide and fat.

CAS Number
1310.73.2
Synonym
Caustic soda; Soda lye; Sodium hydrate

Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. 
Sodium hydroxide is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−.
Sodium hydroxide is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. 

Sodium hydroxide is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. 
Sodium hydroxide forms a series of hydrates NaOH·nH2O. 
The monohydrate NaOH·H2O crystallizes from water solutions between 12.3 and 61.8 °C. 

The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to Sodium hydroxide instead of the anhydrous compound.
As one of the simplest hydroxides, sodium hydroxide is frequently utilized alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students.
Sodium hydroxide is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents, and as a drain cleaner. 
Worldwide production in 2004 was approximately 60 million tons, while demand was 51 million tons.

Uses
Sodium hydroxide is a popular strong base used in industry. 
Sodium hydroxide is used in the manufacture of sodium salts and detergents, pH regulation, and organic synthesis. 
In bulk, Sodium hydroxide is most often handled as an aqueous solution, since solutions are cheaper and easier to handle.

Sodium hydroxide is used in many scenarios where Sodium hydroxide is desirable to increase the alkalinity of a mixture, or to neutralize acids.
For example, in the petroleum industry, sodium hydroxide is used as an additive in drilling mud to increase alkalinity in bentonite mud systems, to increase the mud viscosity, and to neutralize any acid gas (such as hydrogen sulfide and carbon dioxide) which may be encountered in the geological formation as drilling progresses.
Another use is in Salt spray testing where pH needs to be regulated. 
Sodium hydroxide is used with hydrochloric acid to balance pH. 

The resultant salt, NaCl, is the corrosive agent used in the standard neutral pH salt spray test.
Poor quality crude oil can be treated with sodium hydroxide to remove sulfurous impurities in a process known as caustic washing. 
As above, sodium hydroxide reacts with weak acids such as hydrogen sulfide and mercaptans to yield non.volatile sodium salts, which can be removed. 
The waste which is formed is toxic and difficult to deal with, and the process is banned in many countries because of this. 

Occurrence/Use
Chemical base, acid neutralizer, caustic cleaning agent, solvent, production of paper or fibers (kraft pulping), tissue digestion, dissolving amphoteric metals, saponification (production of hard soap), manufacture of fabric and plastic, food processing, livestock management (cattle dehorning)

NaOH

Sodium hydroxide is highly soluble in water, ethanol and methanol, making Sodium hydroxide an excellent compound to mix with these liquids. 
Sodium hydroxide is also a deliquescent, meaning Sodium hydroxide has strong absorption capabilities, so it easily and quickly absorbs moisture and carbon dioxide in the air. 
Because of these chemical attributes, major uses for sodium hydroxide are:
.As an aqueous solution
.Use in the chemical industry
.Creation of sodium salts
.Detergents
.pH regulation
.Aluminum production
.Increasing the alkalinity of a mixture
.Neutralizing acids
.Food processing (peeling vegetables, processing cocoa, soaking olives)
.Removing impurities from oil
.As an additive in drain declogging formulas
.Part of the paper.making process

Sodium Hydroxide (NaOH) is white and odorless solid. 
Sodium hydroxide is a common ingredient in cleaning supplies, and perhaps most notably appears in drain and oven cleaning chemicals. 
Sodium hydroxide causes skin to burn upon contact and will cause irrevocable damage if ingested. 
However, sodium hydroxide is FDA approved and is “generally recognized as safe” (GRAS). 
Used across a multitude of industries, some applications of sodium hydroxide include textiles, soap and cleaning products, paper, aluminum processing, petroleum, and bleach production.

Sodium hydroxide is also known as lye or soda , or caustic soda.
At room temperature, sodium hydroxide is a white crystalline odorless solid that absorbs moisture from the air. 
Sodium hydroxide is a synthetically manufactured substance. When dissolved in water or neutralized with acid it releases substantial amounts of heat, which may prove sufficient to ignite combustible materials. 
Sodium hydroxide is highly corrosive .
Sodium hydroxide is generally used as a solid or a diluted in a 50% solution. 
This chemical is used to manufacture soaps, rayon, paper, explosives, dyestuffs, and petroleum products.
Sodium hydroxide is also used in processing cotton fabric, laundering and bleaching, metal cleaning and processing, oxide coating, electroplating, and electrolytic extracting. 
Sodium hydroxide is commonly found in commercial drain/ oven cleaners. 
According to the the FDA, sodium hydroxide is considered a direct food recognized as safe, where Sodium hydroxide serves as a pH control agent and follows good manufacturing guidelines 3.
Interestingly, sodium hydroxide has been studied for Sodium hydroxides use in the treatment of prion disease (as occurs in mad cow disease and kuru). 
The use of this compound has been shown to effectively reduce prion levels in an in vitro inactivation assay.

Storage
Careful storage is needed when handling sodium hydroxide for use, especially bulk volumes. 
Following proper NaOH storage guidelines and maintaining worker/environment safety is always recommended given the chemical's burn hazard.
Sodium hydroxide is often stored in bottles for small.scale laboratory use, within intermediate bulk containers (medium volume containers) for cargo handling and transport, or within large stationary storage tanks with volumes up to 100,000 gallons for manufacturing or waste water plants with extensive NaOH use. 
Common materials that are compatible with sodium hydroxide and often utilized for NaOH storage include: polyethylene (HDPE, usual, XLPE, less common), carbon steel, polyvinyl chloride (PVC), stainless steel, and fiberglass reinforced plastic (FRP, with a resistant liner).
Sodium hydroxide must be stored in airtight containers to preserve Sodium hydroxides normality as Sodium hydroxide will absorb water from the atmosphere.

Sodium Hydroxide Solution 10%, Purified Water
Sodium Hydroxide Solution 10% is supplied in a 2 oz. amber glass bottle.

Used to destroy or kill the mail matrix (matrixectomies). 
Sodium Hydroxide 10% forms a strongly alkaline and caustic solution. 
As a caustic agent, Sodium hydroxide is used to destroy organic tissue by chemical action.

Use two 10 second applications. 
NaOH must be neutralized with 5%

For external use only. 
Harmful if taken internally. 
For Physician use only. 
May cause skin irritation. 
Do not get in eyes, on skin, or on clothing. 
In case of contact, immediately flush skin or eyes with plenty of water for at least 15 minutes. 
Contact a Physician. 
Keep out of reach of children.

.sodium hydroxide (also known as caustic soda and soda lye) is a white, odourless solid at room temperature
.Sodium hydroxide is used in the production of other chemicals, in the pulp and paper industry and various household products including drain cleaners
.Sodium hydroxide does not persist in the environment
.people may be exposed to small amounts of sodium hydroxide in cleaning products
.Sodium hydroxide causes irritation of eyes, nose and throat, cough, chest tightness, headache, fever and confusion
.ingestion causes immediate burning of the mouth and throat, breathing difficulty, drooling, difficulty swallowing, stomach pain and vomiting
.skin contact can cause pain, burns and ulcers
.eye contact causes pain, twitching of the eyelids, watering eyes, inflammation, sensitivity to light and burns
.individuals with breathing problems such as asthma may be more susceptible to the effects of inhaled sodium hydroxide 

Hydroxyde de sodium
Natriumhydroxyde
Sodium hydroxide dimer
White caustic solution
Sodium hydrate solution
Sodio(idrossido di)
Sodium(hydroxyde de)
MFCD00003548
Sodium hydroxide (Na2(OH)2)
sodium;hydroxide
Sodium hydroxide, pellets
UNII.55X04QC32I
Sodium hydroxide, flake
Sodium hydroxide, pearl
Sodium hydroxide, solid
LYE

Production
For historical information, see Alkali manufacture.
Sodium hydroxide is industrially produced as a 50% solution by variations of the electrolytic chloralkali process.
Chlorine gas is also produced in this process.
Solid sodium hydroxide is obtained from this solution by the evaporation of water. 
Solid sodium hydroxide is most commonly sold as flakes, prills, and cast blocks.

Water treatment
Sodium hydroxide is sometimes used during water purification to raise the pH of water supplies. 
Increased pH makes the water less corrosive to plumbing and reduces the amount of lead, copper and other toxic metals that can dissolve into drinking water.

SYNONYMS:
Caustic soda, sodium hydrate, soda lye, lye, natrium hydroxide

CHEMICAL AND PHYSICAL PROPERTIES:
.Molecular Formula: NaOH
.White solid, crystals or powder, will draw moisture from the air and become damp on exposure
.Odorless, flat, sweetish flavor
.Pure solid material or concentrated solutions are extremely caustic, immediately injurious to skin, eyes and respiratory system

WHERE DOES IT COME FROM?
Sodium hydroxide is extracted from seawater or other brines by industrial processes.

WHAT ARE THE PRINCIPLE USES OF SODIUM HYDROXIDE?
Sodium hydroxide is an ingredient of many household products used for cleaning and disinfecting, in many cosmetic products such as mouth washes, tooth paste and lotions, and in food and beverage production for adjustment of pH and as a stabilizer. 
In its concentrated form (lye) Sodium hydroxide is used as a household drain cleaner because of its ability to dissolve organic solids. 
Sodium hydroxide is also used in many industries including glassmaking, paper manufacturing and mining. 
Sodium hydroxide is used widely in medications, for regulation of acidity. 
Sodium hydroxide may be used to counteract acidity in swimming pool water, or in drinking water.

IS SODIUM HYDROXIDE NATURALLY PRESENT IN DRINKING WATER?
Yes, because sodium and hydroxide ions are common natural mineral substances, they are present in many natural soils, in groundwater, in plants and in animal tissues. 
Water supplies in limestone areas contain significant amounts of sodium and hydroxide ions. 

In 2004, world production was estimated at 60 million dry tonnes of sodium hydroxide, and demand was estimated at 51 million tonnes.
In 1998, total world production was around 45 million tonnes. 
North America and Asia each contributed around 14 million tonnes, while Europe produced around 10 million tonnes. 
In the United States, the major producer of sodium hydroxide is Olin, which has annual production around 5.7 million tonnes from sites at Freeport, Texas, and Plaquemine, Louisiana, St Gabriel, Louisiana, McIntosh, Alabama, Charleston, Tennessee, NiagaraFalls, New York, and Becancour, Canada. Other major US producers include Oxychem, Westlake, Shintek and Formosa. 
All of these companies use the chloralkali process.

Historically, sodium hydroxide was produced by treating sodium carbonate with calcium hydroxide in a metathesis reaction which takes advantage of the fact that sodium hydroxide is soluble, while calcium carbonate is not. 
This process was called causticizing.
Ca(OH)2(aq) + Na2CO3(s) → CaCO3(s) + 2 NaOH(aq)
This process was superseded by the Solvay process in the late 19th century, which was in turn supplanted by the chloralkali process which we use today.
Sodium hydroxide is also produced by combining pure sodium metal with water. 
The byproducts are hydrogen gas and heat, often resulting in a flame.
2Na + 2H2O → 2NaOH + H2
This reaction is commonly used for demonstrating the reactivity of alkali metals in academic environments; however, Sodium hydroxide is not commercially viable, as the isolation of sodium metal is typically performed by reduction or electrolysis of sodium compounds including sodium hydroxide.

CHEBI:32145
Sodium Hydroxide, 0.1M solution
55X04QC32I
Soda, hydrate
Natrium causticum
Soda, kaustische
Na (O H)
Buffer Solution, pH 8.00
Lewis.red devil lye
Caustic soda, liquid
Sodium hydroxide, pure, pellets
Caswell No. 773
sodiumhydroxide
Natriumhydroxid [German]
Natriumhydroxyde [Dutch]
Natrium.hydroxid, reinstes
UN 1823 (solid)
UN 1824 (solution)

Paper industry: One of the key steps in the process of creating paper out of wood is chemical pulping. 
This step, and other steps involved in the process of making paper require strong alkaline environments of above 10.5 PH.
Food industry: The food industry widely uses Sodium Hydroxide for chemical peeling or washing of vegetables and fruits. 
Cocoa beans are also processed with caustic soda. 
Some methods for softening olives also involve sodium hydroxide.
Cleaning agent: Sodium Hydroxide can easily remove fats, oils, grease and protein based compounds and therefore, is used widely as an industrial cleaning agent where it is commonly known as “caustic”. 
One of the typical methods of using sodium hydroxide is to heat Sodium hydroxide as a solution and then spray it with high pressure. 
Sodium hydroxide in the form of a thick liquid gel or dry crystal is also used in homes as a drain opener.

What are sodium hydroxide uses?
Sodium hydroxide is a highly versatile substance used to make a variety of everyday products, such as paper, aluminum, commercial drain and oven cleaners, and soap and detergents.

What is purpose of sodium hydroxide?
Sodium hydroxide, also known as caustic soda or lye, is a highly versatile substance used in a variety of manufacturing processes to make other products like paper or aluminum, for example.

Sodium hydroxide, 98%, pure, flakes
Sodium hydroxide, 1N standard solution
Sodium hydroxide, extra pure, micropearls
Hydroxyde de sodium [French]
Sodium hydroxide, 0.1 N standard solution
Sodium hydroxide, 0.2 N standard solution
Sodium hydroxide, for analysis, micropearls
HSDB 229

Sodium Hydroxide
Synonyms: Caustic soda
Purity Limit: ≥ 99% (Assay)
Molecular Formula: NaOH
Molecular Weight: 40.00
CAS No: 1310.73.2
MDL No: MFCD00003548
Appearance: White granular beads
Density: 2.13 g/mL
Warnings: Corrosive! Toxic!
Storage Temp: Store at RT

Sodio(idrossido di) [Italian]
Sodium(hydroxyde de) [French]
Sodium hydroxide, 98%, extra pure, pellets
Sodium hydroxide, 97+%, ACS reagent, pellets
Sodium hydroxide [NF]
Sodium hydroxide, 98.5%, for analysis, pellets
EINECS 215.185.5
UN1823
UN1824

What is sodium hydroxide (NaOH)?
Sodium hydroxide is sometimes called caustic soda or lye.  
Sodium hydroxide is a common ingrediet in cleaners and soaps.  

At room temperature, sodium hydroxide is a white, odorless solid.  
Liquid sodium hydroxide is colorless and has no odor. 
Sodium hydroxide can react violently with strong acids and with water.  
Sodium hydroxide is corrosive.  
NaOH can react with moisture from the air and may generate heat as it dissolves.  
This heat can be enough to cause a fire if it is near flammable materials.

Sodium hydroxide is useful for its ability to alter fats.  
Sodium hydroxide is used to make soap and as a main ingredient in household products such as liquid drain cleaners.  
Sodium hydroxide is usually sold in pure form as white pellets or as a solution in water.
What are some uses of sodium hydroxide?
Sodium hydroxide is used in bar soaps and detergents.  
Sodium Hydroxide is also used as a drain cleaner to unclog pipes.

Around 56% of sodium hydroxide produced is used by industry, with 25% of NaOH used in the paper industry.  
Some other uses include fuel cell production, to cure food, to remove skin from vegetables for canning, bleach, drain cleaner, oven cleaner, soaps, detergent, paper making, paper recycling, aluminum ore processing, oxide coating, processing cotton fabric, pickling, pain relievers, anticoagulants to prevent blood clots, cholesterol reducing medications, and water treatment.

Another option is to neutralize any base on the skin with a weak acid, such as vinegar, and then rinse with water.
Stir the sodium hydroxide, a little at a time, into a large volume of water and then dilute the solution to make one liter. 
Add sodium hydroxide to water—do not add water to solid sodium hydroxide.
Be sure to use borosilicate glass (e.g., Pyrex) and consider immersing the container in a bucket of ice to keep the heat down. 
Inspect the glassware prior to use to make sure Sodium hydroxide is free from any cracks, scratches or chips that would indicate a weakness in the glass. 
If you use a different type of glass or weak glass, there's a chance the temperature change could cause it to shatter.
Wear safety goggles and gloves since there is a chance the sodium hydroxide solution could splash up or the glassware could break. 
Concentrated solution of sodium hydroxide are corrosive and should be handled with care.

BCP26108
ANW.41118
NSC135799
Sodium hydroxide pellets ACS reagent
AKOS015913904
AKOS015951419
Sodium Hydroxide Pellets Reagent Grade
DB11151
NSC.135799
Sodium hydroxide, 10N aqueous solution

Chemical formula NaOH
Molar mass 39.9971 g mol−1
Appearance White, hard (when pure), opaque crystals
Odor odorless
Density    2.13 g/cm3 
Melting point  323 °C (613 °F; 596 K) 
Boiling point 1,388 °C (2,530 °F; 1,661 K) 
Solubility in water 418 g/L (0 °C)
1000 g/L (25 °C) 
3370 g/L (100 °C)

At room temperature, sodium hydroxide is a white crystalline odorless solid that absorbs moisture from the air. 
Sodium hydroxide is a manufactured substance. 
When dissolved in water or neutralized with acid Sodium hydroxide liberates substantial heat, which may be sufficient to ignite combustible materials.
Sodium hydroxide is very corrosive. 
Sodium hydroxide is generally used as a solid or a 50% solution. Other common names include caustic soda and lye. 
Sodium hydroxide is used to manufacture soaps, rayon, paper, explosives, dyestuffs, and petroleum products.
Sodium hydroxide is also used in processing cotton fabric, laundering and bleaching, metal cleaning and processing, oxide coating, electroplating, and electrolytic extracting. 
Sodium hydroxide is commonly present in commercial drain and oven cleaners.

Solubility soluble in glycerol
negligible in ammonia
insoluble in ether
slowly soluble in propylene glycol
Solubility in methanol 238 g/L
Solubility in ethanol <<139 g/L
Vapor pressure <2.4 kPa (at 20 °C)
Basicity (pKb) 0.2
Magnetic susceptibility (χ) −15.8·10−6 cm3/mol (aq.)
Refractive index (nD) 1.3576

Sodium hydroxide, for analysis, 50% solution in water
EPA Pesticide Chemical Code 075603
NSC 135799
Sodium hydroxide, extra pure, 33wt.% solution in water
Sodium hydroxide, extra pure, 50 wt% solution in water
sodiumhydroxid
hydroxyl sodium
sodium hydoxide
sodium hydroxid
sodium hyroxide
soude caustique
hydroxide sodium
Lye solution

Japan imported Sodium hydroxides salt in solid form and, until the development of the membrane process, also favored the mercury cell for production. 
Sodium hydroxide, NaOH, mol wt 39.998, is a brittle, white, translucent crystalline solid. 
Because of Sodium hydroxides corrosive action on all human body tissue, Sodium hydroxide is also known as caustic soda. 
Aqueous solutions of caustic soda are highly alkaline.
Hence caustic soda is primarily used in neutralization reactions to form sodium salts. 
Reactions of NaOH with natural products are complex. 

They include solubilization of cotton in rubber reclaiming, cotton scouring, refining of vegetable oils, and removal of lignin and hemicellulose in the Kraft pulping process. 
The only caustic soda production process besides electrolysis is the soda–lime process, practiced by companies which do not participate in the chlorine market. 
Three forms of caustic soda are produced to meet customer needs: purified diaphragm caustic (50% Rayon grade), 73% caustic, and anhydrous caustic. 
Caustic soda is classified as a corrosive material by the DOT, and it has a marked corrosive action on all body tissue. 
Inhalation of the dust or mist can cause damage to the upper respiratory tract. 
During handling, all persons should wear proper protective clothing, safety goggles or a full face shield, rubber gloves, boots, and a caustic.resistant apron or suit. 
Disposal of waste or spilled caustic soda must be carried out by properly trained personnel.

Sodium hidroxide
Sodium hydroxyde
Sodium.hydroxide
Natrii hydroxidum
Caustic soda, dry
Caustic Soda Flake
Caustic soda, Lye
Caustic soda, bead
Caustic soda, flake
Caustic soda, solid
Caustic soda 50%

Sodium or potassium hydroxide, preferably the latter. 
The corresponding alkoxide also can be used, but prohibitively expensive. 
Best if Sodium hydroxide has ≥85 per cent potassium hydroxide. Even best grades of potassium hydroxide have 14–15 per cent water which cannot be removed. 
Sodium hydroxide should be low in carbonate, because the carbonate is not an efficient catalyst and may cause cloudiness in the final ester. 
Sodium hydroxide pellets have given very good results. 
Because quantity of catalyst used is quite less, good quality catalyst (in spite of high cost) can be used.

Sodium hydrate.[d]
Sodium hydroxide, dry
Sodium hydroxide beads
Caustic soda, granular
Sodium hydroxide liquid
Sodium hydroxide, bead
Sodium hydroxide 50%
Sodium hydroxide (TN)
ACMC.1BRPG
Sodium hydroxide (flake)
Sodium hydroxide (liquid)
Sodium hydroxide, granular
Sodium hydroxide, solution
WLN: NA Q
EC 215.185.5

Sodium hydroxide (caustic soda) is highly soluble in water, and sodium hydroxide solutions are strong bases. 
The annual world production of sodium hydroxide is on the order of 60 million tons. 
Sodium hydroxide is universally used as a neutralisation agent in the chemical industry, paper making, etc. 
Soda lye contains in general 30 wt% of sodium hydroxide.

Sodium hydroxide, anhydrous
1N Sodium hydroxide solution
Sodium hydroxide pellets, EP
Sodium hydroxide, micropearls
Sodium hydroxide (JP17/NF)
Sodium hydroxide solution 25%
CHEMBL2105794
DTXSID0029634

Sodium Hydroxide, better known as lye or caustic soda, is a powerful and corrosive base that is useful not only in cleaning, but in manufacturing as well.

Formula: NaOH
Molecular mass: 40.0
Boiling point: 1388°C
Melting point: 318°C
Density: 2.1 g/cm³
Solubility in water, g/100ml at 20°C: 109 (very good) 

Sodium Hydroxide 1N Concentrate
Sodium hydroxide, 40% solution
Sodium hydroxide, 50% solution
Sodium hydroxide pellets USP.NF
Sodium Hydroxide 10N Concentrate
Sodium Hydroxide Solution, 2.5N
Sodium Hydroxide, 1.0M solution
Sodium Hydroxide, 2.0M solution

Sodium hydroxide, in aqueous solution with sodium carbonate, is occasionally used to remove the last traces of carbon dioxide from hydrogen, or other gases, where the bulk of the carbon dioxide has been removed by a more economical, but less efficient regenerative process. 
Caustic scrubbing is also used to remove CO2 from small volumes of air where CO2.free air is required.

Amount of NaOH to Make Sodium Hydroxide Solution
Prepare solutions of sodium hydroxide using this handy reference table which lists the amount of solute (solid NaOH) that is used to make 1 L of base solution. 
Follow these lab safety guidelines:
Don't touch sodium hydroxide.
Sodium hydroxide is caustic and could cause chemical burns.
If you do get NaOH on your skin, immediately rinse it with a large volume of water. 

Sodium hydroxide can also be used in tasks such as processing cotton fabric, metal cleaning and processing, oxide coating, electroplating, and electrolytic extraction. 
Sodium hydroxide is often found in commercial drain and oven cleaners.
Use bleach, oven cleaners, and drain cleaners
Work in food processing plants

Work in public water treatment plants
Use sodium hydroxide for making paper, glass, detergents, soaps, and other products
Mine alumina and produce aluminum
NIOSH recommends that employers use a Hierarchy of Controls to prevent injury.  
If you work in an industry that uses sodium hydroxide, please read the chemical label and the Safety Data Sheet for information on how Sodium hydroxide can harm you and how to protect yourself. 
Visit NIOSH’s page on Managing Chemical Safety in the Workplace to learn more about preventing contact with chemicals in the workplace.

The following resources provide information about workplace exposure to sodium hydroxide. 
Useful search terms for sodium hydroxide include “lye”, “caustic soda”, “soda lye”, and “sodium hydrate”.

Sodium hydroxide is used to manufacture many everyday products, such as paper, aluminum, commercial drain and oven cleaners, and soap and detergents.

Sodium Hydroxide in Cleaning & Disinfectant Products
Sodium hydroxide is used to manufacture soaps and a variety of detergents used in homes and commercial applications. 
Chlorine bleach is produced by combining chlorine and sodium hydroxide. 

E.33
Sodium hydroxide pellets Biochemical Grade
Sodium hydroxide, 5% w/v aqueous solution
FT.0645105
FT.0689261
S0542
S0543

Sodium hydroxide is a corrosive, strong, inorganic base and alkali. 
Sodium hydroxide is water.soluble and can absorb moisture and carbon dioxide from air; used as a lab reagent, in acid neutralization and titration, in manufacturing processes, in household chemicals, etc.

Sodium hydroxide (also termed lye, caustic soda, and sodium hydrate) is a white solid that dissolves in water to produce a strongly alkaline solution. 
Both the solid and liquid forms can cause severe injury to all tissues. 
Sodium hydroxide is most commonly found in the home as drain and oven cleaners in concentrations between 0.5% and 54%. 
Industrial uses include acid neutralization, petroleum refining, and treatment of cellulose, plastics, and rubber. 

Another potential source of exposure is associated with automobile airbag deployment.
Sodium hydroxide and talc powder liberated during airbag deployment have resulted in corneal keratitis, abrasions, and chemical burns.
The penetration rate of sodium hydroxide is second only to that of ammonium hydroxide; consequently, eye damage can be similarly devastating (see discussion of ammonium hydroxide in the earlier section on Ammonia). 
Studies performed on rabbit eyes demonstrated severe injury and perforation following a 30.second exposure to a drop of 1.N (4%) sodium hydroxide; both mild and severe injury following 15 to 20 seconds of exposure to a 2.N solution; and mild burns from a 0.5.N solution for 30 seconds.
Sodium Hydroxide (Caustic Soda) falls in a group of commodity chemicals which also includes chlorine, Cl2, sodium carbonate (soda ash), Na2CO3; potassium hydroxide (caustic potash), KOH; and hydrochloric acid (muriatic acid or anhydrous), HCl. 

Chlorine and caustic soda are the two most important products in this group, ranking among the top ten chemicals in the United States. 
The applications for chlorine and the alkalies are so varied that there is hardly a consumer product which is not dependent on one or both of them at some manufacturing stage. 

Chlorine and caustic soda are coproducts of the electrolysis of aqueous solutions of sodium chloride, NaCl (commonly called brine). 
Conversion of aqueous NaCl to Cl2 and NaOH is achieved in three types of electrolytic cells: the diaphragm cell, the membrane cell, and the mercury cell. 
The distinguishing feature of these cells is the manner by which the electrolysis products are prevented from mixing with each other, thus ensuring proper purity. 
Solution mining of salt and the availability of asbestos resulted in the dominance of the diaphragm process in North America, whereas solid salt and mercury availability led to the dominance of the mercury process in Europe.