Basic knowledge of chemistry, take a look at it for junior high school students! ! !
1. Colors of common substances in junior high school chemistry
(1) Color of solids
1. Red solids: copper, iron oxide
2. Green solid: basic copper carbonate
3. Blue solid: copper hydroxide, copper sulfate crystal
4. Purple black solid: potassium permanganate
p>5. Light yellow solid: sulfur
6. Colorless solid: ice, dry ice, diamond
7. Silvery white solid: silver, iron, magnesium, aluminum , mercury and other metals
8. Black solid: iron powder, charcoal, copper oxide, manganese dioxide, ferric oxide, (carbon black, activated carbon)
9. Reddish brown Solid: iron hydroxide
10. White solid: sodium chloride, sodium carbonate, sodium hydroxide, calcium hydroxide, calcium carbonate, calcium oxide, copper sulfate, phosphorus pentoxide, magnesium oxide
p>(2) Color of liquid
11. Colorless liquid: water, hydrogen peroxide
12. Blue solution: copper sulfate solution, copper chloride solution, Copper nitrate solution
13. Light green solution: ferrous sulfate solution, ferrous chloride solution, ferrous nitrate solution
14. Yellow solution: ferric sulfate solution, ferric chloride Solution, iron nitrate solution
15. Purple solution: potassium permanganate solution
16. Purple solution: litmus solution
(3) Gas Color
17. Red-brown gas: nitrogen dioxide
18. Yellow-green gas: chlorine
19. Colorless gas: oxygen, nitrogen, hydrogen , carbon dioxide, carbon monoxide, sulfur dioxide, hydrogen chloride gas and most other gases.
2. Acidity and alkalinity of junior high school chemistry solutions
1. Acidic solutions: acid solutions and certain salt solutions (sodium bisulfate, potassium bisulfate, etc.)
2. Alkaline solutions: alkaline solutions and certain salt solutions (sodium carbonate, sodium bicarbonate, etc.)
3. Neutral solutions: water and most salt solutions
3. The mass of junior high school chemistry exposed to the air changes
(1) The mass increases
1. The mass increases due to water absorption: hydrogen oxidation Sodium solid, calcium chloride, magnesium chloride, concentrated sulfuric acid;
2. Added due to reaction with water: calcium oxide, barium oxide, potassium oxide, sodium oxide, copper sulfate;
3. Increased due to reaction with carbon dioxide: sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide;
(2) Decreased mass
1. Due to Reduced by volatilization: concentrated hydrochloric acid, concentrated nitric acid, alcohol, gasoline, concentrated ammonia;
2. Reduced by weathering: sodium carbonate crystals.
IV. Inspection of chemical substances in junior high schools
(1) Inspection of gases
1. Oxygen: put the wooden stick with sparks into the bottle, if the wood If the article ignites again, it is oxygen.
2. Hydrogen: ignite the gas with a glass tip, cover it with a dry and cold beaker, observe whether there are water droplets on the wall of the beaker, pour clear lime water into the beaker, if it does not become turbid, it is hydrogen.
3. Carbon dioxide: Pour in clear lime water. If it becomes turbid, it is carbon dioxide.
4. Ammonia gas: Use moist purple-red litmus paper. If the test paper turns blue, it is ammonia gas.
5. Water vapor: If the white solid turns blue through anhydrous copper sulfate, it contains water vapor.
(2) Test of ions.
6. Hydrogen ions: dropwise add purple litmus test solution/add zinc particles
7. Hydroxide Ions: phenolphthalein test solution/copper sulfate solution
8. Carbonate ions: dilute hydrochloric acid and clear lime water
9. Chloride ions: silver nitrate solution and dilute nitric acid, if produced The white precipitate is chloride ions
10. Sulfate ions: barium nitrate solution and dilute nitric acid/first drop dilute hydrochloric acid and then drop barium chloride
11. Ammonium ions : Sodium hydroxide solution and heated, put moist red litmus paper on the mouth of the test tube
12. Copper ions: Add sodium hydroxide solution dropwise, if blue precipitate is produced, it is copper ions
13. Iron ions: Add sodium hydroxide solution dropwise. If a reddish-brown precipitate is produced, it is iron ions
(3) Related examples
14. How to test NaOH Whether it has deteriorated: add dilute hydrochloric acid dropwise, if bubbles are generated, it means it has deteriorated
15. Check whether the quicklime contains limestone: add dilute hydrochloric acid dropwise, if bubbles are generated, it means it contains limestone
16. Inspection Whether NaOH contains NaCl: first add a sufficient amount of dilute nitric acid dropwise, and then add AgNO3 solution dropwise. If a white precipitate is produced, it contains NaCl.
17. Check whether the three bottles of test solution are dilute HNO3, dilute HCl, and dilute H2SO4?
Add Ba(NO3)2 solution dropwise into the three test tubes respectively. If white precipitate is produced , it is dilute H2SO4; then add AgNO3 solution dropwise, if a white precipitate is produced, it is dilute HCl, and the remainder is dilute HNO3
18. Starch: Add iodine solution, if it turns blue, it contains starch.
19. Glucose: Add newly prepared copper hydroxide. If a brick-red cuprous oxide precipitate forms, it contains glucose.
5. Junior High School Chemistry Part 3
1. The three major chemical processes in ancient my country: paper making, gunpowder making, and porcelain burning.
2. Three types of oxidation reactions: explosion, combustion, and slow oxidation.
3. Three types of particles that make up matter: molecules, atoms, and ions.
4. Three types of uncharged particles: molecules, atoms, and neutrons.
5. Three views on the composition and composition of matter:
(1) Carbon dioxide is composed of carbon and oxygen elements;
(2) , Carbon dioxide is composed of carbon dioxide molecules;
(3). A carbon dioxide molecule is composed of one carbon atom and one oxygen atom.
6. There are three types of particles that make up atoms: protons, neutrons, and electrons.
7. Three causes of water pollution: (1) arbitrary discharge of industrial "three wastes", (2) arbitrary discharge of domestic sewage (3) arbitrary application of pesticides and fertilizers
8. There are three collection methods: drainage method (gases that are not compatible with water), upward air discharge method (gases with a density greater than air), and downward air discharge method (gases with a density less than air).
9. The three invariants of the law of conservation of mass are: the type of atom remains unchanged, the number of atoms remains unchanged, and the atomic mass remains unchanged.
10. Three ways to change an unsaturated solution into a saturated solution:
Increase the solute, reduce the solvent, and change the temperature (increase or decrease).
11. Three conditions for metathesis reaction to occur: generation of water, gas or precipitation
12. Three major chemical fertilizers: N, P, K
13. Three gas pollutants emitted into the air: carbon monoxide, nitrogen oxides, and sulfur oxides.
14. Burn substances that emit white light: magnesium bars, charcoal, candles (carbon dioxide and water).
15. Combustible and reducing substances: hydrogen, carbon monoxide, elemental carbon.
16. The three flammable gases are: hydrogen (ideal), carbon monoxide (toxic), and methane (commonly used).
17. Three chemical properties of CO: flammability, reducibility, and toxicity.
18. The three major fossil fuels: coal, oil, and natural gas. (All mixtures)
19. Three black metals: iron, manganese, and chromium.
20. Three oxides of iron: ferrous oxide, ferric oxide, and ferric tetraoxide.
21. Three oxides for iron-making: iron ore, coke, and limestone.
22. Three common strong acids: hydrochloric acid, sulfuric acid, and nitric acid.
23. The three characteristics of concentrated sulfuric acid: water absorption, dehydration, and strong oxidation.
24. There are three common names for sodium hydroxide: fire soda, caustic soda, and caustic soda.
25. Three oxides are generated by thermal decomposition of basic copper carbonate: copper oxide, water (hydrogen oxide), and carbon dioxide.
26. Three substances that cannot be used to prepare CO2 in the laboratory: nitric acid, concentrated sulfuric acid, and sodium carbonate.
27. The three flames of the alcohol lamp: inner flame, outer flame, and flame core.
28. There are three prohibitions on using an alcohol lamp: it is prohibited to add alcohol to a burning lamp, it is prohibited to use an alcohol lamp to ignite another alcohol lamp, and it is prohibited to blow out an alcohol lamp with your mouth.
29. The three functions of the glass rod in the purification of coarse salt: stirring, drainage, and transfer
30. Three relies on the liquid filtration operation: (1) Beaker when pouring the filtrate The mouth of the funnel is close to the glass rod, (2) the glass rod rests lightly on one end of the three-layer filter paper, (3) the mouth of the lower end of the funnel is close to the inner wall of the beaker.
31. Three steps for preparing solid solutions: calculation, weighing, and dissolving.
32. Three steps for mixing concentrated with dilute: calculation, measurement, and dissolution.
33. Three instruments for mixing thick and dilute: beaker, measuring cylinder, and glass rod.
34. Three substances that release heat when exposed to water: concentrated sulfuric acid, sodium hydroxide, and quicklime.
35. The reasons why the filtrate is still turbid after filtering twice: the filter paper is damaged, the instrument is not clean, and the liquid level is higher than the edge of the filter paper.
36. Three principles of medicine handling: Do not touch the medicine with your hands, do not put your nostrils to the container to smell the medicine, and do not taste any medicine.
37. Three meanings of the order of metal activity: (1) The higher the position of the metal, the easier it is to lose electrons and become ions in the aqueous solution, and the stronger its activity is; (2) the ranking The metal in front of the hydrogen can replace the hydrogen in the acid, but the metal behind the hydrogen cannot replace the hydrogen in the acid; (3) The metal in front can replace the metal in the back from their salt solution.
38. The effect of temperature on the solubility of solids: (1) The solubility of most solid substances increases with the increase of temperature, (2) The solubility of a few solid substances does not change much due to the influence of temperature ( 3) The solubility of very few solid substances decreases with increasing temperature.
39. Factors that affect the dissolution rate: (1) Temperature, (2) Whether to stir or not (3) Size of solid particles
40. Three substances that make iron rust: Iron, water, oxygen.
41. There are three states of solute: solid, liquid and gaseous.
42. Three factors affect solubility: the nature of the solute, the nature of the solvent, and temperature.
6. Important components of common mixtures in junior high school chemistry
1. Air: nitrogen (N2) and oxygen (O2)
2. Water gas: carbon monoxide (CO ) and hydrogen (H2)
3. Coal gas: carbon monoxide (CO)
4. Natural gas: methane (CH4)
5. Limestone/marble: ( CaCO3)
6. Pig iron/steel: (Fe)
7. Charcoal/coke/carbon black/activated carbon: (C)
8. Rust: (Fe2O3)
7. Common names of common substances in junior high school chemistry
1. Sodium chloride (NaCl): table salt
2. Sodium carbonate (Na2CO3): soda ash , soda, oral alkali
3. Sodium hydroxide (NaOH): fire soda, caustic soda, caustic soda
4. Calcium oxide (CaO): quicklime
5. Calcium hydroxide (Ca(OH)2): hydrated lime, slaked lime
6. Carbon dioxide solid (CO2): dry ice
7. Hydrochloric acid (HCl): hydrochloric acid
8. Basic copper carbonate (Cu2(OH)2CO3): patina
9. Copper sulfate crystal (CuSO4 .5H2O): blue vitriol, bile vitriol
10. Methane (CH4): biogas
11. Ethanol (C2H5OH): alcohol
12. Acetic acid (CH3COOH): acetic acid
13. Hydrogen oxide (H2O2): hydrogen peroxide
14. Mercury (Hg): mercury
15. Sodium bicarbonate (NaHCO3): baking soda
8. Substances Impurity removal
1. CO2 (CO): Pass the gas through hot copper oxide,
2. CO (CO2): Pass a sufficient amount of sodium hydroxide solution
3. H2 (water vapor): through concentrated sulfuric acid/through sodium hydroxide solid
4. CuO(C): burning mixture in air (in oxygen flow)
5. Cu(Fe): Add sufficient amount of dilute sulfuric acid
6. Cu(CuO): Add sufficient amount of dilute sulfuric acid
7. FeSO4(CuSO4) : Add sufficient iron powder
8. NaCl(Na2CO3): Add sufficient hydrochloric acid
9. NaCl(Na2SO4): Add sufficient barium chloride solution
p>
10. NaCl (NaOH): Add a sufficient amount of hydrochloric acid
11. NaOH (Na2CO3): Add a sufficient amount of calcium hydroxide solution
12. NaCl ( CuSO4): Add a sufficient amount of barium hydroxide solution
13. NaNO3 (NaCl): Add a sufficient amount of silver nitrate solution
14. NaCl (KNO3): Evaporate the solvent
p>15. KNO3 (NaCl): Cool the hot saturated solution.
16. CO2 (water vapor): through concentrated sulfuric acid.
9. The best of chemistry
1. The most ideal fuel in the future is H2.
2. The simplest organic compound is CH4.
3. The gas with the smallest density is H2.
4. The substance with the smallest relative molecular mass is H2.
5. The oxide with the smallest relative molecular mass is H2O.
6. The smallest particle in chemical changes is the atom.
7. When PH=0, the acidity is the strongest and the alkalinity is the weakest.
When PH=14, it is the most alkaline and the weakest acidity.
8. The three elements N, K, and P are most lacking in the soil. The most efficient nitrogen fertilizer is urea.
9. The hardest naturally occurring substance is diamond.
10. The first country to utilize natural gas is China.
11. The most abundant element in the earth’s crust is oxygen.
12. The most abundant metal element in the earth’s crust is aluminum.
13. The most abundant gas in the air is nitrogen.
14. The most abundant element in the air is nitrogen.
15. The three most important fossil fuels in the world today are coal, oil and natural gas.
16. The element that forms the most types of compounds: carbon
10. Relevant differences
1. The physical properties of diamond and graphite are different: because of the arrangement of carbon atoms different.
2. The properties of pig iron and steel are different: because of the different carbon content.
3. The chemical properties of carbon monoxide and carbon dioxide are different: this is because their molecular compositions are different.
(The chemical properties of oxygen and ozone are different because of different molecular compositions; the chemical properties of water and hydrogen peroxide are different because of different molecular compositions.)
4. Different types of elements: because The number of protons is different.
5. The valence of elements is different: This is because the number of electrons in the outermost shell is different.
6. The chemical properties of sodium atoms and sodium ions are different: because the number of electrons in the outermost shell is different
11: Toxic substances
1. Toxic Solids: sodium nitrite (NaNO2), lead acetate, etc.;
2. Toxic liquids: mercury, copper sulfate solution, methanol, solutions containing Ba2 (except BaSO4);
3. Toxic gases: CO, nitrogen oxides, sulfur oxides.
Twelve: Laboratory preparation method
△
1. Laboratory oxygen: 2KMnO4=====2K2MnO4 MnO2 O2↑
MnO2
2KClO3=======2KCl 3O2↑
△
MnO2
2H2O2===== ==2H2O O2↑
2. Laboratory hydrogen production
Zn H2SO4===ZnSO4 H2↑ (commonly used) Fe H2SO4===FeSO4 H2↑
Mg H2SO4===MgSO4 H2↑ 2Al 3H2SO4==Al2(SO4)3 3H2↑
Zn 2HCl===ZnCl2 H2↑ Fe 2HCl===FeCl2 H2↑
Mg 2HCl===MgCl2 H2↑ 2Al 6HCl===2AlCl3 3H2↑
4. Laboratory preparation of CO2:
CaCO3 2HCl==CaCl2 CO2↑ H2O
Thirteen: Industrial Preparation Method
1. O2: Separation of liquid air
High temperature
2. CO2: High temperature calcined limestone (CaCO3==== =====CaO CO2↑)
3. H2: natural gas and water gas
High temperature
4. Quicklime: high temperature calcined limestone (CaCO3=== ======CaO CO2↑)
5. Hydrated lime: CaO H2O==Ca(OH)2
6. Caustic soda: Ca(OH)2 Na2CO3=== CaCO3↓ 2Na OH