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The diameter of a tree is 12cm, the height is 10m ~ how many cubic meters of wood can it produce~
12 cm = 0.12 m 0.12 / 2 = 0.06 m 3.14 * 0.06 M2 * 10 = 0.11304 M3
How many cubic meters is a 20 meter high tree 15 cm in diameter
3.14 × (0.15 △ 2) × (0.15 △ 2) × 20 = 0.35325 (cubic)
Grade 9 Volume 1 Chemical expression
1、 Properties of oxygen:
(1) Reaction of simple substance with oxygen: (compound reaction)
1. Combustion of magnesium in air: 2mg + O2 = ignition = 2MgO
2. Combustion of iron in oxygen: 3Fe + 2O2 = ignition = Fe3O4
3. Copper heated in air: 2Cu + O2 = heating = 2CuO
4. Combustion of aluminum in air: 4Al + 3O2 = ignition = 2al2o3
5. Combustion in hydrogen and air: 2h2 + O2 = ignition = 2H2O
6. Combustion of red phosphorus in air: 4P + 5o2 = ignition = 2p2o5
7. Sulfur powder burning in air: S + O2 = ignition = SO2
8. Carbon burns well in oxygen: C + O2 = ignition = CO2
9. Incomplete combustion of carbon in oxygen: 2C + O2 = ignition = 2CO
(2) Reaction of compound with oxygen:
10. Combustion of carbon monoxide in oxygen: 2CO + O2 = ignition = 2co2
11. Methane combustion in air: CH4 + 2O2 = ignition = CO2 + 2H2O
12. Alcohol burning in air: C2H5OH + 3O2 = ignition = 2co2 + 3H2O
(3) Source of oxygen:
13. Experiment on composition of air by Boyle 2hgo = heating = Hg + O2 ↑
14. Heating potassium permanganate: 2kmno4 = heating = k2mno4 + MnO2 + O2 ↑ (principle of oxygen production in laboratory 1)
15. Decomposition of hydrogen peroxide with manganese dioxide as catalyst
H2O2 (MnO2 catalyst) = 2H2O + O2 ↑ (principle of oxygen production in laboratory 2)
2、 Water in nature:
16. Water decomposes under the action of direct current
2H2O = power on = 2h2 ↑ + O2 ↑
17. Quicklime dissolves in water: Cao + H2O = = Ca (OH) 2
18. Carbon dioxide is soluble in water: H2O + CO2 = = H2CO3
3、 Law of conservation of mass:
19. Combustion of magnesium in air: 2mg + O2 = ignition = 2MgO
20. Reaction between iron and copper sulfate solution: Fe + CuSO4 = = = FeSO4 + Cu
21. Reduction of CuO by hydrogen: H2 + CuO = heating = Cu + H2O
22. Reduction of copper oxide by magnesium: Mg + CuO = heating = Cu + MgO
4、 Carbon and carbon oxides:
(1) Chemical properties of carbon
23. Carbon burns well in oxygen: C + O2 = ignition = CO2
24. Reduction of CuO by charcoal: C + 2CuO = high temperature = 2Cu + CO2 ↑
25. Reduction of iron oxide by coke: 3C + 2fe2o3 = high temperature = 4Fe + 3co2 ↑
(2) Three reactions in coal furnace: (several reactions)
26. Bottom layer of coal furnace: C + O2 = ignition = CO2
27. Middle layer of coal furnace: CO2 + C = high temperature = 2CO
28. Generation of blue flame in the upper part of coal stove: 2CO + O2 = ignition = 2co2
(3) Preparation and properties of carbon dioxide:
29. Reaction of marble with dilute hydrochloric acid (carbon dioxide produced in laboratory)
CaCO3 + 2HCl == CaCl2 + H2O + CO2↑
30. The carbonic acid is unstable and separated into H2CO3 = = H2O + CO2 ↑
31. Carbon dioxide is soluble in water: H2O + CO2 = = H2CO3
32. High temperature calcined limestone (industrial carbon dioxide): CaCO3 = high temperature = CaO + CO2 ↑
33. Reaction of lime water with carbon dioxide (identification of carbon dioxide)
Ca(OH)2 + CO2 === CaCO3 ↓+ H2O
(4) Properties of carbon monoxide:
34. Reduction of copper oxide by carbon monoxide: CO + CuO = heating = Cu + CO2
35. Flammability of carbon monoxide: 2CO + O2 = ignition = 2co2
Other reactions:
36. Reaction of sodium carbonate with dilute hydrochloric acid (principle of fire extinguisher)
Na2CO3 + 2HCl == 2NaCl + H2O + CO2↑
5、 Fuel and its utilization:
37. Methane combustion in air: CH4 + 2O2 = ignition = CO2 + 2H2O
38. Alcohol burning in air: C2H5OH + 3O2 = ignition = 2co2 + 3H2O
39. Combustion in hydrogen and air: 2h2 + O2 = ignition = 2H2O
6、 Metals
(1) Metal reacts with oxygen
40. Combustion of magnesium in air: 2mg + O2 = ignition = 2MgO
41. Combustion of iron in oxygen: 3Fe + 2O2 = ignition = Fe3O4
42. Copper heated in air: 2Cu + O2 = heating = 2CuO
43. Aluminum forms oxide film in air: 4Al + 3O2 = 2al2o3
(2) Metal element + acid -------- Salt + hydrogen (displacement reaction)
44. Zinc and dilute sulfuric acid Zn + H2SO4 = ZnSO4 + H2 ↑
45. Iron and dilute sulfuric acid Fe + H2SO4 = FeSO4 + H2 ↑
46. Magnesium and dilute sulfuric acid Mg + H2SO4 = MgSO4 + H2 ↑
47. Aluminum and dilute sulfuric acid 2Al + 3h2so4 = Al2 (SO4) 3 + 3h2 ↑
48. Zinc and dilute hydrochloric acid Zn + 2HCl = = ZnCl2 + H2 ↑
49. Iron and dilute hydrochloric acid Fe + 2HCl = = FeCl2 + H2 ↑
50. Magnesium and dilute hydrochloric acid Mg + 2HCl = = MgCl2 + H2 ↑
51. Aluminum and dilute hydrochloric acid 2Al + 6hcl = = 2alcl3 + 3h2 ↑
(3) Metal element + salt (solution) -- new metal + new salt
52. Reaction between iron and copper sulfate solution: Fe + CuSO4 = = FeSO4 + Cu
53. Reaction between zinc and copper sulfate solution: Zn + CuSO4 = = ZnSO4 + Cu
54. Reaction of copper with mercuric nitrate solution: Cu + Hg (NO3) 2 = = Cu (NO3) 2 + Hg
(3) Smelting principle of metal iron:
55.3co + 2fe2o3 high temperature 4Fe + 3co2 ↑
7、 Acid, alkali, salt
1. Chemical properties of acids
(1) Acid + metal -------- Salt + hydrogen (see above)
(2) Acid + metal oxide salt + water
56. Reaction of iron oxide with dilute hydrochloric acid: Fe2O3 + 6hcl = = 2fecl3 + 3H2O
57. Reaction of iron oxide with dilute sulfuric acid: Fe2O3 + 3h2so4 = = Fe2 (SO4) 3 + 3H2O
58. Reaction of copper oxide with dilute hydrochloric acid: CuO + 2HCl = = CuCl2 + H2O
59. Reaction of copper oxide with dilute sulfuric acid: CuO + H2SO4 = = CuSO4 + H2O
(3) Acid + base -------- Salt + water (neutralization reaction)
60. Hydrochloric acid reacts with caustic soda: HCl + NaOH = = NaCl + H2O
61. Reaction of hydrochloric acid and calcium hydroxide: 2HCl + Ca (OH) 2 = = CaCl2 + 2H2O
62. Treatment of gastric acidosis with aluminum hydroxide: 3hcl + Al (OH) 3 = = AlCl3 + 3H2O
63. Reaction of sulfuric acid and caustic soda: H2SO4 + 2naoh = = Na2SO4 + 2H2O
(4) Acid + salt --- another acid + another salt
64. Reaction of marble with dilute hydrochloric acid: CaCO3 + 2HCl = = CaCl2 + H2O + CO2 ↑
65. Reaction of sodium carbonate with dilute hydrochloric acid: Na2CO3 + 2HCl = = 2nacl + H2O + CO2 ↑
66. Reaction of sodium bicarbonate with dilute hydrochloric acid: NaHCO3 + HCl = = NaCl + H2O + CO2 ↑
67. Reaction of sulfuric acid and barium chloride solution: H2SO4 + BaCl2 = = BaSO4 ↓ + 2HCl
2. Chemical properties of alkali
(1) Alkali + nonmetal oxide salt + water
68. Caustic soda deteriorates when exposed to air: 2naoh + CO2 = = Na2CO3 + H2O
69. Caustic soda absorbs sulfur dioxide: 2naoh + SO2 = = Na2SO3 + H2O
70. Caustic soda absorbs sulfur trioxide gas: 2naoh + SO3 = = Na2SO4 + H2O
71. Slaked lime metamorphoses in air: Ca (OH) 2 + CO2 = = CaCO3 ↓ + H2O
72. Absorption of sulfur dioxide by hydrated lime: Ca (OH) 2 + SO2 = = CaSO3 ↓ + H2O
(2) Alkali + acid -------- Salt + water (neutralization reaction, equation see above)
(3) Alkali + salt --- another alkali + another salt
73. Calcium hydroxide and sodium carbonate: Ca (OH) 2 + Na2CO3 = = CaCO3 ↓ + 2naoh
3. Chemical properties of salt
(1) Salt (solution) + metal element ------ another metal + another salt
74. Reaction between iron and copper sulfate solution: Fe + CuSO4 = = FeSO4 + Cu
(2) Salt + acid --- another acid + another salt
75. Reaction of sodium carbonate with dilute hydrochloric acid: Na2CO3 + 2HCl = = 2nacl + H2O + CO2 ↑
Sodium bicarbonate reacts with dilute hydrochloric acid: NaHCO3 + HCl = = NaCl + H2O + CO2 ↑
(3) Salt + alkali --- another alkali + another salt
76. Calcium hydroxide and sodium carbonate: Ca (OH) 2 + Na2CO3 = = CaCO3 ↓ + 2naoh
(4) Salt + salt -- two new salts
77. Sodium chloride solution and silver nitrate solution: NaCl + AgNO3 = = AgCl ↓ + NaNO3
78. Sodium sulfate and barium chloride: Na2SO4 + BaCl2 = = BaSO4 ↓ + 2nacl
Let's get points. How about 2, 2, 7, 8, addition, subtraction, multiplication and division equal to 24?
8+2+7×2=24
8×(7-2-2)=24
8×(7-2×2)=24
If Y1 is less than Y2, then the value range of X is
y1=3x-1
y2=-x+3
Let Y1 < Y2
Then 3x-1 < - x + 3
So x < 1
The perimeter of a circular fountain is 62.8m. How many square meters does the fountain cover?
2, = 3.14 × 102, = 314 square meters; a: it covers an area of 314 square meters
5.5.5.1, how to calculate 24 o'clock
5 times (5-1 / 5) = 24
A formula for calculating the curvature of a curve
The calculation formula of curvature is as follows
What does the physical density formula mean?
Represents the weight of the substance in a unit volume
The top and bottom surfaces of a straight hexagonal prism are regular hexagons with side lengths of 1 and side lengths of 10 respectively. The surface area of a straight hexagonal prism is calculated
A straight hexagon is composed of two regular hexagons and six rectangles with the same area. The area of six rectangles is: 6 * 10 * 1 = 60. The area of regular hexagons is: six regular triangles. Therefore, the area is: 6 * (1 / 2 * 1 * radical 3 / 2) = 3 radical 3 / 2
So the surface area is 60 + 3, radical 3
RELATED INFORMATIONS
- 1. It's 10 centimeters in diameter and 8 meters long
- 2. I'm going to buy a piece of wood, 5cm thick, 13cm wide and 4m long. How much is the cube?
- 3. Cylindrical wood, 150 cm long, cross-section diameter is 12 cm, if according to the ratio of 2:3 according to it into two sections, then the shorter section volume is how many cubic centimeters?
- 4. The volume of a cuboid wood is 216 cubic decimeters, the cross section area is 24 square decimeters, and the length of this wood is () decimeters
- 5. A 2-meter-long cuboid wood has a cross-sectional area of 16 square decimeters. How many cubic meters is its volume? Determinant
- 6. Saw the 1.2 meter long cuboid wood into three sections, the surface area increased by 48 square decimeters, the original volume of the wood is______ ．
- 7. A square table is made of a table top and four legs. It is known that one cubic meter of wood can be used to make 50 tables or 300 legs. Now five cubic meters of wood, what should we do Cutting material, can make the table top and table leg just match?
- 8. A square table consists of a table top and four legs. It is known that one cubic meter of wood can be used for 50 tables or 300 legs (equations only) A square table consists of a table top and four legs. It is known that one cubic meter of wood can make 50 tables or 300 legs. Please help the carpenter to calculate how many square tables can be made with five cubic meters of wood The equation can be set up linear equation in two unknowns
- 9. Now you need to buy 1 cubic meter of wood. For example, 4 meters long, 0.08 meters wide, 0.05 meters high is less than 3 cubic meters For example, 4 meters long, 0.08 meters wide, 0.05 meters high is equal to less cubic? If you have, please teach me more carefully! Teach me how to calculate! Now I need it very much!
- 10. I want a unit of length under millimeter To be less than millimeter, there must be a progressive rate, for example: kilometer × 100 = meter × 10 = decimeter × 10 = centimeter
- 11. A cuboid wood is 5.2 meters long. If it is sawn 10 cm short, its volume will be reduced by 1000 cubic centimeters. What is the original volume of this wood?
- 12. The surface area increases by 4 square meters after two cylinders are cut into 10 cm on one cylinder?
- 13. The length of a cylindrical wood is 4dm, and the bottom radius is 10cm. After cutting it into three sections, the surface area increases by () cm2? A.942 b.1256 c.1884
- 14. A cuboid wood is 3 meters long. Now, after sawing the wood into 4 sections, the surface area increases by 48 square decimeters. The volume of the cuboid wood is 3 meters______ Cubic decimeter
- 15. A section of cuboid wood is one meter long. If it is sawn two centimeters short, its volume will be reduced by 20 cubic centimeters. What is the original volume of this section of wood?
- 16. After sawing a 2-meter-long cuboid into two sections, its surface area increases by 100 square centimeters, and its volume is () A.100 cubic centimeters After sawing a 2-meter-long cuboid into two sections, its surface area increases by 100 square centimeters, and its volume is () A. 100 cc b.200 CC C. 10000 cm3 D.2 DM3
- 17. How can a 2m long wood with a diameter of 20cm be counted as a cube? For example, the cubic formula of wood processing plant: Diameter 10cm = 0.019, how did this 0.019 come from? Diameter 12cm = 0.027? Diameter 14cm = 0.036? Diameter: 16cm = 0.047? Diameter 18cm = 0.059? Diameter 20cm = 0.072? Diameter 22cm = 0.086? Diameter 24cm = 0.102? Diameter 26cm = 0.12? All the above are two meters in length. What's the reason for his formula? If it's three meters or 3.5 meters in length, how should it be calculated?
- 18. A cylindrical timber with a radius of 20cm. After sawing it into three equal small cylinders, how many square centimeters has the surface area increased
- 19. The bottom radius of a section of cylindrical wood is 20cm, and the height is 2m. How much is the surface area increased by sawing this section of wood into two cylinders of the same size from the middle? Note: the units are different
- 20. To make a table and four legs, 20 tables can be made from 1 cubic meter of wood, or 400 table legs can be made from 12 cubic meters of wood. How many tables can be made