He Iron sulfide (II) , Also called ferrous sulfide, is a chemical compound of formula FeS. Iron sulphide powder is pyrophoric (spontaneously ignites in the air).
Iron (II) sulphide is obtained by heating sulfur and iron according to the reaction:
Fe + S → FeS
The reaction is very exothermic (releases heat) and the ratio of iron to sulfur should be 7: 4 (NileRed, 2014).
Figure 1: Structure of iron (II) sulphide.
Ferrous sulfide may also be obtained in aqueous medium by dissolving sulfur in an ionic solution of iron (II). The sulfur, upon dissolving, forms hydrogen sulfide which reacts reversibly with the iron (II) ions according to the reaction
Faith 2+ + H 2 S FeS (s) + 2H +
However, this reaction competes with the iron (II) sulfate formation reaction as follows:
Faith 2+ + 2HS- → Fe (HS) 2 (S)
Subsequently iron (II) sulfate decomposes to ferrous sulfate, although the reaction occurs very slowly (Rickard, 1995).
Physical and chemical properties of iron sulfide (II)
Iron (II) sulfide is a dark brown or black metal-looking solid. When it is pure it is colorless (National Center for Biotechnology Information, S.F.). Figure 2 shows the appearance of ferrous sulfide.
Figure 2: Iron sulfide (II) appearance.
The compound has a molecular weight of 87.910 g / mol and a density of 4.84 g / ml. It has a melting point of 1195 ° C and is insoluble in water and nitric acid (Royal Society of Chemistry, 2015).
Ferrous sulfide reacts in acid media to form ferrous oxide and hydrogen sulphide vapors that are extremely toxic. This is observed in the following reaction:
FeS + 2H + → Faith 2+ + H 2 S
Reacts with dilute solutions of sulfuric acid to form ferrous oxide, sulfur dioxide and water according to the reaction:
FeS + H 2 SW 4 → FeO + H 2 O + SO 2
Reactivity and hazards
Ferrous sulfide is an unstable compound and reacts with air to form ferrous oxide and sulfur. The compound is pyrophoric and may ignite spontaneously or also the product of a strong impact, so it is not advisable to grind it in a mortar when it is synthesized and must be treated with care.
Reacts with oxidizing agents and when heated decomposes emits toxic fumes of sulfur oxides. The compound is very dangerous in case of ingestion and dangerous in case of contact with the eyes (irritant) and inhalation (Material Safety Data Sheet Ferrous sulfide, 2013).
In case of contact with eyes, they should be rinsed with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids.
If the compound comes into contact with the skin, it should be rinsed with copious amounts of water for at least 15 minutes while removing contaminated clothing and shoes.
If swallowed, if the victim is conscious and alert, he should be given 2-4 cups of milk or water. Never give anything by mouth to an unconscious person.
In case of inhalation, remove the victim from the exposure area and move to a cool place. If it does not breathe, artificial respiration should be given. If breathing is difficult, give oxygen.
In all cases, immediate medical attention should be obtained (fisher scientific, 2009).
Iron sulfide is involved in a rare benign condition known as pseudomelanosis duodeni. This is manifested endoscopically as discrete, flat, brown-black spots on the duodenal mucosa.
It produces no symptoms and can be reversible. With electron microscopy and X-ray analysis of energy dispersion by electron probe, the pigment mainly corresponds to an accumulation of ferrous sulfide (FeS) in macrophages within the lamina propria (Cheng CL, 2000).
Handling and storage
Ferrous sulfide should be kept away from heat and sources of ignition. Empty containers represent a risk of fire, the residue must be evaporated under an extractor hood. Ground all equipment containing material to avoid electrical sparks.
Do not breathe dust. Avoid contact with the eyes. Wear suitable protective clothing. In case of insufficient ventilation, wear suitable respiratory equipment. If you do not feel well, you should seek medical attention and show the product label as much as possible. The compound should be kept away from incompatible substances such as oxidizing agents and acids.
The container containing the compound should be kept dry, in a cool place. And it should be tightly closed in a ventilated place. Combustible materials should be stored away from extreme heat and away from strong oxidizing agents.
Applications
Iron sulfide is used in the alloy and stainless steel industries to control the embrittlement of hydrogen. The iron and steel industry uses iron sulfide as a resulfurization agent in the manufacture of carbon, alloy and stainless steel free cutting steels.
It also acts as a degrading agent to improve the capacity of the steel casting machine, which are used in the production of various steel parts. In the purification of crude phosphoric acid, iron sulfide is used as a reducing agent to remove the heavy impurities of phosphoric acid.
Another use of iron sulphide is in the production of malleable iron. Iron sulphide combined with ferrous silicon and ferromanganese is used to increase the sulfur content of steel and iron.
Iron sulfide is also used as a laboratory chemical for the preparation of hydrogen sulfide gas. In hair dyes, paint, ceramics, bottles and glasses, iron sulfide is used as a pigment. It is also used in lubricants and to treat exhaust gases.
Iron sulfide has uses compatible with sulfates. Sulphate compounds are water soluble and are used in the treatment of water. Iron sulfide is also used in the production of metal castings.
Iron sulfide is mineral pyrite that resembles gold and is dubbed"fool's gold". Pyrite is used in the production of sulfur and sulfuric acid and is also used in coal mining (JAINSON LABS (INDIA), S.F.).
References
- Cheng CL, e.g. to. (2000). Pseudomelanosis duodeni: case report. Changgeng Yi Xue Za Zhi 23 (6), 372-376.
- Fisher scientific. (2009, August 20). Material Safety Data Sheet Iron (II) Sulfide. Retrieved from lasecsa.
- JAINSON LABS (INDIA). (S.F.). Uses of Ferrous Sulphide. Retrieved from jainsonfes.
- Material Safety Data Sheet Ferrous sulfide. (2013, May 21). Retrieved from sciencelab.
- National Center for Biotechnology Information. (S.F.). PubChem Compound Database; CID = 14828. Retrieved from PubChem.
- (2014, May 15). Preparing Iron (II) Sulfide (cool reaction). Retrieved from youtube.
- Rickard, D. (1995). Kinetics of FeS precipitation: Part 1. Competing reaction mechanisms. Geochimica et Cosmochimica Acta Volume 59, Issue 21, 4367-4379.
- Royal Society of Chemistry. (2015). Iron (II) sulfide. Retrieved from chemspider: chemspider.com.