About the identification of substances in chemistry

1.Dissolved to see the color, the copper sulfate solution is blue.

2.Dissolved, carbon dioxide, precipitated is calcium hydroxide.

3.A small amount of hydrochloric acid is added, and sodium carbonate is formed by bubbles.

4.Same as 3 5Smell the smell, there is a special smell is alcohol.

6.Add purple litmus reagent, from left to right colors red, purple, blue 7Add a small amount of manganese dioxide solids, and a large amount of gas is generated into hydrogen peroxide8

Dilute sulfuric acid (barium chloride with white precipitate, sodium carbonate generated by bubbles, hydrochloric acid without obvious phenomenon), purple litmus reagent (solution purple for barium chloride, red for hydrochloric acid, blue for sodium carbonate), sodium carbonate (white precipitate for barium chloride, bubbles for hydrochloric acid, no obvious phenomenon for sodium carbonate).

The test substance is considered from the physical properties and chemical properties, and pays attention to the differences between the two substances.

1.Copper sulphate and sodium sulphate.

You can tell the difference by looking at it directly, copper sulphate is blue.

2.Sodium hydroxide and calcium hydroxide.

A solution with carbonate can be added to form a calcium carbonate precipitate.

3.Sodium carbonate and sodium sulfate.

Barium nitrate is added dropwise to form a barium sulfate precipitate.

4.Sodium chloride and sodium carbonate.

Dilute hydrochloric acid is added dropwise, and the carbonate will produce bubbles.

5.Water and alcohol.

Drops of potassium dichromate solution, potassium dichromate can react with alcohol, and the solution changes from orange-red to green.

6.hydrochloric acid, sodium chloride and sodium hydroxide.

Magnesium chloride is added dropwise to form magnesium hydroxide precipitate; Silver nitrate is added dropwise to form a silver chloride precipitate.

7.water and hydrogen peroxide.

With the addition of manganese dioxide, hydrogen peroxide will produce oxygen, which has bubbles.

8.Barium chloride, sodium carbonate and dilute hydrochloric acid three solutions, three people with different reagents to achieve the purpose of identification, which three?

1) Copper sulfate is added dropwise to form barium sulfate precipitate; Dilute hydrochloric acid is added dropwise, and the carbonate will produce bubbles.

2) Barium chloride is added dropwise to form barium carbonate precipitate; Copper sulfate is added dropwise to form a barium sulfate precipitate.

3) Add sodium carbonate dropwise, dilute hydrochloric acid will react with the mass to produce bubbles; Barium chloride is added dropwise to form a barium carbonate precipitate;

1 is dissolved with water, and the blue one you see is copper sulfate.

2.It is CO2, and the gas is introduced to see if there is precipitation, and the precipitated is calcium hydroxide 3Barium nitrate is added first, and then hydrochloric acid is added, and there is a gas generation after precipitation is sodium carbonate 4Hydrochloric acid is added to produce sodium carbonate as a gas.

5.With your nose, and the smell of alcohol is alcohol.

6.Add sodium carbonate, there is gas to generate hydrochloric acid, and the rest of the copper sulfate can be added to see the blue precipitate of sodium hydroxide.

7.It is also possible to use the nose with a faint special smell for hydrogen peroxide.

8.It can be reflected in pairs, if a substance is added to two substances and then precipitated and the gas is the solution that is sodium carbonate and the precipitated is barium chloride, and the gas is hydrochloric acid.

Sleepy, the rest of you come.

1. Solid? Add water to dissolve, copper sulfate blue, sodium sulfate colorless.

2. Add water to dissolve, the temperature is increased by sodium hydroxide, and calcium hydroxide is unchanged.

3. Sampling with dilute hydrochloric acid, bubble sodium carbonate, no obvious phenomenon sodium sulfate.

4. Dilute hydrochloric acid was added to the sampling, there was bubble sodium carbonate, and there was no obvious phenomenon of sodium chloride.

5. Take samples and smell smells; Or ignite, which can be ignited by alcohol.

6. Take sampling, add purple litmus, turn red into hydrochloric acid, do not taste sodium chloride, and turn blue sodium hydroxide.

7. Sampling, manganese dioxide added, bubble hydrogen peroxide, no obvious phenomenon water.

Add purple litmus, turn blue sodium carbonate, turn red hydrochloric acid, and do not change barium chloride; Add sulfuric acid, precipitate barium chloride, gas sodium carbonate, and no obvious phenomenon hydrochloric acid. (For the time being, I only think of two kinds, and I also found that calcium bicarbonate solution, barium chloride without phenomenon, bubble hydrochloric acid, and white precipitated sodium carbonate).

I can't guarantee the accuracy rate...

I'll help you ask the teacher tomorrow.

1. Copper ions have color, sky blue, should be well identified, it is really not good, add ammonia, first precipitate, then dissolve, and sky blue; 2. Carbon dioxide is introduced, and calcium hydroxide is precipitated; Sodium carbonate is produced by adding acid and bubbling with gas; 4. Or add acid, bubbles are sodium carbonate, sodium carbonate aqueous solution is alkaline; 5 Needless to say, smell it with your nose; 6. The acidic is hydrochloric acid, the alkaline is sodium hydroxide, and the rest is sodium chloride; 7. Hydrogen peroxide is weakly acidic, and it is easy to bubble when heated slightly; 8. pH test strip, dilute sulfuric acid solution, ammonium sulfate solution (react with barium chloride to produce white precipitate, and react with sodium carbonate to release ammonia).

1.Copper sulfate crystals or solutions are blue, which can be identified by looking at them.

2.Add water to dissolve, and the insoluble matter after standing is calcium hydroxide, because calcium hydroxide is slightly soluble.

3.Add dilute hydrochloric acid, and sodium carbonate is released with bubbles.

4.Same as 3 5It is alcohol that can be ignited.

6.Solution with purple litmus. It is hydrochloric acid that turns red, sodium chloride that remains purple, and sodium hydroxide that turns blue.

7.Manganese dioxide is added separately, and hydrogen peroxide is released with bubbles.

8.Potassium carbonate solution. Purple litmus solution.

1.Add water and observe the color of the solution, the blue one is copper sulfate, and the colorless one is sodium sulfate.

2.After adding water, a small amount of CO2 is introduced, and calcium hydroxide is generated by precipitation, and sodium hydroxide is generated without precipitation.

3.Add water to dissolve, and then add hydrochloric acid dropwise, sodium carbonate is generated with gas, and sodium sulfate is generated without gas.

4.Ditto. 5.Smell the smell.

6.Measure the pH

7.When heated, hydrogen peroxide appears as gas, and water as there is no gas.