CHEMISTRY GLOSSARY

smoke    →   dim

Smoke is a fine suspension of solid particles in a gas. In general smoke particles range downward from about 5 μm in diameter to less than 01 μm in diameter. Smoke generally refers to a visible mixture of products given off by the incomplete combustion of an organic substance such as wood, coal, fuel oil etc. This airborne mixture general contains small particles (dusts) of carbon, hydrocarbons, ash etc. as well as vapors such as carbon monoxide, carbon dioxide, and water vapor.

sodium    →   natrij

Sodium was discovered by Sir Humphry Davy (England) in 1807. The origin of the name comes from the Latin word natrium meaning sodium carbonate. It is soft silvery-white metal. Fresh surfaces oxidize rapidly. Reacts vigorously, even violently with water. Reacts with water to give off flammable gas. Burns in air with a brilliant white flame. Sodium is obtained by electrolysis of melted sodium chloride (salt), borax and cryolite. Metallic sodium is vital in the manufacture of organic compounds. Sodium chloride (NaCl) is table salt. Liquid sodium is used to cool nuclear reactors.

supercritical carbon dioxide    →   superkritični ugljikov dioksid

Supercritical carbon dioxide (scCO₂) is a powerful, cheap, non-toxic and environmental friendly solvent. When used at a supercritical state (over 74 bar and 31 °C), it achieves similar solvating power as its organic competitors, such as hydrocarbons and chlorinated solvents. Supercritical carbon dioxide is one of few solvents that can be unrestrictedly used for food processing.

supercritical fluid extraction    →   superkritična fluidna ekstrakcija

Supercritical fluid extractions (SFE) have solvating powers similar to liquid organic solvents, but with higher diffusivities, lower viscosity, and lower surface tension. The main advantages of using supercritical fluids for extractions is that they are inexpensive, contaminant free, and less costly to dispose safely than organic solvents. For non-destructive isolation choose SFE, which is simply the best technology for sensitive raw materials. For these reasons supercritical carbon dioxide (scCO₂) is the reagent used to extract caffeine from coffee and tea. Its gaslike behavior allows it to penetrate deep into the green coffee beans, and it dissolves from 97 % to 99 % of the caffeine present.

tin    →   kositar

Tin has been known since ancient times. The origin of the name comes from the Latin word stannum meaning tin. It is silvery-white, soft, malleable and ductile metal. Exposed surfaces form oxide film. Resists oxygen and water. Dissolves in acids and bases. Organic tin compounds may be highly toxic. Tin is principally found in the ore cassiterite (SnO₂) and stannine (Cu₂FeSnS₄). Used as a coating for steel cans since it is non-toxic and non-corrosive. Also in solder (33 %Sn:67 %Pb), bronze (20 %Sn:80 %Cu) and pewter. Stannous fluoride (SnF₂), a compound of tin and fluorine is used in some toothpaste.

toxin    →   toksin

Toxins are effective and specific poisons produced by living organisms. They usually consist of an amino acid chain which can vary in molecular weight between a couple of hundred (peptides) and one hundred thousand (proteins). They may also be low-molecular organic compounds. Toxins are produced by numerous organisms, e.g., bacteria, fungi, algae and plants. Many of them are extremely poisonous, with a toxicity that is several orders of magnitude greater than the nerve agents. Botulinum toxin, produced by the bacteria Clostridium botulinum, is the most poisonous substance known.

triols    →   trioli

Trihydric alcohols (i.e. Triols) are organic compounds containing three hydroxyl groups. The simplest trihydric alcohol is 1,2,3-propane-triol, CH₂(OH)CH(OH)CH₂(OH), which is also known as glycerol (from the Greek glykys meaning sweet) or glycerin. Glycerol is commercially produced by the hydrolysis of fats.

Glycerol is a by-product in the soap industry and is recovered by suitable means.

water gas    →   vodeni plin

Water gas (blue gas, synthesis gas) is a fuel gas used in industrial synthesis of organic chemicals, and in welding, glassmaking, and other high-temperature industrial applications. Water gas is made by passing steam over a bed of hot coal or coke. It mainly consists of carbon monoxide (CO) and hydrogen (H₂), contaminated with small amounts of CO₂, N₂, CH₄, and O₂.

Winkler’s method    →   Winklerova metoda

Winkler’s method was once a common method used to determine the dissolved oxygen concentration by titration. Now rarely used due to the accuracy and low price of oxygen meters.

The water sample is first treated with excess manganese(II) sulfate solution and then with an alkaline solution of potassium iodide. The Mn(OH)₂ initially formed reacts with the dissolved oxygen. The amount of MnO(OH)₂ formed is determined by reaction with iodide ion in acidic solution. The iodine formed may be titrated against standard thiosulfate solution, using starch as an indicator.

Wohler’s synthesis    →   Wohlerova sinteza

Wöhler’s synthesis is a synthesis of urea performed by the German chemist Friedrich Wöhler (1800-1882) in 1828. He discovered that urea (CO(NH₂)₂) was formed when a solution of ammonium isocyanate (NH₄NCO) was evaporated. At the time it was believed that organic substances such as urea could only be made by living organisms, and its production from an inorganic compound was a notable discovery.