Some junior chemistry questions, one junior chemistry question

1.It does not react because there is no lake gas.

2.reaction, all carbonates can react with acids.

3.Reduction, substitution into the chemical equation calculation, neutralization of the same mass of sulfuric acid, the mass of potassium hydroxide required is smaller than sodium hydroxide.

Because only it does not react with sulfuric acid.

5.A lot, such as iron powder, the most economical. It can also be magnesium (too expensive, people who are not sick do not use it), aluminum (not cheap), zinc, iron (the cheapest), copper, mercury (toxic, if you use it, you are poisoned).

The equation is too lazy to write, you can hi me, I have a document, send it to you.

Not reacting. React. No change. Pick B

Sodium chloride is fine.

I remember that if you want to react, the product will either have gas or precipitation, that is, you will generate a weak electrolyte Judge from this Hypothesis 1 Reaction Hydrochloric acid and zinc nitrate do not conform 2 Generate carbonic acid Unstable Produce carbon dioxide There is a gas reaction The third question is the hydroxide ion involved in the reaction And potassium and sodium and hydroxide are all one to one so it does not change Choose b The others should react with sulfuric acid The sodium chloride solution only plays the role of dilution Reduce the concentration The reaction will be slower Add sodium chloride In the third year of junior high school, only chloride ions react with nitrate Okay Hey, I'm waiting to watch the game Bored Help you answer the answer, I learned it a long time ago, and it may not be comprehensive.

2mg+O2=2mgo (condition is ignition) compound.

mg+2HCl=mgCl2+H2 (gas symbol to be indicated) substitution.

2Cu+O2=2cuO (Heated) Compounding.

4HCl+O2==2Cl2+2H2O (the condition is copper chloride as a catalyst, the temperature is 450 degrees, it is estimated that you will not need this) replacement.

CO2 is reduced by C at high temperature to form CO, and the equation is CO2 + C = 2CO (condition is high temperature) compounding.

Ignite 2mg+O2==2mgo (compound).

Heating. 2cu+o2==2cuo (compound).

mg+2HCl==2mgCl+H2 (displacement).

2mg+O2=2MGO chemical reaction (oxidation reaction), 2Cu+O2=2cuO, chemical reaction (oxidation reaction), mg+2HCl=mgCl2+H2 (gas symbol), displacement reaction, CO2 and C reaction, to generate 2CO

Ignite 2mg+O2==2mgo (compound).

Heating. mg+2HCl==2mgCl+H2 (displacement).

2cu+o2==2cuo (compound) jiayou

26 carbonates.

27 The nail is not tight, if there are silver ions in the solution to be tested, a white precipitate is produced, and it is insoluble in nitric acid, so it is not possible to judge whether there is an example of sulfate.

B is strictly acidified with hydrochloric acid first to eliminate the interference of carbonate, and after the first step, there is no precipitation, then the interference of silver ions can be excluded.

1 na2co3

2. The first is not tight, and it may be an agno3 solution.

B......I do not know.

In the first question, this salt is carbonate, because silver chloride and barium sulfate are insoluble in dilute nitric acid, and when they react with dilute nitric acid, they release gas, so they can only be carbonates. In the second question, student B's method is more rigorous. Because if there are silver ions in the solution, they will react with chloride ions and precipitate, and it is impossible to determine whether it is silver chloride precipitation or barium sulfate precipitation.

Hydrochloric acid was added to the solution first, and there was no precipitation, which could rule out the existence of silver ions. Later, barium chloride solution was added and an insoluble white precipitate appeared, indicating the presence of sulfate in the solution.

To calculate the mass of oxygen is direct.

2kClO3 = mnO2 heating = 2kCl + 3O2x Y

245/x=149/y=96/

x= y=mnO2 kCl in the remaining solid

Because there are gaps between the molecules.

The first question is yes, because it is okay to react to it and not to react.

Question 2: Molecules move faster as the temperature increases, so they rise, and conversely, when the temperature decreases, the rate of motion decreases.

The mass of oxygen produced is grams, and according to the chemical equation, the formation of potassium chloride is grams, so the remaining solids are grams of potassium chloride and grams of manganese dioxide (catalyst, non-reacting).

That's right. The law of conservation of mass can be introduced to the mass of oxygen =

The KCl in the remaining solids can be calculated by the chemical equation column relation and you should be.