Health and safety

Most organic solvents are flammable or highly flammable, depending on their volatility. Exceptions are some chlorinated solvents like dichloromethane and chloroform. Mixtures of solvent vapors and air can explode. Solvent vapors are heavier than air; they will sink to the bottom and can travel large distances nearly undiluted. Solvent vapors can also be found in supposedly empty drums and cans, posing a flash fire hazard; hence empty containers of volatile solvents should be stored open and upside down.

General health hazards associated with solvent exposure include toxicity to the nervous system, reproductive damage, liver (печень) and kidney (почки) damage, respiratory impairment, cancer, and dermatitis.

Many solvents can lead to a sudden loss of consciousness (сознание) if inhaled in large amounts. Solvents like diethyl ether and chloroform have been used in medicine as anesthetics, sedatives, and hypnotics for a long time. Ethanol (grain alcohol) is a widely used and abused psychoactive drug. Diethyl ether, chloroform, and many other solvents (e.g., from gasoline or glues (клей)) are used recreationally in glue sniffing, often with harmful long term health effects like neurotoxicity or cancer. Methanol can cause permanent blindness and death. It is also dangerous because it burns with an invisible flame.

It is interesting to note that ethanol has a synergistic effect when taken in combination with many solvents. For instance a combination of toluene / benzene and ethanol causes greater nausea / vomiting than either substance alone.

Some solvents including chloroform and benzene (an ingredient of gasoline) are carcinogenic. Many others can damage internal organs like the liver, the kidneys, or the brain.

Chronic exposure to organic solvents in the work environment can produce a range of adverse neuropsychiatric effects. For example, occupational exposure to organic solvents has been associated with higher numbers of painters suffering from alcoholism.

General precautions

Avoid being exposed to solvent vapors by working in a fume hood, or with local exhaust ventilation (LEV), or in a well ventilated area

Keep the storage containers tightly closed

Never use open flames near flammable solvents; use central heating or electrical heating instead

Never flush flammable solvents down the drain; read safety data sheets for proper disposal information

Avoid the inhalation of solvent vapors

Avoid contact of the solvent with the skin – many solvents are easily absorbed through the skin. They also tend to dry the skin and may cause sores and wounds.

Тема 5. «Углерод. Свойства, история открытия. Типы угля. Угли Кузбасса и их использование». Module 7

Task 1. Remember the following words:

carbon – углерод coal – уголь occur – встречаться discover – открывать limestone – известняк charcoal – древесный уголь conditions – условия discovery – открывать phenomenon (phenomena) – явление

transparent – прозрачный opaque – abundant – доступный resist – сопротивляться fraction – фракция, класс крупности origin – происхождение conduct – проводить acid – кислота bond – связь soot – сажа, копоть

Task 2. Use a dictionary to read the word properly. Remember the pronunciation

tetravalent, covalent, graphite, element, electron, amorphous, allotrope, temperature, nature, mass, stable, oxide, dioxide, fraction, allotrope

Task 3.Translate the words with the same root

metal – nonmetal – metallic –nonmetallic, conduct – conductor – conductivity, occur – naturally-occurring, react – reaction, resist – resistant, mix – mixture – admixture, allotrope – allotropic, decay – decaying, coal – charcoal, carbon – carbonaceous

Task 4. Read the text and answer the following questions

1. What is carbon? What is its symbol and atomic number?

2. When was carbon discovered? What forms were discovered first?

3. Why was it named “carbon”? What is the origin of the name?

4. How abundant is carbon on Earth?

5. What properties does carbon have?

6. What is “allotropes”?

7. How many allotropes does carbon have? What are their main properties?

8. What is the difference between diamond and graphite?

9. Why is carbon so unique?

10. Who started the investigation of carbon and what were their contributions?

11. Why is carbon so useful for industry?

Spectral lines of Carbon

1. Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent – making four electrons available to form covalent chemical bonds. 2. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.

Carbon was discovered in prehistory and was known in the forms of soot and charcoal to the earliest human civilizations. 3. Diamonds were known probably as early as 2500 BC in China, while carbon in the form of charcoal was made around Roman times by the same chemistry as it is today, by heating wood in a pyramid covered with clay to exclude air.

There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is the hardest naturally-occurring material known, while graphite is soft enough to form a streak on paper (hence its name, from the Greek word "γράφω" which means "to write"). Diamond has a very low electrical conductivity, while graphite is a very good conductor.

4. Under normal conditions, diamond, carbon nano-tube and graphene have the highest thermal conductivities of all known materials.

5. All carbon allotropes are solids under normal conditions with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and other transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil and methane clathrates. 6. Carbon forms more compounds than any other element, with almost ten million pure organic compounds described, which in turn are a tiny fraction of such compounds that are theoretically possible under standard conditions.

Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. 7. It is present in all known life forms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen. This abundance, together with the unique diversity of organic compounds and their unusual polymer-forming ability at the temperatures commonly encountered on Earth, make this element the chemical basis of all known life.

8. In 1722, Renй Antoine Ferchault de Rйaumur demonstrated that iron was transformed into steel through the absorption of some substance, now known to be carbon. In 1772, Antoine Lavoisier showed that diamonds are a form of carbon; when he burned samples of charcoal and

diamond and found that neither produced any water and that both released the same amount of carbon dioxide per gram. In 1779, Carl

Wilhelm Scheele showed that graphite, which had been thought of as a form of lead, was instead identical with charcoal but with a small admixture of iron, and that it gave "aerial acid" (his name for carbon dioxide) when oxidized with nitric acid. In 1786, the French scientists Claude Louis Berthollet, Gaspard Monge and..

C A Vandermonde confirmed that graphite was mostly carbon by oxidizing it in oxygen in much the same way Lavoisier had done with diamond. Some iron again was left, which the French scientists thought was necessary to the graphite structure. However, in their publication they proposed the name carbon (Latin carbonum) for the element in graphite which was given off as a gas upon burning graphite. Antoine Lavoisier then listed carbon as an element in his 1789 textbook.

Task 5. Translate the numbered sentences from the text in writing. Define the type of non-finite forms of the verbs used