Iron oxide is Fe2O3 (commonly known as iron red), iron oxide is a reddish-brown solid, and FeO (ferrous oxide) is a black solid.
Listen to chemistry lessons well, memorize formulas well, and be familiar with chemical experiment operations, properties of substances, etc.
The following is what I have summarized: summary of basic knowledge of junior high school chemistry and common formulas
1. Scientific name, common name and chemical formula of substances
⑴Diamond, graphite: C⑵Mercury, mercury: Hg (3) Quicklime, calcium oxide: CaO (4) Dry ice (solid carbon dioxide): CO2 ( 5) Hydrochloric acid, hydrochloric acid: HCl (6) Sulfurous acid: H2SO3 (7) Hydrogen sulfuric acid: H2S (8) Hydrated lime, slaked lime: Ca(OH)2 (9) Caustic soda, caustic soda, caustic soda: NaOH (10) Soda ash: Na2CO3 Sodium carbonate crystal, soda ash crystal: Na2CO3?10H2O (11) Sodium bicarbonate, acid sodium carbonate: NaHCO3 (also called baking soda) (12) Bile alum, blue vitriol, copper sulfate crystal: CuSO4?5H2O (13 ) Patina, Malachite: Cu2(OH)2CO3 (a substance that decomposes to form three oxides) (14) Methanol: CH3OH Toxic, blind, death (15) Alcohol, ethanol: C2H5OH (16) Acetic acid, acetic acid (16.6℃ ice Acetic acid) CH3COOH (CH3COO- acetate ion) has acidic properties (17) Ammonia gas: NH3 (alkaline gas) (18) Ammonia water, ammonia monohydrate: NH3?H2O (is a common base and has alkaline properties , is a base that does not contain metal ions) (19) Sodium nitrite: NaNO2 (industrial salt, toxic)
2. Color status of common substances
1. White solid: MgO, P2O5, CaO, NaOH, Ca(OH)2, KClO3, KCl, Na2CO3, NaCl, anhydrous CuSO4; iron and magnesium are silvery white (mercury is silvery white liquid)
2 , Black solid: graphite, carbon powder, iron powder, CuO, MnO2, Fe3O4▲KMnO4 is purple-black
3. Red solid: Cu, Fe2O3, HgO, red phosphorus ▲Sulfur: light yellow ▲ Cu2( OH)2CO3 is green
4. The color of the solution: the solution containing Cu2+ is blue; the solution containing Fe2+ is light green; the solution containing Fe3+ is brown, and the other solutions are generally not free. color. (Potassium permanganate solution is purple-red)
5. Precipitation (i.e., salts and alkali insoluble in water): ① Salt: white ↓: CaCO3, BaCO3 (soluble in acid) AgCl, BaSO4 (also Insoluble in dilute HNO3), etc. ②Alkali: blue ↓: Cu(OH)2 reddish brown ↓: Fe(OH)3 white ↓: other alkali.
6. (1) Gases with irritating gases: NH3, SO2, HCl (all colorless)
(2) Colorless and odorless gases: O2, H2, N2, CO2, CH4, CO (highly toxic)
▲Caution: Liquids with pungent odor: hydrochloric acid, nitric acid, acetic acid. Alcohol is a liquid with special gas.
7. Toxic, gas: CO Liquid: CH3OH Solid: NaNO2 CuSO4 (can be used as a bactericide, mixed with slaked lime to form a sky blue viscous substance - Bordeaux liquid)
< p>3. Solubility of substances1. Solubility of salt
Substances containing potassium, sodium, nitrate, and ammonium are all soluble in water
Among the compounds containing Cl, only AgCl is insoluble in water, and the others are soluble in water;
Among the compounds containing SO42-, only BaSO4 is insoluble in water, and the others are soluble in water.
Only K2CO3, Na2CO3, and (NH4) 2CO3 are soluble in water, and the others are insoluble in water.
2. Solubility of alkali
Alkali that are soluble in water include: barium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide and ammonia. Other alkali are insoluble in water. Among the poorly soluble alkali, Fe(OH)3 is a reddish brown precipitate, Cu(OH)2 is a blue precipitate, and other poorly soluble alkali are white.
(Including Fe (OH) 2) Note: AgCl and BaSO4 in the precipitate are insoluble in dilute nitric acid.
Other precipitates are soluble in acid. Such as: Mg(OH)2 CaCO3 BaCO3 Ag2 CO3, etc.
3. Most acids and acidic oxides can be dissolved in water. (Acidic oxide + water → acid) Most alkaline oxides are insoluble in water. Water can dissolve: barium oxide, potassium oxide, calcium oxide, sodium oxide (alkaline oxide + water → alkali)
IV. The best of chemistry
1. Earth’s crust The most abundant metallic element is aluminum. 2. The most abundant non-metallic element in the earth's crust is oxygen.
3. The most abundant substance in the air is nitrogen. 4. The hardest naturally occurring substance is diamond.
5. The simplest organic compound is methane. 6. The most mobile metal in the metal activity sequence is potassium.
7. The oxide with the smallest relative molecular mass is water. The simplest organic compound is CH4
8. The gas with the smallest density under the same conditions is hydrogen. 9. The most conductive metal is silver.
10. The atom with the smallest relative atomic mass is hydrogen. 11. The metal with the smallest melting point is mercury.
12. The most abundant element in the human body is oxygen. 13. The element that makes up the most types of compounds is carbon.
14. The most widely used metal in daily life is iron. 15. China was the first to use natural gas; China's largest coal base is in Shanxi Province; China was the first to use hydrometallurgy to smelt copper (discovered in the Western Han Dynasty [Liu An's "Huainan Wanbi Shu" "Zeng Qing gets iron and turns it into copper"] , applied in the Song Dynasty); the first person to discover electrons was Thomson of England; the first person to conclude that air is composed of N2 and O2 was Lavoisier of France.
5. "Three" in junior high school chemistry
1. The three types of particles that make up matter are molecules, atoms, and ions.
2. There are three commonly used reducing agents for reducing copper oxide: hydrogen, carbon monoxide, and carbon.
3. Hydrogen has three major advantages as a fuel: it is rich in resources, has high calorific value, and the product after combustion is water and does not pollute the environment. 4. There are generally three types of particles that make up atoms: protons, neutrons, and electrons. 5. There are only three types of ferrous metals: iron, manganese and chromium. 6. The elements that constitute matter can be divided into three categories: (1) metallic elements, (2) non-metallic elements, and (3) rare gas elements. 7. There are three types of iron oxides, and their chemical formulas are (1) FeO, (2) Fe2O3, and (3) Fe3O4.
8. There are three characteristics of a solution (1) homogeneity; (2) stability; (3) mixture.
9. Chemical equations have three meanings: (1) It expresses what substances participate in the reaction and what substances are produced as a result; (2) It expresses the ratio of the number of particles of molecules or atoms among reactants and products; (3) Indicates the mass ratio between reactants and products. Chemical equations have two principles: based on objective facts; and following the law of conservation of mass. 10. Pig iron is generally divided into three types: white iron, gray iron, and ductile iron.
11. Carbon steel can be divided into three types: high carbon steel, medium carbon steel, and low carbon steel.
12. There are three types of iron ores commonly used in ironmaking: (1) Hematite (main component is Fe2O3); (2) Magnetite (Fe3O4); (3) Siderite ( FeCO3). 13. There are three main equipments for steelmaking: converter, electric furnace and open hearth.
14. The three reaction conditions often related to temperature are ignition, heating, and high temperature.
15. There are two ways to change a saturated solution into an unsaturated solution: (1) raising the temperature, (2) adding a solvent; there are three ways to change an unsaturated solution into a saturated solution: cooling down, adding a solute, and evaporating the solvent at a constant temperature. (Note: Substances whose solubility decreases with temperature, such as: calcium hydroxide solution changes from a saturated solution to an unsaturated solution: cooling, adding solvent; there are three ways to change an unsaturated solution to a saturated solution: raising the temperature, adding solute, and evaporating the solvent at a constant temperature).
16. There are generally three methods for collecting gas: drainage method, upward emptying method, and downward emptying method.
17. The three main causes of water pollution: (1) waste residue, waste gas, and waste water in industrial production; (2) arbitrary discharge of domestic sewage; (3) pesticides and chemical fertilizers used in agricultural production It flows into the river with rainwater.
18. There are three commonly used fire extinguishers: foam fire extinguishers; dry powder fire extinguishers; liquid carbon dioxide fire extinguishers.
19. The solubility of solid substances changes with temperature can be divided into three categories: (1) The solubility of most solid substances increases with temperature; (2) The solubility of a few substances is affected by temperature. The effect is very small; (3) The solubility of very few substances decreases with the increase of temperature. 20. There are three reasons why CO2 can extinguish fires: it cannot burn, it cannot support combustion, and it is denser than air. 21. Elemental substances can be divided into three categories: metallic elements; non-metallic elements; and rare gas elements. 22. The three most important fossil fuels in the world today are: coal, oil, and natural gas.
23. The three black oxides that should be remembered are: copper oxide, manganese dioxide, and ferric oxide.
24. Hydrogen and carbon elements have three similar chemical properties: stability at room temperature, flammability, and reducibility.
25. Three times light blue appears in the textbook: (1) Liquid oxygen is light blue (2) Sulfur burns in the air with a weak light blue flame, (3) Hydrogen burns in the air Burns with light blue flame.
26. Three blue colors related to copper element: (1) copper sulfate crystal; (2) copper hydroxide precipitation; (3) copper sulfate solution. 27. There are "three *" in the filtration operation: (1) The lower end of the funnel is tightly * on the inner wall of the beaker; (2) The end of the glass rod is lightly * on the third layer of the filter paper; (3) The edge of the beaker holding the filtrate is tightly * on the glass Support and attract traffic.
28. Three major gas pollutants: SO2, CO, NO2
29. The flame of the alcohol lamp is divided into three parts: outer flame, inner flame, and flame core. The outer flame The highest temperature.
30. There are "three no's" principles when taking medicines: (1) Do not touch the medicines with your hands; (2) Do not put your nose to the mouth of the container to smell the gas; (3) Do not taste the medicines . 31. The three major chemical processes in ancient times: paper making, gunpowder making, and porcelain burning. 32. Three industrial wastes: waste water, waste residue, and waste gas. 34. Three instruments that can be directly heated: test tubes, crucibles, and evaporating dishes (in addition There are also burning keys)
35. The three invariants of atoms explained by the conservation of mass: the type does not change, the number does not increase or decrease, and the quality does not change
36. It may explode when mixed with air and ignited Three gases: H2, CO, CH4 (actually any flammable gas and dust). 37. Three products of coal carbonization (chemical change): coke, coal tar, and coke oven gas
38. Three characteristics of concentrated sulfuric acid: water absorption, dehydration, and strong oxidation
39. Three prohibitions on using alcohol lamps: burning, adding alcohol to the burning lamp, and blowing it out with your mouth
40. Three steps for preparing a solution: calculation, weighing (measurement), and dissolution
< p>41. The top three most abundant elements in biological cells: O, C, H42. Three equations in atoms: Nuclear charge = Number of protons = Number of electrons outside the nucleus = Atomic number
43. Three types of particles that make up matter: molecules, atoms, and ions
1. Basic reaction types:
Combination reaction: polymorphic-decomposition reaction: One to many
Displacement reaction: one to one metathesis reaction: exchange of ions
2. Valence (positive valence) of common elements:
One The valence elements sodium chloride, potassium and silver, the divalent elements oxygen, calcium, zinc, barium and magnesium, the trivalent metal elements aluminum and iron;
It is not difficult to change the valency, two and four carbon silicon, trivalent nitrogen and phosphorus, Two, four and six sulfur are complete.
3. The steps for preparing oxygen in the laboratory:
"Tea (check), Zhuang (installation), fix, point, collect, benefit (leave), breath (extinguish) ”
“Check” the air tightness of the device, “install” the medicine, and connect the device
“fix” the test tube on the iron stand, “point” and light the alcohol lamp for heating< /p>
"Collect" to collect gas and "Lift" the tube to move away from the water surface
"Exit" to extinguish the alcohol lamp and stop heating.
4. Experimental steps for reducing copper oxide with CO:
“One pass, two points, three extinguishments, four stops, and five treatments”
“One pass” First pass the hydrogen gas, and then light the alcohol lamp for heating after "two o'clock";
After the "three extinguishments" experiment is completed, first extinguish the alcohol lamp, and "four stops" wait until room temperature before stopping the hydrogen gas; "five treatments" "Treat exhaust gas and prevent CO from polluting the environment.
5. Experimental phenomenon of electrolyzing water:
"Positive oxygen and negative hydrogen, positive one and negative two": the positive electrode releases oxygen and the negative electrode releases hydrogen; the volume ratio of oxygen to hydrogen is 1 :2.
6. Elements that make up the earth’s crust: ions (oxygen, silicon, aluminum)
7. The relationship between the outermost layer of atoms and the formation of ions and valences:
"Losing positive yang, getting negative negative, the value remains unchanged": After the outermost layer of the atom loses electrons, it forms a cation, and the valence of the element is positive; after the outermost layer of the atom gains electrons, it forms an anion, and the valence of the element is negative; we get Or the number of electrons lost = the number of charges = the valence value.
8. Basic operating instructions for chemical experiments:
For solids, you need a spoon or a paper slot, one to put two vertically and three to bounce; for solid blocks, tweezers are better, one horizontally, two slowly and three vertically.
The liquid should be put into a narrow-mouth bottle, labeled by hand before pouring; the reading should be level with the cut surface, low when looking up and high when looking down
Put the dropper into the pinch tip, and hang it vertically to avoid staining; If it is not flat, do not place it randomly, and don’t forget to clean it after use
The balance of the pallet must be leveled, and the screw needle of the balance must be centered; put the items on the left and the right, and use tweezers to clamp the big ones and the small ones
Cut the test paper into small pieces first to test the liquid, and it is best to dip the glass rod into the liquid for the best test; wet the test paper to test the gas first, then stick it to the rod and lean it against the gas
Use an external flame for heating with a wine lamp, two-thirds of it is limit; stir the sulfuric acid into the water, and slowly inject it to prevent boiling and splashing
First check the air tightness in the experiment, and heat the cup and bottle with a mesh; after draining and collecting gas, remove the tube first and then move the light
9. The order of metal activity:
The order of metal activity from strong to weak: K Ca Na Mg Al Zn Fe Sn Pb (H) Cu Hg Ag Pt Au
(Recite in order) Potassium, calcium, sodium, magnesium, aluminum, zinc, iron, tin, lead (hydrogen), copper, mercury, silver, platinum
(...total one hundred kilograms)
10 , "Cross method" formula for writing chemical formulas:
"With positive valence on the left and negative valence on the right, reduce the number of crosses to a simplified number, write the right and bottom to check whether it is right or wrong."
11. Filtration operation tips:
The bucket holder, beaker, glass rod, filter paper and funnel angle are the same; let them stand before filtration, don’t forget the three and two.
12. Rules in the experiment:
① Anyone who uses solid heating to produce gas should use potassium permanganate to produce O2 equipment (solid-solid heating type);
Hydrogen peroxide O2 production device (solid-liquid non-heating type) should be used for any reaction between solid and liquid that does not require heating to produce gas.
② Whenever heating a test tube solid, it must be preheated first, and the test tube mouth should be slightly tilted downwards.
③ Any gas generated that is insoluble in water (does not react with water) can be collected by drainage.
Any gas produced that is denser than air can be collected using the upward air exhaust method.
Any gas generated that is less dense than air can be collected by the downward air exhaust method.
④ During any gas production experiment, first check the air tightness of the device. The tube should have 1-2ml of rubber plug exposed, and the iron clamp should be clamped 1/3 away from the tube mouth.
⑤When using a long-neck funnel to make gas experiments, the end nozzle of the long-neck funnel should be inserted under the liquid surface.
⑥Whenever igniting flammable gas, its purity must be tested first.
⑦ Whenever toxic gases are used for experiments, the exhaust gas must be disposed of at the end.
⑧Whenever reducing gas is used to reduce metal oxides, it must be "one pass, two points, three extinguishments, and four stops"
13. Reaction rules: ??
< p>Displacement reaction:(1) Metal element + acid → salt + hydrogen
(2) Metal element + salt (solution) → another metal + another salt
(3) Metal oxide + charcoal or hydrogen → metal + carbon dioxide or water
Metathesis reaction:
① Basic oxide + acid → salt + H2O ②Alkali+acid→salt+H2O
③Acid+salt→new salt+new acid ④Salt 1+salt 2→new salt 1+new salt 2
⑤Salt+base→new salt + New Base
14. Metal + Acid → Salt + H2↑:
① Equal masses of metal react with a sufficient amount of acid to release hydrogen in the order of more than least: Al>Mg> Fe>Zn (how fast or slow)
② Different acids of equal mass react with a sufficient amount of metal. The smaller the relative molecular mass of the acid, the more hydrogen gas is released.
③ When equal masses of the same acid react with sufficient amounts of different metals, the same amount of hydrogen is released.
④After the reaction of metal + acid → salt + H2↑, the solution mass becomes heavier and the metal becomes lighter.
In metal + salt solution → new metal + new salt:
① When the relative atomic mass of the metal > the relative atomic mass of the new metal, the mass of the solution becomes heavier after the reaction, and the metal Become lighter.
② When the relative atomic mass of the metal < the relative atomic mass of the new metal, the mass of the solution after the reaction becomes lighter and the metal becomes heavier.
15. Catalyst: one changes to the other (a substance that changes the reaction rate of a substance but does not change its chemical properties and mass is a catalyst)
Oxidant and reducing agent: get The reducing properties of oxygen redox agents, and the oxidizing properties of oxygen-losing reduction oxidants (substances that take away oxygen elements are reducing agents, and substances that lose oxygen elements are oxidizing agents)
16. The connection of using a gas scrubber to remove impurities: Changjin Short out
The connection for draining and collecting gas from a scrubbing bottle: short in and long out
The connection for draining and collecting gas from a scrubbing bottle: if the density is small, the short in will be long and if the density is tight, the connection will be short and long. The big ones are long in and short out
17. Principle of experimental impurity removal: remove other things first, then remove water vapor
Experimental inspection principle: test water first, then other things
< p>18 Hydrogen reduces copper oxidePut in hydrogen first, then light the lamp. If the substance turns red, turn off the lamp; cool down to room temperature and then stop the hydrogen
Alcohol lamps are "late and leave early", hydrogen "Come early and leave late"
"Bao Gong was sitting quietly in the crystal room, with the breeze blowing on his face, beaming with joy. Suddenly a fire started from the ground, and Bao Gong turned into Guan Yunchang. Yun Chang immediately ordered the fire to subside, leaving only the breeze to warm the house."