Molecular formula: HNO?
Chemical properties: it is a strong oxidizing and corrosive inorganic acid, and the anhydride is nitrogen pentoxide. Nitric acid is less acidic than sulfuric acid and hydrochloric acid (PKa=- 1.3) and completely ionized in water.
Physical properties: easily soluble in water, its dilute solution is colorless and transparent at room temperature, and its concentrated solution is brown.
Note: Nitric acid is unstable and easily decomposed by light. It should be stored in a brown bottle, protected from light, and it is forbidden to contact with reducing agent.
Uses: Nitric acid is mainly produced by ammonia oxidation in industry, which is used to make fertilizers, explosives, nitrates, etc. In organic chemistry, the mixture of concentrated nitric acid and concentrated sulfuric acid is an important nitration reagent.
Glass cleaner
Glass cleaning agent is used to clean the oil stain on the glass surface. Its main component is surfactant, which is slightly alkaline or neutral.
There are both hydrophilic polar groups and lipophilic nonpolar groups in the molecules of glass cleaner. When a small amount is added, the surface tension and liquid interfacial tension of solvent (usually water) can be greatly reduced, and it has the functions of lubrication, solubilization, emulsification, dispersion and washing.
Glass cleaner is widely used in cleaning of family life and industrial production.
sodium hydroxide
Chemical molecular formula: NaOH
Commonly known as caustic soda, caustic soda and caustic soda, it is called Costa in Hong Kong because there is another name, caustic soda. White crystal at room temperature, with strong corrosiveness. 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.
dichloromethane
Score: dichloromethane.
Colorless transparent volatile liquid. It has a pungent smell similar to ether.
Molecular weight 84.94
Boiling point: 39.8℃
The vapor pressure is 30.55 kPa (10℃).
Melting point -95. 1℃
Relative density 1.3266(20/4℃)
Water-soluble 20g/L (20? c)
The autoignition point is 640℃.
Viscosity (20℃) 0.43 MPa sec
Refractive index nD(20℃) 1.4244.
The critical temperature is 237 DEG C,
The critical pressure is 6.0795 MPa.
The solubility is about 50 times that of water, and it is soluble in phenol, aldehyde, ketone, glacial acetic acid, triethyl phosphate, ethyl acetoacetate and cyclohexylamine. It is miscible with other chlorinated hydrocarbon solvents, such as ethanol, ether and N, N- dimethylformamide.
After pyrolysis, HCl and trace phosgene are produced, which are heated with water for a long time to produce formaldehyde and HCl. Further chlorination can produce CHCl3 and CCl4. Colorless volatile liquid. Hard to burn. Steam and air form an explosive mixture with an explosion limit of 6.2% ~ 15.0% (by volume). Dichloromethane reacts with sodium hydroxide to form formaldehyde. In industry, dichloromethane is produced by the reaction of natural gas and chlorine, and purified by rectification.
Non-flammable low-boiling solvents are often used to replace flammable petroleum ether and ether, and can be used as dental local anesthetics, refrigerants and fire extinguishing agents.
Pure ammonia water
Molecular formula: NH3·H2O
Molecular weight: 35.045
Description: Colorless and transparent liquid with strong pungent smell.
Melting point: -78℃
Steam pressure: 1.59 kPa (20 degrees Celsius)
Steam density: (air = 1) 0.6
Solubility in water: completely miscible.
Specific gravity: (water = 1) 0.9
Relative density: The more ammonia content, the smaller the density. The relative density of 28% ammonia water is 0.9 1, and that of 35% ammonia water is 0.88.
Ionization constant: K= 1.8× 10ˇ-5(25℃)
Stability: easy to decompose when heated or exposed to light.
Others: easily volatilize ammonia. Concentrated ammonia can irritate respiratory tract and skin, and can damage central nervous system. It is weakly alkaline.
hairiness
Ammonia is volatilized from ammonia water, and the volatilization rate increases with the increase of temperature and storage time, and the volatilization amount increases with the increase of concentration.
corrosivity
Ammonia water has a certain corrosive effect, and the corrosion of carbonized ammonia water is more serious. Copper is corrosive, steel is poor, and cement is not corrosive. It also has a certain corrosive effect on wood.
alkalescence
The following chemical equilibria exist in ammonia water:
NH3+H2O= (reversible) = NH3 H2O
NH3 H2O = (reversible) =NH4+ +OH-
Therefore, only a small part of ammonia molecules react with water to generate ammonium ion NH4+ and hydroxyl ion OH-, so it is weakly alkaline.
Ammonia has the commonness of alkali:
① It can make colorless phenolphthalein test solution turn red, purple litmus test solution turn blue and wet red litmus test paper turn blue. This method is often used to test the presence of NH3 in the laboratory.
② It can react with acid to generate ammonium salt. When concentrated ammonia meets volatile acids (such as concentrated hydrochloric acid and concentrated nitric acid), it will produce white smoke.
NH3+HCl=NH4Cl (white smoke)
NH3+HNO3=NH4NO3 (white smoke)
But in the case of non-volatile acids (such as sulfuric acid and phosphoric acid), this phenomenon does not exist. This method can be used to test the presence of NH3 or ammonia in the laboratory.
In industry, the weak alkalinity of ammonia water is used to absorb the tail gas of sulfuric acid industry to prevent environmental pollution.
SO2+2 NH3·H2O =(NH4)2so 3+H2O
(NH4)2SO3+SO2+H2O=2NH4HSO3
reductant
Common reducing agents mainly include:
Hydrogen (H2), carbon (carbon), carbon monoxide (carbon monoxide)
Active metal elements, such as sodium, aluminum, zinc, iron, etc. Some nonmetallic elements, such as H2, carbon, silicon, etc. Oxides of elements (such as C, S, etc.). ) low price, such as CO, SO2, etc. Elemental acids (such as chlorine, sulfur, etc.). ) low price, such as HCl and H2S. Elements (such as iron, sulfur, etc.
In the redox reaction with valence, the substance with valence from low to high is called reducing agent, which can be used as antioxidant, reducing and being oxidized, and its product is called oxidation product.
Reducing agent is a relative concept, because the same substance may show the characteristics of reducing agent or oxidant with different reaction substances.
For example, SO2 is the reducing agent in the reaction of SO2+2HNO3→H2SO4+2H2O+NO2. But in H2S+SO2→S+H2O, SO2 is the oxidant.
Cleaning agent (household)
The main components are sodium bicarbonate (industrial baking soda), surfactant, a small amount of white mud for adsorption, fine sand for friction, and a small amount of alkali for decontamination, which is corrosive. Many bags are added with friction agent (fine sand/silica), which is why it can make the items look clean after use, but it will cause tiny scratches on the surfaces of the items.
Many unscrupulous restaurants marinate beef and pork with decontamination powder. One is to make shredded pork swell and taste, and the other is to make the meat tender and increase the good taste. Some people put some decontamination powder (cooking powder) when cooking vegetables to keep the water fresh and green.
active agent
Active agent; activate
(1) activator is one of the regulators in flotation reagents. It is used to eliminate the influence of inhibitors by changing the chemical composition of mineral surface, making it easy to adsorb collectors. Such as ethylenediamine phosphate, propylene diamine phosphate, xylene, sodium fluorosilicate, ammonium sulfate, ammonium chloride, ferrous sulfate, ammonium hydroxide, etc.
(2) It consists of PdCl2 2H2O, complexing agent and stabilizer. Low palladium content, low acidity and good stability. The working temperature is 15 ~ 32℃ and the soaking time is 3 ~ 7min. Used for pretreatment of electroless copper plating system for printed boards.
(3) refers to the substance that can increase the activity of accelerator after mixing rubber, thus reducing the dosage of accelerator or shortening the vulcanization time. Sometimes called a promoter. Adding a small amount of active agent can greatly improve the vulcanization degree and heat resistance of vulcanized rubber. Active agents are divided into inorganic and organic. Inorganic active agents are mainly metal oxides, among which zinc oxide and active zinc oxide are the most important. The organic active agent is represented by stearic acid. When the amount of fatty acid is large, the vulcanization speed will be reduced, but vulcanization will be sufficient, and a cross-linked structure with good heat resistance will be obtained.
resin
1. Unique fragrance in pine forest.
2. Another name for turpentine.
3. Refers to the substance after distillation of turpentine. Solid, transparent, insoluble in water, hard and brittle, light yellow or brown. It is an industrial raw material for making paint, soap, paper, matches, etc.
4. Rosin is an oil flowing from the trunk of pine trees, which melts into water at high temperature and becomes a massive solid after drying (no fixed melting point). Its color is reddish brown and it is an important chemical raw material. In daily life, it is mainly used as flux for soldering circuit boards. In musical instruments, rosin is coated on the bow hairs of bowstring instruments such as erhu, violin and Ma Touqin to increase the friction between the bow hairs and chords.
Physical properties: Rosin is a light yellow to yellowish red transparent solid with softening point of 70 ~ 90℃, specific gravity of 1.070 ~ 1.085, heat of solution of 15.8 kcal/kg, heat capacity of 0.54 kcal/kg℃ and thermal conductivity of 0.65435. Rosin also has crystallization characteristics, easy to crystallize, and easy to crystallize in organic solvents such as acetone. The critical crystallization temperature is about 100℃, and the melting point of crystalline rosin is 1 10 ~ 135℃, so it is difficult to saponify. In addition, rosin also has optical rotation, and the specific rotation value of rosin is controlled between 0 ~ 15 (the best point is +7), that is, rosin with no crystallization phenomenon and the lowest crystallization trend.
Rosin is an important chemical raw material, which is widely used in various industrial sectors. Its main uses are as follows:
1. Soap-making industrial rosin is boiled with soda ash or caustic soda to form rosin soap. Rosin soap has strong detergency, soluble in water, soluble in oil and easy to foam. Rosin is sticky, which makes soap not easy to crack and rancid.
2. Paper industry Rosin is used as a paper-making compound in the paper industry. Rosin and caustic soda are made into rosin sodium soap, which is the sizing agent. The sizing agent is mixed with paper pulp, and alum is added to make rosin become water-insoluble free resin acid particles attached to fine fibers. When the pulp is heated by rolling on the dryer, rosin softens and fills between fibers. This effect is called sizing or sizing. After sizing paper, it can enhance water resistance, prevent ink penetration, improve strength and smoothness, and reduce flexibility.
3. Rosin in paint and coating industry is easy to dissolve in various organic solvents, and it is easy to form a film with luster, which is one of the basic raw materials for paint and coating. The role of rosin in paint is to make the paint bright, dry quickly, and the paint film is smooth and not easy to fall off.
4. Ink industry Rosin is mainly used as a color carrier in printing ink to enhance the adhesion of ink to paper. If rosin is not used in the ink, the printed ink will be dim and fuzzy.
5. Adhesives Industrial adhesives based on rosin esters and hydrogenated rosin esters are often used as hot-melt adhesives, pressure-sensitive adhesives and rubber tackifiers.
6. Rubber industry Rosin is used as a softener in rubber industry, which can increase its elasticity. Disproportionated rosin potassium soap can be synthesized.
7. In the food industry, hydrogenated rosin glyceride, natural rubber, wax, vinyl acetate, etc. It is heated and melted together, and then added with spices, sugar and pigment to make chewing gum. When slaughtering pigs, cattle and sheep in slaughterhouses, the hairs left on the animals' bodies and heads can be removed by depilatory consisting of 88-94% molten rosin and 6- 12% cottonseed oil.
8. Insulating oil made of 35% rosin and 65% bright oil in electrical industry is used as protective film on cables, which plays the role of insulation and heat resistance. Rosin is mixed with phenolic resin and other artificial resins to make insulating paint.
9. Building materials industry Rosin is mainly used as a foaming agent for concrete and a binder for floor tiles in building materials industry. Rosin is also used as an adhesive for vinyl chloride asbestos tiles. Rosin can be mixed with linseed oil, calcium carbonate, charcoal and pigment to make carpet tiles.
abrasive powder
Polishing powder is usually composed of cerium oxide, aluminum oxide, silicon oxide, iron oxide, zirconium oxide, chromium oxide and other components. Different materials have different hardness and chemical properties in water, so they are used in different occasions. The Mohs hardness of alumina and chromium oxide is 9, that of cerium oxide and zirconium oxide is 7, and that of iron oxide is even lower. Cerium oxide and silicate glass have high chemical activity and similar hardness, so they are widely used in glass polishing.
In order to improve the polishing speed of cerium oxide, fluorine is usually added to cerium oxide polishing powder to improve the polishing speed. Mixed rare earth polishing powder with low cerium content is usually doped with 3-8 fluorine; Pure cerium oxide polishing powder is usually not doped with fluorine.
For ZF or F series glass, fluorine-free polishing powder is better because of its low hardness and high fluorine content in the material itself.
Insect movies
Lac is a thermosetting natural resin, which is formed by concentrating and drying the exudate produced by lac insects sucking and digesting sap on lac trees. Boil shellac in water to remove some colored substances, and the yellow-brown sheet is shellac. The chemical composition of shellac is complex, and the main components are some resinous substances in the mixture of hydroxycarboxylic lactone and lactide, and the average relative molecular weight is about 1000. The main components of alkaline hydrolysate are 9, 10, 16- trihydroxyhexadecanoic acid and tricyclic sesquiterpene acid, in addition to other long-chain hydroxyl fatty acids such as hexahydroxytetradecanoic acid.
The worm membrane is insoluble in water and acid at room temperature, but soluble in organic solvents such as alcohol (125℃ heating for 2.5 hours, insoluble in alcohol). It can be dried quickly, producing glossy and durable films, showing high adhesion, firmness and elasticity to various surfaces. So it is waterproof, moisture-proof, rust-proof, corrosion-proof, and protects articles. Can resist ultraviolet rays.
A good film with high adhesion can be formed in alkaline solution.
Resistant to hydrocarbon solvents such as gasoline. , and has oil resistance.
It is a non-conductor with low heat and small expansion coefficient, and it is a good insulator.
Appearance: light yellow fragments
Product features:
Insect-proof film has excellent characteristics such as moisture-proof, rust-proof, anti-corrosion, oil resistance, acid resistance, strong adhesion, good insulation and stable chemical properties. Used as coating agent, insulating paint, plastic film packaging adhesive and metal-to-metal (or glass, bakelite)/mold/food preservative, etc.