Sodium hydroxide (NaOH), commonly known as caustic soda, caustic soda, and caustic soda, is also called caustic soda in Hong Kong because of its other name: caustic soda. It is a white solid at room temperature and is highly corrosive. Easily soluble in water, its aqueous solution is strongly alkaline and can turn phenolphthalein red. Sodium hydroxide is a very commonly used base and one of the essential medicines in the chemistry laboratory. Sodium hydroxide easily absorbs water vapor in the air, so it must be sealed and stored with a rubber stopper. Its solution can be used as a washing liquid.
【Environmental impact】
1. Health hazards. Invasion routes: inhalation and ingestion. Health hazards: This product is highly irritating and corrosive. Dust or smoke can irritate the eyes and respiratory tract and corrode the nasal septum; direct contact between the skin and eyes and NaOH can cause burns; accidental ingestion can cause gastrointestinal burns, mucous membrane erosion, bleeding and shock.
2. Environmental hazards and hazardous characteristics: This product will not burn. It will generate a large amount of heat when exposed to water and water vapor, forming a corrosive solution. Neutralizes with acid and releases heat. Highly corrosive. Combustion (Decomposition) Products: May produce harmful toxic fumes.
[Emergency treatment methods]
1. Leak emergency response: Isolate the leaked contaminated area and set up warning signs around it. It is recommended that emergency responders wear gas masks and chemical protective suits. Do not come into direct contact with the leaked material. Use a clean shovel to collect it in a dry, clean and covered container. Add a small amount of NaOH to a large amount of water, adjust it to neutral, and then put it into the wastewater system. You can also rinse with large amounts of water and put the diluted wash water into the wastewater system. If there is a large amount of leakage, collect and recycle or dispose of it after harmless treatment.
2. Protective measures Respiratory system protection: Wear a gas mask when necessary. Eye protection: Wear chemical safety glasses. Protective clothing: Wear overalls (made of anti-corrosion materials). Hand protection: Wear rubber gloves. Others: After work, shower and change clothes. Pay attention to personal hygiene. 3. First aid measures Skin contact: Rinse immediately with plenty of water, then apply 3%-5% boric acid solution. Eye contact: Immediately lift eyelids and flush with running water or saline for at least 15 minutes. Or rinse with 3% boric acid solution. Seek medical attention. Inhalation: Move quickly to fresh air. Provide artificial respiration if necessary. Seek medical attention. Ingestion: Toxins in the mouth should be washed away as soon as possible with something like protein, such as milk, yogurt and other dairy products. Rinse your mouth immediately when the patient is awake, take diluted vinegar or lemon juice orally, and seek medical attention. Fire extinguishing methods: mist water, sand, carbon dioxide fire extinguisher.
【Chemical Properties】
1. NaOH is a strong base and has all the properties of a base.
2. A large number of OH- ions are ionized in the aqueous solution: NaOH=Na+OH
3. Reaction with acid: NaOH + HCl = NaCl + H2ONaOH + HNO3 = NaNO3 + H2O
4. Can react with some acidic oxides: 2NaOH + SO2 (insufficient) = Na2SO3 + H2ONaOH + SO2 (excess) = NaHSO3 (the generated Na2SO3 and water react with excess SO2 to form NaHSO3) 2NaOH + 3NO2 = 2NaNO3 + NO + H2O
5. Reaction of sodium hydroxide solution and aluminum: 2Al + 2NaOH + 2H2O = 2Na [Al(OH)4] + 3H2↑ (Moreover, the reaction that occurs when NaOH is insufficient is 2Al + 6H2O = (NaOH) = 2Al(OH )3↓+ 3H2↑)
6. A strong alkali can be used to prepare a weak alkali: NaOH + NH4Cl = NaCl + NH3·H2O
7. Can react with certain salts: 2NaOH + CuSO4 = Cu(OH)2↓+ Na2SO42NaOH + MgCl2 = 2NaCl + Mg(OH)2↓ (Laboratory test OH-)
8. NaOH is highly corrosive and can destroy the structure of proteins.
9. NaOH can absorb carbon dioxide. The reaction process is as follows: 2NaOH + CO2 = Na2CO3 + H2O (a small amount of CO2) NaOH + CO2 = NaHCO3 (excess CO2)
10. NaOH can react with silica, SiO2+ 2NaOH = Na2SiO3 + H2O (Because Na2SiO3 is the main component of glass glue, if a glass stopper is used to hold sodium hydroxide in a glass bottle, the stopper will adhere to the bottle body, making it difficult to Open, so generally when glass bottles contain sodium hydroxide, rubber stoppers should be used)
11. Can react with indicators. “Alkali properties” will turn red when exposed to colorless phenolphthalein (too concentrated sodium hydroxide will also cause phenolphthalein to fade), and turn blue when exposed to purple litmus test solution.
12. It is easy to deliquesce when placed in the air, and absorbs CO2 in the air and deteriorates. Therefore, it should be placed in a dry environment and can also be used to dry gas. 【Notes】Pack tightly and store in a cool, dry place. Separate storage and transportation of acids and flammable materials. In case of skin (eye) contact, rinse with plenty of running water. If it is skin, apply boric acid afterwards. If swallowed by mistake, rinse mouth with water, drink milk or egg white. Fire-fighting measures: water, sand. Some vendors in the market use industrial sodium hydroxide when processing frozen shrimps, which is not allowed. Impurity removal is neutral. CO2 mixed in alkaline gas can be removed by the following reaction: CO2+2NaOH=Na2CO3+H2O. Calcium hydroxide is a slightly soluble substance and cannot absorb more CO2 under the same conditions, so NaOH is generally used for absorption. To prove CO2, calcium hydroxide is used.
Post time: Sep-02-2024
