Writing chemistry equations in high school, writing steps and precautions for high school chemistry

fe+s=△=fes

2so2o2

SO3 Note that this reaction is reversible, and the equal sign in the equation should be changed to a reversible sign. The catalyst is V2O5 A Cu + 2H2SO4 (concentrated) = = CuSo4 + SO2 + 2H20

b c + 2h2so4 (concentrated) = = co2 +2so2 +2h2oh2so4

ba（oh）2

baso4↓+2h2o

SO2 minor) +2NaOH = Na2SO3H2OSO2

sufficient) + NaOH = NaHSO3

2so2cl2

2h2o=2h2

so4 so2

H2O = Reversible = H2

so3 s+o2

ignition = SO2

so22h2

s=3s↓+2h2

o cao+so2===caso3

2caso3+o2=2caso4

so3ca（oh）2

caso4h2

o caso4+bacl2==baso4↓+cacl2so3h2

o=h2so4

2h2so3o22h2

SO4 ion Ba22

2oh-2h+

so42-baso4+2h2o

so22oh-=so3

h2oso2oh-

hso3so2

cl2 + 2 h2o = cl-

4 h+ so42-

14 so2

H2O = Reversible = H2

SO3 sulfurous acid is a weak electrolyte and cannot be disassembled).

15 2h2so3o2

4h+2so4

It's best to write it yourself or look for it in a book.

1. Problems that should be paid attention to when writing ion equations

1. Reactions that are not in the state of freely moving ions cannot write ion equations.

Example: 2kclo3=2kcl+3o2

2. Ion equations can be written for reactions with ion generation.

Example: 2Na + 2H2O = 2NaOH + H2

2. Writing the splitting principle of ionic equations

1. Elemental matter and oxide are all written with chemical formulas.

Example: Cusna2OSo2 H2O, etc.

2. Weak alkalis, weak acids and their acid ions cannot be disassembled and written in the ion equation.

Examples: HACHF H2S HCO3-, HSO3-, S2O32-, HPO42-, H2PO4-

3. Insoluble substances ( ) and volatile substances ( ) should be written with chemical formulas, and H2CO3 and H2SO3 must be written separately in the products.

3. Writing methods and steps:

Method: Steps--- examples.

Write the chemical equation ---bacl2+na2so4==baso4 +2nacl

The non-reactive ions --- ba2++so42-==baso4 were deleted

Check whether the number of particles and the total number of charges are equal.

Fourth, the method of checking whether the ion equation is correct must consider the following principles

1. According to the objective law of material reaction.

2. The law of conservation of mass.

3. The principle of conservation of electric charge.

4. The redox reaction must comply with the principle of conservation of electrons of gain and loss.

5. Questions about ionic reactions

1.Write ion equations based on chemical equations.

2.Write chemical equations based on ionic equations.

3.Questions about ion coexistence.

4.The problem of judging the valency of the resulting physicochemical products.