Chemistry Questions!! Write the process and do a chemistry problem!!

It can be calculated based on the apparent neutrality of the compound.

In this compound, Ca is +2, Mg is +2, Si is +4, O is -2, and OH is -1.

Yes. 2*2+2*x+4*y+(-2)*22+(-1)*2=0 is simplified to x+2y=21, bringing in ABCD 4 answers, only A matches.

So the answer is A

According to the compound, the total valency should be 0

Ca is +2 valence, Mg is +2 valence, SI is +4 valence, O is -2 valence, and OH is -1 valence.

So 2 2 + 2x + 4y-44-2 = 0

Calculate x:y=5:8

8 Calcium and magnesium are both positive bivalent, silicon is positive tetravalent, and the total valency must be 0.

2*2+2x+4y=2*22+2*1=46x=5 y=8.

ca=+2 mg=-2 oh=-1 o=-2 si=44+2x+4y=46

This gives x+2y=21

The answer is that asbestos is written as (cao)2(mgo)5(sio2).

According to the total valence is zero.

ca +2 ,mg +2,si +4 o -2 (0h) -12*(+2)+x*(+2)+4*(+4)+22*(-2)+2*(-1)=0 and x,y are integers.

x=5 y=8 * is a multiplier sign.

According to the total valency of the compound, it should be 0 to choose a

Use the chemical valence plus or minus 4-2-22*2=-42 2x+4y=42 to substitute the answer into option a

The amount of gaseous substances before and after the reaction does not change, as long as the added matter is converted to xy and proportional to 2molx and 3moly, the volume fraction of each substance remains unchanged.

1) The volume fraction remains unchanged, and the added substance is equal to 2 times 2molx and 3moly, then the concentration at equilibrium is also 2 times, that is, the amount of the substance of z is 2amol

2) Convert the reactants to x and y, and add z to the chemical equation of the reaction: x

2y==3z

The amount of material before transformation --- 3---2---t

The amount of the transformed substance is --t 3---2t 3---t The amount of the transformed substance is -3+t 3---2+2t 3--0(3+t 3):(2+2t 3)=2:3

Solution. t=15, that is, adding z is 15mol

3) In equilibrium, z is equivalent to adding 2 and 3

Let y be amol, z be bmol

The chemical equation for this reaction: x

2y==3z

The amount of pre-transformation substance.

The amount of the transformed substance – b 3---2b 3---b the amount of the transformed substance.

a+2b/3=

Solution. b=,a=

That is, you need to join.

Choose A. Easy method: MNO2 is a catalyst, does not react, and is insoluble in water.

After heating, KCLO3 decomposes into KCl and oxygen, and KCl dissolves in water, so the black solid is MNO2. As if the number of molecules in K and Cl is the same according to the chemical formula, then their mass ratio is the relative molecular mass ratio. In 100 grams, k is 39 grams, chlorine is grams, and the rest is the mass of oxygen produced.

100－。General method: set:

KCLO3 has x grams and KCL has Y grams. According to the total mass 100g, x y. Based on the mass fraction of k, (39 divided by 100 39.

Just solve the equation.

1. Take samples and drop them into sodium carbonate solution. Phenomenon and conclusion: Hydrochloric acid is produced by bubbles.

2. Take samples and drop them into copper chloride solution. Phenomena and conclusions: There is a blue flocculent precipitate of calcium hydroxide.

3. Sampling and carbon dioxide gas are introduced respectively. Phenomenon and conclusion: Calcium hydroxide appears when there is white cloudiness.

4. Take samples and drop them into ferric chloride solution. Phenomena and conclusions: There is a reddish-brown precipitate that appears calcium hydroxide.

5. Take samples and add iron powder separately. Phenomenon and conclusion: Hydrochloric acid is produced by bubbles.

It must be absolutely correct, and the teacher will praise you.

1. Steps: Take a sample, add magnesium powder, Phenomenon and conclusion: If there are bubbles, it is hydrochloric acid, and vice versa, calcium hydroxide solution.

2. Steps: Take the sample, add copper oxide powder, heat, Phenomenon and conclusion: If there is a solution that turns blue, it is hydrochloric acid, and vice versa, it is calcium hydroxide solution.

3. Steps: Take a sample, add sodium carbonate powder, Phenomenon and conclusion: If there are bubbles, it is hydrochloric acid, and vice versa, calcium hydroxide solution.

4. Steps: Take a sample, add copper hydroxide to precipitate, Phenomenon and conclusion: if there is a precipitate disappearing, it is hydrochloric acid, and vice versa, calcium hydroxide solution.

5. Steps: Take a sample, add calcium carbonate, Phenomenon and conclusion: If there are bubbles, it is hydrochloric acid, and vice versa, calcium hydroxide solution.

6. Steps: Take a sample, add sodium hydroxide solution with phenolphthalein, Phenomenon and conclusion: if there is red disappearing, it is hydrochloric acid, and on the contrary, calcium hydroxide solution.

1. Add sodium carbonate solution, if there is precipitation to generate calcium hydroxide, no precipitation to generate hydrochloric acid 2, add urea, if there is ammonia smell (and white precipitation to generate) for calcium hydroxide, no for hydrochloric acid 3, add silver nitrate, such as only white precipitate for hydrochloric acid, there is precipitation and then gradually turn into black silver oxide for calcium hydroxide.

4. Add dilute sulfuric acid, if there is precipitation to generate calcium hydroxide, if there is none, it is hydrochloric acid 5. Add oxalic acid, if there is precipitation, calcium hydroxide is generated, and if there is none, it is hydrochloric acid.

Hydrogen is mg--h2

zn--h2

al--3/2h2

The metal activity is mg--al--zn, and the previous reaction must be completed to react, and the rest can only be reacted if it is all mg reaction, then the mass is 3g

If it's all zn, the mass of the reaction is.

So the quality is.

c+caco3=cao+2co

The mass fraction of charcoal in the original mixture is.

In the air carbon and calcium oxide are not reflected.

There must be no correct solution

The total number of electrons of the compound is 74, and c is again positive bivalent. Hence there are 2 R atoms in each molecule.

If there is 1 c atom, the number of electrons outside the nucleus of c is 6, and the number of nuclear charges of r is 34.

If there are 3 c atoms, then the number of nuclear charges of r is 28. There are really not many trivalent metals, most of them are 34.

What is X? Is it the subscript x of CRX? Then I think that if we consider carbon in terms of the number of electrons alone, then 6+ax=74 (assuming a is the number of nuclear charges), then ax is 68. From the perspective of multiple-choice questions, you can only choose ,. In fact, it is carbon tetrachloride.

But from the metal element you said, you don't need to do this problem, because only d is feThe others are S, Br, Cl, and all three are non-metallic elements.

I prefer the answer to carbon tetrachloride, which is C, and it seems that iron is not directly bonded to C alone.

2fe(oh)3=fe2o3+3h2o

Red Fe2O3 powder.

Calculate the fe for.

It turned out to be added.

Then there is Fe in the original compound

Fe2+ is completely precipitated.

2Fe2+ +4OH- +O2=2Fe(OH)3 is calculated to have Fe

Then "only a pure oxynate (non-double salt) without crystalline water can be obtained, and there is no Fe2+ in the original solution, then the salt is K2SO4

Or the consumption is calculated by Fe2+ just completely precipitated.

So there's potassium from compounds.

Suppose x:fe:k=1:2:4 does not match the calculated quality and the problem and round off fe:k=1:2 then x=fe y=k

It can be calculated that the molar mass of the compound is 198

198-56-78) 4=16g mol z=o The compound is K2FeO4

Your question is not clear, according to the above question, this question cannot be calculated.