The past and present life of hydrogen sulfide gas of special gas

The past and present life of hydrogen sulfide gas of special gas

Yingyan: Understanding Hydrogen Sulfide - From "notorious" to "industrial darling"

What's the pungent smell you've ever smelled? Is it the lingering odor in public toilets, or the stench emitted by rotten organic matter next to the trash can? These frowning smells may contain the same chemical substance - hydrogen sulfide. This gas, marked by "rotten eggs", is the product of life activities on ancient Earth, and plays an indispensable role on the modern industrial stage. It can be called the most contradictory "double-faced" in nature.

The "notorious" of hydrogen sulfide has a long history. As a colorless and highly toxic gas, its olfactory threshold is as low as 0.00041ppm, but after high concentration inhalation, it will quickly numb the olfactory nerves, making people "not smelling that they have been poisoned." Historically, its toxicity has caused many tragedies: in the 2003 major blowout accident in Kaixian, Chongqing, 243 deaths, and in 2020, a 19-year-old girl in Busan, South Korea died of hydrogen sulfide poisoning in a business toilet. These events make it a "invisible killer" in the eyes of the public.

However, it is this gas that is beyond evasion that has accomplished an amazing "value counterattack" in the industrial field. In the copper smelting industry, it can increase the arsenic removal rate in dirty acids to more than 99%. In oil and natural gas mining, it is the main raw material for sulfur production, and even in the sewage treatment process, it can efficiently precipitate heavy metal ions. What is even more surprising is that in recent decades, scientists have discovered that it is an important gas signal molecule in organisms, participating in physiological processes such as cardiovascular regulation, making this "toxic substance" transform into a "new scientific research.

This transformation from ancient life metabolites to core raw materials of industry, from deadly poison gas to hot research topics is the most fascinating feature of hydrogen sulfide. It reminds us that many substances labeled as "harmful" may be just treasures that have not been unlocked yet.

Historical Discovery: Unveiling the Science of "rotten egg gas"

Metallurgists of the 18th century were often troubled by a mystery: silverware in the laboratory would always turn black inexplicably. This seemingly searching for production is actually the initial clue of human hydrogen sulfide. It was not until 1663 that British chemist Robert Boyle first revealed the mystery through experiments - it was this unknown gas that reacted chemically with silver to produce black silver sulfide.

The Swedish chemist Carl Wilheim Scheller really made the appearance of hydrogen sulfide reveal his true appearance. In 1772, he placed sulfur powder in hydrogen in the laboratory and burned it successfully prepared pure hydrogen sulfide gas, recorded the "disgusting sulfur smell" of the gas, and found that sulfur could be precipitated by oxidants. In 1777, Scheller formally confirmed the unique identity of this gas.

In 1796, French chemist Bettorre confirmed through rigorous experiments that hydrogen sulfide molecules contain no oxygen, and its pungent odor and acidity are evident from the direct combination of sulfur and hydrogen. This theoretical breakthrough completely corrected previous cognitive biases and laid the foundation for understanding its chemical properties.

In 1829, German chemist Rosai established a systematic qualitative analysis method with hydrogen sulfide as the core: hydrogen sulfide is introduced into the hydrochloricated solution, and different metal ions will generate sulfide precipitates of characteristic colors, and the metal components in the solution can be accurately identified. This method quickly became the cornerstone of analytical chemistry and is still a classic method today.

The progressive beauty of scientific exploration: From the discoloration of silverware that Boyle accidentally observed, to Scheller's quantitative experiment, to Bettorre's theoretical clarification, Rosey finally transformed basic research into experimental methods - the history of discovery of hydrogen sulfide, which is a microcosm of scientific development.

Chemical properties: The molecular structure and physical characteristics of "spurious temper" and "tenderness" in V-shaped molecules.

The mysterious properties of microstructure determines macroscopic properties - hydrogen sulfide (H₂S), which starts with its molecular configuration. Similar to water molecules, hydrogen sulfide molecules have a V-shaped structure: the central sulfur atom adopts sp³ inequality impurities, and is covalently connected with two hydrogen atoms to form a "bent" configuration with a bond angle of 92°. This structure makes hydrogen sulfide weak in polarity and no hydrogen bonds, which is completely different from water.

Structural model of hydrogen sulfide molecules (yellow is sulfur atom and white is hydrogen atom)

Hydrogen sulfide is a colorless gas with a melting boiling point far lower than water (melting point -85.5℃, boiling point -60.7℃), and always exists in a gaseous form under normal temperature and pressure. Its density is greater than that of air (1.19, air = 1.00), and it is easy to gather in low-lying places, forming invisible and dangerous areas.

The most well-known feature of hydrogen sulfide is the strong smell of rotten eggs, but it is a fatal trap: when the concentration exceeds 100 ppm, it quickly paralyzes the olfactory nerves and makes people lose their perception. In addition, its explosion limit is 4.3%~46.0%, the flame is blue, and the spontaneous ignition temperature is only 260℃. It is very easy to cause explosion when exposed to open flames or high temperatures.

Safety warning: Never rely on the smell to judge the concentration of hydrogen sulfide! Professional gas detectors must be equipped during operation to ensure that the concentration is below the safety threshold (10 ppm, 8-hour weighted average).

"Double-sided" in chemical reactions

Experimental Theater: Chemical Variations of Hydrogen Sulfide

Act 1: The thermal instability breakdown show

When heated to 300°C, the hydrogen sulfide molecules will decompose into hydrogen and sulfur element, showing thermal instability.

Act 2: The Mystery of Burning Blue Flame

When hydrogen sulfide is burning, the sulfur element stages a "dressing party": it is completely burned to produce sulfur dioxide (+4 valence), and incomplete combustion produces sulfur element (0 valence), and the flame is blue.

Act 3: "Dyeing Game" of Metal Ions

Hydrogen sulfide reacts with metal ions to generate sulfide precipitates of characteristic colors, such as black CuS, yellow CdS, and white ZnS. These colors become the "fingerprints" of metal ions, making hydrogen sulfide a "detective" in analytical chemistry.

The "transformation code" of sulfur element: -2 (hydrogen sulfide) →0 (sulphur elemental) →+4 (sulphur dioxide). This dance of valence changes allows hydrogen sulfide to show completely different "double-sided" products during combustion.

Preparation method: From laboratory bottles and cans to industrial production lines

Laboratory method: "Steal Source" in Qipu Generator

The most classic preparation method in the laboratory is to use ferrous sulfide (FeS) and dilute sulfuric acid to react without heating: FeS + H₂SO₄ (dilute) → FeSO₄ + H₂S↑. The exquisite design of the Qipu generator realizes precise control of "using whenever you open, and shutting whenever you turn off".

Modern laboratories more often use thioacetamide hydrolysis: CH₃CSNH₂ + H₂O → CH₃CONH₂ + H₂S↑. This method reduces the experimental risk by slowly releasing gas by controlling the rate of hydrolysis.