Hydrochloric acid is one of the strongest monobasic acids and is produced with dissolving the hydrogen chloride gas (HCl) in water, - transparent colorless liquid with characteristic smell of chlorine. Dilute hydrochloric acid (as well as phosphoric acid) it is often used to remove oxides from metal brazing.
Sometimes HCl gaseous compound is mistakenly called hydrochloric acid. But HCl is a gas that forms hydrochloric acid when dissolved in water.
Hydrogen chloride is a colorless gas with a sharp suffocating smell of chlorine. It goes into a liquid state with -840C, and with -1120C - goes into a solid state.
Hydrogen chloride dissolves in water very well. So with 00C in 1 liter of water dissolves 500 liters of hydrogen chloride.
In the dry state, the hydrogen chloride gas is inert, but can already react with some organic substances, such as acetylene (a gas that is released when the carbide is lowered into the water).
Chemical properties of hydrochloric acid- chemical reaction with metals:
2HCl + Zn =ZnCl2 + H2 - salt is formed (in this case, a transparent solution of zinc chloride) and hydrogen
- chemical reaction with metal oxide:
2HCl + CuO = CuCl2 + H2O - salt is formed (in this case, a solution of green copper chloride salt) and water
- chemical reaction with bases and alkalis (or neutralization reaction)
HCl + NaOH = NaCl + H2O - neutralization reaction - formed salt (in this case, a transparent solution of sodium chloride) and water.
- chemical reaction with salts (with chalk СaCO3):
HCl + СaCO3 = CaCl2 + CO2 + H2O - formed carbon dioxide, water and a transparent solution of calcium chloride CaCl2.
Obtaining hydrochloric acid
Hydrochloric acid is produced with chemical reaction compounds:
H2 + Cl2 = HCl - this reaction takes place at an elevated temperature
As well as the reaction of food salt and concentrated sulfuric acid:
H2SO4 (конц.) + NaCl = NaHSO4 + HCl
In this reaction, if NaCl is solid, HCl is a gas hydrogen chloride that forms hydrochloric acid when dissolved in water
There are complex chemical substances similar in chemical structure to hydrochloric acid, but containing in the molecule from one to four oxygen atoms. These substances can be called oxygen-containing acids. The increase the number of oxygen atoms the increases the resistance of the acid and its oxidizing ability.
To oxygen-containing acids:
- chlorate (HClO),
- chloride (HClO2),
- chlorinated (HClO3),
- chloric (HClO4).
Each of these chemicals has all the properties of acids and is capable to form salts. Chloric acid (HClO) forms hypochlorites, for example, the substance NaClO - sodium hypochlorite. Itself chloric acid is formed with dissolving chlorine in cold water at the chemical reaction:
H2O + Cl2 = HCl + HClO,
As you can see, this reaction produces two acids at once - hydrochloric HCl and chlorinated HClO. But the latter is an unstable chemical compound gradually oxidizes to the hydrochloric acid;
Chloride HClO2 forms chlorites, salt NaClO2 - sodium chlorite;
chlorinated (HClO3) - chlorates, compound KClO3, - potassium chlorate (or berlet salt) - incidentally, this substance is widely used to manufacturing matches.
And finally the strongest of the known monobasic acids - chlorine (HClO4) - colorless, fuming in air, highly hygroscopic liquid, it forms the perchlorate, for example, KClO4 - potassium perchlorate.
Salts formed with chlorinatedHClO and chloride HClO2 acids are in free form unstable and are strong oxidizing agents in aqueous solutions. But the salts formed wiht chlorinated HClO3 and chlorine HClO4 acids with alkaline metals (for example, tagge bertoletova salt KClO3) - quite stable and do not exhibit oxidative properties.