Chromic Acid

Chromic acid include of acid substances, generally refers to a collection of compounds generated by the acidification of solutions containing chromate and dichromate anions or the dissolving of chromium trioxide in sulfuric acid. Often the species are assigned the formulas H2CrO4 and H2Cr2O7. The anhydride of these "chromic acids" is chromium trioxide, also called chromium (VI) oxide; industrially, this compound is sometimes sold as "chromic acid."


Chromic acid is very soluble in water, chromium acid have unlimited solubility in water, the color of this chemicals is red brown in solid state or called as chromic acid flake. The solution color in water is red. Because chrome itself is metal after dilute in water this chrome can attract by negative pole of electric current. The solution of chromic acid flake called as chromic acid. As on solid state chromium acid have formula CrO3 and after dilute in water the formula become H2CrO4.

Chromic acid is an intermediate in chromium plating, and is also used in ceramic glazes, and colored glass. Because a solution of chromic acid in sulfuric acid (also known as a sulfochromic mixture) is a powerful oxidizing agent, it can be used to clean laboratory glassware, particularly of otherwise insoluble organic residues. This application has declined due to environmental concerns. Furthermore the acid leaves trace amounts of paramagnetic ions Cr(III) and Cr(V) that can interfere with certain applications, such as NMR spectroscopy. This is especially the case for NMR tubes.

Chromic acid has also been widely used in the band instrument repair industry, due to its ability to "brighten" raw brass using bright chromium plating technique. A chromic acid dip leaves behind a bright yellow patina on the brass. Due to growing health and environmental concerns, many have discontinued use of this chemical in their repair shops.

Hexavalent chromium compounds are toxic and carcinogenic. For this reason, chromic acid oxidation is not used on an industrial scale. On working with this chemical must use a hands glove, glass, and special masker, because fume of this chemical is carcinogenic. I my selves use this chemical just for experiment and not use in long time duration. For people that work on this chemicals environment must discipline for use safety equipment as describe above.

Sulfuric Acid

Sulfuric acid has the formula of H2SO4. Sulfuric acid is the most important sulfur compound and one of the largest volume industrial chemicals. To produce it by the method known as contact process, sulfur is first burned in air to yield dioxide SO2. The subsequent oxidation of SO2, is slow reaction, therefore a catalytic surface made of platinum or vanadium pentoxide is required. Sulfur trioxide reacts with water to yield sulfuric acid, because the oxide reacts with water to yield sulfuric acid; because the direct reaction of SO2 and water produces a mist of H2SO4 that is difficult to condense, the final stage of production takes place in two steps, SO2 is first dissolved in H2SO4 to produce pyrosulfuric acid; H2SO4, then sulfuric acid is produced by subsequent dilution of H2S2O2 with water:

SO2 + H2SO4 → H2S2O2
H2S2O2 + H2O → 2 H2SO4

Pure sulfuric acid, a colorless oily liquid, is an extremely powerful dehydrating agent. When concentrated sulfuric acid is added to water, much heat is evolved as the acid ionized in two steps:

H2SO4 → H+ + HSO4-
HSO4- → H+ + SO4-

Because the first step is complete, sulfuric acid is strong acid (chemical rules). Hot concentrated sulfuric acid is an oxidizing agent of sufficient strength to dissolve event such metal as copper. Dilute sulfuric acid behave as a normal acid.

Large quantities of sulfuric acid are used in the manufacture of fertilizers (superphosphates), paint (titanium dioxide), synthetic fibers (rayon and plastics), detergent (alkylaryl sulphonates), organic chemicals (dyestuff, explosives and drugs), and other acids (hydrochloric and hydrofluoric acids). It is also used in lead acid batteries and in extraction of alkenes in gasoline refining.

Sulfuric acid is used in many purpose and almost all large industy use this chemical. Fiber industry, paper industry, electroplating industry, anodizing industry, adhesive industry, glass industry, plastic industry and many others.