About writing chemical equations according to the text of the topic

Car exhaust (including CO, NO, etc.), urban air pollution**. One of the methods of treatment is to install a "catalytic converter" (including catalyst) on the exhaust pipe of the car, so that CO and NO can react at high temperature to produce non-toxic gas, which can participate in the ecological cycle in the atmosphere. The chemical equation for this reaction is 2CO +2 NO=catalyst= 2CO2 + N2

The chemical properties of nitrogen are very stable, but under certain conditions (such as discharge) it will react to produce polluted air NO; NO is easily oxidized by oxygen in the air to form nitrogen dioxide; Nitrogen dioxide reacts with water to produce nitric acid (nitric acid) and NO. Write the chemical equation for this series of reactions.

N2 + O2 = Discharge = 2NO

2no + o2 = 2no2

3no2 + h2o = 2hno3 + no

What is the substance in the question, you first write its chemical formula, and then write what substance is generated, you will tell in the question, or speculate by yourself, and finally according to the law of conservation of mass, the balance is added to the reaction conditions...

It's almost the following, the valency you see that the total valency of a substance must be zero, you calculate, some valencies are fixed.

So which chemical equation is it? The problem needs to be clarified.

1.Iron reacts with oxygen to form ferric oxide (or iron oxide) 4Fe+3O2=2Fe2O3 2Lead reacts with oxygen to form lead oxide 2pb+o2=(=ignition)2pbo 3

Magnesium reacts with oxygen to form magnesium oxide 2mg+o2=(=ignition)2mgo 4Sodium hydroxide reacts with copper sulfate to form sodium sulfate and copper hydroxide 2NaOH+CuSO4=Na2SO4+Cu(OH)2 5Sodium hydroxide reacts with ferric chloride to form sodium chloride and hydroxide slip pin iron 3NaOH+FeCl3=3NaCl+Fe(OH)3 6

Hydrogen peroxide reacts with oxygen to form oxygen and water 2H2O2=(=MnO2)2H2O+O2 7Potassium chlorate reacts under the conditions of manganese dioxide catalysis and heating to produce potassium chloride and oxygen 2kclo3=(=write mno2 above and write below )2kcl+3o2 8Potassium permanganate reacts under heating conditions to produce potassium manganate, manganese oxide and oxygen 2kmNO4=(=written above)K2mNO4+MNO2+O2 9

Second, let Kai carbon oxide react with clarified lime water to form CO2 + Ca(OH)2=CaCO3 +H2O

Chinese. Literal expressions are expressions that use Chinese characters to express chemical search reactions and reaction conditions. Such as sulfur combustion: sulfur + oxygen dioxide pin leaks sulfur (write the word "ignite" above the arrow).

The chemical equation not only indicates the reactants, products, and reaction conditions. At the same time, the stoichiometric number represents the quantitative relationship between the reactants and the product substances, and the mass relationship between the substances can also be expressed through the relative molecular mass or relative atomic mass, that is, the mass ratio between the substances. For gas reactants and products, the volume ratio can also be obtained directly from the stoichiometric number.

Some chemical equations understand how they work, and it may be more important.

It's good to summarize it yourself, and you can deepen your impression.

Write the chemical equation according to the topic, trim means that the number of each atom on both sides of the equation should be equal, for example:

AH2+BFE2O3== (Conditional High Temperature) CFE+DH2O, first choose the most ** or the lowest price as a reference to start the trim.

Fe: 2b=c Suppose b=1 then c=2 then the number of o atoms on the left is 3, and the number of atoms on the right is d=3 a=3

Derive the equation for balancing:

3H2+Fe2O3==(Conditional High Temperature)2Fe+3H2OIf the calculated ABCD is not an integer, then take the least common multiple and reduce it to an integer, and then get the complete trim equation.

H2+Fe2O3== (high temperature) Fe + H2O trim looks at the same rise and fall of valence.

H has risen from 0 to +1, and H2 has risen to +2.

FE has dropped from +3** to 0 price, FE2 has dropped +6 price.

o has always been -2 price, no rise or fall.

Therefore, if the valency rise and fall of H2 and Fe2O3 are the same, H2 should be matched with 3 on the left and then compared with the right, and the same element matter is conserved.

The equation 3H2+Fe2O3== (Conditional High Temperature) 2Fe+3H2O is easy to balance.

Na2CO3 + CaCl2 ==CaCO3 (precipitation symbol) + NaCl This equation is the reaction in solution. And there is no increase in the price of the valence, so it is balanced by conservation.

This kind of direct can see the balance, it is not difficult.

You just need to memorize the valency and be able to write the chemical formula of the reactant and the product, which is the key, and as for the trim, the chemical reaction in junior high school is very simple, just observe. However, it is important to remember that stoichiometric numbers are the simplest integers.

H2 + Fe2O3 = 2Fe + 3H2O (the condition is high temperature heating) (when balancing, it is matched according to the conservation of electrons gained and lost, H loses six electrons, Fe gets six electrons, and the coefficient in front of the chemical equation is determined according to their valency changes, that is, the stoichiometric number).

2. Na2CO3 + CaCl2 + CaCO3 (precipitate) + 2NaCl.

Generally read first and write later (i.e., read from back to front).

P2O5, phosphorus pentoxide, Fe3O4, ferric oxide, Al2O3, alumina.

NaCl Sodium Chloride CaCl2 Calcium Chloride FeCl2 Ferrous Chloride FeCl3 Ferric Chloride.

NaOH sodium hydroxide Ca(OH)2 calcium hydroxide AL(OH)3 aluminum hydroxide.

KNO3 potassium nitrate CA(NO3)2 calcium nitrate FE(NO3)3 ferric nitrate.

CuSO4 copper sulfate K2SO4 potassium sulfate Al2(SO4)3 aluminum sulfate.

CaCO3 Calcium Carbonate Na2CO3 Sodium Carbonate NaHCO3 Sodium Bicarbonate NH4HCO3 Ammonium Bicarbonate.

Magnesium is burned in oxygen to form magnesium oxide.

Phosphorus is burned in oxygen to form phosphorus pentoxide.

Sodium peroxide. It reacts with water to generate a simple system.

Hydrogen balance is sodium oxide.

and oxygen. Sodium peroxide reacts with carbon dioxide to form it.

Sodium carbonate. and oxygen.

According to the title, the solute of the reaction solution only has FeCl2, and Cl comes from hydrochloric acid, so Acacia n(Fe)=n(

Fe2)=1 2(Cl)=1 This sedan eggplant 2, m(Fe)=56g mol=

gfeo+2hcl==fecl2+h2o

fe+2hcl==

fecl2h2

fe3o4hcl---fecl2+2

fecl3h2o

fe+2fecl3==3fecl2

Calcium carbonate plus hydrochloric acid produces carbon dioxide and water.