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2426) Naphtha

Gist

Naphtha is a flammable liquid mixture of hydrocarbons, primarily derived from crude oil distillation, that serves as a crucial feedstock and fuel in various industries. It is used to produce high-octane gasoline, petrochemicals for plastics, fertilizers, and is also used as a solvent and for fuels like lighter fluid or camp stoves. Due to its flammability, it must be handled with care, and its vapor is heavier than air and can travel to an ignition source.

The main uses of crude oil naphtha fall into the general areas of (i) precursor to gasoline and other liquid fuels, (ii) solvents or diluents for paints, (iii) dry-cleaning solvents, (iv) solvents for cutback asphalt, (v) solvents in rubber industry, and (vi) solvents for industrial extraction processes.

Summary

Naphtha is any of various volatile, highly flammable liquid hydrocarbon mixtures used chiefly as solvents and diluents and as raw materials for conversion to gasoline. Naphtha was the name originally applied to the more volatile kinds of petroleum issuing from the ground in the Baku district of Azerbaijan and Iran. As early as the 1st century ad, naphtha was mentioned by the Greek writer Dioscorides and the Roman writer Pliny the Elder. Alchemists used the word principally to distinguish various mobile liquids of low boiling point, including certain ethers and esters.

In modern usage the word naphtha is usually accompanied by a distinctive prefix. Coal-tar naphtha is a volatile commercial product obtained by the distillation of coal tar. Shale naphtha is obtained by the distillation of oil produced from bituminous shale by destructive distillation. Petroleum naphtha is a name used primarily in the United States for petroleum distillate containing principally aliphatic hydrocarbons and boiling higher than gasoline and lower than kerosene.

Details

Naphtha is a flammable liquid hydrocarbon mixture. Generally, it is a fraction of crude oil, but it can also be produced from natural-gas condensates, petroleum distillates, and the fractional distillation of coal tar and peat. In some industries and regions, the name naphtha refers to crude oil or refined petroleum products such as kerosene or diesel fuel.

Naphtha is also known as Shellite in Australia.

Modern period

Since the 19th century, solvent naphtha has denoted a product (xylene or trimethylbenzenes) derived by fractional distillation from petroleum; these mineral spirits, also known as "Stoddard Solvent," were originally the main active ingredient in Fels Naptha laundry soap. The naphtha in Fels Naptha was later removed as a cancer risk.

The usage of the term "naphtha" during this time typically implies petroleum naphtha, a colorless liquid with a similar odor to gasoline. However, "coal tar naphtha," a reddish brown liquid that is a mixture of hydrocarbons (toluene, xylene, and cumene, etc.), could also be intended in some contexts.

Petroleum

In older usage, "naphtha" simply meant crude oil, but this usage is now obsolete in English. There are a number of cognates to the word in different modern languages, typically signifying "petroleum" or "crude oil."

The Ukrainian & Belarusian word (nafta), Lithuanian, Latvian, & Estonian "nafta," and the Persian naft mean "crude oil." The Russian word (neft') means "crude oil," but (nafta) is a synonym of ligroin. Also, in Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Finland, Italy, Serbia, Slovenia, and Macedonia nafta (нафта in Cyrillic) is colloquially used to indicate diesel fuel and crude oil. In the Czech Republic and Slovakia, nafta was historically used for both diesel fuel and crude oil, but its use for crude oil is now obsolete and it generally indicates diesel fuel. In Bulgarian, nafta means diesel fuel, while neft, as well as petrol (петрол in Cyrillic), means crude oil. Nafta is also used in everyday parlance in Argentina, Uruguay and Paraguay to refer to gasoline/petrol. Similarly, in Flemish, the word naft(e) is used colloquially for gasoline. In Poland, the word nafta means kerosene, and colloquially crude oil (the technical name for crude oil is ropa naftowa, also colloquially used for diesel fuel as ropa).

Types

Naphtha has been divided into two types by many sources in order to differentiate between common grades more clearly:

One source distinguishes by boiling point as well as carbon atom count per molecule:

* Light naphtha is the fraction boiling between 30 and 90 °C (86 and 194 °F) and consists of molecules with 5–6 carbon atoms.
* Heavy naphtha boils between 90 and 200 °C (194 and 392 °F) and consists of molecules with 6–12 carbon atoms.

Chemistry of Hazardous Materials differentiates light and heavy based on the carbon atom count and hydrocarbon structure:

* Light [is] a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from five to six carbon atoms per molecule.
* Heavy [is] a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from seven to nine carbon atoms per molecule.

Some sources also define petroleum naphtha, which contains both heavy and light naphtha, and typically consists of 15-30% of crude oil by weight.

Uses:

Heavy crude oil dilution

Naphtha is used to dilute heavy crude oil to reduce its viscosity and enable/facilitate transport; undiluted heavy crude cannot normally be transported by pipeline, and may also be difficult to pump onto oil tankers. Other common dilutants include natural-gas condensate and light crude. However, naphtha is a particularly efficient dilutant and can be recycled from diluted heavy crude after transport and processing. The importance of oil dilutants has increased as global production of lighter crude oils has fallen and shifted to exploitation of heavier reserves.

Fuel

Light naphtha is used as a fuel in some commercial applications. One notable example is wick-based cigarette lighters, such as the Zippo, which draw "lighter fluid"—naphtha—into a wick from a reservoir to be ignited using the flint and wheel.

It is also a fuel for camping stoves and oil lanterns, known as "white gas", where naphtha's low boiling point makes it easy to ignite. Naphtha is sometimes preferred over kerosene because it clogs fuel lines less. The outdoor equipment manufacturer MSR published a list of trade names and translations to help outdoor enthusiasts obtain the correct products in various countries.

Naphtha was also historically used as both a fuel and a working fluid in some small boats where steam technology was impractical; most were built to circumvent safety laws relating to traditional steam launches.

As an internal combustion engine fuel, petroleum naphtha has seen very little use and suffers from lower efficiency and low octane ratings, typically 40 to 70 RON. It can be used to run unmodified diesel engines, though it has a longer ignition-delay than diesel. Naphtha tends to be noisy in combustion due to the high pressure rise rate. There is a possibility of using naphtha as a low-octane base fuel in an octane-on-demand concept, with the engine drawing a high-octane mix only when needed. Naptha benefits from lesser emissions in refinement: fuel energy losses from "well-to-tank" are 13%; lower than the 22% losses for petroleum.

Plastics

Naphtha is a crucial component in the production of plastics.

Additional Information

Naphtha is a term used to refer to a group of volatile, flammable mixtures of liquid hydrocarbons that are used mainly as solvents, diluents, or raw materials for gasoline conversion. It is a lightweight petrochemical feedstock that is separated from crude oil in the fractional distillation process along with kerosene and jet fuel.

There are many specific types of naphtha that vary in the amounts and types of hydrocarbons contained in their unique blend. Refineries can produce various forms of naphtha, and each has specific guidelines in how it should be handled and stored. Generally speaking, the flammability and volatility of naphtha should be taken into consideration as they are significant safety hazards.

Uses and Safety

As mentioned above, naphtha is commonly used as a solvent. It is used in hydrocarbon cracking, laundry soaps, and cleaning fluids. Naphtha is also used to make varnishes, and sometimes is used as a fuel for camp stoves and as a solvent (diluent) for paint. Although naphtha has many uses, some forms of it can be dangerous. Many kinds of naphtha can cause skin irritation, upset stomachs, and other health problems if people are exposed to them. Some forms are also carcinogens, and thus inhalation or ingestion of the chemical should be avoided.

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#10629. What does the term in Geography Central business district mean?

#10630. What does the term in Geography Centroid mean?

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#2506. What does the medical term Ileocecal valve mean?

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#6280.

2425) Gemology

Gist

Gemology is the science of studying and identifying natural and artificial gemstones. A gemologist examines gemstones for their beauty, durability, and rarity by studying their composition, physical and optical properties, origin, and treatments. This field involves techniques like microscopic inspection, hardness tests, and the use of specialized tools like refractometers to identify and grade gems for purposes in the jewelry, astrological, and industrial sectors.

Summary

Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a specific interdisciplinary branch of mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identify and evaluate gems.

Background

It is often difficult to obtain an expert judgement from a neutral laboratory. Analysis and estimation in the gemstone trade usually have to take place on site. Professional gemologists and gemstone buyers use mobile laboratories, which pool all necessary instruments in a travel case. Such so-called travel labs even have their own current supply, which makes them independent from infrastructure. They are also suitable for gemological expeditions.

Gemstones are basically categorized based on their crystal structure, specific gravity, refractive index, and other optical properties, such as pleochroism. The physical property of "hardness" is defined by the irregular Mohs scale of mineral hardness.

Gemologists study these factors while valuing or appraising cut and polished gemstones. Gemological microscopic study of the internal structure is used to determine whether a gem is synthetic or natural by revealing natural fluid inclusions or partially melted exogenous crystals that are evidence of heat treatment to enhance color.

The spectroscopic analysis of cut gemstones also allows a gemologist to understand the atomic structure and identify its origin, which is a major factor in valuing a gemstone. For example, a ruby from Myanmar (Burma) will have definite internal and optical activity variance from a Thai ruby.

When the gemstones are in a rough state, the gemologist studies the external structure; the host rock and mineral association; and natural and polished color. Initially, the stone is identified by its color, refractive index, optical character, specific gravity, and examination of internal characteristics under magnification.

Details

Gemology is the science of studying, cutting, and valuing precious stones, but the essence of gemology is in identifying the gemstones. One who works in the field of gemology is called a gemologist, and jewelers and goldsmiths also may be gemologists.

Some collectors and investors may be interested only in gems' monetary value, but to distinguish one gemstone from another, they will need to seek out a gemologist. Gemologists examine gemstones—both discovered raw and synthesized in the laboratory—using microscopes, computerized tools, and other grading instruments.

Key Takeaways

* Gemology is the science of identifying gemstones.
* Gemologists examine gemstones—both discovered raw and synthesized in the laboratory—using microscopes, computerized tools, and other grading instruments.
* The field of gemology contains professionals such as appraisers, goldsmiths, jewelers, lapidaries, and scientists.
* Investing in gemstones may be risky, but the precious metals sector can be less speculative for inexperienced investors.
* Unlike other types of investments, gemstones may not be as easily liquidated if you have an urgent need for cash.

Understanding Gemology

At its heart, gemology is about identifying gems. Gemologists identify a gemstone by its specific characteristics and properties, such as cut, color, quality, and clarity. Some rubies and garnets, for example, are impossible to distinguish by their appearance, but their underlying physical properties differ considerably. Many people are familiar with a group of criteria that is used in gemology to identify diamonds—the 4Cs of color, clarity, cut, and carat.

Gemology and Its Professionals

In addition to gemologists, the field of gemology contains numerous other professionals, including appraisers, jewelers, lapidaries, metalworkers, and scientists.

Gemologists may become certified as professional appraisers, whose expertise is useful in many other industries, including jewelry sales and investing. Jewelers need to understand gemology to answer their customers’ questions and identify any gems brought to them. Goldsmiths and other metalworkers need specific knowledge about the physical characteristics of gems to create appropriate settings. For example, a setting that would be ideal for a diamond could damage an opal, and the amount of pressure used to set the prongs on a garnet could break a stone of tanzanite.

Lapidaries, or gem cutters, also need special knowledge, as appropriate cutting and polishing techniques vary from gem to gem. What would work well for one gemstone would be a waste of time or even disastrous for another gem. Scientists with degrees in geology, chemistry, and even physics make up the smallest group of gemologists, although they are very influential. Scientists add to gemology's knowledge base by developing new testing techniques and researching new gemstones.

Tip

The International Gem Society offers an online Professional Gemologist certification course while The Gemological Institute of America offers a Graduate Gemologist program.

Gemstones as Investments

When returns in the stock market decline, aggressive investors often seek out alternatives that may hold more promise of increasing returns on invested capital (ROIC) than traditional investment types. Or, some investors might want to consider tangible assets simply as a way to diversify their holdings even during good market conditions. Investing in gemstones—in particular, those that are rare or of exceptional quality—likely would at least retain, and probably increase in value.

However, unlike other types of investments, gemstones may not be as easily liquidated if you have an urgent need for cash. This drawback is especially founded for rare, precious stones and jewelry that would appeal to elite buyers only. Gemstone investing can seem exciting to those who want to make quick returns, but it is highly speculative and should only be undertaken by experienced professionals. Investing in the precious metals sector, however, is different because there are standards as well as specific investment vehicles for them in the financial markets.

The term "investment-grade" is often tossed around by those who want to sell gems or try to convince other people to invest in them. However, this practice is frowned upon in financial services because there are no formal standards for what constitutes investment-grade gemstones, as there are for investment-grade bonds, for example.

Careers in Gemology

With advances in gemstone synthesis, gemology has become an important field of study. A credential in gemology can offer numerous career paths:

* Appraiser. Evaluate gemstones, antique and contemporary jewelry, and fine watches. Write detailed descriptions and determine valuation.
* Auction Specialist. Oversee buying and selling during the lively process of auctioning privately owned one-of-a-kind jewelry.
* Bench Jeweler. Manufacture and repair fine jewelry using craftsmanship skills and expert techniques.
* Buyer. Monitor industry and consumer trends and seek out gems and finished jewelry pieces to sell profitably.
* Designer. Create unique jewelry designs using precious gemstones.
* Lab and Research Professional. Investigate new gem finds, treatment processes, and detection methods in the field and laboratory.
* Retailer. A career in the fast-paced environment of retail jewelry sales can be rewarding, exciting, and lucrative.
* Wholesaler. Import and sell diamonds, colored stones, cultured pearls, finished jewelry, and watches from locations around the world.

How to Become a Gemologist

In the field of gemology, there are many career opportunities. Some of the most common include appraisers, retail associates, lab gemologists, and jewelry designers. However, it can be tough to break into these fields; most require at least some formal training. In general, here are the steps you should follow if you want to break into a career in the field of gemology:

Determine What Area of Gemology You Want to Work In

As a professional gemologist, there are a number of different careers you can pursue. Before you can figure out the right educational path, you must first decide what area of gemology you want to pursue. You might consider reading about different career paths or speaking to people that already work in these professions.

Assess Your Skills

Any profession should utilize or enhance your current skills. The most general job requirements for a gemologist are being detail-oriented and having good interpersonal skills, hand-eye coordination, and finger dexterity. In addition, being a good salesperson may make you particularly successful in a retail outlet or as a gemstone wholesaler. If you are creative or have a special interest in fashion, pursuing a career as a gemstone designer might be a good fit. Finally, if you are very meticulous or pay close attention to detail, working as an appraiser or as someone who repairs jewelry might be a good fit for you.

Additional Information

Gemology is the scientific study of gemstones. Although there may be investors and collectors who are only interested in the monetary value of gems, they'll need a scientific approach when the time comes to distinguish one gemstone from another. Whom will they seek out? Gemologists.

Goldsmiths (and other metalworkers) need specific knowledge about the physical characteristics of gems in order to create appropriate settings. For example, a setting that would be ideal for a diamond could damage an opal, and the amount of pressure used to set the prongs on a garnet could break a tanzanite. Some gems can withstand the heat of repair work involving high temperature soldering. If metalworkers take precautions, they can leave them in their settings. Other gemstones are so heat sensitive they would need to remove them.

Lapidaries, or gem cutters, also need special knowledge. Appropriate cutting and polishing techniques vary from gem to gem. What would work well for one gemstone would be a waste of time or even disastrous on another gem. Faceting and gemstone color management go hand in hand. How cutters orient the rough can greatly impact the appearance of the finished gem. Cutting style is also a part of color management.

The choice of cut can lighten or darken a gem, which will considerably affect both the appearance and the value of the stone. The shape, number, and location of facets influence the brilliance of the gem. Lapidaries much choose angles for facet cutting carefully. They must consider all these factors to minimize the amount of gemstone rough sacrificed to create a beautiful faceted gem.

The Scientists

Although scientists with degrees in geology, chemistry, and even physics make up the smallest group of gemologists, they're influential. The systematic measurement and recording of the physical and optical properties used to identify gemstones is a well-established but ongoing scientific process.

For centuries, the lapidary was in the best position to recognize the differences in gems with similar appearances. The faceting process offered a perspective on gemstones no other gemologist had. Many inclusions, materials trapped inside gemstones, and physical characteristics, such as hardness, were readily apparent when cutting and polishing a gem.

Scientists continue to add to this knowledge by developing new testing techniques and researching new gemstones discovered in nature and synthesized in the laboratory.

Gemstone Identification

Gem identification is the heart of gemology. For example, some rubies and garnets are impossible to distinguish by their appearance, but their physical properties differ considerably. Ruby and garnet crystallography varies greatly. While the visible shapes of individual stones may vary, the crystal structures of these gems at the atomic level are distinctive. Garnets form in the isometric or cubic system, while rubies form in the hexagonal system.

Mineralogical techniques are also used to help identify gemstones. Scratch tests, in which various substances are used to scratch an unknown gem, determine hardness. A gem's reaction to acid and even heat can yield important clues to its identity. Of course, these destructive tests aren't appropriate for cut gems.

Scientists have also devised non-destructive tests to identify gemstones. They have designed instruments to measure the physical and optical properties of gems — like specific gravity and refractive index — without damaging them. Today, even people without extensive scientific training or expensive laboratory equipment can use these methods for gem identification.

Getting Started in Gemology

If you're interested in learning about gems, first, learn how they're categorized and the terms used to describe them. Next, study their physical and optical properties. With this background, you can start learning how to identify gemstones.

Of course, there are many side roads to travel as you study gemology. Perhaps you'll become fascinated with phenomenal gems or with inclusions found in natural gems. People interested in gemstone collecting may also become interested in learning how to cut gems and make jewelry.

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#10627. What does the term in Biology Ecological efficiency mean?

#10628. What does the term in Biology Ecological pyramid mean?

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#9774.

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2625.

2372) Odd Hassel

Gist:

Work

In nature organisms are composed of an enormously varied number of chemical compounds, with the element carbon as a common component. The binding energy between atoms in carbon compounds determines their structure, but the structures are not completely rigid. They are flexible to a certain degree. Consequently, molecules can assume different conformations, which has ramifications for their way of reacting with other substances. At the end of the 1940s, Odd Hassel published pioneering works about different conformations for ring-shaped molecules with six carbon atoms.

Summary

Odd Hassel (born May 17, 1897, Kristiania [now Oslo], Nor.—died May 11, 1981, Oslo) was a Norwegian physical chemist and corecipient, with Derek H.R. Barton of Great Britain, of the 1969 Nobel Prize for Chemistry for his work in establishing conformational analysis (the study of the three-dimensional geometric structure of molecules).

Hassel studied at the University of Oslo and received his doctorate at the University of Berlin in 1924. He joined the faculty of the University of Oslo in 1925 and from 1934 to 1964 was a professor of physical chemistry and director of the physical chemistry department. He began intensive research on the structure of cyclohexane (a 6-carbon hydrocarbon molecule) and its derivatives in 1930 and discovered the existence of two forms of cyclohexane. At this time he set forth the basic tenets of conformational analysis and wrote Kristallchemie (1934; Crystal Chemistry). After the mid-1950s Hassel’s research dealt mainly with the structure of organic halogen compounds.

Details

Odd Hassel (17 May 1897 – 11 May 1981) was a Norwegian physical chemist and Nobel Laureate.

Biography

Hassel was born in Kristiania (now Oslo), Norway. His parents were Ernst Hassel (1848–1905), a gynaecologist, and Mathilde Klaveness (1860–1955). In 1915, he entered the University of Oslo where he studied mathematics, physics and chemistry, and graduated in 1920. Victor Goldschmidt was Hassel's tutor when he began studies in Oslo, while Heinrich Jacob Goldschmidt, Victor's father, was Hassel's thesis advisor. Father and son were important figures in Hassel's life and they remained friends. After taking a year off from studying, he went to Munich, Germany to work in the laboratory of Professor Kasimir Fajans.

His work there led to the detection of absorption indicators. After moving to Berlin, he worked at the Kaiser Wilhelm Institute, where he began to do research on X-ray crystallography.[5] He furthered his research with a Rockefeller Fellowship, obtained with the help of Fritz Haber. In 1924, he obtained his PhD from Humboldt University of Berlin, before moving to his alma mater, the University of Oslo, where he worked from 1925 through 1964. He became a professor in 1934.

His work was interrupted in October, 1943 when he and other university staff members were arrested by the Nasjonal Samling and handed over to the occupation authorities. He spent time in several detention camps, until he was released in November, 1944.

Work

Heinrich Jacob Goldschmidt was Hassel's thesis advisor and father of Victor Goldschmidt.

Hassel originally focused on inorganic chemistry, but beginning in 1930 his work concentrated on problems connected with molecular structure, particularly the structure of cyclohexane and its derivatives. He introduced the Norwegian scientific community to the concepts of the electric dipole moments and electron diffraction. The work for which he is best known established the three-dimensionality of molecular geometry. He focused his research on ring-shaped carbon molecules, which he suspected filled three dimensions instead of two, the common belief of the time. By using the number of bonds between the carbon and hydrogen atoms, Hassel demonstrated the impossibility of the molecules existing on only one plane. This discovery led to him being awarded the Nobel Prize in Chemistry for 1969.

Honors

Hassel was awarded the Nobel Prize in Chemistry in 1969, shared with English chemist Derek Barton.

He received the Guldberg-Waage Medal (Guldberg-Waage Medal) from the Norwegian Chemical Society and the Gunnerus Medal from the Royal Norwegian Society of Science and Letters, both in 1964.

Hassel held honorary degrees from the University of Copenhagen (1950) and Stockholm University (1960). An annual lecture named in his honor is given at the University of Oslo.

He was an honorary Fellow of the Norwegian Chemical Society, Chemical Society of London, Norwegian Academy of Science and Letters, Royal Danish Academy of Sciences and Letters and Royal Swedish Academy of Sciences.

He was made a Knight of the Order of St. Olav in 1960.