Hydrogen Sulfide (H2S) is a colourless, flammable, and highly toxic gas. This gas has a strong odour of rotten eggs. It is produced by the anaerobic bacterial decomposition of protein and other sulphur-containing organic matter. Hydrogen Sulphide is also known as sewer gas or swamp gas.
This article thoroughly explains hydrogen sulphide, structure of hydrogen sulphide, along with its properties and applications.
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Hydrogen Sulphide Overview |
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Chemical Formula |
H2S |
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Odour |
Pungent, Rotten Egg |
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Appearance |
Colourless gas |
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Molar Mass |
34.086 amu |
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Boiling Point |
-60°C (-76°F). |
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Melting Point |
-82°C (-116°F). |
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Solubility |
Soluble in Water |
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Conjugate Base |
Sulfonium |
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Conjugate Acid |
Bisulfide |
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Density |
1.36 kg/m3 |
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Nature |
Toxic |
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Bond Angle |
92° |
Table of Content
What is Hydrogen Sulphide?
Hydrogen Sulphide (H2S) is a colourless, highly toxic gas with a distinctive odour as that of rotten eggs. It is composed of two hydrogen atoms bonded to a sulphur atom and is commonly found in natural gas, petroleum, volcanic gases, and sulphur deposits.
It has many practical applications in various industries, including the production of sulphur and in organic synthesis but hydrogen sulphide poses significant health risks at high concentrations.
Hydrogen Sulphide Chemical Formula
The chemical formula for hydrogen sulphide is H2S.
Hydrogen Sulphide Molecular Mass
Molecular mass of hydrogen sulphide (H2S) can be calculated by adding the atomic masses of its constituent atoms.
Sulphur (S) has an atomic mass of approximately 32.07 atomic mass units (amu), and hydrogen (H) has an atomic mass of approximately 1.008 amu. Therefore, the molecular mass of H2S is approximately 2.016 + 32.07 = 34.086 amu.
The molecular mass of Hydrogen Sulphide is 34.086 amu.
Structure of Hydrogen Sulphide
Chemical structure of hydrogen Sulphide(H2S) consists of two hydrogen atoms bonded to a central sulphur atom. It is represented as H-S-H, indicating that the two hydrogen atoms are bonded to the sulphur atom through single covalent bonds.
This arrangement allows the sulfur atom to complete its outer electron shell, stabilizing the molecule. Additionally, the sulfur atom possesses a lone pair of electrons, contributing to the overall geometry of the molecule.
Hydrogen Sulphide Lewis Structure
The Lewis structure of hydrogen sulphide shows a central sulphur atom bonded to two hydrogen atoms. Sulphur has six valence electrons, and hydrogen has one each, giving a total of eight valence electrons for the H2S molecule. The Lewis structure shows a lone pair of electrons on sulphur.
Hydrogen Sulphide Bond Angle
Due to the repulsion between electron pairs, hydrogen Sulphide adopts a bent or V-shaped configuration. As a consequence, the bond angle between the hydrogen atoms in hydrogen Sulphide is approximately 92°. This bent molecular structure reflects the distribution of electron density within the molecule, providing insights into its chemical properties and behavior in various contexts.
Below is the diagrammatical representation of the Hydrogen Sulphide Structure and Bond Angle:
Properties of Hydrogen Sulphide
Hydrogen Sulphide (H2S) exhibits a range of physical and chemical properties that define its behavior and interactions in various environments. The complete description of physical and chemical properties of hydrogen sulphide is given below:
Physical Properties of Hydrogen Sulphide
- Color and Odor: Hydrogen Sulphide is a colorless gas with a distinct foul odor similar to that of rotten eggs, which is detectable even at low concentrations.
- State: Under standard temperature and pressure conditions, hydrogen Sulphide exists as a gas.
- Solubility: Hydrogen Sulphide is moderately soluble in water, with solubility increasing as the temperature decreases.
- Boiling Point: Hydrogen Sulphide has a boiling point of -60°C (-76°F).
- Melting Point: Hydrogen Sulphide has a melting point of -82°C (-115.6°F).
- Flammability: Hydrogen Sulphide is highly flammable gas and can form explosive mixtures.
Chemical Properties of Hydrogen Sulphide
- Reactivity: Hydrogen Sulphide is a reducing agent and reacts readily with many metals and metal ions, forming metal sulphides. It also reacts with oxidizing agents, such as chlorine, to produce sulphur and hydrochloric acid.
- Acidity: In aqueous solutions, hydrogen Sulphide behaves as a weak acid, dissociating partially to form hydrosulphide ions (HS–) and hydrogen ions (H+).
- Corrosivity: Concentrated hydrogen Sulphide gas can corrode metals, especially in the presence of moisture, leading to the formation of metal Sulphide.
- Toxicity: Hydrogen Sulphide is highly toxic to humans and animals, primarily affecting the respiratory and nervous systems.
- Formation of Complexes: Hydrogen Sulphide can form complexes with certain metal ions, giving rise to various coordination compounds with distinct chemical and physical properties.
Hydrogen Sulphide in Water
Hydrogen sulphide is sparingly soluble in water, and it forms a weak acid called hydrosulphuric acid when dissolved in water. The presence of hydrogen sulphide in water can lead to a variety of environmental and health issues.
Hydrogen Sulphide Geometry
Geometry around the sulphur atom in hydrogen sulphide is approximately bent or V-shaped. This is due to the presence of two bonding pairs and one lone pair of electrons around the sulphur atom, resulting in a trigonal planar electron geometry and a bent molecular geometry.
Hydrogen Sulphide Hybridization
In hydrogen sulphide, the sulphur atom undergoes sp3 hybridization, where one 3s orbital and three 3p orbitals hybridize to form four sp3 hybrid orbitals. These orbitals are then used to form bonds with the two hydrogen atoms and accommodate the lone pair of electrons.
Read More, Hybridization
Production of Hydrogen Sulphide
Hydrogen Sulphide (H2S) is produced through various natural and industrial processes, each with its own methods and applications. Here are some common ways in which hydrogen Sulphide is produced:
- Biological Processes: Hydrogen Sulphide is generated naturally through biological processes, particularly in anaerobic environments where organic matter undergoes decomposition in the absence of oxygen. Sulfur-reducing bacteria metabolize organic compounds and produce hydrogen Sulphide as a metabolic byproduct. This occurs in environments such as swamps, marshes, sewage systems, etc.
- Industrial Synthesis: Hydrogen sulfide can be produced industrially by reacting hydrogen gas (H2) with sulphur vapor (S) in the presence of a catalyst at a high temperature of about 450℃.
H2 + S → H2S
- Volcanic Activity: Hydrogen Sulphide is emitted naturally during volcanic eruptions and geothermal activity. Volcanic gases, which include hydrogen Sulphide, sulphur dioxide, and other sulphur compounds, are released into the atmosphere during volcanic events.
Applications of Hydrogen Sulphide
Hydrogen Sulphide (H2S) finds its applications across various industries due to its unique properties. Some of the key applications of H2S include:
- Chemical Synthesis: Hydrogen Sulphide is used in chemical synthesis to produce a wide range of sulfur-containing compounds. These compounds are utilized in the production of pharmaceuticals, pesticides, and organic chemicals.
- Metal Processing: H2S is employed in metallurgy for the extraction of metals from their ores. It facilitates the precipitation of metal Sulphides, which can then be further processed to obtain pure metals. For example, hydrogen sulphide is used in the purification of copper, zinc, and lead ores.
- Oil and Gas Industry: H2S is used in the refining of crude oil to remove impurities such as mercaptans.
- Analytical Chemistry: Hydrogen Sulphide is utilized as a reagent in analytical chemistry for the detection of metal ions.
- Wastewater Treatment: Hydrogen sulphide is utilized in wastewater treatment to remove heavy metals from contaminated water. It forms insoluble metal sulphide with metal ions present in wastewater, allowing for their precipitation and subsequent removal from the water.
Also Check,
Hydrogen Sulphide: FAQs
Is H2S Heavier than Air?
Yes, hydrogen sulphide (H2S) is heavier than air. Its molecular weight is about 34 g/mol, which is heavier than the average molecular weight of air (which is about 29 g/mol).
What is Smell of Hydrogen Sulphide?
Hydrogen sulphide (H2S) has a distinct and unpleasant odor similar to the smell of rotten eggs.
Is H2S Soluble in Water?
Yes, H2S is soluble in water. It forms a weak acid when dissolved in water, known as hydrosulfuric acid.
What is Hydrogen Sulphide (H2S)?
Hydrogen sulphide is a colorless, highly toxic gas with a distinctive odor of rotten eggs. It consists of two hydrogen atoms bonded to a sulphur atom (H-S-H).
What are Health Effects of Hydrogen Sulphide?
Inhalation of hydrogen sulphide gas can cause respiratory irritation, nausea, headaches, and in high concentrations, it can lead to loss of consciousness, respiratory paralysis, and even death.
What are Environmental Impacts of Hydrogen Sulphide?
Hydrogen sulphide emissions can contribute to air pollution, foul odors, and environmental contamination. In aquatic environments, it can harm marine life and disrupt ecosystems.
What is Hydrogen Sulphide Used for?
Hydrogen Sulphide is used in chemical synthesis, metal processing, wastewater treatment, analytical chemistry, and biological research.
How is Hydrogen Sulphide Detected?
Hydrogen sulphide can be detected by its characteristic odor even in small concentrations. However, at higher concentrations, it deadens the sense of smell, making detection more difficult. Various sensors and analytical methods are used to detect hydrogen sulphide.