Have you done any experiments with hydrogen chloride yet? Did your chemistry teacher not show you the reaction between sodium hydroxide and hydrogen chloride? Well, in this chapter, we will look at the compound of hydrogen chloride and look at its properties and more. In the end, we will also see some of the important reactions of hydrochloric acid and its uses in various industries. Let’s begin.
Manufacture of Hydrogen Chloride
NaCl + H2SO4 → NaHSO4 + HCl
We get Sodium bisulphate as a by-product which is insoluble. Therefore, we further mix it with more sodium chloride. This mixture has to be further warmed to a higher temperature of around 823K. It gives dissolvable sodium sulfate and HCl gas.
NaHSO4 + NaCl → Na2SO4 + HCl
We dry this HCl by treating it with concentrated sulphuric acid. HCl is not dried over phosphorus pentoxide or brisk lime. This is because it reacts with both of these compounds.
Properties of Hydrogen Chloride
- Hydrogen Chloride is a vapid gas. It has a very sharp and pungent odour.
- It can melt to a colourless fluid at 189K. HCl forms a white solid at 159K upon freezing.
- It is very soluble in water. An aqueous solution of Hydrogen Chloride is what we know as the hydrochloric acid.
- Hydrochloric acid has a higher dissociation constant and is, therefore, a strong acid.
- It reacts with metals and salts to give various chlorides. For example, it reacts with zinc to form zinc chloride.
- Hydrochloric acid reacts with iron to form ferrous chloride.
Fe + 2HCl → FeCl2 + H2
Some Important Reactions of HCl
- Noble metals react with a mixture of nitric acid and hydrochloric acid in the proportion of 1:3. This arrangement what we call aquaregia.
- Hydrochloric acid reacts with the salts of weaker acids. Some of them include sodium carbonate, sodium bicarbonate etc.
- Hydrochloric acid also reacts with sodium carbonate and sodium bicarbonate and forms sodium chloride, carbon dioxide, and water.
- It also breaks down sodium sulphate to sodium chloride, sulfur dioxide, and water.
- Reaction with Sodium Carbonate:
Na2CO3 + 2HCl → 2NaCl + CO2↑ + H2O
- Reaction with Sodium Bicarbonate:
NaHCO3 + HCl → NaCl + CO2↑ + H2O
- Reaction with Sodium Sulphate:
Na2SO3 + 2HCl → 2NaCl + SO2↑ + H2O
Solved Example for You
Q: Give some uses of Hydrochloric acid.
Ans: The uses of the Hydrochloric acid include:
- We use hydrochloric acid in the process of fabrication of chlorine, and chlorides like ammonium chloride. It is also a common ingredient in the fabrication of glucose from corn starch.
- We also use hydrochloric acid as a research facility reagent and in medicines.
- We use a saturated arrangement of zinc chloride in dilute hydrochloric acid in removing the contaminations on a metal surface prior to welding or electroplating.