Chemistry master, hurry, hurry, junior high school questions

Any oxide that can react with acid to form salts and water is called an alkaline oxide. Most metal oxides are basic oxides.

Basic oxides must be metal oxides, but metal oxides are not necessarily basic oxides, such as manganese heptaoxide

Acid oxides are not necessarily non-metal oxides, but may also be metal oxides, such as the oxide of aluminum is an amphoteric oxide, that is, alumina is an amphoteric oxide (aluminum hydroxide is also an amphoteric compound).

Most metal oxides are basic oxides.

Metal oxides are not all basic oxides.

Some can react with acids and alkalis, which are neither acidic oxides nor basic oxides.

Many metal oxides are dissolved in water to form alkalis, such as Na2O dissolved in water to form NaOH, Cao dissolved in water to form Ca(OH)2, and so on.

There are some oxides that are not metal oxides and are not soluble in water, but there are also their relative bases, such as silicic acid, which is the case with SIO.

Some acidic oxides, whether soluble in water or not, are called hydrates.

Metal oxides are mostly basic, but metal oxides are a part of basic oxides.

Substances such as SO4 and CO3 that are combined with other elements are combined with H to become acidic substances such as sulfuric acid, carbonic acid, etc.

Combined with metal ions, such as Cu and Zn, it becomes a metal oxide, which is a mitigating substance.

Acidity and alkalinity are generally like this.

Metal oxides are mostly basic (zinc and aluminum are neutral).

Basic oxides, which are divided into non-metallic and metallic basic oxides.

There are CAO (calcium oxide or quicklime), Fe3O4 and so on.

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,,, according to the amount of zinc, referring to the above reaction order, when n(zn) n(feso4), the reaction is 1 3.then a is cu, which does not fit the topic.

When N(FeSO4) N(Zn) N(FeSO4)+N(CuSO4), the reaction is , then A is Fe, Cu, and the second group is compliant.

N(Zn) N(FeSo4)+N(CuSO4), the reaction is , then a is Zn, Fe, Cu, and the fourth group is compliant.

Since the metallicity of Zn is stronger than that of Fe, when Zn exists, Fe in FeSo4 solution must be replaced, and then Cu in CuSo4 solution will be replaced, and the first group is wrong.

Similar to the above, the metallicity of Zn and Fe is stronger than that of Cu, so it is inevitable that the replaced Cu will be wrong.

That is, the metallicity of one metal is more metallic than that of another, and if the latter exists, the former must exist).

For reference, it should be right.

The first one is unreasonable: Zn is added to the solution, and according to the table of metal activity sequence, a displacement reaction will occur, and the remaining solid in the solution cannot be only Zn.

The second is reasonable. If the amount of Zn is just enough to replace Fe and Cu in the solution;

The third is unreasonable. According to the order of metal activity, if Zn and Fe are present, both can be displaced.

The fourth is reasonable. If zn is excessive, it will do.

a.Unreasonable, there will be at least the presence of cu in the composition.

b.Reasonable, Zn first replaced Cu, and then replaced Fe, at this time the Zn powder was not excessive.

c.Unreasonable, there will be at least the presence of cu in the composition.

d.Reasonable, at this time zn is sufficient.

Choose A. Zinc is the most reactive metal here. Replace the copper first; Replace the iron again (there is no question).

1.Add some zinc powder to the mixed solution of ferrous sulfate and copper sulfate, and Zn reacts with CuSO4 first, because Cu is the least active among the three. Then substance a has Cu2

Put A into a small amount of dilute sulfuric acid, there is gas to produce Cu does not react with H2SO4, so it is possible to replace Cu in the replacement of Fe, then A has Cu and Fe It is also possible to have excess, then A substance may have Zn, Fe, Cu!!

According to the law of conservation of mass, the reduction is carbon dioxide, and the mass of calcium carbonate in the actual reaction is calculated according to the equation, so the actual mass fraction of calcium is 20%, because it is just a complete reaction, so the mass of dilute hydrochloric acid reaction can be obtained, so the mass fraction of hydrochloric acid is, what questions can be asked.

caco3+2hcl=cacl2+h2o+co2↑x y

Get: x=2, y=

1) The actual mass fraction of calcium in calcium supplements.

2) The mass fraction of the solute in the dilute hydrochloric acid used.

1) Decreased, indicating that this is CO2, according to the chemical reaction equation, the mass of CAC3 is 5g, according to the mass fraction of calcium in CAC3 is 40%, it can be seen that the mass of calcium is 2g, and the calcium supplement is 10g, so the mass fraction of calcium supplementation is 20%.

2) decreased, indicating that this is CO2, according to the chemical reaction equation, indicating that the mass of HCl participating in the reaction is, because it happens to react, it means that the HCl reaction is finished, so the mass fraction is.

It's very simple, CaCO3+2HCl=CO2+H2O+CaCl2, according to the reaction equation, it can be seen that CO2 is scattered in the air, so the reduced mass is CO2, 1)N(CO2)=, so m(CaCO3)=so W=5 10=50%.

2)m(hcl)=;w=

You may not have learned the quantity of matter yet, but it will be easy.

Question 1: An appropriate amount of white phosphorus consumes the oxygen in the hollow of the original device, and it oxidizes itself into solid oxide, resulting in a decrease in the pressure of the device and a shift in the piston, while the oxygen content in the air is about one-fifth, so the volume of the gas after combustion is reduced to four-fifths of the original.

Question 2: I don't have a picture of what I think. The oxygen content in the air is about one-fifth, the air pressure of the device is less than the atmospheric pressure, and one-fifth of the gas consumed by the original device is the same as the atmospheric pressure after connecting the syringe, and one-fifth of the volume of gas must be supplemented by the syringe, that is, 10ml, and the amount of supplementation is how much oxygen volume is consumed by white phosphorus combustion. :

I'm not a teacher, so I'm not going to say it.

To be honest, I always feel that the description of your topic does not match the ** number issued, but the general meaning of the title is clear, that is, the piston moves west after combustion, and there is air inside the test tube before it is sealed, so sodium combustion consumes the oxygen in the test tube, and the oxygen content in the air is 1 5

So the piston moved the scale by 10ml.

White phosphorus burns and consumes oxygen in the air. There is about 21% oxygen in the air, so the original 5 volumes of air consume about 1 volume of L of oxygen, and the remaining 4 volumes of gas, so the piston stops at 4.

2.There is no picture, and I can't answer it yet.

1 Acid can turn purple litmus solution red.

2 Water does not make the litmus solution red, the purple color remains the same.

3 It means that when carbon dioxide dissolves in water and produces acid, when the test tube is heated, the red color gradually recedes and turns purple again, indicating that the carbon dioxide is decomposed and runs away.

It can make the purple litmus solution red.

Turns red, ( unchanged.

It turned purple again.

4:3, because the relative molecular mass of SO2 is 48, where the mass of the oxygen element is 32, the relative molecular mass of SO3 is 54, and the oxygen is 48, 32:48=2:

3。So 3SO2 = 2SO3, 3*48:2*54=4:3