There are several chemistry questions that can be added, and urgent chemistry questions can be added

1、(1)na2o;(2)co2;(3)h2co3;(4)naoh;(5)na2co3;(6)nahco3

2. Add BA (NO3)2

Ba(NO3)2+Na2SO4=BASO4 precipitate+2nano33, BA(NO3)2

Ba(NO3)2+H2SO4=BaSO4 precipitates 2HNO3 is not available for AGnO3 because AG2SO4 is slightly soluble).

4. NaOH quality: 20 20 4g

2naoh+h2so4=na2so4+2h2o4g xx=

，co2 ，h2co3 ，naoh ，na2co3 ，nahco32.Add barium nitrate solution dropwise.

BE(NO3)2 + NaSO4 = BaSO4 precipitate + 2 NaNo3

Metathesis. H2SO4 + BACl2 = BaSO4 precipitate + 2 NaCl

h2so420g*20% x

4g：x = 80：98x =

1,1) Na2O (Seems to be. )

2)co23)h2co3

4)naoh

5) NACo3 (Doesn't seem to be.) )

6)nahco3

Na2SO4 + BA(NO3)2 = 2nano3 + BaSO4 BAC2H2SO4 + BACL2 = BaSO4 +2HClHCL and BACL2 do not react.

4. Let this quantitative amount of petroleum products contain sulfuric acid as m

2naoh+h2so4=na2so4+2h2o20%*20g m

Do the rest for yourself. I don't know if it's right.

[Condition combing].

WZ belongs to the same main family.

x is adjacent to wy, respectively.

v and w v and z can form covalent compounds with a number of atoms of 4:1.

And you can draw a sketch on paper and roughly understand it.

The main conditions, one is [4:1] and the other is [covalent compounds] are very important.

Because wz is in the same family, the valency can only be -1, it cannot be -2, and if so, v is +8 valence, which does not exist.

Therefore, it can be determined that Wz is in the seventh main group, and because it is in a short period, W is [F fluorine] and z is [Cl chlorine].

X is adjacent to W and has a smaller atomic number than W, then X is [O Oxygen].

X is adjacent to Wy, and Y is larger than X atomic number, indicating that it is adjacent to the top and bottom, so Y is [S sulfur].

There is one V left, because it is +4 valence, which can be judged to be in the fourth main group, which may be [C carbon] or [Si silicon], and according to the increase in the atomic number of the five short-period elements of VXWYZ, V can be determined to be [C carbon].

C carbon] [F fluorine] o oxygen [s sulfur] cl chlorine].

Hello, I also looked at the answers of the people upstairs, and found that we disagreed on the question of 4:1, so I will consider it as two cases.

If the quantity ratio is v:w=4:1, then it is the answer of several people upstairs.

v:h x:b w:c y:al z:si

If the quantity ratio is w:v=4:1, then that's my answer.

v w x y z

C carbon] [F fluorine] o oxygen [s sulfur] cl chlorine].

That's it.

v-hw-c

x-by-al

The Z-Si breakthrough is that "V and W V and Z can form covalent compounds with a 4:1 atomic number".

This sentence shows that the valence of w and z + 4 valence can only be carbon group elements.

It is clear that V is hydrogen, X is boron, W is carbon, Y is aluminum, and Z is silicon. To give me extra points, it took me nearly two minutes.

(1) The molar mass of the S atom is 32g mol 1molH2SO4 with a mass of 98g

1molH2SO4 contains about 2 sulfuric acid molecules, 2 hydrogen atoms, and 4 oxygen atoms.

contains molecules.

2) The ratio of the mass of two substances SO2 and SO3 is 5:4, the ratio of the total number of atoms contained in them is 15:16, and the ratio of the number of oxygen atoms contained in them is 5:

The ratio of the number of sulfur atoms contained in 6 is 5:4

3), there are five substances: 10mlH2O (density of 24 power HCL 147GH2SO4

The largest amount of matter in them is the largest number of molecules

The one with the largest number of atoms is the one with the largest mass filled in the blank with an ordinal number).

Helium particle count: 2 Mass: 8g, Amount of substance: 2mol Molar mass: 4g mol

H2SO4 particle count: 22 power, mass: amount of substance: molar mass: 98g mol

Number of H2O particles: Mass: 9g Amount of substance: molar mass: 18g mol

This is really easy, look up the book yourself.

1. The enthalpy criterion is the energy criterion, which should be from high energy to low energy, and the exothermic change, so D is chosen

2. Use free energy to judge: <0, so it can be spontaneous, that is, choose A

It's almost time to find a materialization and review it, I haven't read it for too long.

1. D oil is insoluble in water.

2. A Flour is insoluble in water, and there are many substances in flour, which have different changes in water at different temperatures, such as gelatinization of starch.

3. B oil is insoluble in water.

4. A Due to saturation, the BCD option will still make the original solution saturated, and the solute mass fraction will not change.

5. A baking soda is NaHCO3, soluble in water; The main component of limestone is caCO3, which is insoluble in water.

6. D leveling balance game code is always at the left end; Sodium hydroxide solids can not be weighed with filter paper, and a beaker should be applied; It cannot be dissolved with a graduated cylinder.

7. D A can be replaced with a metal that is more active than MG; B can be burned with H2; c can add bacl2; D incapacitated with NO3- to form precipitated ions.

8. C Activated carbon is used to adsorb tiny particles, and cannot soften hard water.

9. d is identified by the thermal effect of the reaction.

10. C NaOH absorbs HCl, and CO reduces Cuo to generate CO2

11. C a counterexample NaHCO3+NaOH===Na2CO3+H20

b counterexample 2H2S + SO2 === 2H2O + 3S

d Not all 10g is converted into a product.