【Daily Question】11.16 Multiple-choice question: When ferrous sulfide comes into contact with air, it will undergo ( )
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Multiple-choice question: When ferrous sulfide comes into contact with air, what happens? (BC) A: Explosion B: Combustion C: Oxidation reaction D: Reduction reaction. Participation earns +2 points; correct answers earn +5 points. In-depth discussions earn +8 points. Participate in the activity “I’m the Craziest” to get +20 points. To promote this activity, mention @Guan Gongyu. When posting on the forum, include the following two links; for each link, reply with your post address and you will receive 5 points as a reward (an additional +10 points for the main post). [Petroleum Chemistry Activity] Registration page for “I’m the Craziest” activity. [Petroleum and Chemicals Section] Registration page for the “Show off your SimSun font” activity. “My Plant, My Home” – Photo competition (+10 points per photo). http://bbs.hcbbs.com/thread-1495069-1-1.html (Source: Haichuan Chemicals Forum)
When ferrous sulfide comes into contact with air, it undergoes (b) A: explosion B: combustion C: oxidation reaction D: reduction reaction
When ferrous sulfide comes into contact with air, it undergoes an oxidation reaction; if there are flammable materials present, self-ignition can occur once the temperature rises to a certain level.
Multiple-choice question: When ferrous sulfide comes into contact with air, it will undergo (B). A: Explosion B: Combustion C: Oxidation reaction D: Reduction reaction. The causes of the formation of ferrous sulfide and its mechanism of spontaneous combustion. Causes of the formation of ferrous sulfide: (1) Ferrous sulfide is formed through electrochemical corrosion reactions. More than 80% of the sulfur in crude oil is found in atmospheric-pressure residue; these sulfides have complex structures, and under high temperatures, especially in the presence of catalysts, they easily decompose to form hydrogen sulfide and smaller molecular thiol compounds. In the presence of water, these hydrogen sulfides and thiol compounds have a significant corrosive effect on iron-based equipment. The reaction processes are as follows:
H2S → H+ + HS-
HS- → H+ + S2-
This is an electrochemical corrosion process:
Anodic reaction: Fe → Fe2+ + 2e-
Cathodic reaction: 2H+ + 2e- → H2 (penetrating into the steel)
Fe2+ reacts with S2- and HS- to form FeS↓:
Fe2+ + S2- → FeS↓
Fe2+ + HS- → FeS↓ + H+
Additionally, sulfur can react directly with iron to form ferrous sulfide: Fe + S → FeS↓
The resulting ferrous sulfide has a loose structure and adheres evenly to the inner walls of equipment and pipes. (2) Atmospheric corrosion reactions produce ferrous sulfide. Due to prolonged shutdown of the facility, the internal components are exposed to air for extended periods, which leads to atmospheric corrosion and the formation of rust. Since rust is difficult to remove completely, it reacts with hydrogen sulfide during the production process to form ferrous sulfide. The reactions are as follows: Fe + O2 + H2O → Fe2O3•H2O; Fe2O3•H2O + H2S → FeS↓ + H2O. These reactions proceed relatively easily, and due to prolonged shutdowns, equipment with inadequate corrosion protection tends to produce ferrous sulfide. Mechanism and phenomena of spontaneous combustion of ferrous sulfide (1) Mechanism of spontaneous combustion of ferrous sulfide When ferrous sulfide and other iron sulfides are exposed to heat or light in the air, the following reactions occur: FeS + 3/2O2 = FeO + SO2 + 49 KJ; 2FeO + 1/2O2 = Fe2O3 + 271 KJ; FeS2 + O2 = FeS + SO2 + 222 KJ; Fe2S3 + 3/2O2 = Fe2O3 + 3S + 586 KJ. (2) Phenomena of spontaneous combustion of ferrous sulfide During the spontaneous combustion of ferrous sulfide, if there is no combustible material present to support the reaction, white SO2 gas is produced, which is often mistaken for water vapor and has a pungent odor ； A large amount of heat is released at the same time. When other flammable materials (such as oils) are present in the vicinity, thick smoke will be produced, leading to fires and explosions. Factors affecting the formation rate of ferrous sulfide As can be understood from the mechanism of ferrous sulfide formation, in everyday production, the formation of ferrous sulfide is a chemical corrosion reaction that occurs as iron reacts with active sulfides. Therefore, controlling the chemical corrosion reaction is a key means to limit the formation of ferrous sulfide. As long as we identify the areas of the production equipment prone to sulfur corrosion and take effective measures based on the characteristics of each area, we can reduce the amount of ferrous sulfide generated, thereby preventing the occurrence of spontaneous combustion incidents caused by ferrous sulfide. Factors such as the sulfur content of the oil, temperature, the presence of water and Cl-, are important factors that influence the rate of this electrochemical corrosion reaction.
H2S → H+ + HS-
HS- → H+ + S2-
This is an electrochemical corrosion process:
Anodic reaction: Fe → Fe2+ + 2e-
Cathodic reaction: 2H+ + 2e- → H2 (penetrating into the steel)
Fe2+ reacts with S2- and HS- to form FeS↓:
Fe2+ + S2- → FeS↓
Fe2+ + HS- → FeS↓ + H+
Additionally, sulfur can react directly with iron to form ferrous sulfide: Fe + S → FeS↓
The resulting ferrous sulfide has a loose structure and adheres evenly to the inner walls of equipment and pipes. (2) Atmospheric corrosion reactions produce ferrous sulfide. Due to prolonged shutdown of the facility, the internal components are exposed to air for extended periods, which leads to atmospheric corrosion and the formation of rust. Since rust is difficult to remove completely, it reacts with hydrogen sulfide during the production process to form ferrous sulfide. The reactions are as follows: Fe + O2 + H2O → Fe2O3•H2O; Fe2O3•H2O + H2S → FeS↓ + H2O. These reactions proceed relatively easily, and due to prolonged shutdowns, equipment with inadequate corrosion protection tends to produce ferrous sulfide. Mechanism and phenomena of spontaneous combustion of ferrous sulfide (1) Mechanism of spontaneous combustion of ferrous sulfide When ferrous sulfide and other iron sulfides are exposed to heat or light in the air, the following reactions occur: FeS + 3/2O2 = FeO + SO2 + 49 KJ; 2FeO + 1/2O2 = Fe2O3 + 271 KJ; FeS2 + O2 = FeS + SO2 + 222 KJ; Fe2S3 + 3/2O2 = Fe2O3 + 3S + 586 KJ. (2) Phenomena of spontaneous combustion of ferrous sulfide During the spontaneous combustion of ferrous sulfide, if there is no combustible material present to support the reaction, white SO2 gas is produced, which is often mistaken for water vapor and has a pungent odor ； A large amount of heat is released at the same time. When other flammable materials (such as oils) are present in the vicinity, thick smoke will be produced, leading to fires and explosions. Factors affecting the formation rate of ferrous sulfide As can be understood from the mechanism of ferrous sulfide formation, in everyday production, the formation of ferrous sulfide is a chemical corrosion reaction that occurs as iron reacts with active sulfides. Therefore, controlling the chemical corrosion reaction is a key means to limit the formation of ferrous sulfide. As long as we identify the areas of the production equipment prone to sulfur corrosion and take effective measures based on the characteristics of each area, we can reduce the amount of ferrous sulfide generated, thereby preventing the occurrence of spontaneous combustion incidents caused by ferrous sulfide. Factors such as the sulfur content of the oil, temperature, the presence of water and Cl-, are important factors that influence the rate of this electrochemical corrosion reaction.
When ferrous sulfide comes into contact with air, it undergoes (BC). A: Explosion B: Combustion C: Oxidation reaction D: Reduction reaction
In the oxidation reaction of C, if ferrous sulfide accumulates in large quantities, it can catch fire on its own