Sodium hydroxide (NaOH), commonly known as caustic soda, caustic soda and caustic soda, is called Costa in Hong Kong because of another name. It is a white crystal with strong corrosiveness at room temperature. Soluble in water, its aqueous solution is strongly alkaline, which can turn phenolphthalein red. Sodium hydroxide is a very commonly used alkali, and it is also one of the essential drugs in chemistry laboratory. Its solution can be used as washing liquid.

English name: sodium hydroxide

Chemical formula: NaOH

Relative molecular weight: 40.0 1

Chemical category: inorganic strong base

Control: Yes.

catalogue

Brief introduction of sodium hydroxide control information

shape

shop

use

safety measure

Deterioration inspection

Physical and chemical constants

Laboratory determination

Inherent water absorption

strong basicity

Other attributes

The use of sodium hydroxide

Industrial preparation method of sodium hydroxide

Make a small amount of sodium hydroxide

Precautions for use and storage

Environmental impact. health hazard

Second, toxicological data and environmental behavior.

Emergency treatment and disposal methods. Emergency treatment of leakage

Second, the protective measures

Third, first aid measures.

chemical property

Brief introduction of sodium hydroxide control information

shape

shop

use

safety measure

Deterioration inspection

Physical and chemical constants

Laboratory determination

Inherent water absorption

strong basicity

Other attributes

The use of sodium hydroxide

Industrial preparation method of sodium hydroxide

Make a small amount of sodium hydroxide

Precautions for use and storage, environmental impact

I. Health hazards. Toxicological data of environmental behavior and emergency treatment and disposal methods

First, the emergency treatment of leakage. Protection measure three. Precautions for chemical properties of first aid measures Start editing the introduction of sodium hydroxide in this paragraph.

Regulatory information

Sodium hydroxide (corrosive) is managed by the public security department according to the Regulations on Safety Management of Hazardous Chemicals.

shape

Melted white particles or strips are now often made into small pieces. Easy to absorb moisture and carbon dioxide in the air. 1g is soluble in 0.9ml cold water, 0.3ml boiling water, 7.2ml absolute ethanol and 4.2ml methanol, and in glycerol. When it is dissolved in water or ethanol, or when the solution is mixed with acid, it generates intense heat. The solution is strongly alkaline. The relative density is 2. 13. The melting point is 365438 08℃. The boiling point is 1390℃. The median lethal dose (mice, abdominal cavity) was 40mg/kg. Corrosive.

shop

Sealing, drying and storing. (that is, you can't leave it open. The air contains water vapor (h? O), carbon dioxide (CO? ), and NaOH is easily deliquesced by water vapor and easily reacts with carbon dioxide to generate sodium carbonate (Na? CO？ ), it will deteriorate)

use

Widely used sewage treatment agent, alkaline analytical reagent, standard alkaline solution for preparation and analysis, absorbent of a small amount of carbon dioxide and water, and sodium salt of neutralized acid. Preparing other reagents containing hydroxyl ions; It has important applications in papermaking, printing and dyeing, wastewater treatment, electroplating and chemical drilling. Domestic brands are: Tianhui brand, Tiangong brand and Jinda brand.

safety measure

Sodium hydroxide amplification

Sealed and stored in a cool and dry place. With acid, ammonium, flammable (combustible) materials, etc. Do not touch the skin. In case of skin (eyes) contact, rinse with running water and apply boric acid solution. If you eat by mistake, rinse your mouth with water and drink milk or egg white (such as acidic and harmless food).

Edit this section of deterioration inspection.

1. If the dilute hydrochloric acid in the sample has bubbles, sodium hydroxide will deteriorate. Principle: 2 NaOH+CO2 = = Na2CO3+H2O2 HCl+Na2CO3 = = 2 NaCl+CO2 ↑+H2O (air contains a small amount of carbon dioxide, and an open NaOH solution can react with CO2, and hydrogen ions in HCl can react with carbonate ions to generate gas) 2. Add clear limewater to the sample. If white precipitate is produced, sodium hydroxide will deteriorate. Principle: Na2CO3+Ca (OH) 2 = = CaCO3 ↓+2NaOH.

Edit the physical and chemical constants of this paragraph.

Density: 2. 130g/cm3 melting point: 3 18.4℃ water solubility:. Soluble in aqueous solution, colorless boiling point: 1390℃, alkali dissociation constant (Kb)= 3.0, logarithm reciprocal of alkali dissociation constant (pKb)= -0.48, lethal dose: 40mg/kg. Middle school identification method of sodium hydroxide: adding magnesium chloride produces white precipitate. Flame reaction, the flame is yellow. CASNo.: 13 10-73-2

Edit this laboratory measurement

Name of method: sodium hydroxide-determination of sodium hydroxide-scope of application of neutralization titration: This method uses titration to determine the content of sodium hydroxide. This method is suitable for sodium hydroxide. Method principle: After the sample is dissolved in newly boiled cold water, cool it, dilute it to scale with water, shake it evenly, accurately measure 25mL, add 3 drops of phenolphthalein indicator, titrate with sulfuric acid titration solution (0. 1mol/L) until the red color disappears, and record the volume (mL) of the consumed sulfuric acid titration solution (0. 1mol/L). Continue to add sulfuric acid titration solution (0. 1mol/L) until it is orange-red. According to the volume (mL) of sulfuric acid titration solution (0. 1mol/L) consumed twice before and after, the total alkali content (calculated as NaOH) in the sample is calculated, and according to the consumption of sulfuric acid titration solution (0. 1mol/L) after adding methyl orange indicator solution. Reagent: 1. Water (fresh boiling and cooling) II. Sulfuric acid titration solution (0. 1mol/L) 3. Phenolphthalein indicator solution 4. Indicating solution of methyl orange: take 0. 1g methyl orange and add 100mL water to dissolve it. Instruments and equipment: sample preparation: 1. Preparation of sulfuric acid titration solution (0. 1mol/L): Take 6mL of sulfuric acid, slowly inject it into a proper amount of water, cool it to room temperature, dilute it with water to 1000mL, and shake well. Calibration: Take about 0.3g of standard anhydrous sodium carbonate dried at constant weight at 270-300℃, accurately weigh it, add 50mL of water to dissolve it, add 10 drop of methyl red-bromocresol green mixed indicator, titrate with this solution until the solution changes from green to purple, boil for 2 minutes, cool it to room temperature, and continue to titrate until the color of the solution changes from green to deep purple. Every 1mL sulfuric acid titration solution (0. 1mol/L) is equivalent to 10.60mg anhydrous sodium carbonate. According to the consumption of the solution and the amount of anhydrous sodium carbonate, the concentration of the solution is calculated. 2. Phenolphthalein indicator solution is phenolphthalein 1g, and dissolved in ethanol 100mL. Operating Steps: Take about 2g of this product, accurately weigh it, put it in a 250mL volumetric flask, add a proper amount of newly boiled cold water to dissolve it, let it cool, dilute it to scale with water, shake it evenly, accurately measure 25mL, add 3 drops of phenolphthalein indicator, titrate it with sulfuric acid titration solution (0. 1mol/L) until it disappears, and record the consumption of sulfuric acid titration solution (0.65438. Continue to add sulfuric acid titration solution (0. 1mol/L) until it is orange-red. According to the volume (mL) of sulfuric acid titration solution (0. 1mol/L) consumed twice before and after, the total alkali content (calculated as NaOH) in the sample is calculated, and according to the consumption of sulfuric acid titration solution (0. 1mol/L) after adding methyl orange indicator solution. Every 1mL sulfuric acid titration solution (0. 1mol/L) is equivalent to 8.00mg NaOH or 2 1.20mg Na2CO3. Note 1: "accurate weighing" means that the weighing should be accurate to one thousandth of the weighed weight, and "accurate weighing" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in the national standard. References: China Pharmacopoeia, edited by National Pharmacopoeia Committee, Chemical Industry Press, 2005, Part II, p. 904.

Edit the characteristics of this paragraph

Water absorption

It has strong corrosiveness and water absorption (so the quality of NaOH placed in the open air will increase) and can be used as a desiccant. However, acid gases such as sulfur dioxide, carbon dioxide, nitrogen dioxide and hydrogen chloride cannot be dried because they will react with CO2 and deteriorate. (It will react with acid gas. ) and it is easy to deliquesce and liquefy in the air (the phenomenon of dissolution due to water absorption belongs to physical change); Soluble in water, while giving off a lot of heat. It can make phenolphthalein red and purple litmus test solution blue, which belongs to strong alkali. The corrosion of aluminum is not the corrosion of plastic. Just leave it in the air for a few minutes, and it will absorb water and become liquid poison. Its melting point is 3 18.4℃. Besides being soluble in water, sodium hydroxide is also easily soluble in ethanol and glycerol. But insoluble in ether, acetone and liquid ammonia.

strong basicity

Its liquid is a colorless, astringent and greasy liquid. Sodium hydroxide will react with carbon dioxide in the air and deteriorate. The chemical equation of the reaction is: 22 NaOH+CO2 = = = Na2CO3+H2O sodium (Na) reacts with water (when reacting with water, use a beaker and cover the beaker with a glass sheet. During the reaction, sodium blocks float on the water surface, melt into a ball, swim on the water surface, hiss and splash), and an enlarged picture of NaOH crystals is generated in strongly alkaline NaOH solution.

And release hydrogen. In solid NaOH, OH is bound by O-H*** valence bond, and Na and OH are bound by strong ionic bond. When dissolved in water, its dissociation degree is close to 100%, so its aqueous solution is strongly alkaline, which can turn colorless phenolphthalein test solution into red or PH test paper and purple litmus solution into blue.

Other attributes

Pure anhydrous sodium hydroxide is a white translucent crystalline solid. Sodium hydroxide is easily soluble in water, and its solubility increases with the increase of temperature. When dissolved, a large amount of heat can be released, and its saturated solution concentration can reach16.4 mol/L (1:1) at 288K. Its aqueous solution has astringency and satiny, and the solution is strongly alkaline, which can react with acidic substances and has all the commonness of alkali. There are two kinds of caustic soda on the market: pure solid alkali is white, blocky, flaky, rod-shaped, granular and brittle; Pure liquid alkali is a colorless and transparent liquid. Sodium hydroxide is also soluble in ethanol and glycerol; But insoluble in ether, acetone and liquid ammonia. Corrosive to fiber, skin, glass, ceramics, etc. When dissolved or diluted with concentrated solution, heat will be released; The neutralization reaction with inorganic acids can also generate a lot of heat and generate corresponding salts; Reacting with metallic aluminum and zinc, nonmetallic boron and silicon to release hydrogen; Disproportionation reaction with chlorine, bromine, iodine and other halogens. Can precipitate metal ions in aqueous solution into hydroxide; It can saponify oil and generate corresponding sodium salts and alcohols of organic acids, which is the principle of removing oil stains from fabrics. Note: As long as sodium hydroxide is taken out and put in the air, it will quickly absorb water molecules in the air (that is, deliquescence) and generate a highly toxic solution-sodium hydroxide solution.

Edit the purpose of sodium hydroxide in this paragraph.

Sodium hydroxide is widely used. In chemical experiments, it is not only used as a reagent, but also used as an alkaline desiccant because of its strong water absorption and easy deliquescence. Sodium hydroxide is widely used in the national economy, and many industrial departments need sodium hydroxide. The most used sector of sodium hydroxide is chemical manufacturing, followed by papermaking, aluminum smelting, tungsten smelting, man-made fiber, man-made fiber and soap manufacturing. In addition, in the production of dyes, plastics, medicine and organic intermediates, the regeneration of old rubber, the electrolysis of sodium metal and water, and the production of inorganic salts, a large amount of caustic soda is also used to prepare borax, chromium salt, manganate and phosphate. Sodium hydroxide for industrial use shall conform to the national standard GB 209-2006；; ; Sodium hydroxide by ion exchange membrane method for industrial use shall conform to the national standard GB/T11199-89; Sodium hydroxide for chemical fiber shall meet the national standard GB11212-89; Edible sodium hydroxide should meet the national standard GB 5 175-85. Absorb carbon dioxide in photosynthesis experiment. In industry, sodium hydroxide is usually called caustic soda, or caustic soda or caustic soda. This is because the concentrated sodium hydroxide solution splashed on the skin will corrode the epidermis and cause burns. It can dissolve protein, and has strong irritation and corrosiveness (alkali burn is more difficult to heal than acid burn because it can dissolve protein). Dropping 0.02% solution into rabbit eyes can cause corneal epithelial injury. LD50: 40 mg/kg intraperitoneal injection in mice and 500 mg/kg oral injection in rabbits. Dust irritates eyes and respiratory tract and corrodes nasal septum; Splash on skin, especially mucous membrane, can produce soft scab, penetrate into deep tissue, and leave scars after burn; Splashing into the eye will not only damage the cornea, but also damage the deep tissue of the eye, which can cause blindness in severe cases; Miseating can cause digestive tract burns, colic, mucosal erosion, hematemesis of stomach contents, bloody diarrhea, sometimes hoarseness, dysphagia, shock, perforation of digestive tract, and gastrointestinal stenosis in the later stage. Because of its strong alkalinity, it can pollute water bodies, so attention should be paid to plants and aquatic organisms.

Edit the industrial preparation method of sodium hydroxide in this paragraph.

(1) Filter seawater (2) Add excessive sodium hydroxide to remove calcium and magnesium ions, and filter Ca2++2OH-= = = Ca (OH) 2 (Ca (OH) 2 is slightly soluble and may cause turbidity) Mg2++2OH-= = Mg (OH) 2 (. Remove calcium ions and excess barium ions, filter Ca2++Co32-= = = CaCO3 ↓ Ba2++Co32-= = = BACO3 ↓ ⑤ Add appropriate amount of hydrochloric acid, remove excess carbonate ions as 2h++Co32-= = = CO2 ↑+H2O6, heat to drive off carbon dioxide, and send to the ion exchange tower.

Edit this paragraph to make a small amount of sodium hydroxide

You can find some sodium bicarbonate (baking soda) (if sodium carbonate is better) and some calcium oxide (quicklime) (small bags commonly used in food packaging bags as water absorbent, such as seaweed packaging and ice cream). Put quicklime into water and react to become lime slurry. Add sodium bicarbonate (or sodium carbonate) solid particles to lime slurry (concentrated solution is also acceptable). In order to ensure the purity of sodium hydroxide, excess lime slurry must be made. Reason: Refer to the solubility of calcium hydroxide and sodium carbonate. Stir to speed up the reaction, and let it stand for a period of time after the reaction. With the precipitation of calcium carbonate, the supernatant is sodium hydroxide, which can be poured out carefully. If purification is needed, it can be heated for a period of time to evaporate some water, so that relatively pure sodium hydroxide can be obtained. CaO+H2O = = = = Ca(OH)2 nah co 3+Ca(OH)2 = = = = CaCO3↓+NaOH+H2O Ca(OH)2+na2co 3 = = = = CaCO3↓+2 NaOH 2Na+2H2O = = = = 2 NaOH+H2↑

Notes on editing, using and saving this paragraph

Regulations on Safety Management of Hazardous Chemicals (promulgated by the State Council 1987 in February), Detailed Rules for the Implementation of Regulations on Safety Management of Hazardous Chemicals (Hua Laofa [1992] No.677) and Provisions on Safe Use of Chemicals in Workplaces ([1996] No.423). This substance belongs to Class 8.2 alkaline corrosive products in Classification and Labeling of Commonly Used Hazardous Chemicals (GB 13690-92). The Technical Specification for the Safety of Diaphragm Caustic Soda Production (HGA00 1-83) and the Technical Specification for the Safety of Mercury Caustic Soda Production (HGA002-83) have made special provisions on this. Protective articles should be worn when exposed to caustic soda in large quantities, and work clothes or working caps should be made of cotton cloth or appropriate synthetic materials. Operators must wear work clothes, masks, protective glasses, rubber gloves, rubber aprons, rubber boots and other labor protection articles when working. Neutral and hydrophobic ointments should be applied to the skin. When contacting flake or granular caustic soda, the workplace should be ventilated. The maximum allowable concentration in indoor air is 0.5mg/m3 for MAC in China and 2mg/m3 for ACGIH TLVC in America. When it is possible to come into contact with its dust, you must wear a hood-type electric air supply and dust filtering respirator. Wear air respirator if necessary. Operators must be specially trained and strictly abide by the operating procedures. It is recommended that the operator wear a hood-type electric air supply and dust filtering respirator, a rubber acid and alkali resistant suit and a rubber acid alkali resistant gloves. Keep away from flammable and combustible materials. Avoid dust. Avoid contact with acids. When handling, handle with care to prevent the packaging and containers from being damaged. Equipped with leakage emergency treatment equipment. Empty containers may leave harmful substances behind. If you want to keep sodium hydroxide solid, you need to put it in a sealed container with desiccant. When diluting or preparing the solution, alkali should be added to the water to avoid boiling and splashing. Wear protective glasses and gloves when dealing with the leakage, sweep it clean, slowly pour a lot of water, rinse the ground with water, and put the diluted sewage into the wastewater system. When lye contacts the skin, it can be cleaned with 5 ~ 10% magnesium sulfate solution; If it spills into eyes, it should be cleaned immediately with a large amount of boric acid aqueous solution; When a small amount is eaten by mistake, it should be neutralized with vinegar, 3 ~ 5% acetic acid or 5% dilute hydrochloric acid, and a large amount of orange juice or lemon juice. , and give egg white, milk or vegetable oil, and seek medical advice quickly. Vomiting or gastric lavage is not allowed. Crystal morphology of sodium hydroxide

Solid sodium hydroxide can be packed in steel drums with a thickness of 0.5 mm, which are tightly sealed, and the net weight of each drum does not exceed 100 kg; Steel drums with full openings outside or in the middle of plastic bags or double-layer kraft paper bags; Screw-capped glass bottles, iron-capped glass bottles, plastic bottles or ordinary wooden cases outside metal barrels (cans); The threaded glass bottle, plastic bottle or tinned steel barrel (can) is sheathed with a bottom plate lattice box, a fiberboard box or a plywood box; Tin-plated steel drums (cans), metal drums (cans), plastic bottles or corrugated boxes with metal hoses. Packaging containers should be complete, sealed and marked with "corrosive substances". In railway transportation, steel drums can be transported by open cars. The package shall be intact during shipment and the loading shall be safe. During transportation, it is necessary to ensure that the container does not leak, collapse, fall or be damaged, and is moisture-proof and rain-proof. If the packaging container is found to be rusty, cracked, perforated, melted and dripping, it should be replaced immediately or shipped as soon as possible. Damaged containers can be repaired by welding. It is strictly prohibited to transport with flammable or combustible substances, acids and edible chemicals. Transport vehicles should be equipped with leakage emergency treatment equipment during transportation. Do not mix with flammable materials and acids. In case of fire, water, sand and various fire extinguishers can be used to put out the fire, but firefighters should pay attention to the corrosiveness of caustic soda dissolved in water.

Edit the environmental impact of this paragraph.

I. Health hazards

Bottled sodium hydroxide

Invasion route: inhalation and ingestion. Health hazard: This product is highly irritating and corrosive. Dust or smoke can irritate eyes and respiratory tract and corrode nasal septum; Direct contact between skin and eyes with NaOH can cause burns; Incorrect intake can lead to digestive tract burns, mucosal erosion, bleeding and shock.

Second, toxicological data and environmental behavior.

Hazard characteristics: this product will not burn, and when it meets water and steam, it will release a lot of heat and form a corrosive solution. Neutralize with acid and release heat. It is very corrosive. Combustion (decomposition) products: harmful toxic smoke may be produced.

Edit the emergency treatment and disposal methods in this paragraph.

First, the emergency treatment of leakage

Isolate the leakage and pollution areas, set warning signs around them, and suggest that emergency personnel wear gas masks and chemical protective clothing. Do not directly touch the leakage, collect it in a dry and clean container with a clean shovel, add a small amount of NaOH to a large amount of water, adjust it to neutrality, and then put it into the wastewater system. It can also be washed with a large amount of water, and the diluted washing water is put into the wastewater system. If there is a large amount of leakage, collect and recycle or harmless NaOH bags.

Disposal and disposal.

Second, the protective measures

Respiratory protection: Wear a gas mask if necessary. Eye protection: Wear chemical safety glasses. Protective clothing: wear work clothes (made of anticorrosive materials). Hand protection: wear rubber gloves. Others: Take a shower and change clothes after work. Pay attention to personal hygiene.

Third, first aid measures.

Skin contact: rinse immediately with plenty of water, and then apply 3%-5% boric acid solution. Eye contact: lift the eyelid immediately and rinse it with running water or normal saline for at least 15 minutes. Or rinse with 3% boric acid solution. See a doctor. Inhalation: leave the scene quickly and go to a place with fresh air. Give artificial respiration if necessary. See a doctor. Ingestion: protein and other things should be used as soon as possible to clean toxic substances in the mouth, such as milk, yogurt and other dairy products. After the patient wakes up, rinse his mouth immediately, take diluted vinegar or lemon juice orally, and seek medical advice. Fire extinguishing method: water mist, sand and carbon dioxide fire extinguisher.

Edit the chemical properties of this paragraph.

(1)NaOH is a strong alkali, which has all the commonness of alkali. Sodium hydroxide standard titration

(1) ionizes a large number of OH- ions in aqueous solution: NaOH=Na++OH- (2) can react with acid: NaOH+HCl = = = NaCl+H2O (3 3) can react with some acid oxides; 2NaOH+SO2 (insufficient) = = Na2SO3+H2O NaOH+SO2 (excessive). = = = nahso3① (① generated Na2SO3 and water react with excessive SO2 to generate nahso3) 2nnaoh+3no2 = = 2nano3+no+H2O (4) sodium hydroxide solution reacts with aluminum 2al+2n NaOH+2h2o = = 2nalo2+3h2 = (and when the amount of NaOH is insufficient, The reaction is 2al+6H2O = = (NaOH) = = = 2al (OH) 3 ↓+3H2 ↑) (5) Weak base can be prepared from strong alkali; (8)NaOH can absorb carbon dioxide. The reaction process is as follows: 2 NaOH+CO2 = = Na2CO3+H2O (less CO2) NaOH+CO2 = = = nahco3 (CO2 (excess CO2)) (9)NaOH can react with silica, and SiO2 SiO2+ 2NaOH==== Na2SiO3+H2O+H2O (because Na2SiO3 is the main component of glass glue, if it is used in glass stoppers, Therefore, when sodium hydroxide is put in a glass bottle, the rubber stopper (10) can react with the indicator, colorless phenolphthalein will turn red (too concentrated sodium hydroxide will also make phenolphthalein fade), and purple litmus test solution will turn blue (1 1). Therefore, it should be placed in a dry environment and can also be used as a dry gas.

Notes for editing this paragraph

Sealed and stored in a cool and dry place. It is stored and transported in the same amount as acid and flammable (combustible) substances. In case of skin (eyes) contact, rinse with running water. If you eat by mistake, rinse your mouth with water and drink milk or egg white. Fire fighting measures: water and sand. Some vendors in the market use industrial sodium hydroxide when handling frozen shrimp, which is not allowed.