Urgently seeking a chemistry question, the third year of junior high school, urgent

Solution: Copper oxide x is required for copper extraction.

h2+cuo=cu+h2o

x80/64=x/

x = A: The quality of the copper oxide required is.

To do this kind of problem, you need to find the equation, accurately substitute the mass and molecular weight, and find the unknown quantity.

Solution: Copper oxide x is required for copper extraction.

H2+Cuo = Heating Cu+H2O

x80/64=x/

x = A: The quality of the copper oxide required is.

Solution: Copper oxide x is required for copper extraction.

h2+cuo=cu+h2o

x80/64=x/

x=A: The mass of copper oxide that needs to be oxidized is.

Calculate with equations

d k2cr2o7

Potassium +1 valence, oxygen-2 valence;

cr2(so4)3

Sulfate-2 valence.

(1) In the step: the substance to be added is , and the method of separating the obtained mixture is .

2) In the step: the substance to be added is , and the chemical equation for the reaction is .

3) Do you think it is reasonable for a student to think that the solid obtained after the step is pure silver and does not need to be processed? , the reason is . .

4) Why do you want to mix solution 2 and solution 3 in step 3? .

Is that the problem?

Here's the answer. 1).FE Filtration(2).Dilute sulfuric acid Fe+H2SO4=FeSO4+H2 (3).

Unreasonable Because for the ag+ to be completely displaced, an excess of iron (4) must be addedBoth filtrates contain ferrous sulfate, which can obtain more ferrous sulfate and be used comprehensively (other reasonable answers are also acceptable).

Excess iron is added to the wastewater and filtered to obtain a solid (silver and iron) solution 1 (ferrous sulfate solution); Excess dilute sulfuric acid is then added to the solid of silver and iron to obtain silver by filtration; Then add excess iron to solution 2 and solution 3 (both ferrous sulfate solution) to obtain all pure ferrous sulfate solution, and then evaporate and cool crystallization to precipitate ferrous sulfate crystals.

1.Filter 2Elemental iron is added for the displacement reaction 3Crystallized.

The first step is filtration, the second step is the addition of elemental iron, and the third step is the evaporation of the solvent.

The mass of the original solution is 50g, the solute mass is 50*10%=5g, and the solute is only dissolved by adding 10g, then the solution mass is 50+5=55g, the solute mass is 5+5=10g, and the mass fraction of the solute in the solution is 10, 55*100%= The idea is like this.

If it is helpful to the landlord, I hope to adopt it.

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The following information can be extracted from the question stem: the mass of the original solution is 50g, of which the solute mass fraction is 10%, that is, 50x10%=5g, after adding 10g of solute and stirring, there is still 5g undissolved, that is to say, after stirring, the solute mass in the solution is 5+10-5=10g, and the total mass of the solution at this time is 50+10-5=55g, therefore, the mass fraction of the solute in the solution at this time is 10 55=.

Add 10g of the substance to the solution of a substance, and after full stirring, there is still 5g of solid undissolved, indicating that the original solution can only be dissolved for another 5g to become saturated, so the mass fraction of the obtained solution = solute mass Solution mass (undissolved 5g cannot be included in the solution) * 100% = (50g * 10% + 5) (50 + 5) * 100% = (10 55) * 100% =, rounded to.

m The original substance is 50g * 10% = 5g

m added substance is 10g-5g = 5g

mm, the current substance is (m original substance + m added substance) 5g + 5g = 10gm, and the current solution is (m original solution + m added substance) 50g + 5g = 55g mass fraction is (m present solution m now substance) 10g 55g = that is, select b

Before the substance is added, there is 5g of solute (50g of 10%), and 50g of solution; Add 10g of the substance, but only dissolve 5g, which is equivalent to adding 5g, at this time the solute mass is 5g + 5g = 10g, and the solution mass is 50g + 5g = 55g.

The mass fraction of the solute is 10g 55g 100%=.

Soluble mass: 50*10%+5=10

Solution mass: 50+5 = 55

50*10%=5 This is the solute in the original solution.

5g of 10g is not soluble 10-5=5, which is the solute that is dissolved again, and now the solute is 5+5=10

The solution is 50 + 5 = 55

10 55=, that is.

Soluble mass = 50 * 10% + 5 = 10g

Mass fraction of solute = 10 50 + 5 =

Pick B. It is important to note that undissolved 5g solids are not a component of the solution.

50g of a solution of a substance with a solute mass fraction of 10% so the solute (50*10%) is obtained

Add 10g of the substance, and after full stirring, there is still 5g of solid undissolved, so the current solute is (50*10% +10-5)g, and the mass of the solution is (50 + 10- 5)g

Find the quality score.

What is a quality score? Solute solution, right?

What is Solution? The original solution + post-solid-residual solid mass is right, the remaining solid does not belong to the solution, which does not explain well... This has something to do with the definition of the dispersion system, is it a total of 55g of solution, how much solute is there?

50 10% + 10-5 = 10g, so the mass fraction is 10 55 100% = b, right?

First, calculate the mass of calcium carbonate: 59*;

According to the reaction formula, one part of calcium carbonate produces one part of carbon dioxide, so the mass of carbon dioxide:

The second question, according to the reaction formula, one part of calcium carbonate needs 2 parts of hydrochloric acid, so the mass of hydrochloric acid is: and the mass fraction is:

The third question, from the overall point of view, according to the conservation of mass, the mass of the solution is the mass of the total mass excluding impurities and the resulting carbon dioxide, i.e., 59+500-59*

The solute is calcium chloride, and one part calcium chloride is produced from one part calcium carbonate, and the mass of calcium chloride is obtained

So the quality score is:

What is the topic in the workbook, explain it clearly.

CaCO3 + 2HCl = CaCl2 +CO2 +H2O calcium carbonate mass;

You can calculate the mass of each substance, do your own calculations.

One part of calcium carbonate and two parts of hydrochloric acid react, then N(HCl)=2N(CaCO3)=2*59g*25% 100g*mol-1=

Answer: (1) The relative molecular mass of the three elements is 180 (2) (3) 10kj 5%=

I said, big brother, no matter how people look at your picture, I can't see it clearly.