Adding acid to a salt solution will cause gas to form

Hydrochloric acid and sulfuric acid will be added dropwise to carbonate, bicarbonate, sulfite, bisulfite, sulfur and bisulfide.

co32- +2h+ ===co2↑+h2o hco3- +h+ ===co2↑+h2o

so32- +2h+ ===so2↑+h2o hso3- +h+ ===so2↑+h2o

s2- +2h+ ===h2s↑ hs- +h+===h2s↑

Dropwise addition of hydrochloric acid to a permanganate solution will cause gas.

2mno4- +16h+ +10cl- ===5cl2↑+8h2o+2mn2+

Adding dilute nitric acid or concentrated nitric acid to ferrous salts and sulfur salt solutions will cause gas.

Rare: 6Fe2+ +8H+ 2NO3- ===4H2O+2NO+6Fe3+

3s2- +8h+ 2no3- ===4h2o+2no↑+3s↓

Concentrated: Fe2+ +2H+ NO3- ===H2O+NO2 +Fe3+

s2- +4h+ 2no3- ===2h2o+2no2↑+s↓

Carbonate, bicarbonate, sulfite, bisulfite. Wait a minute.

Sodium carbonate solid dissolves in water and reacts with hydrochloric acid to form a colorless and odorless gas

na₂co₃+2hcl=2nacl+h₂o+co₂↑

There are many similar solids, such as potassium carbonate, lithium carbonate, sodium bicarbonate and so on.

1) Sodium carbonate Na2CO3 + 2HCI = 2Naci + CO2 + H2O

2) Sodium hydrogen hydrogen hydrocarbonate NaHCO3 + HCI = NACI + CO2 + H2O

Carbonates, such as CaCO3 – to generate CO2; Acidic salts of carbonic acid, such as NaHCO3, can also be used.

Sulfites, such as barium sulfite BaSO3 – to form SO2; Acid salts of sulphurous acid are also available.

Sulfides, such as sodium sulfide, - generate H2S (generally believed to require concentrated hydrochloric acid) Mno2, oxidize HCl - generate Cl2 (require concentrated hydrochloric acid) F2, oxidize HCl - generate Cl2

These are probably the common ones in middle school.

Carbonates, such as caCO3

generation of CO2; Acidic salts of carbonic acid, such as NaHCO3, can also be sulfites, such as barium baso3 sulfite

--Generate SO2; Acid salts of sulphurous acid are also available.

Sulfides, such as sodium sulfide, ,--

Produces H2S (concentrated hydrochloric acid is generally thought to be required).

MnO2, oxidized HCl

- Produces Cl2 (concentrated hydrochloric acid is required).

F2, oxidized HCl

--Generate cl2

These are probably the common ones in middle school.

Carbonates, such as caCO3

generation of CO2; Acidic salts of carbonic acid, such as NaHCO3, can also be sulfites, such as barium baso3 sulfite

--Generate SO2; Acid salts of sulphurous acid are also available.

Sulfides, such as sodium sulfide, ,--

Produces H2S (concentrated hydrochloric acid is generally thought to be required).

MnO2, oxidized HCl

- Produces Cl2 (concentrated hydrochloric acid is required).

F2, oxidized HCl

--Generate cl2

These are probably the common ones in middle school.

Sodium sulfite or sodium bisulfite.

NaSO3 or NAHso3

It can react with oxygen under the action of a catalyst such as Cu2+, but at a high temperature of around 450 degrees.

4HCl+O2=(heating, catalyst) 2H2O+Cl2

As for hydrochloric acid, it will not react when the lid is opened at room temperature, and the phenomenon that occurs is because the boiling point of HCl is low, and the solution has a certain volatility at room temperature, and the volatile HCl gas is easy to absorb water in the air, forming small droplets in the form of mist.

It's not a chemical reaction, the formation of white fog is a physical change!

The principle is that concentrated hydrochloric acid is easy to volatilize HCl gas that is very soluble in water, and the gas combines with water vapor in the air to form small droplets of hydrochloric acid, so it forms a white mist, and because no new substances are generated, it is a physical change.

hno3+3hcl=nocl+cl2+2h2oa：b=1：3

In fact, it is aqua regia, one volume of concentrated nitric acid and three volumes of concentrated hydrochloric acid.

The central product, NOCL, nitrosyl chloride.

It seems that concentrated hydrochloric acid cannot react with anything in the air Concentrated hydrochloric acid volatilizes at room temperature.