thiophene-2-methanethiol

Lead-mercury-2-naphtha is a unique thing, and its physical properties are unique.
Looking at its shape, under normal circumstances, naphtha is mostly a flowing liquid, like smart water, but its color may be yellowish, or clear and transparent, just like jade nectar. Its texture is light, if not to touch, and the smoothness overflows at the fingertips.
When it comes to smell, naphtha exudes a unique smell, neither a rich fragrance nor a pungent smell, but a unique smell between the two. Although its smell is not strong, the smell can also make people alert, as if warning the extraordinary of this thing.
Furthermore, the density of naphtha is lighter than that of water. If you pour it on the water, you can see that it floats leisurely on the water surface, as if it does not blend with the water, and it is bounded by each other. And its boiling point is not high, at an appropriate temperature, you can see that it gradually gasifies, curls and rises, like a cloud and mist.
The solubility of naphtha is also quite unique, it can dissolve with many organic solvents, as if it fits well with each other and fuses into one. However, for water, it is distinct and incompatible with each other.
Its conductivity is weak, almost nothing, just like an insulator. In the field of electricity, it rarely shows the characteristics of conductivity.
Naphtha has such physical properties that it has unique uses in various processes and affairs. However, due to its special properties, it should be used with extra caution to prevent unexpected changes.

Alum is a general term for a class of compounds. There are many kinds of alum, among which potassium alum, also known as potassium alum, has unique chemical properties. Today, I will describe the chemical properties of potassium alum in detail.
First word Solubility, potassium alum is easily soluble in water, and can dissociate potassium ions ($K ^ + $), aluminum ions ($Al ^ {3 +} $) and sulfate ions ($SO_ {4} ^ {2 - }$）。 This dissociation process is very important, because the ions it produces make potassium alum exhibit specific properties in many chemical reactions.
Aluminum ions will undergo hydrolysis in water. The hydrolysis formula is: $Al ^ {3 + } + 3H_ {2} O\ rightleftharpoons Al (OH) _ {3} + 3H ^{ + }$ 。 Hydrolysis produces hydrogen ions, so the aqueous solution of potassium alum is acidic. This acidic property makes it useful in some reactions or applications that require acidic environments.
Furthermore, potassium alum can react with bases. For example, when a small amount of sodium hydroxide is added to the potassium alum solution, a white precipitate of aluminum hydroxide ($Al (OH) _ {3} $) is formed, and the reaction equation is: $Al ^ {3 + } + 3 OH ^{ - } = Al (OH) _ {3}\ downarrow $. If there is an excess of sodium hydroxide, the aluminum hydroxide precipitate will continue to react with hydroxide ions to form metaaluminate ions ($AlO_ {2 }^{-}$）， precipitate and dissolve. The reaction formula is: $Al (OH) _ {3} + OH ^{ - } = AlO_ {2 }^{-} + 2H_ {2} O $. < Br >
At the level of redox reaction, potassium and aluminum in potassium alum are usually difficult to undergo redox reaction because their valence is relatively stable. However, sulfate ions may undergo reduction reactions under specific conditions, such as strong reducing agents and in acidic environments, but such reaction conditions are more harsh.
In addition, potassium alum can undergo metathesis reactions with certain metal ions. For example, when it encounters barium ions ($Ba ^ {2 +} $), sulfate ions will combine with barium ions to form a white precipitate of barium sulfate ($BaSO_ {4} $). The reaction formula is: $Ba ^ {2 + } + SO_ {4} ^ {2 - } = BaSO_ {4}\ downarrow $. This reaction is often used to test the presence of sulfate ions in solutions.
Potassium alum has rich and diverse chemical properties and is used in many fields, such as water purification, food processing, medicine, etc., all of which rely on its unique chemical properties to play a role.

"Tiangong Kaiwu" says: "Where the arsenic is, all the soil is born, but between Heng and Shao, it is only prosperous. How to get it: The mountain soil is more than ten feet high, or five or six feet high, and the soil surface produces minerals, just like earthworm mud. There is arsenic under it, which is dug and fried."
Arsenic is an oxide of arsenic, a highly toxic substance. Common methods of preparation are mostly derived from the smelting of arsenic-containing minerals.
In ancient times, it was often extracted from specific arsenic-containing ores. For example, some arsenic sulfide ores can be obtained by roasting and other processes. Arsenic-containing ores are first mined, mostly excavated from the mines in the mountains. Such ores are often hidden deep underground, and it is necessary to identify the direction of the ore veins according to experience and dig them accurately. < Br >
After the ore is recovered, it is roasted by the method of roasting. In a special stove, the ore is stacked, and firewood is used as fuel, and roasted at high temperature. During roasting, arsenide is sublimated at high temperature, and then collected by a condensing device. This condensed material is crude arsenic.
However, this crude arsenic has a lot of impurities and needs to be purified again. Often by the method of dissolution, filtration, and recrystallization. Crude arsenic is dissolved in an appropriate solvent, filtered to remove insoluble impurities, and then controlled by temperature and other conditions to precipitate arsenic crystals, so that pure arsenic can be obtained.
It needs to be clear that although arsenic is highly toxic, it also has specific uses in medicine, agriculture and other fields. Ancient healers, after special processing, used trace amounts of arsenic as medicine to treat certain intractable diseases. In agriculture, it was also used to prevent insects, but due to its severe toxicity, it should be used with extreme caution.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty. Although there is no precise corresponding record on the synthesis method of mercury-2-ethyl amalgam, it can be speculated one or two based on the wisdom of the ancients and related chemical principles and similar processes.
Amalgam is an alloy formed by mercury and other metals. To synthesize mercury-2-ethyl amalgam, one method can be as follows: Select high-quality mercury and place it in a special crucible. The mercury made by the ancients is often obtained by heating and decomposing Dan sand (mercury sulfide). Pure mercury should be selected as the raw material. Another metal compound containing ethyl is prepared, which is ground into a fine powder for full reaction. Heat the crucible slowly over a charcoal fire to bring the mercury to a slightly boiling state and maintain a mild heat. Slowly sprinkle the powder containing the ethyl metal compound into the crucible, and stir at a constant speed with special bamboo chopsticks or metal rods. This process requires extreme caution, because mercury and its compounds are many toxic. Continue stirring and heating to fully react and combine mercury with the ethyl metal compound. Although the ancients did not have modern precision equipment, they could roughly judge the reaction process by observing the color change, odor and material form changes of the reaction. After the reaction is completed, cool the crucible to obtain mercury-2-ethyl amalgam.
Furthermore, wet synthesis may be attempted. Take an appropriate amount of mercury, place it in a porcelain container, add a specific solvent, and dissolve the ethyl-containing metal compound in it. Stir well, so that the mercury and the dissolved ethyl-containing metal ions are fully contacted, and a displacement reaction or complexation reaction occurs, and mercury-2-ethyl amalgam is gradually formed. However, in this process, the choice of solvent, the control of reaction temperature and time are extremely critical. The ancients may have repeated practice to determine the best reaction conditions.
In short, although the synthesis of mercury-2-ethyl amalgam is not detailed in "Tiangong Kaiwu", the corresponding synthesis route can be explored with the help of the chemical process experience and wisdom accumulated by the ancients. This is also one of the spots where the ancients explored material changes and created inventions.

Mercury is a highly toxic substance, and its divalent mercury salts, such as mercury chloride, etc., must be paid attention to when it is in use.
Safety is the first priority. Mercury salts are highly toxic, damaging to people's organs, nerves, and even life-threatening. Therefore, for storage, a sturdy and airtight device must be selected to prevent its leakage. Store in a cool, dry, and well-ventilated place, away from fire and heat sources, and away from direct sunlight. Due to heat, light, or changes in properties, it increases the risk of leakage.
When taking it, be sure to operate according to the specifications. Prepare protective equipment first, such as gloves, masks, goggles, and lab clothes to prevent mercury salts from touching the body and inhaling. Take it with clean and special equipment, weigh it accurately, use the equipment, and wash it immediately to prevent cross-contamination caused by mercury salt residues.
Furthermore, the disposal of mercury salt waste liquid is crucial. It should not be dumped at will, but must be collected in a centralized manner and disposed of in accordance with environmental protection regulations. Usually, a chemical precipitation method is used to add a precipitant to precipitate mercury ions into insoluble mercury compounds, separate, recycle, or hand them over to professional institutions for disposal.
In places where mercury salts are stored, it is advisable to prepare emergency materials, such as mercury-absorbing materials and detoxification drugs. In the event of a leakage accident, evacuate personnel quickly, ventilate and ventilate, collect mercury with mercury-absorbing materials, and sprinkle residual mercury with sulfur powder to dissolve mercury sulfide and reduce toxicity.
Anyone who uses mercury must strictly abide by the regulations, prioritize safety and environmental protection, and must not slack a little to avoid major disasters.