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Anonymous users2024-02-061.The black solid is Cuo, where the mass of Cu is 8g*64 80 = that is, the mass of the copper element reacting with NaOH is.
2naoh---cu
xx=8g, that is, the mass of NaOH is 8g
The solute mass fraction of the original NaOH solution is 8g 80g = 10% 2In the analysis of these substances, the gas must be the reaction of carbonate and hydrogen ions, and at the beginning K2CO3 will react with HCl or BaCl2, so D can only be selected
3.Note that the NO3 ions in B can oxidize the SO3 ions, and the produced SO4 ions react with the BA ions
4.(1) Let the mass of Na2CO3 be X
na2co3---co2
x gets x=2) because the reaction is complete, so only the NaCl solute is present in the solution, and the mass of NaCl is Y
2nacl---co2
117 44yy=
Total mass of solution =
So the mass fraction of sodium chloride in the solution is.
Pay attention to the correct writing of the chemical formula, otherwise the exam will be deducted!
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Anonymous users2024-02-05The first breakthrough: the red metal powder has only copper, so d is Cu
Y is a ferrous metal powder, considering the color, and Cu, it can be guessed that it is Cuo, so C to D and G to D are two reduction reactions.
A can react with both acid and alkali, and it is easy to guess sodium carbonate (or sodium bicarbonate), so considering that C as a reducing agent, it should be carbon element or carbon monoxide, so the above path is, sodium bicarbonate + acid --- carbon dioxide, carbon dioxide + carbon dioxide (X, black powder) - carbon monoxide (C), carbon monoxide + copper oxide --- copper.
The alkali that can react with sodium carbonate is obviously lime water (calcium hydroxide), the reaction produces calcium carbonate and sodium hydroxide, because E to F is a neutralization reaction, so E must be sodium hydroxide, and the product of the neutralization reaction is water and salt, and the common salt is definitely not liquid at room temperature, so F is water, considering that G should also be a reducing agent, so G is hydrogen electrolyzed by water.
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Anonymous users2024-02-041. D red metal is of course copper, so y black solid is copper oxide, c is a reducing substance, it should be CO, it is made of black solid X (should be C) B is CO2 A is Na2CO3
2. CO2 + C = high temperature = 2co The use of carbon monoxide: as a fuel, smelting metals 3, it is inferred that the following Na2CO3 + Ca(OH) 2== CaCO3 + 2NaOH E-F is a neutralization reaction, so E is NaOH, F is the water generated by the neutralization reaction, and the water is electrolyzed into g It should be hydrogen, so that it can also reduce Y copper oxide to generate copper.
na2co3+ca(oh)2==caco3+2naoh naoh+hcl=nacl+h2o
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Anonymous users2024-02-03(1) Soda.
nahco3
2）c＋co2＝2co
as fuel (3) Naoh
4) 2H2O (energized) 2H2 O2
Wrong.. Shifting..
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Anonymous users2024-02-02Acid: HCl base: Ca(OH)2A:
naco3(nahco3) b:co2 c:co d:
cu e:naoh f:h2o g:
h2 x:c y:cuo The rest of the equation is written by yourself.
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Anonymous users2024-02-011) Three kinds: hydrated lime, limestone.
Four: NAHC3
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Anonymous users2024-01-312kmno4 == k2mno4 + mno2 + o22kclo3 == 2kcl + 3o2
Therefore, only one O in KMno4 generates O2, and all 3 O's in KCLO3 generate O2, so KCLO3 loses more mass, i.e., KCLO3 leaves less mass, so the pointer is biased to KMno4, that is, to the left.
Option b is known from the first 15g a all reactions, and then add 10g a to react all 15g b, indicating that 25g a and 15g b are completely reacted, so 15g a and 9g b are completely reacted, so the first b is left with 15 - 9 = 6g, a is wrong.
15g a produces 30g d, so 25g a produces 50g d, b pair.
The mass ratio of A to B in the reaction = 25:15 = 5:3, C is wrong.
The mass ratio of A to C in the reaction = 15:30 = 1:2, D is wrong.
So choose B
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Anonymous users2024-01-30The answer is: b reaction equation: 2kmNO4 = K2mNO4 + O2 + mNO2 relative molecular mass 316 32
2kclo3=2kcl+3o2
From the above, it can be seen that potassium permanganate is heated and runs away less oxygen, so the left side is heavy, and the pointer is left by the known, the first 15g a is all reacted, and then 10g a is added to react all 15g b, indicating that 25g a and 15g b are completely reacted, so 15g a and 9g b are completely reacted, so the first b is left 15 - 9 = 6g, a is wrong.
15g a produces 30g d, so 25g a produces 50g d, b pair.
The mass ratio of A to B in the reaction = 25:15 = 5:3, C is wrong.
The mass ratio of A to C in the reaction = 15:30 = 1:2, D is wrong.
So choose B
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Anonymous users2024-01-29Look at this, it should work.
Example 2, add an appropriate amount of iron powder to the mixture of dilute sulfuric acid and copper sulfate to make it happen to be completely reacted, and the solid obtained by filtration after the reaction is equal to the mass of the added iron powder, then the mass ratio of sulfuric acid and copper sulfate in the original mixture is ( ).
A 80:7 B 8:70 C 7:80 D 56:64 Analysis: This problem can find the relationship between the conditions and the two chemical equations given in the question:
fe + cuso4= feso4+ cu56g 160g 64g
fe + h2so4= feso4 + h2↑64－56g x
If the mass of the generated copper is 64g, then the iron consumed is also 64g, the copper only consumes 56g of iron, and the rest of the iron reacts completely with sulfuric acid, so the mass of sulfuric acid is 14g, and the mass of copper sulfate is 106g, so the mass ratio of sulfuric acid to copper sulfate is 14g:160g 7:80
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Anonymous users2024-01-28In order to have 2 s atoms in each molecule, write all three atoms of abc as 2:
2 h2s 2 so2 2 so3 cs2
In this way, the mass fraction of the sulfur element is the largest relative to the molecule with the smallest molecular mass.
a：2 h2s 34×2=68
b：2 so2 64×2=128
c：2 so3 80×2=160
D: 76 So choose A
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