Look at the requirements to write the chemical reaction equations, and write the chemical equations

1) C+O2CO2 or 2CO+O2CO2CO2;

2）h 2 co 3 =co 2 ↑+h 2 o；

3）co 2 +h 2 o=h 2 co 3 ；

4）co+cuo cu+co 2 ；

5) CO2 +CA(OH) liquid preparation alarm cover 2 =CACo 3 +H2 O,2, write the chemical equation about the reaction according to the requirements of Roller

1) There is a chemical reaction for the generation of carbon dioxide

2) There is a decomposition reaction for the generation of carbon dioxide

3) Chemical reactions with the participation of carbon dioxide

4) Non-chemical reactions with the participation of toxic gases

5) Methods for testing carbon dioxide

Three things of ferric chloride drops into sodium sulfide solution:

Excessive sulfur ions generate sodium chloride, elemental sulfur precipitate, ferrous sulfide (black) Zhibi precipitate.

2FeCl3+3Na2S==6NaCl+4S+2Fes to form a black precipitate.

Sodium sulfide solution drops into ferric chloride solution:

Excess ferric ions generate sodium chloride, ferrous chloride, and elemental sulfur precipitation.

2FeCl3+Na2S==2NaCl+2FeCl2+S to generate pale yellow mask macrodeposits.

That is, the chemical reaction is an experimental fact, and the equation is only used to record and represent, that is to say, there will be a corresponding equation with a chemical reaction, or it is your own conjecture, the equations you have learned so far are to be remembered, there are some principles in it, such as acid energy and alkali reaction, that is, the -oh and -h in it are synthesized into water, you will remember HCl+Naoh=NaCl+H2O, not because you really understand the truth, but just remember it, The fact of the experiment is that these two things react together, and it turns out that the product is these two.

Chemical equations are difficult for a junior high school student. In order to write the chemical equation correctly, you should master the following aspects:

1. Element symbols to remember. 2. The chemical formula should be written correctly, and the valency should be remembered if the chemical formula is written correctly.

3. Learn to balance chemical equations.

Note: Valency memory mouth is fast; Monovalent hydrochloride, potassium, sodium, silver, barium oxide, calcium, magnesium, zinc, 246, sulfur, 244, 6, 24, 6, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 6, 2, 2, 2, 6, 2, 2, 6,

The methods of balancing chemical equations are;

1. Least common multiple method, for example: P+O2==P2O5 The least common multiple of 2 and 5 is 10, 10 divided by 2 to get 5 is the coefficient of O2r, and 10 divided by 5 to get 2 is the coefficient.

2. Observation method, e.g. Fe+O2 - Fe3O4

3. Set a method, that is, set the coefficient of a substance as one, calculate the other coefficients, and multiply the denominator if there is a fraction, and remove the denominator. For example, C2H2+O2 - CO2 + H2O 1C2H2 + 5 2O2 - 2CO2 + 1H2O 2C2H2 + 5O2 ===4CO2 + 2H2O

1. Falsely judge that magnesium sulfate and nitric acid do not react.

2. Magnesium chloride and copper sulfate do not react.

3. Zn(NO3)2+Na2CO3=ZNC3 +2nano34, AGNo3+NaCl=AGCL +nano35, sodium bisulfate and aluminum chloride do not react.

6、co2+2koh=k2co3+h2o

7. Zinc nitrate and ferrous sulfate do not react (if acidic conditions will react) ready for swimming.

8. Na2SO4 + BACL2 = BaSO4 +2NaCl9, iron sulfate and zinc nitrate do not react.

10. NaHCO3 + HCl = NaCl + CO2 + H2O to judge whether it is a reaction: generate water, precipitation, differential rolling gas or weak electrolyte.

(1) Exhaust gas to absorb sulfur dioxide with sodium hydroxide:

2NaOH + SO2 = Na2SO3 + H2O(2) Treat wastewater containing mercury salts (HgSO4) with iron or copper filings.

fe + hgso4 = feso4 + hg

(1) Exhaust gas to absorb sulfur dioxide with sodium hydroxide:

2naoh+so2=na2so3+h2o

At the same time, a reaction may occur.

2na2so3+o2=2na2so4

2) Treat wastewater containing mercury salts (HGSO4) with iron or copper filings.

fe+hgso4=feso4+hg

cu+hgso4=cuso4+hg

1) Chemical properties of dilute sulfuric acid.

1. Reaction with the indicator: dilute sulfuric acid can make the purple litmus test solution red, but the dusty manuscript can change the color of the colorless phenolphthalein test solution.

2. React with metals to generate salt and hydrogen.

2h（+）zn=zn（2+）+h2↑

Note: Use more reactive metals (i.e., metals with metal pie groups that precede hydrogen, but generally not K, Ca, Na). Respectful.

with dilute sulfuric acid. Because concentrated sulfuric acid has strong oxidation, it reacts with metals to form water, and H2 cannot be obtained.

3. React with metal oxides to form salt and water.

2h（+）cuo=cu（2+）+

H2O4, which reacts with alkali to form salt and water.

cu(oh)2+

2h（+）cu（2+）+2h2o

5. React with salt to form another salt and another acid.

2h（+）so4(2-)+ba(2+)=baso4↓+2h(+)

The reaction produces a white barium sulfate precipitate insoluble in dilute nitric acid. This reaction is used to test sulfuric acid and other compounds that can produce sulfate ions when ionized. For example: Na2SO4 + BACL2 = BaSO4 + 2NaCl

2) S (reducing agent) + O2 (oxidant) = = SO2 (4E-).

C (reducing agent) + H2SO4 (concentrated) (oxidant) = = CO2 + SO2 + H2O (4E-).

2H2S (reducing agent) + 3O2 (excess) (oxidant) = 2H2O + 2SO2 (12E-).