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SODIUM HYDROXIDE LIQUID

Sodium hydroxide liquid is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. Sodium hydroxide liquid is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. Sodium hydroxide liquid 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 liquid" is often this monohydrate, and published data may refer to it instead of the anhydrous compound.

CAS No.: 1310-73-2
EC No.: 215-185-5

Synonyms:
Sodium hydroxide; Caustic soda; Lye; Ascarite; naoh; NAOH; White caustic; Sodium hydrate; SODIUM HYDROXIDE; Caustic soda; 1310-73-2; Sodium hydrate; Soda lye; White caustic; Sodium hydroxide (Na(OH)); Aetznatron; Ascarite; Sodium hydroxide solution; Soda, caustic; Natriumhydroxid; Rohrputz; Plung; Collo-Grillrein; Liquid-plumr; Caustic soda solution; Collo-Tapetta; Fuers Rohr; Rohrreiniger Rofix; NaOH; Hydroxyde de sodium; Natriumhydroxyde; Sodium hydroxide dimer; White caustic solution; Sodium hydrate solution; Soda, hydrate; Natrium causticum; Soda, kaustische; Lewis-red devil lye; Sodio(idrossido di); Caustic soda, liquid; Sodium(hydroxyde de); Caswell No. 773; sodiumhydroxide; Sodium hydroxide (Na2(OH)2); Natriumhydroxid [German]; Natriumhydroxyde [Dutch]; sodium;hydroxide; Sodium hydroxide, pellets; Natrium-hydroxid, reinstes; UN 1823 (solid); UN 1824 (solution); Hydroxyde de sodium [French]; SODIUM HYDROXIDE LIQUID; Sodio(idrossido di) [Italian]; Sodium(hydroxyde de) [French]; Sodium hydroxide, flake; Sodium hydroxide, pearl; Sodium hydroxide, solid; EINECS 215-185-5; LYE; EPA Pesticide Chemical Code 075603; Sodium Hydroxide, 0.1M solution; Na (O H); Buffer Solution, pH 8.00; Sodium hydroxide, pure, pellets; Sodium hydroxide, 98%, pure, flakes; Sodium hydroxide, 1N standard solution; Sodium hydroxide, extra pure, micropearls; Sodium hydroxide, 0.1 N standard solution; Sodium hydroxide, 0.2 N standard solution; Sodium hydroxide, for analysis, micropearls; Sodium hydroxide, 98%, extra pure, pellets; Sodium hydroxide, 97+%, ACS reagent, pellets; Sodium hydroxide [NF]; Sodium hydroxide, 98.5%, for analysis, pellets; Sodium Hydroxide [USAN]; Sodium hydroxide, for analysis, 50% solution in water; 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; NAOH; Lye solution; Sodium hidroxide; Sodium hydroxyde; Sodium-hydroxide; Natrii hydroxidum; Caustic soda, dry; Sodium Hydroxide Liquid; Caustic Soda Flake; Caustic soda, Lye; Caustic soda, bead; Caustic soda, flake; Caustic soda, solid; Caustic soda 50%; Sodium hydroxide, dry; Sodium hydroxide beads; Caustic soda, granular; Sodium hydroxide liquid; Sodium hydroxide, bead; Sodium hydroxide 50%; SODIUM HYDROXIDE LIQUID; Sodium hydroxide (TN); Sodium hydroxide (flake); Sodium hydroxide (liquid); Sodium hydroxide, granular; Sodium hydroxide, solution; WLN: NA Q; EC 215-185-5; Sodium hydroxide, anhydrous; 1N Sodium hydroxide solution; Sodium hydroxide pellets, EP; Sodium hydroxide, micropearls; KSC174M8F; Sodium hydroxide (JP17/NF); Sodium hydroxide solution 25%; Sodium Hydroxide 1N Concentrate; Sodium hydroxide, 40% solution; Sodium hydroxide, 50% solution; CTK0H4682; Sodium hydroxide pellets USP-NF; NAOH; Sodium Hydroxide 10N Concentrate; Sodium Hydroxide Solution, 2.5N; Sodium Hydroxide, 1.0M solution; Sodium Hydroxide, 2.0M solution; Sodium Hydroxide Liquid; Sodium hydroxide pellets ACS reagent; Sodium Hydroxide Pellets Reagent Grade; Sodium hydroxide, 10N aqueous solution; Sodium hydroxide pellets Biochemical Grade; Sodium hydroxide, 5% w/v aqueous solution; SODIUM HYDROXIDE BEADS RGT GRADE 1KG; Sodium hydroxide, 20% w/v aqueous solution; Sodium hydroxide, 25% w/v aqueous solution; Sodium hydroxide, 30% w/w aqueous solution; Sodium hydroxide, 40% w/v aqueous solution; Sodium hydroxide, 50% w/w aqueous solution; X4832; Sodium hydroxide, 0.1N Standardized Solution; Sodium hydroxide, 0.5N Standardized Solution; Sodium hydroxide, 1.0N Standardized Solution; Sodium hydroxide, 0.05N Standardized Solution; Sodium hydroxide, solid [UN1823] [Corrosive]; Sodium hydroxide, technical, 30% solution in water; Sodium hydroxide, pellets, Trace Metals Grade 99.99%

Sodium Hydroxide Liquid

Sodium hydroxide liquid, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−.

Sodium hydroxide liquid is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It 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 liquid" is often this monohydrate, and published data may refer to it instead of the anhydrous compound.

As one of the simplest hydroxides, Sodium hydroxide liquid is frequently utilized alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students.

Sodium hydroxide liquid 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 tonnes, while demand was 51 million tonnes.

Properties of Sodium hydroxide liquid
Chemical formula NaOH
Molar mass 39.9971 g mol−1
Appearance White, waxy, 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)
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

Properties of Sodium hydroxide liquid

Physical properties Sodium hydroxide liquid
Pure Sodium hydroxide liquid 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). It 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 liquid 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 of Sodium hydroxide liquid
Concentrated (50%) aqueous solutions of Sodium hydroxide liquid 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 liquid solutions plays a direct role in its application as well as its storage.

Hydrates
Sodium hydroxide liquid can form several hydrates NaOH·nH2O, which result in a complex solubility diagram that was described in detail by S. U. Pickering in 1893. The known hydrates and the approximate ranges of temperature and concentration (mass percent of NaOH) of their saturated water solutions are:

Heptahydrate, NaOH·7H2O: from −28 °C (18.8%) to −24 °C (22.2%).
Pentahydrate, NaOH·5H2O: from −24 °C (22.2%) to −17.7 (24.8%).
Tetrahydrate, NaOH·4H2O, α form: from −17.7 (24.8%) to +5.4 °C (32.5%).
Tetrahydrate, NaOH·4H2O, β form: metastable.
Trihemihydrate, NaOH·3.5H2O: from +5.4 °C (32.5%) to +15.38 °C (38.8%) and then to +5.0 °C (45.7%).
Trihydrate, NaOH·3H2O: metastable.
Dihydrate, NaOH·2H2O: from +5.0 °C (45.7%) to +12.3 °C (51%).
Monohydrate, NaOH·H2O: from +12.3 °C (51%) to 65.10 °C (69%) then to 62.63 °C (73.1%).
Early reports refer to hydrates with n = 0.5 or n = 2/3, but later careful investigations failed to confirm their existence.

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 Sodium hydroxide liquid and water with 1:2 mole ratio (52.6% Sodium hydroxide liquid 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 it 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. it 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 Sodium hydroxide liquid 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 Sodium hydroxide liquid, that solidifies at about 4.9 °C into a mixture of crystals of the dihydrate and of the 3.5-hydrate.

The third stable eutectic has 18.4% (mass) of Sodium hydroxide liquid. It solidifies at about −28.7 °C as a mixture of water ice and the heptahydrate Sodium hydroxide liquid·7H2O.

When solutions with less than 18.4% Sodium hydroxide liquid are cooled, water ice crystallizes first, leaving the Sodium hydroxide liquid in solution.

The α form of the tetrahydrate has density 1.33 g/cm3. It melts congruously at 7.55 °C into a liquid with 35.7% Sodium hydroxide liquid and density 1.392 g/cm3, and therefore floats on it like ice on water. However, at about 4.9 °C it may instead melt incongruously into a mixture of solid Sodium hydroxide liquid·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.

Crystal structure of Sodium hydroxide liquid
Sodium hydroxide liquid 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 OO NaO/... 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. Adjacent O layers are held together by hydrogen bonds between water molecules.

Chemical properties of Sodium hydroxide liquid

Reaction with acids of Sodium hydroxide liquid
Sodium hydroxide liquid reacts with protic acids to produce water and the corresponding salts. For example, when Sodium hydroxide liquid 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 liquid is not used as a primary standard because it is hygroscopic and absorbs carbon dioxide from air.

Reaction with acidic oxides
Sodium hydroxide liquid 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

Reaction with metals and oxides
Glass reacts slowly with aqueous Sodium hydroxide liquid solutions at ambient temperatures to form soluble silicates. Because of this, glass joints and stopcocks exposed to Sodium hydroxide liquid have a tendency to "freeze". Flasks and glass-lined chemical reactors are damaged by long exposure to hot Sodium hydroxide liquid, which also frosts the glass. Sodium hydroxide liquid 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 liquid 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 liquid (-500 kJ/mol), thus the reaction is thermodynamically favorable, although its endothermic nature indicates non-spontaneity. Consider the following reaction between molten Sodium hydroxide liquid 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 liquid.

In 1986, an aluminium road tanker in the UK was mistakenly used to transport 25% Sodium hydroxide liquid 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 liquid and aluminium:
2 Al + 2 NaOH + 6 H2O → 2 NaAl(OH)4 + 3 H2

Precipitant
Unlike Sodium hydroxide liquid, which is soluble, the hydroxides of most transition metals are insoluble, and therefore Sodium hydroxide liquid 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 liquid 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 liquid 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

Saponification
Sodium hydroxide liquid can be used for the base-driven hydrolysis of esters (as in saponification), amides and alkyl halides. However, the limited solubility of Sodium hydroxide liquid in organic solvents means that the more soluble potassium hydroxide (KOH) is often preferred. Touching Sodium hydroxide liquid 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. 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 liquid and fat.

Production
For historical information, see Alkali manufacture.
Sodium hydroxide liquid 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 liquid is obtained from this solution by the evaporation of water. Solid Sodium hydroxide liquid is most commonly sold as flakes, prills, and cast blocks.

In 2004, world production was estimated at 60 million dry tonnes of Sodium hydroxide liquid, 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 liquid is the Dow Chemical Company, which has annual production around 3.7 million tonnes from sites at Freeport, Texas, and Plaquemine, Louisiana. Other major US producers include Oxychem, Westlake, Olin, Shintek and Formosa. All of these companies use the chloralkali process.

Historically, Sodium hydroxide liquid was produced by treating sodium carbonate with calcium hydroxide in a metathesis reaction which takes advantage of the fact that Sodium hydroxide liquid 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 liquid is also produced by combining pure sodium metal with water. The byproducts are hydrogen gas and heat, often resulting in a flame.

2 Na + 2 H2O → 2 NaOH + H2
This reaction is commonly used for demonstrating the reactivity of alkali metals in academic environments; however, it is not commercially viable, as the isolation of sodium metal is typically performed by reduction or electrolysis of sodium compounds including Sodium hydroxide liquid.

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

Sodium hydroxide liquid is used in many scenarios where it is desirable to increase the alkalinity of a mixture, or to neutralize acids.

For example, in the petroleum industry, Sodium hydroxide liquid 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 liquid 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 liquid to remove sulfurous impurities in a process known as caustic washing. As above, Sodium hydroxide liquid 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. In 2006, Trafigura used the process and then dumped the waste in Ivory Coast.

Other common uses of Sodium hydroxide liquid include:

It is used for making soaps and detergents. Sodium hydroxide liquid is used for hard bar soap while potassium hydroxide is used for liquid soaps.Sodium hydroxide liquid is used more often than potassium hydroxide because it is cheaper and a smaller quantity is needed.
It is used as drain cleaners that contain Sodium hydroxide liquid convert fats and grease that can clog pipes into soap, which dissolves in water. (see cleaning agent)
It is used for making artificial textile fibres (such as Rayon).
It is used in the manufacture of paper. Around 56% of Sodium hydroxide liquid produced is used by industry, 25% of which is used in the paper industry. (see chemical pulping)
It is used in purifying bauxite ore from which aluminium metal is extracted. This is known as Bayer process. (see dissolving amphoteric metals and compounds)
It is used in de-greasing metals, oil refining, and making dyes and bleaches.

Chemical pulping
Sodium hydroxide liquid is also widely used in pulping of wood for making paper or regenerated fibers. Along with sodium sulfide, Sodium hydroxide liquid is a key component of the white liquor solution used to separate lignin from cellulose fibers in the kraft process. It 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.

Tissue digestion
In a similar fashion, Sodium hydroxide liquid 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 liquid 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 liquid is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors. Due to its availability and low cost, it 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 it.

Sodium hydroxide liquid is a dangerous chemical due to its 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.

Dissolving amphoteric metals and compounds
Strong bases attack aluminium. Sodium hydroxide liquid reacts with aluminium and water to release hydrogen gas. The aluminium takes the oxygen atom from Sodium hydroxide liquid, 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 liquid 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 Na2Al2O4. 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.

In the Bayer process, Sodium hydroxide liquid 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, it dissolves in the Sodium hydroxide liquid, 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 liquid solutions to give sodium zincate and sodium plumbate respectively.

Esterification and transesterification reagent
Sodium hydroxide liquid is traditionally used in soap making (cold process soap, saponification). It was made in the nineteenth century for a hard surface rather than liquid product because it was easier to store and transport.

For the manufacture of biodiesel, Sodium hydroxide liquid is used as a catalyst for the transesterification of methanol and triglycerides. This only works with anhydrous Sodium hydroxide liquid, 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 it 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 liquid 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 liquid for softening; Pretzels and German lye rolls are glazed with a Sodium hydroxide liquid solution before baking to make them crisp. Owing to the difficulty in obtaining food grade Sodium hydroxide liquid in small quantities for home use, sodium carbonate is often used in place of Sodium hydroxide liquid. It is known as E number E524.

Specific foods processed with Sodium hydroxide liquid include:

German pretzels are poached in a boiling sodium carbonate solution or cold Sodium hydroxide liquid 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 liquid 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 liquid.

Cleaning agent

Sodium hydroxide liquid is frequently used as an industrial cleaning agent where it is often called "caustic". It is added to water, heated, and then used to clean process equipment, storage tanks, etc. It can dissolve grease, oils, fats and protein-based deposits. It is also used for cleaning waste discharge pipes under sinks and drains in domestic properties. Surfactants can be added to the Sodium hydroxide liquid solution in order to stabilize dissolved substances and thus prevent redeposition. A Sodium hydroxide liquid soak solution is used as a powerful degreaser on stainless steel and glass bakeware. It is also a common ingredient in oven cleaners.

A common use of Sodium hydroxide liquid is in the production of parts washer detergents. Parts washer detergents based on Sodium hydroxide liquid are some of the most aggressive parts washer cleaning chemicals. The Sodium hydroxide liquid-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 liquid and hot water at pressure against dirty parts for degreasing applications. Sodium hydroxide liquid 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 liquid detergent-based parts washers are considered to be an environmental improvement over the solvent-based cleaning methods.

Hardware stores grade Sodium hydroxide liquid to be used as a type of drain cleaner.

Paint stripping with caustic soda
Sodium hydroxide liquid 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. It 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 liquid 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 liquid 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 liquid relaxers are still available, but they are used mostly by professionals.

A solution of Sodium hydroxide liquid in water was traditionally used as the most common paint stripper on wooden objects. Its use has become less common, because it can damage the wood surface, raising the grain and staining the colour.

Water treatment of Sodium hydroxide liquid
Sodium hydroxide liquid 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.

Historical uses of Sodium hydroxide liquid
Sodium hydroxide liquid 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 liquid. Today, carbon monoxide poisoning can be detected by CO oximetry.

In cement mixes, mortars, concrete, grouts
Sodium hydroxide liquid 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 liquid (NaOH) as the thermal storage or seasonal reservoir medium for domestic space-heating. If water is added to solid or concentrated Sodium hydroxide liquid (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 liquid 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 is working on a reactor design in which NaOH is used as a neutron moderator.

Safety of Sodium hydroxide liquid

Like other corrosive acids and alkalis, drops of Sodium hydroxide liquid solutions can readily decompose proteins and lipids in living tissues via amide hydrolysis and ester hydrolysis, which consequently cause chemical burns and may induce permanent blindness upon contact with eyes. Solid alkali can also express its corrosive nature if there is water, such as water vapor. Thus, protective equipment, like rubber gloves, safety clothing and eye protection, should always be used when handling this chemical or its solutions. The standard first aid measures for alkali spills on the skin is, as for other corrosives, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes.

Moreover, dissolution of Sodium hydroxide liquid is highly exothermic, and the resulting heat may cause heat burns or ignite flammables. It also produces heat when reacted with acids.

Sodium hydroxide liquid is also mildly corrosive to glass, which can cause damage to glazing or cause ground glass joints to bind. Sodium hydroxide liquid is corrosive to several metals, like aluminium which reacts with the alkali to produce flammable hydrogen gas on contact:

2 Al + 6 NaOH → 3 H2 + 2 Na3AlO3
2 Al + 2 NaOH + 2 H2O → 3 H2 + 2 NaAlO2
2 Al + 2 NaOH + 6 H2O → 3 H2 + 2 NaAl(OH)4

Storage
Careful storage is needed when handling Sodium hydroxide liquid 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 liquid 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 liquid 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 liquid must be stored in airtight containers to preserve its normality as it will absorb water from the atmosphere.

History of Sodium hydroxide liquid
Sodium hydroxide liquid was first prepared by soap makers. A procedure for making Sodium hydroxide liquid appeared as part of a recipe for making soap in an Arab book of the late 13th century: Al-mukhtara` fi funun min al-suna` (Inventions from the Various Industrial Arts), which was compiled by al-Muzaffar Yusuf ibn `Umar ibn `Ali ibn Rasul (d. 1295), a king of Yemen. The recipe called for passing water repeatedly through a mixture of alkali (Arabic: al-qily, where qily is ash from saltwort plants, which are rich in sodium ; hence alkali was impure sodium carbonate) and quicklime (calcium oxide, CaO), whereby a solution of Sodium hydroxide liquid was obtained. European soap makers also followed this recipe. When in 1791 the French chemist and surgeon Nicolas Leblanc (1742–1806) patented a process for mass-producing sodium carbonate, natural "soda ash" (impure sodium carbonate that was obtained from the ashes of plants that are rich in sodium) was replaced by this artificial version. However, by the 20th century, the electrolysis of sodium chloride had become the primary method for producing Sodium hydroxide liquid.

Sodium hydroxide liquid solution appears as a colorless liquid. More dense than water. Contact may severely irritate skin, eyes, and mucous membranes. Toxic by ingestion. Corrosive to metals and tissue.

Caustic soda reacts with all the mineral acids to form the corresponding salts. It also reacts with weak-acid gases, such as hydrogen sulfide, sulfur dioxide, and carbon dioxide. Caustic soda reacts with amphoteric metals (Al, Zn, Sn) and their oxides to form complex anions such as AlO2(-), ZnO2(-2), SNO2(-2), and H2 (or H2O with oxides). All organic acids also react with sodium hydroxide liquid to form soluble salts. Another common reaction of caustic soda is dehydrochlorination.

Because of its high-level alkalinity, sodium hydroxide in aqueous solution directly causes bond breakage in proteins (especially disulfide bridges). Hair and fingernails are found to be dissolved after 20 hours of direct contact with sodium hydroxide at pH values higher than 9.2. Sodium hydroxide has depilatory effects which have been described after accidental contact with solutions in the workplace. The breakage of bonds in proteins may lead to severe necrosis to the application site. The level of corrosion depends on the period of contact with the tissue, and on the concentration of sodium hydroxide.

Liquid or solid sodium hydroxide is a severe skin irritant. It causes second and third degree burns on short contact and is very injurious to the eyes.

The organic chemical industry uses Sodium hydroxide liquid for saponification reactions, production of nucleophilic anionic intermediates, etherification and esterification, basic catalysis, and the production of free organic bases. Sodium hydroxide liquid solution is used for scrubbingwaste gases and neutralizing wastewater.

In inorganic chemistry, Sodium hydroxide liquid is used in the manufacture of sodium salts, for alkaline ore digestion, and for pH regulation.

The textile industry uses Sodium hydroxide liquid solution to manufacture viscose and viscose staple fibers. The Sodium hydroxide liquid solution used must contain only traces of chloride ions (rayon quality). The surface of cotton can be improved by treatment with Sodium hydroxide liquid solution (mercerization).

In the aluminum industry, Sodium hydroxide liquid is used mainly for the treatment of bauxite.

Waterworks use dilute Sodium hydroxide liquid solution to regenerate ion exchangers for water purification and wastewater treatment.

In the food industry, Sodium hydroxide liquid is used for degreasing, cleaning, and for peeling potatoes.

Chlorine and Sodium hydroxide liquid are usually coproduced /by brine electrolysis/ in a ratio of 1 ton of chlorine to 1.1 tons of Sodium hydroxide liquid.

Workplace monitoring: Sampling and analysis may be performed by collection of Sodium hydroxide liquid in a glass bubble containing hydrochloric acid, followed by subsequent titration.

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

Volumetric Sodium hydroxide liquid soln used in laboratory must be protected from air to avoid formation of carbonate.

Sodium hydroxide liquid in contact with water may generate enough heat to ignite adjacent combustible materials.

Mixing Sodium hydroxide liquid and acrolein in a closed container caused the temperature and pressure to increase.

Sodium hydroxide liquid used as a general purpose food additive in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.

Esophageal burns were induced in male rats by the administration of 10% Sodium hydroxide liquid. Lipid peroxidation (LPO) products were then measured at the following times: 0, 1, 6, 24, 48 and 72 hr after treatment. Tissue hydroxyproline (HP) concentrations in the injured area were assessed at 14 days after the administration of Sodium hydroxide liquid. The groups received either systemic melatonin or normal saline. There were two, non-ischemic, sham control groups treated with or without melatonin. LPO products, malondialdehyde (MDA) and 4-hydroxyalkenal (4-HDA), increased immediately after the administration of Sodium hydroxide liquid; this indicates the participation of free radicals in the development of damage. Melatonin diminished the oxidative response and the amount of HP in the late phase of the lesion. Melatonin reduced oxidative damage in the early phase of the esophageal burns induced by Sodium hydroxide liquid.

Human poisoning cases indicate that a dose of 10 grams orally is fatal. Sodium hydroxide liquid is toxic by oral ingestion. Sodium hydroxide liquid is corrosive to all tissues. Concentrated vapors lead to serious damage to the eyes and respiratory system. Oral ingestion of Sodium hydroxide liquid, which occurs frequently in children, causes severe tissue necrosis, with stricture formation of the esophagus, often resulting in death. Contact with the skin may result in contact dermatitis, hair loss, as well as necrosis due to severe irritation. Increased incidence of esophageal carcinoma after severe intoxication with Sodium hydroxide liquid has been reported in man. In animal studies, long-term dermal contact with substances leading to pH changes in the skin causes the development of tumors, as a result of severe tissue irritation and reparative cell growth. Mutagenic for mammalian somatic cells. May cause damage to the following organs: mucous membranes, upper respiratory tract, skin, eyes [MSDS]. Tumors are not to be expected if the effects of irritation are prevented. To date, there are no relevant studies of the prenatal toxic effects of Sodium hydroxide liquid.

Acute Exposure/ Keratin material in the skin underwent rapid decomposition in Sodium hydroxide liquid above pH 9.2. Aliquots of washed human hair and fingernails were mixed with various amounts of sodium solution and the extent of keratin breakdown was measured by estimating the cystine produced. The cystine portion of the keratin complex of human hair or nails was readily cleaved by Sodium hydroxide liquid in the S-S bond. After 20 hr of contact with 0.1N or 0.25N Sodium hydroxide liquid, 61.4% and 97.6%, respectively, of the nail keratin were decomposed. Thus, a high degree of destruction of tissue even by a dilute Sodium hydroxide liquid solution can occur from prolonged contact.

In the case of a solid, anhydrous Sodium hydroxide liquid spill on soil, ground water pollution will occur if precipitation occurs prior to clean up. Precipitation will dissolve some of the solid (with much heat given off) and create an aqueous solution of Sodium hydroxide liquid, which then would be able to infiltrate the soil. However, prediction of the concentration and properties of the solution produced would be difficult.

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.

Uses & Benefits of Sodium hydroxide (NaOH)
Sodium hydroxide liquid is used to manufacture many everyday products, such as paper, aluminum, commercial drain and oven cleaners, and soap and detergents.

Sodium hydroxide liquid in Cleaning & Disinfectant Products
Sodium hydroxide liquid 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 liquid. Drain cleaners that contain Sodium hydroxide liquid convert fats and grease that can clog pipes into soap, which dissolves in water.

Sodium hydroxide liquid in Pharmaceuticals & Medicine
Sodium hydroxide liquid 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 liquid in Energy
In the energy sector, Sodium hydroxide liquid 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 liquid, are used in wind turbines.

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

Sodium hydroxide liquid in Food Production
Sodium hydroxide liquid 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 liquid 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 liquid in Wood & Paper Products
In many paper making processes, wood is treated with a solution containing sodium sulfide and Sodium hydroxide liquid. 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 liquid is used to separate the ink from the paper fibers allowing the paper fibers to be reused again.

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

Sodium hydroxide liquid in Aluminum Ore Processing
Sodium hydroxide liquid 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. In building and construction, aluminum is used in materials that enable building facades and window frames.

Sodium hydroxide liquid in Other Industrial Manufacturing Uses
Sodium hydroxide liquid is used in many other industrial and manufacturing processes. It is used to manufacture rayon, spandex, explosives, epoxy resins, paints, glass and ceramics. It 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.

Safety Information of Sodium hydroxide liquid
Due to its strong corrosive qualities, exposure to Sodium hydroxide liquid in its solid or solution form can cause skin and eye irritation, according to the U.S. Centers for Disease Control and Prevention Agency for Toxic Substances and Disease Registry. Workers in facilities where Sodium hydroxide liquid is manufactured or used should follow product safety instructions.

The U.S. Occupational Safety & Health Administration (OSHA) has set guidelines and permissible exposure limits for workers in industries and facilities where Sodium hydroxide liquid substances are used, available on OSHA’s website.

The National Institute for Occupational Safety and Health provides general safety information about transporting Sodium hydroxide liquid, including guidance on packaging and storage, spillage, disposal, and packaging and labeling for workers.

The Food and Drug Administration (FDA) allows Sodium hydroxide liquid as a food additive at levels lower than 1 percent.

What are Sodium hydroxide liquid uses?
Sodium hydroxide liquid 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 liquid?
Sodium hydroxide liquid, 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.

What Is Sodium hydroxide liquid?

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

The chemical is synthesized through electrolysis where chemical decomposition is achieved by passing an electric current through a solution of sodium chloride (commonly referred to as table salt) to yield Sodium hydroxide liquid and chlorine gas.

Sodium hydroxide liquid Fast Facts
Sodium hydroxide liquid Density: 2.13 g/cm3

Common Names for Sodium hydroxide liquid: Caustic soda, lye, soda lye, and sodium hydrate
Sodium hydroxide liquid Melting Point: 604.4°F
Sodium hydroxide liquid Boiling Point: 2,530°F
Molar Mass of Sodium hydroxide liquid: 39.997 g/mol

Common Uses of Sodium hydroxide liquid

1. Sodium hydroxide liquid for Cleaning
The beauty of Sodium hydroxide liquid for use in cleaning lies in its ability to transmute hard grease and fat buildup– attributed to clogging drains– into dissolvable soap. Sodium hydroxide liquid excels in the cleaning industry due to its accessibility, affordability, ease of detection, and disposal. When used as a cleaning agent handlers must exhibit caution, as the chemical is known to burn human skin and cause severe internal damage if inhaled or ingested. Sodium hydroxide liquid is particularly damaging if its fumes are allowed to permeate the eyes.

On a micro scale, Sodium hydroxide liquid is credited with eliminating proteins and nucleic acids while disabling most viruses it comes into contact with. The chemical also eradicates yeasts, fungi, and endotoxins. Because of its efficacy in removing microorganisms, Sodium hydroxide liquid is commonly leveraged in the medical industry as a critical sanitation component.

2. Sodium hydroxide liquid for Medicinal Use
Considering Sodium hydroxide liquid is utilized heavily as a cleaning agent and is harmful to humans, its immersive use as a medicinal component may surprise you! Sodium hydroxide liquid is a component in common pain relievers, a piece of the puzzle in creating effective anticoagulants, and is used in cholesterol maintenance prescriptions. Some common prescriptions including Sodium hydroxide liquid as an inactive ingredient are Aspir-Low aspirin, Cyclobenzaprine hydrochloride extended-release, diclofenac sodium and misoprostol delayed-release, Divalproex sodium delayed-release, Didanosine, Edarbyclor, Nexium, and Sutent.

3. Sodium hydroxide liquid for Beauty
In small dilutions (5%), Sodium hydroxide liquid is commonly found in the following beauty products:

Hairspray
Fragrances
Soapmaking
Foot powders
Hair dye
Makeup
Nail care products
Shampoos
Shaving products
Depilatories
Suntan oils
Chemical hair straighteners

The inclusion of Sodium hydroxide liquid in many beauty products is attributed to its ability to stabilize pH levels. The inclusion of Sodium hydroxide liquid in hair products creates a less acidic environment for the scalp, skin, and hair. The leveling effect of Sodium hydroxide liquid helps regulate external influences which may have otherwise changed healthy pH levels. A common example is the mixture of residual oils on one’s hands introduced to the conditioning product upon application.