Химия. Экология. Медицина



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QUARTZ

Ayman Olleik, group 3. Science adviser is Svetlana Kozub.


Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2.

There are many different varieties of quartz, several of which are semi-precious gemstones. Especially in Europe and the Middle East, varieties of quartz have been since antiquity the most commonly used minerals in the making of jewelry and hardstone carvings.

Crystal habit and structure:

Quartz belongs to the trigonal crystal system. The ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end. In nature quartz crystals are often twinned, distorted, or sointergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive.

Quartz is an essential constituent of granite and other felsic igneous rocks. It is very common in sedimentary rocks such as sandstone and shale and is also present in variable amounts as an accessory mineral in most carbonate rocks. It is also a common constituent of schist, gneiss, quartzite and other metamorphic rocks. Because of its resistance to weathering it is very common in stream sediments and in residual soils. Quartz, therefore, occupies the lowest potential to weather in the Goldich dissolution series.

Quartz crystals have piezoelectric properties; they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. One of the most common piezoelectric uses of quartz today is as a crystal oscillator.


BLANC REACTION

Sarra Ben Hassen, group 3. Science adviser is Svetlana Kozub.


The reaction of triphenylphosphine and tetrahalomethanes (CCl4, CBr4) with alcohols is a ready method to convert an alcohol to the corresponding alkyl halide under mild conditions. The yields are normally high.

This reaction is somewhat similar to the MitsunobuReaction , where the combination of a phosphine, a diazo compound as a coupling reagent, and a nucleophile are used to invert the stereochemistry of an alcohol or displace it.Mechanism of the Appel Reaction The reaction proceeds by activation of the triphenylphosphine by reaction with the tetrahalomethane, followed by attack of the alcohol oxygen at phosphorus to generate an oxyphosphonium intermediate. The oxygen is then transformed into a leaving group, and an SN2 displacement by halide takes place, proceeding with inversion of configuration if the carbon is asymmetric.

Blanc reaction:

This reaction, which is comparable to a Friedel-Crafts Alkylation , is useful for the preparation of chloromethylatedarenes (for example, the Merrifield resin based on polystyrene) from the parent arene with formaldehyde, HCl, and ZnCl2.Mechanism of the Blanc Reaction The Lewis acid ZnCl2 effects formation of an oxonium ion which is reactive in electrophilic aromatic substitution. The intermediate zinc alkoxide reacts with the arene to form the chloromethylated product and zinc oxides.



HERMANN EMIL FISCHER

Ali Xamadi, group 4. Science adviser is Olga Levashova.


Fischer was born in Euskirchen, near Cologne, the son of a businessman. After graduating he wished to study natural sciences, but his father compelled him to work in the family business until determining that his son was unsuitable. Fischer then attended the University of Bonn in 1871, but switched to the University of Strasbourg in 1872. He earned his doctorate in 1874 under Adolf von Baeyer with his study of phthalein and was appointed to a position at the university.

In 1875 von Baeyer was asked to succeed Liebig at the University of Munich and Fischer went there with him to become an assistant in organic chemistry.

In 1878 Fischer qualified as a Privatdozent at Munich, where he was appointed Associate Professor of Analytical Chemistry in 1879. In the same year he was offered, but refused, the Chair of Chemistry at Aachen.

In 1881 he was appointed Professor of Chemistry at the University of Erlangen and in 1883 he was asked by the BadischeAnilin- und Soda-Fabrik to direct its scientific laboratory. Fischer, however, whose father had now made him financially independent, preferred academic work.

In 1885 he was asked to become Professor of Chemistry at the University of Würzburg and here he remained until 1892, when he was asked to succeed A. W. Hofmann in the Chair of Chemistry at the University of Berlin. Here he remained until his death in 1919 from chronic phenylhydrazine poisoning.

In 1875 Fischer discovered phenylhydrazine while working in Stassburg with von Baeyer. (This compound would play a critical role in Fischer's later research on sugars.) While he was at Munich, Fischer continued to work on the hydrazines and, working there with his cousin Otto Fischer, who had followed him to Munich, he and Otto worked out a new theory of the constitution of the dyes derived from triphenylmethane, proving this by experimental work to be correct.

At Erlangen, Fischer studied the active principles of tea, coffee and cocoa, namely, caffeine and theobromine, and established the constitution of a series of compounds in this field, eventually synthesizing them.

In 1884 Fischer began his great work on the sugars, which transformed the knowledge of these compounds and welded the new knowledge obtained into a coherent whole. Even before 1880, the aldehyde formula of glucose had been indicated, but Fischer established it by a series of transformations such as oxidation into aldonic acid and the action of phenylhydrazine which he had discovered and which made possible the formation of the phenylhydrazones and the osazones. By passage to a common osazone, he established the relation between glucose, fructose and mannose, which he discovered in 1888. In 1890, by epimerization between gluconic and mannonic acids, he established the stereochemical and isomeric nature of the sugars, and between 1891 and 1894 he established the stereochemical configuration of all the known sugars and exactly foretold the possible isomers, by an ingenious application of the theory of the asymmetrical carbon atom of Van't Hoff and Le Bel, published in 1874. Reciprocal syntheses between different hexoses by isomerization and then between pentoses, hexoses, and heptoses by reaction of degradation and synthesis proved the value of the systematics he had established.



REACTION IN CHEMISTRY

Emil Shbeta, group 4. Science adviser is Olga Levashova.


Reaction in chemistry are a cracking links in the reactants for the production of new links in the resulting materials, which leads to the formation of new materials in the various chemical and physical characteristics together.

Types of chemical reactions :

1) Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

2) Synthesis: A synthesis reaction is when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of:

A + B ---> AB

One example of a synthesis reaction is the combination of iron and sulfur to form iron (II) sulfide:

8 Fe + 8S ---> 8 FeS

3) Decomposition: A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:

AB ---> A + B

One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:

2 H2O ---> 2 H2 + O2

4) Single displacement: This is when one element trades places with another element in a compound. These reactions come in the general form of:

A + BC ---> AC + B

One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:

Mg + 2 H2O ---> Mg (OH) 2 + H2

5) Double displacement: This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:

AB + CD ---> AD + CB

One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

Pb (NO3) 2 + 2 KI ---> PbI2 + 2 KNO3

6) Acid-base: This is a special kind of double displacement reaction that takes place when an acid and base react with each other. The H + ion in the acid reacts with the OH-ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water:

HA + BOH ---> H2O + BA

One example of an acid-base reaction is the reaction of hydrobromic acid (HBr) with sodium hydroxide:

HBr + NaOH --->NaBr + H2O



ANTOINE-LAURENT DE LAVOISIER

Habib Al-Miski, group 4. Science adviser is Olga Levashova.


Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution; 26 August 1743 – 8 May 1794; was a French nobleman and chemist central to the 18th-century Chemical Revolution and a large influence on both the histories of chemistry and biology. He is widely considered to be the "Father of Modern Chemistry."

It is generally accepted that Lavoisier's great accomplishments in chemistry largely stem from the fact that he changed the science from a qualitative to a quantitative one. Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783) and opposed the phlogiston theory. Lavoisier helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. He predicted the existence of silicon (1787) and was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same.

Lavoisier was an administrator of the FermeGénérale and a powerful member of a number of other aristocratic councils. All of these political and economic activities enabled him to fund his scientific research. At the height of the French Revolution, he was accused by Jean-Paul Marat of selling adulterated tobacco and of other crimes, and was eventually guillotined a year after Marat's death.

NAMED REACTION IN CHEMISTRY

Muhammad Iraqi, group 4. Science adviser is Olga Levashova.


A name reaction is achemical reaction named after its discoverers or developers. Well known examples include the Wittig reaction, the Claisen condensation, the Friedel-Crafts acylation, and the Diels-Alder reaction. Among the tens of thousands of organic reactions that are known, hundreds of such reactions are well-known enough to be named after people. Books have been published devoted exclusively to name reactions; the Merck Index, a chemical encyclopedia, also includes an appendix on name reactions.

As organic chemistry developed during the 20th century, chemists started associating synthetically useful reactions with the names of the discoverers or developers; in many cases, the name is merely a mnemonic. Some cases of reactions that were not really discovered by their namesakes are known. Examples include the Pummerer rearrangement, the Pinnick oxidation and theBirch reduction.

Although systematic approaches for naming reactions based on the reaction mechanism or the overall transformation exist (such as the IUPAC Nomenclature for Transformations), the more descriptive names are often unwieldy or not specific enough, so people names are often more practical for efficient communication.

REACTION IN CHEMISTRY

Shadi abed elhay, group 4. Science adviser is Olga Levashova.


Chemical reactions: are a cracking links in the reactants for the production of new links in the resulting materials, which leads to the formation of new materials in the various chemical and physical characteristics together.

Types of chemical reactions:

1) Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

2) Synthesis: A synthesis reaction is when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of:

A + B ---> AB

One example of a synthesis reaction is the combination of iron and sulfur to form iron (II) sulfide:

8 Fe + S8 ---> 8 FeS

3) Decomposition: A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:

AB ---> A + B

One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:

2 H2O ---> 2 H2 + O2

4) Single displacement: This is when one element trades places with another element in a compound. These reactions come in the general form of:

A + BC ---> AC + B

One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:

Mg + 2 H2O ---> Mg (OH) 2 + H2

5) Double displacement: This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:

AB + CD ---> AD + CB

One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

Pb (NO3) 2 + 2 KI ---> PbI2 + 2 KNO3

6) Acid-base: This is a special kind of double displacement reaction that takes place when an acid and base react with each other. The H + ion in the acid reacts with the OH-ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water:

HA + BOH ---> H2O + BA

One example of an acid-base reaction is the reaction of hydrobromic acid (HBr) with sodium hydroxide:

HBr + NaOH ---> NaBr + H2O



THE NAMED REACTION IN CHEMISTRY

Marta Nandjila Amukwaya, group 4. Science adviser is Olga Levashova.


A neutralization reaction is when an acid and a base react to form water and a salt. This reaction involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7. The neutralization of a strong acid and weak base will have a pH of less than 7, and conversely, the resulting pH when a strong base neutralizes a weak acid will be greater than 7.

When a solution is neutralized, it means that salts are formed from equal weights of acid and base. The amount of acid needed is the amount that would give one mole of protons (H+) and the amount of base needed is the amount that would give one mole of (OH-). Because salts are formed from neutralization reactions with equivalent concentrations of weights of acids and bases: N parts of acid will always neutralize N parts of base.

A salt is any compound which can be derived from the neutralization of an acid and a base. The word "neutralization" is used because the acid and base properties of H+ and OH- are destroyed. In the reaction, H+ and OH- combine to form HOH or H2O. Neutralization is a type of double replacement reaction. A salt is the product of an acid-base reaction and is a much broader term then common table salt.

The following are some examples of neutralization reactions to form salts.

a. HCl{(acid)} + NaOH{base} → NaCl{salt} + H2O{water}

In a neutralization reaction with Gas formation, the bases reacts with hydrogen ions {H+} to form molecular compounds. Sulfide ion and carbonate ion are an example of such reaction.

HCl (aq) + Na2S (aq) → H2S (g) + 2NaCl (aq)

When you get rid of all of the spectator ions, the net ionic equation shows the H+ and OH- ions forming water in a strong acid, strong base reaction. When a strong acid and a strong base fully neutralize then the pH is neutral, which means that the pH is equal to 7.00 at 25 degrees Celsius. At this point of neutralization, there are equal amounts of OH- and H3O+. There is no excess NaOH. The solution is NaCL at the equivalence point. When a strong acid neutralizes a strong base, the pH of the salt solution will always be 7.

Antacids are supposed to decrease the amount of hydrochloric acid in the stomach by reacting with excess acid. They are used in the treatment of gastric hyperacidity and peptic ulcers. Some of the ingredients in antacids are: Magnesia (MgO), milk of magnesia (Mg(OH)2, calcium carbonate (CaCO3), sodium bicarbonate (NaHCO3), dihydroxyaluminum sodium carbonate (NaAl(OH)2CO3), aluminum hydroxide gel (Al(OH)3).


THE WILLIAMSON ETHER SYNTHESIS

Sara Woldu, group 4. Science adviser is Olga Levashova.


The William ether synthesis, developed by Alexander Williamson in 1850, is an organic reaction between alcohols and organohalides, which results in the formation of ethers. This reaction is suitable for laboratory and industrial preparations of a wide variety of both symmetrical and unsymmetrical ethers, which can be used as solvents. It proceeds via a typical SN2 reaction mechanism, in which an alkoxide (prepared in situ under basic condition) undergoes nucleophilic substitution reaction with organohalides. This method works well for primary organohalides. However, for sterically demanding organohalides with accessible protons, the alkoxide can react as a base as well as a nucleophile, forming side product via elimination reaction. Thus, the Williamson reaction competes with the base-catalyzed elimination reactions for secondary organohalides.

An example and the mechanism of the Williamson ether synthesis is given below respectively:







CALCIUM

Theophilie Emilie Tomas, group 4. Science adviser is Olga Levashova.


Distribution of calcium is very wider ,it is found in almost every terrestrial area in the world , is the most abudant metal in human body. the good sources of calcium is milk ,hard cheese bread etc. our body may not be ale to absorb enough calcium sometimes mostly during old age.

Calcium. is among other minerals is a natural occurring substance wich is important for our health to keep our bone strong. our body get sufficient calcium from what we eat, sometimes our body may not able to absorb enough calcium from food ,in this case calcium supplement may be useful.

People who have kidney failure development of phosphate became high , so calcium binds to the phosphate and this allow it to be removed and keep the lever normal. We find this calcium supplementary on pharmacies. As chewable; effervescent tablets and oral, vitamin D oral .high calcium in blood can be a result of some cancers. Calcium needed to help blood vessels and muscles contacts and expand to send message through the nervous system and to secret hormones and enzymes .This is an abundant mineral in the body an makes up 1% -2% of adult human body weight. Over of it is stored in prevention bones and teeth with the rest stored in blood muscle and other tissue

Effectiveness of calcium.

Calcium used in treatment and prevention of low calcium level and high cholesterol, Lyme disease to reduce high fluoride level in children . is a mineral essential part of bone and teeth ,heart nerves and blood clotting system . low calcium resulting bone condition including osreoporosis (weak bone ,due to low density and osteomalacia ( softening of bone , involving pain. Calcium is also used in premenstrual syndrome ,leg clamp in pregnancy ,high blood pressure. reducing high lead levels calcium carbonate is used as an antacid for heart burn and calcium acetated also used for phosphate lever in people with kidney disease .main sources of calcium is table salt that we are used in our food

Even we need calcium too much calcium can cause stomach upset , and if this occur stick to simple food and drink plenty of water

Calcium is very crucial element in human body it keep our bone and teeth strong and healthy ,and cause some diseases when consumed in a higher amount.

Научное издание

ХИМИЯ. ЭКОЛОГИЯ. МЕДИЦИНА


Материалы V студенческой

межфакультетской конференции

первокурсников,

посвященной 110-й годовщине

со дня рождения Гапона Е.М.
Ответственные за выпуск: Козуб С.Н., Наконечная С.А.

Подписано к печати 14.01.2014. Формат А5. Бумага офсетная.



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