Hydrochloric Acid

1、 Introduction

Hydrochloric acid is an aqueous solution of hydrogen chloride (HCl). It belongs to monobasic inorganic strong acid and is widely used in industry. Hydrochloric acid is a colorless and transparent liquid with strong pungent smell and high corrosivity. Concentrated hydrochloric acid (mass fraction is about 37%) is highly volatile. Therefore, after the container containing concentrated hydrochloric acid is opened, the hydrogen chloride gas will volatilize and combine with the water vapor in the air to produce small droplets of hydrochloric acid, resulting in acid mist above the bottle mouth. Hydrochloric acid is the main component of gastric acid. It can promote food digestion and resist microbial infection.

2、 Preparation method

The industrial preparation of hydrochloric acid mainly adopts electrolytic method.

1）Electrolyze saturated salt water to obtain sodium hydroxide, hydrogen is generated at the cathode and chlorine is generated at the anode:

2） In the reactor, hydrogen and chlorine are passed to the burner made of quartz for ignition and combustion to generate hydrogen chloride gas and emit a lot of heat:

3）After cooling, hydrogen chloride gas is absorbed by water to become hydrochloric acid.

In the reaction process of chlorine and hydrogen, the toxic chlorine is surrounded by excess hydrogen, which makes the chlorine react fully and prevents air pollution. In production, the method of making another raw material excessive is often adopted to fully react the harmful and expensive raw materials.