1, the use of volatility. Concentrated hydrochloric acid is volatile and volatile acid; while concentrated sulfuric acid is a non-volatile acid, so, open the bottle cap, the bottle mouth appears white mist is concentrated hydrochloric acid, and vice versa is concentrated sulfuric acid.

2, the use of density. Both have no color in appearance, but different density. The mass of the same volume of concentrated sulfuric acid is much higher than that of concentrated hydrochloric acid. So you can only pick up the reagent bottle and shake the reagent bottle. If there is a "wall" phenomenon, it is concentrated hydrochloric acid, otherwise it is concentrated hydrochloric acid.

3, the use of water absorption. Concentrated sulfuric acid also has a physical property different from concentrated hydrochloric acid, that is, water absorption. Therefore, a small amount of liquid can be taken in the container, and the two non-color liquids are diluted with concentrated sulfuric acid respectively. It was observed that the bubbling heating of the cup wall was concentrated sulfuric acid, and concentrated hydrochloric acid was not obvious.

4, the use of corrosive. As we all know, concentrated hydrochloric acid is very corrosive, but unlike concentrated hydrochloric acid, its corrosive is dehydration. Therefore, a small amount of droplets can be taken on paper, cloth, etc. Carbonized into black paper or cloth is concentrated sulfuric acid, concentrated hydrochloric acid is not obvious change.

5, the use of chemical properties. The chemical properties of concentrated hydrochloric acid and sulfuric acid are very similar, the difference is that their acid ions, one is chloride ion, the other is sulfate ion. Sulfate ions can combine with barium ions to form barium sulfate precipitates, while chloride ions cannot.