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Anonymous users2024-02-08Georgxx - Magister Level 10 is right.
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Anonymous users2024-02-07；This question tests whether students have accurately memorized the order of metal liveliness.
Explanation: According to the metal activity order table "potassium, calcium, sodium, magnesium, aluminum, zinc, iron, tin, lead, hydrogen, copper, mercury, silver, platinum, gold", zinc can replace copper but not aluminum, and there is an excess of zinc.
16.The white precipitate is Baso4 (insoluble in acid) (or CaSO4, slightly soluble in water, excess can be regarded as precipitate), the reaction equation is: H2SO4 + BACl2==BaSO4 +2HCl or H2SO4 + Ca(OH)2==CaSO4+2H2O; If it is dissolved, it must not be BaSO4 (barium sulfate), then it may be CaSO4 (calcium sulfate), and the reaction equation is as follows:
h2so4+ca(oh)2==caso4+2h2o
This question tests the student's mastery of the solubility of a substance.
19.(How can there be only five kinds of sodium, hydrogen, and oxygen, and I'll tell you when you complete it).
chloride ions), omitted (the specific remains the same, as long as the barium chloride is changed to barium nitrate.) ）
This question tests whether the student is familiar with the ion test;
From (1) and (2), it can be seen that the prepared solution contains SO4- (because the three substances are soluble in water, the first step can not prove anything, there are carbonate ions and sulfate ions that can form precipitation with barium ions, but the two precipitation and acid reaction phenomena are different, barium carbonate reacts with acid to generate gas, and barium sulfate is insoluble in acid, so it can be sure that there are sulfate ions and no carbonate ions). However, the third step cannot prove that there are chloride ions in the solution, because chloride ions are added in the second step, so the chloride ions should be replaced by nitrate ions.
Help the above to solve it, because the blue precipitate generated by copper salt must be copper hydroxide (by the way, the green is basic copper carbonate [patina], and the blue-green is copper carbonate), and the precipitation generated by sulfate must be barium sulfate (also tell you by the way, potassium, sodium, ammonium, and nitrate have no precipitation), adding copper sulfate to solution 2 has a blue precipitate to generate a blue precipitate that once again proves that there are hydroxide ions in the original solution, that is, the original solution a is a barium hydroxide solution, and b and c are copper hydroxide and barium sulfate respectively.
From top to bottom, (1) CuCl2 + Ba(OH)2 = Cu(OH)2 + BaCl2
2)bacl2+agno3=agcl2↓+bano3
3)ba(oh)2+k2so4=baso4↓+2koh
4)2koh+cuso4=cu(oh)2↓+k2so4
Question 2: Let the mass of NaCO3 be x and the mass of NaOH be y
List the relation: Na2CO3 2Naoh Na2CO3 CaCO3 Naoh H2SO4
x y x 2y
Solve x=y=4g
A: The mass of NaCO3 is, and the mass of NaOH is 4g
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Anonymous users2024-02-06mg43.(1) O2 (2) Downward emptying method (3) Phenolphthalein solution turns red.
b．③ c．② d．⑧
It is not rigorous, and the pH test paper can only measure the substance as alkaline, which cannot mean that the substance is Ca(OH)2
CaCO3, which reacts with dilute hydrochloric acid, produces a large number of bubbles.
38.(1) Physical chemistry.
2) Acidity of the acid Oxidation of the acid.
3) H2 is elemental, CO2 is a compound, and CO2 is an oxide.
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Anonymous users2024-02-05mg2+
43.(1) Oxygen (2) Downward emptying method (3) The color in the water turns red.
b．③ c．② d．⑧
Not tight, the pH test paper can only measure the alkalinity of the substance, the substance is not necessarily Ca(OH)2CaCO3, react with dilute hydrochloric acid, a large number of bubbles are generated, and it is passed into the clarified lime water to observe whether the solution is turbid.
38.(1) Physical chemistry.
2) Acidity of the acid Oxidation of the acid.
3) H2 is elemental, CO2 is a compound, and CO2 is an oxide.
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Anonymous users2024-02-04mg fe
43.(1) O2 (2) Downward air exhaust method (3) The phenolphthalein solution turns red, and the solution enters the test tube.
b．③ c．② d．⑧
It is not rigorous, and the pH test paper can only measure the substance as alkaline, which cannot mean that the substance is Ca(OH)2
caCO3, take a test tube, add a small amount of sample, add dilute hydrochloric acid dropwise, bubbles are generated, gas is passed into the clarified lime water, and the clarified lime water becomes turbid.
38.(1) Physical chemistry.
2) Acidic oxidation.
3) H2 is an elemental substance, and CO2 is a compound.
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Anonymous users2024-02-039 (1)a Barium hydroxide.
2) b Copper hydroxide.
c Barium sulfate.
3) Barium hydroxide + copper chloride = barium chloride + copper hydroxide (precipitate) Barium chloride + 2 Silver nitrate = 2 Silver chloride (precipitate) + Barium nitrate Barium hydroxide + sulfuric acid = 2 water + barium sulfate (precipitate) Barium hydroxide + copper sulfate = copper hydroxide (precipitate) + barium sulfate (precipitate).
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Anonymous users2024-02-02caco3+2hcl==cacl2+co2+h2o100 111 44m m
Find m= m=
Now the key is to demand the quality of the solution; We noticed that the CO2 in the product is removed because the gas runs away, and the other substances are still in the solution, and of course the impurities are filtered, so we know that the mass of the solution is.
The mass fraction of calcium chloride is:
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Anonymous users2024-02-01The quality of the solvent is not required for this question.
caco3+2hcl==cacl2+co2+h2o100 111 44x y
x = y = mass fraction of calcium chloride in solution = %.
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Anonymous users2024-01-31The mass of CaCO3 reacting with dilute hydrochloric acid is:
Solution: Let the mass of CaCl2 be x and the mass of H2O be ycaco3+2HCl=CaCl2+CO2? +h2o100 44 18x y
x y solves: x=, y=
The mass of the solution after the reaction is.
cacl2％=———100％≈71％
Answer: After the reaction, the mass fraction of calcium chloride in the solution is 71.
Note: The remaining gram solid mass is the mass of the impurity.
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Anonymous users2024-01-30First of all, it was determined that calcium chloride and carbon dioxide were formed in the experiment, and according to your calculation (I didn't calculate), a total of calcium chloride was generated. According to the equation, carbon dioxide can be generated, and the solids in the reaction are reduced to a total of gas, from which it can be seen that the mass of the solution is increased as, and the other total is added to 25g of hydrochloric acid liquid, that is, the total mass of the solution, and the solvent mass of calcium chloride can be obtained by removing the solvent calcium chloride.
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Anonymous users2024-01-29m: Limestone and hydrochloric acid react to form carbon dioxide, which makes the clarified lime water turbid.
Medium n: cao+h2o===ca(oh)2
The calcium hydroxide (hydrated lime) produced by the reaction is slightly soluble in water, so there will be white cloudiness.
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Anonymous users2024-01-28Standard Answer:
Hydrochloric acid drops into calcium carbonate to produce carbon dioxide, which reacts with clarified lime water to form calcium carbonate precipitate, so it is turbid. You were right.
Another drop of water into calcium oxide, the reaction releases a large amount of heat, the temperature increases, the solubility of calcium hydroxide decreases with the increase of temperature, lime water is originally saturated, the solubility decreases will lead to solute precipitation, and there will also be turbidity, but turbidity is solid calcium hydroxide.
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Anonymous users2024-01-27I hate Haida, concise and accurate is best!
CO2 is produced in m, and calcium carbonate precipitates are formed in saturated lime water.
n In the second test tube, the water releases a lot of heat when it encounters quicklime, and the solubility of lime water decreases with the increase of temperature, so there is precipitation precipitation.
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Anonymous users2024-01-26The temperature in both test tubes will increase, so that the temperature of the two bottles of saturated lime water will increase, and the solubility of calcium hydroxide will decrease with the increase of temperature, so they will become turbid.
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Anonymous users2024-01-25Acids and alkalis. Reactions belong to complex.
dereaction; Type. Sour. Alkali.
Sour. Salt. Salt. Alkali.
Salt. Salt. Can the reaction be dissolved. Condition. Thing.
Requirements:1Water.
Gas. Precipitation. All three are arbitrarily satisfied.
Dot. 2. Reactants.
Requirements: Formula.
Salts. Acid and alkali search are both. Yes. Salt salt.
Both salt and alkali must be dissolved (said. Sour. Alkali.
Sour. Salt. React. To be satisfied. Thing. Request.
Hair. All. Salt. Salt.
Salt. Alkali. Reaction except. To be satisfied.
Thing. Outside the requirements. Hair. React.
Both Sejiaoshan compounds are required. Dissolve. Water.
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Dude, the Tao Te Ching is not a classical Chinese text, especially the first chapter, which is the general outline of the Tao Te Ching, which cannot be translated in modern Chinese, and you have to rely on your own comprehension to understand it, everyone looks at it and understands things differently, you want a ready-made, basically impossible. Even if there is a so-called translation, it has long since changed its taste, and what you see is not the most standard, or even irrelevant.
My mother gave birth to a little brother, but unfortunately died. The police forced us to move, so my mother and I followed my grandmother, who had come to visit her, back to our hometown.
Pan Dongzi's father Pan Xingyi went to night school to study, understood many revolutionary truths, established the Red Guards, became the captain of the Red Guards, and carried his head to fight the local tyrants to divide the fields, in an incident in which his father Pan Xingyi beat the local tyrants, his father's leg was injured, and the doctor's anesthetic was only one of his own operations, which took a long time, but he gave the bullet casing that was taken by the Red Army uncle next door to Pan Dongzi, and then Pan Dongzi's mother also became a party memberIn the end, because his father was a revolutionary, he went outside, and before leaving, his father, Pan Xingyi, gave his son, Pan Dongzi, a shining red star.