We placed the rusted nails in an equal volume, hydrochloric acid and sulfuric acid with equal hydrogen ion concentration. Finally, we found that the rust removal effect of hydrochloric acid is better. It can also be demonstrated by experiments that when other conditions are the same, the reaction rate of dilute sulfuric acid and metal oxide is slower than that of hydrochloric acid.

Then, from the aspects of production, transportation and safe use, which one is more dominant in hydrochloric acid and sulfuric acid? The industrial preparation of hydrochloric acid is to obtain hydrogen and chlorine gas by electrolyzing saturated brine. The two gases react to form hydrogen chloride gas. After water absorption, hydrochloric acid is formed. Hydrogen chloride gas can not be dissolved in water without limitation. Therefore, the concentrated mass fraction of concentrated hydrochloric acid is the most. At around 37%. Sulfuric acid is obtained by calcining pyrite at a high temperature to produce sulfur dioxide. Sulfur dioxide reacts with oxygen to form sulfur trioxide. Sulfur trioxide is absorbed into concentrated sulfuric acid to form pyrosulfuric acid, and pyrosulfuric acid is added to sulfuric acid. Therefore, hydrochloric acid is superior to sulfuric acid in terms of raw materials, preparation processes, and environmental impact. Concentrated hydrochloric acid needs to be sealed and stored in glass bottles or plastic drums. For transportation, special steel tankers with rubber inside are required. Concentrated sulphuric acid has a mass fraction of up to 98%. It can be stored and transported in steel or aluminum containers. In this respect, sulfuric acid is stronger than hydrochloric acid.

Hydrochloric acid with a large solute mass fraction is volatile, and the hydrogen chloride gas volatilized has strong irritating and corrosive effects on the human body, while hydrochloric acid with a low solute mass fraction is relatively stable. Concentrated sulfuric acid needs to be diluted before use. Dilution will generate a lot of heat, which is easy to cause burns, and concentrated sulfuric acid is much more corrosive than concentrated hydrochloric acid. It can be seen that the use of hydrochloric acid is safer.

According to the above information, it is obvious that the rust removal effect of hydrochloric acid is better, the cost is lower, and the use is safer.