Possibly. Sulfuric acid is an inorganic compound with the chemical formula H2SO4 and is the most important oxygen-containing acid of sulfur. Pure sulfuric acid is a colorless oily liquid that crystallizes at 10.36°C. Its aqueous solutions of various concentrations are usually used and are produced by the tower method and the contact method. The former yields crude dilute sulfuric acid, with a mass fraction of generally around 75%; the latter yields concentrated sulfuric acid with a mass fraction of 98.3%, with a boiling point of 338°C and a relative density of 1.84.
Sulfuric acid is the most active binary inorganic strong acid and can react with most metals. High-concentration sulfuric acid has strong water absorption and can be used as a dehydrating agent to carbonize carbohydrate-containing substances such as wood, paper, cotton and linen fabrics, and biological skins. When mixed with water, it also releases a large amount of heat energy. It is highly corrosive and oxidizing, so use it with caution. It is an important industrial raw material that can be used to make fertilizers, drugs, explosives, pigments, detergents, batteries, etc. It is also widely used in industries such as petroleum purification, metal smelting, and dyes. It is commonly used as a chemical reagent and can be used as a dehydrating agent and sulfonating agent in organic synthesis.
Chinese name
Sulfuric acid
Foreign name
Sulfuric acid
Chemical formula
H2SO4
Molecular weight
98.078
CAS registration number
7664-93-9
Discovery history
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In ancient China, dilute sulfuric acid was called "green vitriol oil". From 650 to 683 AD (during the reign of Emperor Gaozong of the Tang Dynasty), the alchemist Gu Gangzi recorded the "method of refining stone gallbladder to extract the essence" in Volume 9 of his book "Yellow Emperor Jiuding Shendan Jingjue", that is, dry distillation of stone gallbladder (gall alum). ) to obtain sulfuric acid.
Sulfuric acid was discovered in the 8th century AD. The Arab alchemist Jabir obtained sulfuric acid by distilling ferrous sulfate crystals. Some early people who studied chemistry, such as Razi, Jabir, etc., also wrote a classification list of sulfuric acid and related minerals; others, such as physician Ibn Sina, paid more attention to the types of sulfuric acid. and their value in medicine. [1]
In the 17th century, the German chemist Johann Rudolf Glauber heated the mixed steam of sulfur and potassium nitrate to produce sulfuric acid. In the process, the potassium nitrate decomposed and oxidized the sulfur to make it Becomes sulfur trioxide (SO3) which can mix with water and become sulfuric acid. Therefore, in 1736, London pharmacist Joshua Ward used this method to develop large-scale sulfuric acid production.
In 1746, John Roebuck used this principle to create the lead chamber method to efficiently produce sulfuric acid in large quantities at a lower cost. After many improvements, this method has been used in industry for nearly two centuries. [2] This method of producing sulfuric acid created by John Roebuck can produce sulfuric acid with a concentration of 65%. Later, French chemist Joseph Louis Gay-Lussac and British chemist John Glover improved it so that it could Sulfuric acid with a concentration as high as 78% is produced, but this concentration is still not sufficient for some industrial purposes.
In the early 18th century, the production of sulfuric acid relied on the following method: metal sulfide ores were burned into low-valent sulfates, which could be decomposed into corresponding metal hydroxides and gaseous sulfates at a certain temperature. sulfur oxides, which are then used to produce sulfuric acid. Unfortunately, the huge cost of this process has hindered the widespread use of concentrated sulfuric acid. [2] An early diagram of the sulfuric acid molecule drawn by John Dalton in 1808 showed that sulfuric acid had a central sulfur atom bonded to three oxygen atoms, as shown on the right.
Early sulfuric acid molecular diagram drawn by John Dalton in 1808
Later, in 1831, British vinegar merchant Peregrine Phillips thought of the contact method, which could produce it at a lower cost Sulfur trioxide and sulfuric acid are produced. This method is widely used today.
Existence
Earth
Acid rain contains sulfuric acid. Sulfur dioxide (SO2) in acid rain reacts with water in the atmosphere to generate sulfurous acid (H2SO3). Sulfurous acid is oxidized by oxygen in the atmosphere to form sulfuric acid, which falls to the ground with rain, causing the formation of acidic soil. Acidic soils are usually neutralized with alkaline substances.
In nature, many sulfur-containing minerals, such as ferrous sulfide, form sulfuric acid after oxidation reactions. The resulting liquid is highly acidic and can oxidize remaining metals and release toxic gases. In the biological world, there is a species of sea slug (Notaspidean pleurobranchs) that can also spray sulfuric acid-containing secretions to defend itself against enemies.
Venus
Sulfuric acid can be found in the upper atmosphere of Venus. This is mainly due to the photochemical effect of the sun on sulfur dioxide, carbon dioxide and water. Ultraviolet photons with wavelengths shorter than 160nm can photolyze carbon dioxide into carbon monoxide and atomic oxygen. Atomic oxygen is very reactive and reacts with sulfur dioxide to become sulfur trioxide. Sulfur trioxide further reacts with water to release sulfuric acid. Sulfuric acid is liquid in the higher and cooler areas of Venus' atmosphere. This thick layer of sulfuric acid clouds about 45 to 70 kilometers away from the planet's surface covers the entire planet's surface. This atmosphere is constantly releasing acid rain.
In Venus, sulfuric acid is formed in a continuous cycle. As sulfuric acid evaporates as it falls from higher, cooler regions of the atmosphere to lower, warmer regions, its water content becomes less and less and its concentration becomes higher and higher. When the temperature reaches 300°C, sulfuric acid begins to decompose into sulfur trioxide and water, and the products are all gases. Sulfur trioxide is very active and decomposes into sulfur dioxide and atomic oxygen. The atomic oxygen then oxidizes carbon monoxide and turns it into carbon dioxide. The sulfur dioxide and water will rise from the middle to the upper atmosphere. They will react to release sulfuric acid again, and the whole process starts again. cycle.
Europa
Images from the Galileo spacecraft show that sulfuric acid may also appear on one of Jupiter's moons, Europa, but details remain Controversial. [3]
Regulatory information
Sulfuric acid (Precursor-3), this product is subject to public security regulations according to the "Regulations on the Safety Management of Hazardous Chemicals" and the "Regulations on the Management of Precursor Chemicals" Sectoral control. [6]
Physical Properties
Pure sulfuric acid is generally a colorless oily liquid with a density of 1.84 g/cm3 and a boiling point of 337°C. It can be miscible with water in any proportion and simultaneously releases a large amount of Heat, making water boil. When heated to 290°C, sulfur trioxide begins to be released, and eventually it becomes a 98.54% aqueous solution, which boils at 317°C to become a boiling mixture. The boiling point and viscosity of sulfuric acid are higher because of the stronger hydrogen bonds within its molecules. Due to its high dielectric constant, sulfuric acid is a good solvent for electrolytes and less ideal as a solvent for non-electrolytes. The melting point of sulfuric acid is 10.371°C. Adding water or sulfur trioxide will lower the freezing point.
The structural formula and bond length of sulfuric acid
The difference in concentration
Although concentrated and pure sulfuric acid can be produced, it is infinitely stable at room temperature (the so-called decomposition The reaction to form an azeotrope occurs at high temperatures close to the boiling point), but the freezing point of pure sulfuric acid is too high (283.4K), so in order to facilitate transportation, it is usually made into 98% sulfuric acid, so the so-called "high-concentration sulfuric acid" refers to It is 98% sulfuric acid. In addition, sulfuric acid has different applications at different concentrations. The following are some common concentration levels:
Ball and stick model of sulfuric acid molecules
H2SO4 specific gravity
Corresponding density (kg/L)
Concentration (mol/L)
Commonly known as
10%
1.07
< p>~1Dilute sulfuric acid
29～32%
1.25～1.28
4.2～5
Lead-acid battery acid
62～70%
1.52～1.60
9.6～11.5
Room acid, fertilizer acid
p>Expand all
Sulfuric acid can also be made into other forms. For example, fuming sulfuric acid can be made by passing high-concentration SO3 into sulfuric acid. Regarding the concentration of oleum, people usually use the percentage of SO3 or the percentage of H2SO4 as the standard. Both can be used. The concentration of "oleum" as it is generally called is 45% (containing 109% H2SO4) or 65% (containing 114.6% H2SO4). When the ratio of SO3 to H2SO4 is 1:1, the product is pyrosulfuric acid (H2S2O7), which is solid with a melting point of 36°C.
Polarity and Conductivity
Pure sulfuric acid is a very polar liquid with a dielectric coefficient of approximately 100. Because its molecules can protonate each other, resulting in its extremely high conductivity, this process is called proton self-migration. The process that occurs is:
Chemical properties
Corrosivity
Pure sulfuric acid is heated to 290°C to decompose and release part of the sulfur trioxide until the acid concentration drops to 98.3 %, then sulfuric acid is a constant boiling solution with a boiling point of 338°C. The acidity of anhydrous sulfuric acid is the ability to donate protons. Pure sulfuric acid is still very acidic. There is basically no difference in acidity between 98% sulfuric acid and pure sulfuric acid. The fuming sulfuric acid that dissolves sulfur trioxide is a superacid system. It is more acidic than pure sulfuric acid, but there is a widespread misconception that dilute sulfuric acid is more acidic than concentrated sulfuric acid. This idea is wrong. Indeed, dilute sulfuric acid is completely ionized in the first step, producing a large amount of hydronium ions H3O+; but concentrated sulfuric acid, like water, self-ionizes itself to produce a part of sulfate hydrogen ions H3SO4+. It is this part of sulfate protons that causes pure sulfuric acid to have Very strong acidity, although less, is much more acidic than hydrated protons, so the Hammett acidity function of pure sulfuric acid is as high as -12.0.
In the sulfuric acid solvent system, H3SO4+ often acts as an acid and can protonate many substances to produce ionic compounds:
Produced by the above reaction with HNO3
< p>, contributes to the nitration reaction of aromatic hydrocarbons.Characteristics of concentrated sulfuric acid
1. Dehydration
Dehydration refers to the removal of non-free water molecules by concentrated sulfuric acid or the removal of organic matter according to the composition ratio of hydrogen and oxygen atoms in water. The process of hydrogen and oxygen elements. As far as sulfuric acid is concerned, dehydration is a property of concentrated sulfuric acid, not dilute sulfuric acid. Concentrated sulfuric acid is dehydrating and has strong dehydration properties. During dehydration, it is removed according to the composition ratio of water. The process of dehydration of substances by concentrated sulfuric acid is a chemical change. During the reaction, concentrated sulfuric acid takes away the hydrogen atoms and oxygen atoms in the dehydrated product or removes non-free crystal water according to the ratio of the number of hydrogen and oxygen atoms in the water molecules (2:1). , such as copper sulfate pentahydrate (CuSO4·5H2O). The substances that can be dehydrated by concentrated sulfuric acid are generally organic substances containing hydrogen and oxygen elements. Among them, organic substances in sucrose, sawdust, paper scraps, cotton and other substances are dehydrated to form black carbon. This process is called carbonization. A typical carbonization phenomenon is the brown bread reaction of sucrose. Put 20g sucrose in a 200mL beaker, add a few drops of water, add an appropriate amount of water, and stir evenly. Then add 15 mL of concentrated sulfuric acid with a mass fraction of 98% and stir quickly. Observe experimental phenomena. You can see that the sucrose gradually turns black, expands in volume, and forms a loose and porous sponge-like charcoal. The reaction releases heat, and you can smell irritating gases.
Concentrated sulfuric acid quickly eats through the towel
Simultaneous reaction between carbon and concentrated sulfuric acid:
2. Strong oxidizing property
Reduction product< /p>
Concentrated sulfuric acid may be reduced to SO2, S or H2S depending on the amount and type of reducing agent: [4]
For example, when the reducing agent is excessive, HBr, H2S and HI respectively Reduction of concentrated sulfuric acid into different substances: [4]
When the reducing dose is different, the products may also be different: [4]
Related reactions
( 1) Reaction with metals
① Concentrated sulfuric acid can passivate iron, aluminum and other metals at room temperature. ② When heated, concentrated sulfuric acid can react with all metals (including gold and platinum) except iridium and ruthenium to generate high-valent metal sulfates, which themselves are reduced to SO2, S, H2S or metal sulfides.
In the above reaction, sulfuric acid shows strong oxidizing and acidic properties.
(2) Reaction with non-metals
Hot concentrated sulfuric acid can oxidize carbon, sulfur, phosphorus and other non-metallic elements to their high valence oxides or oxygen-containing acids, which themselves is reduced to sulfur dioxide. In this type of reaction, concentrated sulfuric acid only exhibits oxidative properties.
[5]
(3) Reaction with other reducing substances
Concentrated sulfuric acid has strong oxidizing properties, and hydrogen sulfide and hydrogen bromide are prepared in the laboratory Reducing gases such as hydrogen iodide and hydrogen iodide cannot be dried with concentrated sulfuric acid.
Characteristics of dilute sulfuric acid
Properties
1. Can react with most metals (more active than copper) and most metal oxides to generate corresponding sulfates and water;
2. Can react with salts containing acid ions that are weaker than sulfate ions to generate corresponding sulfates and weak acids;
3. Can react with alkali The reaction generates the corresponding sulfate and water;
4. It can react with pre-hydrogen metals under certain conditions to generate the corresponding sulfate and hydrogen;
5. It can react under heating conditions Catalyzes the hydrolysis of proteins, disaccharides and polysaccharides;
6. It can react with indicators to turn purple litmus test solution red and colorless phenolphthalein test solution not to change color.
Test
Drugs required: barium chloride solution acidified with hydrochloric acid, magnesium powder.
Test method: Use barium chloride (BaCl2) acidified with hydrochloric acid (HCl). Add a few drops of barium chloride solution that has been acidified with hydrochloric acid into the solution to be tested and shake. If a white precipitate is produced; flammable gas is generated after adding magnesium powder to the solution, then the solution to be tested contains sulfuric acid. But this method is limited to the middle school level.
Common misunderstandings
In middle school, dilute sulfuric acid is generally regarded as
completely ionized twice, but this is not the case. According to the acidity coefficient of sulfuric acid pKa1=-3.00, pKa2=1.99, its secondary ionization is not sufficient. In dilute sulfuric acid, HSO4-=reversible=H++SO42- is not completely ionized. The first-level ionization of 1mol/L sulfuric acid is complete. Secondary ionization is about 1% ionization, which means there is still a large amount of HSO4- in the solution. Even when the NaHSO4 solution is 0.1 mol/L, the hydrogen sulfate is only ionized by about 30%.
Application fields
Industrial uses
Metallurgy and petroleum industry
Used in metallurgical industry and metal processing in the metallurgical industry sector, especially The production process of non-ferrous metals requires the use of sulfuric acid. For example, when refining copper, zinc, cadmium, and nickel by electrolysis, the electrolyte requires the use of sulfuric acid. The refining of certain precious metals also requires sulfuric acid to dissolve and remove other metals. Before cold rolling, cold drawing and stamping processing in the steel industry, the iron oxide on the steel surface must be removed with sulfuric acid. Rolled sheets, cold-drawn seamless steel pipes and other steel products with higher quality requirements must be washed with sulfuric acid every time they are rolled. In addition, seamed steel pipes, thin iron sheets, iron wires, etc. must be pickled with sulfuric acid before being galvanized. In some metal machining processes, such as nickel plating, chromium plating and other metal parts, sulfuric acid is also needed to clean the surface rust. In the ferrous metallurgical enterprise sector, the steel that needs to be pickled generally accounts for about 5% to 6% of the total steel production, and the pickling of each ton of steel consumes about 98% of 30 to 50kg of sulfuric acid.
In the production process of petroleum products such as gasoline and lubricants in the petroleum industry, concentrated sulfuric acid refining is required to remove sulfur-containing compounds and unsaturated hydrocarbons. Each ton of crude oil refining requires about 24kg of sulfuric acid, and each ton of diesel refining requires about 31kg of sulfuric acid. The preparation of activated clay used in the petroleum industry also consumes a lot of sulfuric acid.
In concentrated nitric acid, concentrated sulfuric acid is used as the dehydrating agent; in the chlor-alkali industry, concentrated sulfuric acid is used to dry chlorine, hydrogen chloride, etc.; in the inorganic salt industry, such as cryolite, borax, trisodium phosphate, and phosphoric acid Sulfuric acid is used in the preparation of disodium hydrogen sulfate, lead sulfate, zinc sulfate, copper sulfate, ferrous sulfate and other sulfates. The preparation of many inorganic acids such as phosphoric acid, boric acid, chromic acid (sometimes also referred to as CrO3), hydrofluoric acid, and chlorosulfonic acid; the preparation of organic acids such as oxalic acid, acetic acid, etc. also often requires sulfuric acid as raw material. In addition, the coking chemical industry (using sulfuric acid to react with ammonia in coke oven gas to produce ammonium sulfate as a by-product), electroplating industry, tanning industry, pigment industry, rubber industry, paper industry, paint industry (preparation of organic solvents), and industrial explosives and lead-acid battery manufacturing, etc., all consume considerable amounts of sulfuric acid.
Can be used as hard water softener, ion exchange regenerant, pH adjuster, oxidant and detergent. It can also be used in the manufacture of chemical fertilizers, pesticides, dyes, pigments, plastics, chemical fibers, explosives and various sulfates. It is widely used in petroleum refining, non-ferrous metal smelting, steel pickling, tanning process, coking industry, light textile industry, and national defense industry. Strong acidic cleaning corrosive agent. It is mainly used for silicon wafer cleaning in the integrated circuit manufacturing process.
Solving people's basic necessities of life
The viscose yarn used in the production of chemical fibers, which is familiar to the people, requires the use of a mixture of sulfuric acid, zinc sulfate, and sodium sulfate as viscose spinning of coagulation bath. For every 1 ton of viscose fiber produced, 1.2 to 1.5 tons of sulfuric acid are consumed; for every 1 ton of vinylon short fiber produced, 230kg of 98% sulfuric acid is consumed; for every 1 ton of capron monomer produced, 1.6 tons of 20% oleum are consumed. In addition, a considerable amount of sulfuric acid is also used in the production of chemical fibers such as nylon, acetate fiber, and polyacrylonitrile fiber.
Used to produce polymer compounds other than chemical fibers to produce plastics and other polymer compounds, it plays an increasingly important role in the national economy. For every 1 ton of epoxy resin produced, 2.68 tons of sulfuric acid are needed. For every 1 ton of polytetrafluoroethylene, known as the "King of Plastics," 1.32 tons of sulfuric acid is used; for the production of silicone gum, silicone oil, styrene-butadiene rubber and nitrile-butadiene rubber, etc. , also use sulfuric acid.
There is almost no dye (or its intermediate) used in the dye industry that can be prepared without the use of sulfuric acid. The preparation of azo dye intermediates requires a sulfonation reaction, and the preparation of aniline dye intermediates requires a nitration reaction, both of which require the use of large amounts of concentrated sulfuric acid or fuming sulfuric acid. Therefore, some dye factories have sulfuric acid workshops to meet needs.
Oleum and concentrated sulfuric acid are needed to produce synthetic detergents for daily necessities. Plasticizers for plastics (such as phthalic anhydride and phthalate esters) and nitrocellulose, the raw material for celluloid products, all require sulfuric acid to prepare. The manufacture of cellophane and parchment also requires the use of sulfuric acid. In addition, production sectors such as the textile printing and dyeing industry, enamel industry, hardware industry, soap industry, and artificial flavoring industry also need to use sulfuric acid.
Sulfuric acid is required for the sulfonation reaction in the preparation process of sulfonamide drugs in the pharmaceutical industry and the nitration reaction in the preparation process of the powerful fungicide nitrofurazone. In addition, the preparation of many antibiotics, commonly used drugs such as aspirin, caffeine, vitamin B2, vitamin B12 and vitamin C, certain hormones, isoniazid, mercury bromide, saccharin, etc., all do not require the use of sulfuric acid.
Consolidating national defense
The development of the sulfuric acid industry in some countries was once closely linked to the production of military explosives. Whether military explosives (propellants, explosives) or industrial explosives, most of them contain nitrates or nitrates as their main components. The main ones include nitrocellulose, trinitrotoluene (TNT), nitroglycerin, picric acid, etc. Although the preparation of these compounds relies on nitric acid, concentrated sulfuric acid or fuming sulfuric acid must also be used.
Atomic energy industry and rocket technology
Production of nuclear fuel for atomic reactors, preparation of titanium, aluminum and other alloy materials for reactors, and use in the manufacture of rockets, supersonic jet aircraft and artificial Titanium alloys, the material of satellites, are directly or indirectly related to sulfuric acid. The process of preparing borane from borax requires large amounts of sulfuric acid. Derivatives of borane are the most important high-energy fuels. Borane is also used as a raw material to prepare uranium borohydride to separate uranium-235. It can be seen that sulfuric acid is closely related to the defense industry and cutting-edge science and technology.
Agricultural uses
Soil improvement
In agricultural production, sulfuric acid is increasingly used to improve calcareous soil with high pH value. Over the past 20 years, the production of urea-sulfuric acid fertilizer has increased significantly and is widely applied to soils in the western states of the United States. Injecting sulfuric acid into dairy farm lakes and changing the pH of the lake water can solve several air and water quality problems caused by raising livestock in captivity. When sulfuric acid is applied to agricultural soil and water, its main function is to dissolve carbonates and bicarbonates of calcium and magnesium. . These calcium and magnesium salts then replace the exchangeable sodium salts, which are subsequently removed by leaching with water. When the carbonates and bicarbonates are broken down, the sulfuric acid reacts with more inert materials, releasing plant nutrients such as phosphorus and iron. Simply lowering the pH of the soil can cause changes in the solubility of many elements, increasing their effectiveness to plants. Applying sulfuric acid to calcareous soils with high pH results in stronger plants and increased harvests.
Chemical fertilizer production
Used in the production of fertilizers, ammonium sulfate (commonly known as ammonium sulfate or fertilizer powder) and superphosphate (commonly known as superphosphate lime or calcium superphosphate) are two types of fertilizers. A large amount of sulfuric acid is consumed.
Many pesticides used in the production of pesticides use sulfuric acid as raw materials. For example, copper sulfate and zinc sulfate can be used as plant fungicides, thallium sulfate can be used as rodenticide, and ferrous sulfate and copper sulfate can be used as removers. Herbicide.
The production of the most common pesticides, such as 1059 Emulsion (45%) and 1605 Emulsion (45%), requires the use of sulfuric acid.
Everyday Household Uses
Most acidic chemical drain supplies around the world contain concentrated sulfuric acid. This type of drainage supplies is the same as alkaline drainage supplies, which can dissolve oil stains and food residues clogged in the channels. However, since concentrated sulfuric acid will react with water in a highly exothermic manner, it is recommended to keep the channel as dry as possible before use, pour the relevant chemicals slowly, and wear gloves.
Toxicological properties
It is moderately toxic.
Acute toxicity: LD502140mg/kg (rat oral); LC50510mg/m3, 2 hours (rat inhalation); 320mg/m3, 2 hours (mouse inhalation)
Laboratory Risks
Sulfuric acid, especially in high concentrations, can be extremely damaging to skin and flesh. Just like other corrosive strong acids and alkalis, sulfuric acid can quickly undergo amide hydrolysis and ester hydrolysis with proteins and fats, thereby decomposing biological tissues and causing chemical burns. However, its strong corrosiveness to the flesh is also related to its strong dehydration, because sulfuric acid also reacts with carbohydrates in biological tissues to dehydrate and releases a large amount of heat energy. In addition to causing chemical burns, it can also cause second-degree flame burns. Therefore, the damage caused by sulfuric acid is often greater than that of other comparable strong acids (such as hydrochloric acid and nitric acid). If you accidentally let sulfuric acid come into contact with your eyes, it may cause permanent blindness; if you accidentally take it, it will cause irreversible damage to the organs in the body and even be fatal. Concentrated sulfuric acid is also highly oxidizing and will corrode most metals, so it needs to be stored with care.
A chicken foot was severely corroded and carbonized by concentrated sulfuric acid within tens of seconds.
As the concentration increases, the danger of sulfuric acid also increases. This is because in addition to the increasing proportion of acidic substances, their dehydration and oxidation properties are also increasing. When the sulfuric acid content of a solution is equal to or exceeds 1.5 M, a "corrosive" warning label should be affixed, and if the sulfuric acid content is between 0.5 and 1.5 M, it is "irritant." However, even the "low-concentration" sulfuric acid commonly used in laboratories (concentration of about 1 M, 10% specific gravity) will eat through the paper after a certain period of time.
Old textbooks believe that in order to prevent concentrated sulfuric acid from releasing a large amount of heat after contact with water and further damaging the skin, the concentrated sulfuric acid on the skin should be wiped off with a dry cloth before treatment. However, in actual operation, just like other corrosive substances, it is effective to immediately flush with large amounts of water for at least 10 to 15 minutes. Large amounts of water can quickly cool the damaged tissue and take away the heat. Since concentrated sulfuric acid will quickly char the skin when it comes into contact with it, wiping it with a dry cloth may scratch or even wipe off the damaged skin. If sulfuric acid accidentally splashes on protective clothing, take it off immediately and rinse the skin of the affected area thoroughly.
Since sulfuric acid dissolves in water and releases a lot of heat, when diluting concentrated sulfuric acid, the acid should be poured into the water instead of the water into the acid. This can take advantage of the high specific heat capacity of water and reduce the risk of high-temperature boiling. Risk of acid splash. Generally in the laboratory, diluting 6 M (about 35% specific gravity) or higher concentration of sulfuric acid is the most dangerous, because this amount of sulfuric acid can release enough heat to boil the entire solution when it reacts with water.
Acetonitrile is an organic compound with the chemical formula CH3CN or C2H3N[3]. It is a colorless and transparent liquid with excellent solvent properties. It can dissolve a variety of organic, inorganic and gaseous substances and mix with water. Alcohols are infinitely soluble in each other. Acetonitrile can undergo typical nitrile reactions and is used to prepare many typical nitrogen-containing compounds. It is an important organic intermediate.
Chinese name
Acetonitrile[5]
Foreign name
Acetonitrile[5]
Alias
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Methyl cyanide
Chemical formula
C2H3N[5]
Molecular weight
41.052[5]
Physical and chemical properties
Density: 0.786g/cm3
Melting point: -45℃
Boiling point: 81-82℃
Flash point: 12.8℃ (CC)
Refractive index: 1.344 (20℃)
Saturated vapor pressure: 13.33kPa (27℃)[5]
Critical temperature: 274.7℃[5]
Critical pressure: 4.83MPa[5]
Ignition temperature: 524℃[5]
Explosion limit (V /V): 16.0%[5]
Lower explosion limit (V/V): 3.0%[5]
Appearance: colorless transparent liquid.