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Anonymous users2024-02-071 Table salt NaCl is used to drown salted meat because it kills the cells, making its outer membrane fully permeable, and NaCl naturally enters the cells, while most of the other microorganisms that will make the meat rot cannot survive in high concentrations of NaCl.
2 Nitrogen is necessary for crops to synthesize proteins, as well as some compounds related to photosynthesis, which is the basis of life.
Phosphorus is a component of the energy substance ATP, a component of DNA, RNA, etc., and a component of cell membranes, which is important for life.
Potassium plays a key role in the formation of photosynthetic starch, which is the plant's lodging resistance, regulating cell osmotic pressure, and maintaining the osmotic potential of root water absorption.
3 Since the elements of sucrose are all non-metals, h is the weakest non-metal, showing +1 valence.
O is the strongest of the non-metals, with an apparent -2 valence, and the sum valence of C is zero due to the overall electrically neutral molecule.
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Anonymous users2024-02-06FeO+Co=(High Temperature) Fe+CO2
The black substance turns red.
Gases are produced to make lime water turbid.
Prevents carbon monoxide from entering the air.
Smelting metals. Reductiveness.
Make fuel. Flammability. Oxygen. Iron.
Copper. Carbon. Thank you!
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Anonymous users2024-02-05What, the temperature and solubility are not there, how do you know if it can be dissolved?
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Anonymous users2024-02-04CaCO3 + 2HCl = CO2 + H2O + CaCl2 You can look at the neutralization reaction, which is the acid-base reaction.
Among them, the preparation method of hydrogen, oxygen, and carbon dioxide is more important.
Don't know what exam you're preparing for?
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Anonymous users2024-02-03Mercury is not silver but Hg, pencil is not lead but C, dry ice is not ice but CO2, .,
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Anonymous users2024-02-021. CO+Cuo— CO2+CU (the condition is high temperature).
naoh+co2—→na2co3+h2o
3. The water absorption of concentrated sulfuric acid is the use of concentrated sulfuric acid, and the water absorption of sodium hydroxide is the use of sodium hydroxide (easy to deliquescent in water), both of which belong to physical changes, no chemical changes, and no reaction equations;
Cu+O2—2Cuo (condition is burning).
5、fe+h2so4—→feso4+h2↑
6、cuo+h2so4—→cuso4+h2o
7、fe+cuso4—→feso4+cu
8、na2co3+2hcl—→2nacl+h2o+co2↑
9、na2so4+bacl2—→2nacl+baso4↓
10、naoh+hcl—→nacl+h2o
11、na2co3+ca(oh)2—→2naoh+caco3↓
12、cuso4+ba(oh)2—→baso4↓+cu(oh)2↓
13、nacl+agno3—→nano3+agcl↓
14. Using the difference in the amplitude of the solubility of the two with the change of temperature, the mixture of potassium nitrate and sodium chloride is dissolved in water by evaporation solvent method, and the aqueous solution of the solid solute is heated and evaporated, and the solution reaches saturation, and then evaporated. It is a physical change, no chemical change, and no reaction equation;
15. Taking advantage of the difference in the amplitude of the solubility of the two with temperature, the cooling hot saturated solution method is used to cool a saturated solution of 60 degrees to 20 degrees, and then the potassium nitrate is precipitated, which belongs to physical change, no chemical change, and no reaction equation;
16. Through concentrated sulfuric acid, it is the use of concentrated sulfuric acid water absorption, which belongs to physical change, no chemical change, and no reaction equation.
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Anonymous users2024-02-011 co + cuo = cu + co2↑
2 co2 + 2naoh = na2co3 + h2o
3 Concentrated sulfuric acid and sodium hydroxide are solid water absorption, so there is no need to write.
4 2cu + o2 = 2cuo
5 fe + h2so4 = feso4 + h2↑
6 cuo + h2so4 = cuso4 + h2o
7 cuso4 + fe = feso4 + cu
8 na2co3 + 2hcl = 2nacl + h2o +co2↑
9 naoh + bacl = nacl + baso4↓
10 naoh + hcl = nacl + h2o
11 na2co3 + ca(oh)2 = caco3↓ +2naoh
12 cuso4 + ba(oh)2 = baso4↓ +cu(oh)2↓
13 nacl + agno3 = nano3 + agcl↓
The solubility of 14 kno3 changed rapidly with temperature, while the solubility of NaCl did not change much with temperature.
The solubility of 15 kno3 changed rapidly with temperature, while the solubility of NaCl did not change much with temperature.
16 Concentrated sulfuric acid absorbs water, no need to write.
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Anonymous users2024-01-311 CO + Cuo = High Temperature = Cu + CO2
2 co2 + 2naoh = na2co3 + h2o
3 Physical Methods.
4 2cu + O2 = heating = 2cuo
5 fe + h2so4 = feso4 + h2↑
6 cuo + h2so4 = cuso4 + h2o
7 cuso4 + fe = feso4 + cu
8 na2co3 + 2hcl = 2nacl + h2o +co2↑
9 na2so4 + bacl2 = 2nacl + baso4↓
10 naoh + hcl = nacl + h2o
11 na2co3 + ca(oh)2 = caco3↓ +2naoh
12 cuso4 + ba(oh)2 = baso4↓ +cu(oh)2↓
13 nacl + agno3 = nano3 + agcl↓
14 Physical Methods.
15 Physical Methods.
16 Physical Methods.
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Anonymous users2024-01-30Both 14 and 15 are precipitation, not chemical changes.
16 is the same as 3's.
1. Chemical change: changes in other substances are generated. >>>More
A is not true. First of all, the temperature has an effect on the solubility, such as the 30 degrees of potassium nitrate saturated solution to 40 degrees, it is no longer a saturated solution, and then add a little potassium nitrate, less than the saturated state, but its concentration is already larger than the concentration of the saturated solution at 30 degrees, in addition, the solubility of some substances is reduced with the rise of temperature. Such as some gases. >>>More
It's simple, it's about interest, like I dare to sleep, chat and play with my phone in chemistry class in my third year of junior high school, but chemistry is still okay, it's just about interest. >>>More
First, the substance is dissolved in water or a solvent of any kind. >>>More
CaCO3, BaCO3, Baso4, Baso3, Fe(OH)2 (unstable), Agoh (unstable), Mg(OH)2, Al(OH)3, Zn(OH)2, H4SiO4 (H2SiO3), Zns, NaHCO3 (precipitate produced by CO2 in saturated Na2CO3), CaSO4 (slightly soluble). >>>More