Hydrochloric acid is an aqueous solution of hydrogen chloride, which belongs to one element of inorganic strong acid, with a wide range of industrial uses. Hydrochloric acid is characterized as a colorless and transparent liquid with a strong pungent odor and high corrosiveness, and the following gives you an introduction to its industrial uses.
　　1、Analytical chemistry
　　In analytical chemistry, when acid is used to determine the concentration of alkali, hydrochloric acid is generally used for titration. Titration with a strong acid can make the endpoint more obvious, thus making the result more accurate. At 1 standard atmospheric pressure, 20.2% hydrochloric acid makes up a constant-boiling solution, which is often used as a reference in quantitative analysis under a certain air pressure. Its concentration at constant boiling will change with the change of air pressure.
　　2、Steel pickling
　　An important use of industrial hydrochloric acid is pickling steel. Before subsequent treatment of iron or steel, hydrochloric acid can be used to react off the surface rust or iron oxides. Usually use the concentration of 18% of the hydrochloric acid solution as a pickling agent to clean carbon steel.
　　3、Preparation of organic compounds
　　Another major use of industrial hydrochloric acid is the preparation of organic compounds, such as the synthesis of PVC plastic raw materials, vinyl chloride, ethylene dichloride, polycarbonate precursor bisphenol A, catalytic adhesive polyvinyl alcohol formaldehyde, ascorbic acid and so on. Instead of using commercially available, companies usually use hydrochloric acid prepared in-house when synthesizing PVC. Hydrochloric acid also has great use in pharmaceuticals.
　　4、For flame color reaction
　　Used to test the metal or their compounds often use the flame color reaction, used to test the platinum wire needs to be washed with dilute hydrochloric acid to remove the influence of impurity elements. Test substances before the platinum wire should be cleaned with hydrochloric acid, and then put on the flame burning, until the flame is the original color can be experimental.