When Xiao Ming was doing experiments in the laboratory, he obtained two solutions

1。Limewater.

Because carbon dioxide reacts with lime water to form a white precipitate, the solution changes from clear to turbid.

However, there is no obvious phenomenon in the reaction with sodium hydroxide.

2。Sodium hydroxide.

Because of the high concentration of sodium hydroxide, carbon dioxide can be completely removed, while lime water is calcium hydroxide.

Slightly soluble in water, the concentration is very low, and the absorption is small.

The phenomenon should be considered in the detection experiment, and the effect should be considered in removing impurities :)

The verification of carbon dioxide is lime water, which reacts with carbon dioxide to form a white precipitate of calcium carbonate, which has an obvious effect and is easy to observe.

Carbon dioxide is removed with sodium hydroxide, the reaction product of which is sodium carbonate, or sodium bicarbonate, which is removed completely.

It has been proved that with calcium hydroxide, the removal of sodium hydroxide carbon dioxide can react with calcium hydroxide to form calcium carbonate precipitation, but with sodium hydroxide there is no precipitation, because sodium salts are soluble, and the effect is better when removing sodium hydroxide.

NaOH is used to remove CO2 because both solutions can react with carbon dioxide in the first place. However, lime water is used to test carbon dioxide, it reacts less carbon dioxide in mass compared with NaOH, and Ca(OH)2 is dissolved in water in a small amount, so there is not much Ca(OH)2 in the ionic form in the lime aqueous solution, so it is more appropriate to use NaOH to remove carbon dioxide. However, the premise is that the other gases in the sample gas do not react with sodium hydroxide.

The test has CO2With calcium hydroxide solution, if there is one, calcium carbonate precipitate will be generated, white. Absorption (removal), with sodium hydroxide, the absorption capacity is large (sodium hydroxide is soluble in water, and calcium hydroxide is slightly soluble in water), to generate sodium carbonate,

1.The use of lime water produces white precipitation, and the phenomenon is obvious.

2.With sodium hydroxide solution, the solubility of lime water is relatively small, and the absorption may be incomplete, while the solubility of sodium hydroxide is relatively large, and the amount that can be absorbed is more.

Lime water produces a white precipitate.

Ca(OH)2 + CO2 = CaCO3 (precipitate) + H2O

Sodium hydroxide. 2naoh+co2=na2co3+h2o

Limewater. This is because carbon dioxide can make the clarified lime water cloudy.

Xiao Ming did two classes of infiltration experiments, please call Wang accordingly: (1) Experiment 1: As shown in Figure A, at a certain temperature, Shi Zi added B grams of copper sulfate powder to A grams of saturated copper sulfate solution. Then what is the mass of the reduced saturated solution in grams? How does it work?

Under the condition that the pre-temperature nano degree is unchanged, a little white copper sulfate powder is added to the copper sulfate saturated solution, and the white CuSO4 will bind to the H2O in the solution to form a blue CuSO4·5H2O crystal precipitation, which will lead to the reduction of solvent water in the original saturated solution. Due to the reduction of solvent in the original saturated solution, the solute in the original saturated solution will also precipitate a part, and the solute mass of the original saturated solution will also be reduced; Since the mass of solute and solvent in the original saturated solution decreases, the total mass of the saturated solution also decreases.

Summary. Xiao Ming did two experiments on infiltration outside the class, please shout Wang accordingly: (1) Experiment 1:

Hello people, according to the question you described, the answer is as follows: the quality of the reduced saturated solution is a-c 9025090250 grams (if you think my answer is still satisfied, you can click on my lower corner for evaluation), looking forward to your like, your efforts are very important to me, your avatar is a smile to a consultation. Finally, I wish you good health and a happy mood!

What I want is this specific process.

It's not just an answer, the answer I know.

Okay, you wait a minute.

Hello, the total mass is (A + B) grams, precipitated C grams, and the grinding slag has become A + B-C grams, and the B is replaced by a blind representation of C, and Hengshu B c = 250 160

The experimental materials are: a stable student power supply, three wires of the same thickness, three iron nails of the same length and thickness of the same length, and several paper clip bridges.

1) Based on the above preparations, I speculate that Xiao Ming wants to conduct research and research on the relationship between the magnitude of the magnetic force of the electromagnet and the ——.

2) In addition to this factor, we believe that the magnitude of the magnetic force of the electromagnet is also related to the ——, factor.

Answer: 1) The thickness of the iron core.

2) It is related to factors such as the size of the current, the number of turns of the coil, the length of the core, and the presence or absence of the core. It's so fierce.

Parse. <>

It is related to the number of turns of the coil, and the number of turns of the coil can be changed by the wiring method;

Depending on the magnitude of the current through the conductor, the current through the conductor can be changed by the sliding rheostat, and the current can also be increased by increasing the number of cells;

It is related to the presence or absence of iron core, which is strong when there is an iron core and weak when there is no iron core.

Verify the selection of lime water, because the reaction produces calcium carbonate which is an insoluble substance, and the phenomenon is that the clarified lime water becomes turbid; Sodium hydroxide is removed because carbon dioxide is a weak acid when dissolved in water, that is, carbon dioxide is an acidic oxide that reacts with a strong base such as sodium hydroxide.

1.Cleared lime water is introduced. Turbidity indicates that there is carbon dioxide CO2 + Ca(OH)2 CaCO3 + H2O2

Pass into NaOH solution. Carbon dioxide is a weak acid when dissolved in water, and NaOH is a strong base that is easily soluble. The two react.

2NaOH + CO2 (small amount) Na2CO3 + H2ONAOH + CO2 (overdose) NaHCO3

If it is a secondary school stage: 1. Lime water (calcium hydroxide solution) becomes turbid, and the reason for the turbidity is the formation of insoluble calcium carbonate;

2. Choose NaOH solution, because NaOH is a soluble strong base that is easy to react with acidic oxides.

(1) Verify the presence of carbon dioxide in a bottle of gas sample with clarified lime water; Because CO2 can react with Ca(OH)2, the main component of clarified lime water, to form CaCO3 white precipitate, while CO2 reacts with NaOH solution without obvious phenomenon

Sodium hydroxide solution is used to remove carbon dioxide from gas samples; Because sodium hydroxide is easily soluble in water, calcium hydroxide is slightly soluble in water, and the two are dissolved in the same amount of water, the mass fraction of solute in sodium hydroxide solution is larger than that of solute in calcium hydroxide solution, so sodium hydroxide solution absorbs carbon dioxide better

2) Decomposition reaction to generate gas Students have learned that when hydrogen peroxide is decomposed, oxygen will be released, which will inflate the balloon Hydrogen peroxide is in the dropper, and the bottom of the Erlenmeyer flask is manganese dioxide

Students may not do much about this question, and they may not consider that the CaO+H2O Ca(OH)2 substance CaO reacts with water to release a large amount of heat, and the temperature of the solution rises, causing the gas to expand and the balloon to become larger

The displacement reaction between metal and acid can produce hydrogen gas such as: Zn+H2SO4=ZNSO4+H2

Of course, there are multiple answers to this question, such as sodium carbonate and calcium carbonate for solids; The liquid is hydrochloric acid

Therefore, the answer is: (1) calcium hydroxide [Ca(OH)2]; CO2 can make the clarified lime water turbid, and there is an obvious phenomenon.

Sodium hydroxide (NaOH); NaOH is easily soluble in water and absorbs more CO2.

2）2h2o2

mno.2h2o+o2↑；cao+h2o═ca（oh）2；zn+h2so4=znso4+h2↑．

1) The data in Table 1 or Table 2 can be seen that the rougher the contact surface, the greater the resistance of the trolley, from which it can be seen that the magnitude of the friction force on the trolley is related to the roughness of the contact surface

2) In the experiment, always let the trolley slide down from the same height of the inclined plane, the purpose of this is to make the initial velocity of the trolley when it reaches the horizontal plane equal

3) From the experimental data in Table 1 and Table 2, it can be seen that when the initial velocity of the trolley is the same, the smoother the contact surface, the smaller the resistance of the trolley, and the greater the distance of the trolley sliding

4) According to the experiment in Table 1 or Table 2, it can be seen that the smaller the resistance of the small group car, the slower the change of the trolley, and the greater the sliding distance of the trolley, so that if the horizontal plane is smooth, the trolley is not affected by the resistance, the trolley will remain unchanged, and the trolley will do a uniform linear motion

Therefore, the answer is: (1) roughness; (Omen 2) make the initial velocity of the trolley when it reaches the horizontal plane equal;

3) The smaller the resistance of the trolley, the greater the distance of the trolley sliding; (4) Straight line at uniform speed

Assuming 100 g of solution, 60 g of solvent, 40 g of water, the concentration of added water decreases, 60 48 = 125 g, add 25 g of water

Uh, I don't know how to do without equations, can't you use equations if the problem requires you to use equations?

Let the addition of water be x, then 60 (100+x) = x=25