Definition and Areas of Use :
The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which can contain various compounds, including solid chromium trioxide. This type of chromic acid can be used as a cleaning mixture for glass. Chromic acid can also refer to a molecular species, the trioxide anhydride, which is H, 2 CrO 4. Chromic acid contains chromium in the +6 (or VI) oxidation state. It is a strong and corrosive oxidizing agent.
The anhydride of chromic acid is chromium trioxide (CrO3). Therefore, when chromic acid is mentioned, CrO3 comes to mind. Here, chromium is (6+) valent. It is an unstable compound and reacts with itself to become di(bi) chromate acid (H2Cr2O7). Chromic acid anhydride (CrO3) is a red-pink crystal with a specific gravity between 2.67 and 2.82 g/cm3. It melts at 197°C and slowly decomposes after melting. It absorbs moisture from the air. It is very soluble in water and organic solvents such as acetic acid, pyridine and ether. Crude CrO3 is separated by precipitation from a mixture of saturated sulphate acid and saturated sodium bichromate. This precipitate is purified by crystallization or melting.
Chromic acid is a strong acid and also a strong oxidizing agent. It is quite destructive to plant and animal cells. If it is reduced or brought into contact with an organic compound, a serious explosion may occur.