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Is Sulfur Flammable? (Answered)

Is Sulfur Flammable? (Answered)

Sulfur is a component that many people have encountered in various disinfectants. Its primary function is to produce sulfuric acid used in pesticides, fungicides, and fertilizers. In the past, sulfur was famous for producing match heads for safety matches, though most manufacturers no longer do. Is sulfur flammable based on its most recent use?

In this in-depth article, we explain what sulfur is, whether it is flammable, and how hot it burns. Also, you’ll discover whether sulfur is flammable in water, whether burning sulfur is dangerous, and whether sulfur fumes are flammable. We conclude by informing you if sulfur can self-ignite.

Read: Is Silver Flammable? (Melting and Boiling Point of Silver)

What is Sulfur?

The oxygen group of chemical elements includes sulfur, a non-metallic element. On the periodic table, it is element number 16. It is a yellow, crystalline substance in its natural state. The element was previously known as “brimstone” (burning stone). Sulfur has a foul odor that most people compare to that of rotting eggs. 

In nature, sulfur is a mineral sulfate, sulfide, and pure element.

Sulfur can be found in nature as hydrogen sulfides and naturally occurs close to volcanoes. The sulfide occurs by the thermal breakdown of sulfates in the presence of water and low-valent metals. When oxygen is applied, pure sulfur forms as hydrogen sulfide gas rises to the surface.

It is helpful in both gas and solid forms. Yet one of its disadvantages is that it contributes significantly to a class of pollutants called sulfur oxides—acid rain forms when sulfur dioxide (sulfur particles) and oxygen combine.

Sulfur exposure over time will cause:

  • Irritation of the eyes, nose, and respiratory system,
  • Headache, nausea, lightheadedness,
  • Skin will burn at high concentrations,
  • Sneezing, coughing, and having trouble breathing
  • Fluids accumulate in the lungs (pulmonary edema),
  • Brain vascular damage.

Is Sulfur Flammable?

Sulfur is not highly flammable in its solid state. It is significantly more flammable in liquid or powder form. Heat causes sulfur’s bonding structure to break down swiftly. Sulfur can transform quickly from a solid to a gas without going through the liquid state. You’ll need to store sulfur powder as a potential fire hazard safely. 

S8 is a unique molecular structure that contains sulfur. Eight sulfur atoms are arranged in an octagonal pattern and joined by bonds to form the structure. Heat destroys the bonding structure of the octets in sulfur. The melting point of sulfur is only 239 °F (115 °C). 68 °F (20 °C) is the temperature at which it sublimates.

At 320 °F (160 °C), solid sulfur will ignite. OSHA classifies this temperature as not flammable, but sulfur’s flashpoint in powder form is substantially lower. As a result of the increased surface area to volume ratio of the substance, sulfur powder has significant flammability.

How Hot is Burning Sulfur?

Sulfur has a boiling point of 832°F (444°C). It turns from a liquid to a gas or vapor as it boils. Sulfur is extremely hot, corrosive and can result in severe burns when it reaches this temperature. Hot sulfur is exceptionally flammable at this temperature. Sulfur burns slowly at first, producing a lot of smoke when it ignites.

Due to its solid covalent atoms, sulfur has a higher boiling point than other non-metals. As sulfur atoms share electrons to build a strong structure, breaking these connections and turning liquid sulfur into gas is challenging. Another explanation for sulfur’s high boiling point is the existence of van der Waals forces and the large size of the sulfur molecules.

Although molten sulfur is not poisonous, it emits poisonous gases, including hydrogen sulfide and sulfur dioxide, when heated to high temperatures.

Are Sulfur Fumes Flammable?

Flames of sulfur are flammable. The temperatures at which sulfur turns into gas are higher than average. Due to its lower flash point, sulfur is less likely to become gaseous before igniting in oxygen. In a laboratory, you can produce fumes in the absence of oxygen. So, apart from sulfur fumes being flammable, it is also toxic. 

Ensure that sulfur gas storage cylinders remain upright at all times. When not in use or when empty, keep them firmly closed. Never roll, slide, drag, or drop the cylinders. Keep the cylinders away from any ignition source, including fire and direct heat.

Is Burning Sulfur Dangerous?

Sulfur burning is dangerous. Sulfur dioxide forms from burning sulfur, and when it comes into contact with water, it transforms into sulfuric acid. A powerful acid that can destroy biological material is sulfuric acid. Lungs, eyes, and airways are body parts containing large amounts of water in all living things. Hence, it is now possible for sulfur to react with living things and produce sulfuric acid.

The skin of living organisms has moisture and will also react with sulfur. Sulfur dioxide is poisonous and can aggravate conditions like asthma or COPD (chronic obstructive pulmonary disease. It can cause severe damage to the cornea. 

Sulfur-containing chemicals that burn will pollute the air. When gasoline and diesel burn, sulfur escapes into the atmosphere.

Is Sulfur Flammable in Water?

Sulfur is not flammable in water. Even at high temperatures, it is not soluble in water and does not melt in it. Sulfur will float on the water’s surface or might even get wet. Before reacting with water, sulfur must first react with oxygen. When water and sulfur in powder form mix, the mixture releases sulfur dioxide gas and sulfurous acid.

Read: Is WD-40 Flammable? (What Temperature Does it Burn?)

The reaction between sulfur and water is exothermic and produces heat. When sulfur and water mix, they form sulfurous acid and hydrogen sulfide. The reaction between water and sulfur trioxide produces sulfuric acid. Manufacturers use the acid in the manufacture of the following: 

  • Inorganic salts,
  • Drugs, 
  • Explosives,
  • Dyes,
  • Detergents,
  • Esters,
  • Fertilizers. 

Can Sulfur Self Ignite?

Sulfur can ignite itself. Sulfur quickly ignites when it is floating in the air, especially if sulfur is present in a small area. It is known as self-ignition when sulfur ignites independently without an ignition source. An explosion is more likely to occur when sulfur dust self-ignites. Nonetheless, its solid state will burn moderately.

The temperature at which sulfur self-ignites is 470°F (243°C). The lowest temperature that a material ignites without an external source, such as a fire or a flame. However, the material can only self-ignite in its liquid or gas state. 

Frequently Asked Questions

Is sulfur used in explosives?

Sulfur is a standard fuel in inorganic explosive compositions like black powder replacements, flash powder, and black powder. Carbon, potassium nitrate, and sulfur are the main ingredients in gunpowder. Carbon and sulfur both function as fuels. Blasting agents for explosives might include, but are not limited to gunpowder.

An explosive material explodes forcefully and quickly, releasing vast amounts of heated gas. Due to its accessibility, sulfur is also one of the components of improvised explosive devices(IEDs). Moreover, IEDs are the main compound in the production of homemade explosives.

How do you put out a sulfur fire?

While the first reaction would be to use water to try and extinguish a sulfur fire, don’t use high-pressure water jets or any other medium. Instead, use fine sprays of water or steam. The best medium, however, would be extinguishing foams of carbon dioxide.  

What are the benefits of sulfur in water?

Hydrogen sulfur gas is present in large quantities in sulfur water. DNA needs sulfur to be formed and repaired. Also, it aids in preventing cellular damage, which can result in cancer and other disorders. Sulfur helps you efficiently break down meals while enhancing the condition of your skin, tendons, and ligaments.

Even though sulfur is good for the body, drinking sulfur water can make you sick and eventually dehydrate you. Your plumbing system may become damaged by sulfur.

 What is the color of sulfur fire?

Blue lava is the color of sulfur fire—high-temperature burning of sulfur results in energizing flames. When sulfur burns, it produces “blue lava” flames, an electric blue fire. During sulfur combustion, a neon-blue flame forms.

The term “blue lava” refers to the color of lava. These fires typically happen in places with high sulfur content, like Indonesia’s Kawah Ijen volcano. These places include some mining sites. In some places, sulfur from the volcano’s interior rises to the surface and catches fire, igniting blue flames.

The sulfur melts, sometimes flowing down the face of the volcano carrying flames with it, which appear as if blue lava is flowing. Due to the blue color of the flames, they are only visible at nighttime. 


While sulfur, a non-metallic element typically found in volcanoes, has numerous advantages, it can also be harmful if not handled properly. It is not very flammable while solid, but it is very flammable in powder form. The solid covalent bond makes sulfur the non-metal with the highest boiling point.

Fumes from sulfur are poisonous and flammable. Temperatures at which sulfur fumes ignite are challenging since they do so beyond their low flash point. Sulfur burning is hazardous. Sulfur does not ignite easily and does not react with water. It does, however, self-ignite.

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