or iron(II) sulfate is most commonly encountered as the blue-green heptahydrate, known since ancient times as copperas or green vitriol. Ferrous sulfate can be found in various states of hydration, and several of these forms exist in nature. At 90° C., the heptahydrate form loses water to form the colorless monohydrate.
Ferrous sulfate was used in the manufacture of inks, most notably iron gall ink, which was used from the middle ages until the end of the 18th century. The ink was generally prepared by adding ferrous sulfate to a solution of gallotannic acid. The tannic acid was usually extracted from oak galls (also known as "oak apples" or more correctly "oak marble galls"), or galls of other trees; hence the name. Fermentation or hydrolysis of the extract releases gallic acid, which yields a darker black ink. The fermented extract is combined with the ferrous sulfate and a binder such as gum arabic.
Ferrous sulfate heptahydrate is generally the starting-point in the preparation of iron pigments. When pure, it forms fine sea-green crystals, with an astringent metallic taste, which are not poisonous and are easily soluble in water. After long exposure to the air, ferrous sulfate becomes covered with an ochre-colored crust, consisting of basic ferric sulfate. The ferrous oxide contained in the green vitriol has united with oxygen and been converted into ferric oxide. The latter requires a larger quantity of acid than ferrous oxide for the formation of soluble salts, so that an insoluble basic salt is separated. The same thing occurs when a solution of ferrous sulfate is exposed to the air. When green vitriol, or any other ferrous salt, is exposed to the action of oxidizing agents, such as chlorine or nitric acid, the iron is rapidly changed into the ferric state. This transformation is of particular importance in the manufacture of certain blue pigments.
It also finds use in dyeing as a mordant. Two different methods for the direct application of indigo dye were developed in England in the 18th century and remained in use well into the 19th century. One of these, known as china blue, involved iron(II) sulfate. After printing an insoluble form of indigo onto the fabric, the indigo was reduced to leuco-indigo in a sequence of baths of ferrous sulfate (with reoxidation to indigo in air between immersions). The china blue process could make sharp designs, but it could not produce the dark hues of other methods.
|Chemical Name: ||Iron(II) Sulfate Heptahydrate |
|Chemical Formula: ||FeSO4·7H2O |
|CAS No.: ||7782-63-0 |
|Mesh (%): ||90% 100 mesh |
|Color: ||Blue-green crystalline powder |
Keep in a tightly closed container, stored in a cool, dry, ventilated area. Protect against physical damage. Maintain a constant temperature not to exceed 24° C. (75° F.). Fluctuating temperatures causes product oxidation. Do not use this product if coated with brownish-yellow basic ferric sulfate. Isolate from incompatible substances. Containers of this material may be hazardous when empty since they retain product residues (dust, solids); observe all warnings and precautions listed for the product. Safe Handling
Do not ingest. Do not breathe dust. Wear protective gloves and clean body-covering clothing. Use chemical safety goggles and/or a full face shield where splashing is possible. Refer to Material Safety Data Sheet. WARNING! HARMFUL IF SWALLOWED OR INHALED. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS THE LIVER. Environmental Hazards
Short term and long term adverse effects to the environment are unknown. If product is spilled, comply with Federal, State and local regulations on reporting spills. Refer to Material Safety Sheet and labels for further details.