Chlorine Chlorine is (at room temperature) a greenish-yellow gas that can be readily liquefied at 5170 Tarr or 6.8 atmospheres, at 20 C (68 F), and has a very disagreeable odor. It’s Element Symbol is Cl, atomic number is 17, and atomic mass is 35.453. Chlorine’s melting point is -101 C or 149.8 F. The boiling point is -34.05 C or -29.29 F, at one atmosphere pressure. Chlorine is a member of the halogen group. Chlorine was discovered by Swedish scientist Karl Wilhelm in 1784, but he first thought it was a compound, rather than an element. In 1810, Sir Humphrey Davy named it Chlorine, from the Greek word meaning "greenish-yellow". Chlorine is used in bleaching agents, disinfectants, monomers (plastics), solvents, and pesticides. It is also used for bleaching paper pulp and other organic materials, preparing bromine, (a poisonous element that at room temperature is a dark, reddish-brown), tetraethyl lead, and killing germs in water, particularly in swimming pools and hot tubs. Like every member of the halogen group, chlorine has a tendency to gain one electron and become a chloride ion. Chlorine strongly reacts with metals to form mostly water-soluble chlorides. Chlorine also strongly reacts with nonmetals such as sulfur, phosphorus, and other halogens. If you were to mix hydrogen and chlorine gases and keep them in a cool dark place, the mixture would be stable, but if it were exposed to sunlight, it wo...
"Paul David Buell." Max Planck Institute for the History of Science. Max Planck Institute, n.d. Web.
Despite the significant benefits of pool chlorines in their capacity to kill hazardous bacteria, it is evident that some of the side effects can be disadvantageous. The general smell of chlorine can be overwhelmingly unpleasant, and the agent can irritate the skin and eyes. It is also has the capability to bleach some fabrics, potentially damaging clothing. Most significantly, excessive air pockets of chlorine gas that surround pools can be hazardous for peoples’ health and possibly even be carcinogenic. For these reasons, some industries have started to investigate new alternative methods to chlorine for sterilising pools. According to Smith and Monteath et al. (2006, pp. 1 - 37), ‘some of these are good alternatives, but they do not achieve the cleanliness, oxidation levels or low price that chlorine provides’.
In the late 1800’s it was discovered that papa-amino-phenol, could reduce fever, but the drug was too toxic to use. A less toxic extract called phenacetin was later found to be just as effective but also had pain-relieving properties. In 1949, it was learned that phenacetin was metabolized into an active but also less toxic drug, acetaminophen. Since then, acetaminophen has been sold under many over the counter brand names, most popular being Tylenol.
the battles in World War I might have been lost if it were not for
Silicon is never found as a pure element naturally. Jacob Berzelius is credited for discovering silicon. Although, people thought that Thenard had already tried to obtain silicon in 1809. T. Thomson named the element in 1831. T. Thomson added the ending “on” to emphasize the analogy between
It was discovered by Sir Humphrey Davy in England, in 1807. Sir Davy was able to isolate potassium using electrolysis. Potassium was the first metal isolated by this procedure. Today, it is still not found free in nature. It is obtained by electrolysis of chloride or hydroxide.
Lavoisier, the father of modern chemistry, and when he came to America he brought some of
Lavoisier made-up that all acids must comprise oxygen, and this idea was combined in the names used for this element in the various languages; the English oxygen, from the Greek oxys (sour) and genna (production); the German Sauerstoff, literally acid material; and the Russian kislorod, from kislota (acid). Succeeding the discovery that hydrochloric acid confined no oxygen, Sir Humphry Davy about 1815 first known that the key element in acids was hydrogen. Not all substances that hold hydrogen, however, are acids, and the first really reasonable definition of an acid was given by Justus von Liebig of Germany in 1838. According to Liebig, an acid is a compound having hydrogen in a form in which it can be replaced by a metal. This definition held the field for about 50 years and is still deliberated essentially correct, though somewhat outmoded. At the time of Liebig’s proposal, bases were still stared solely as substances that neutralized acids with the production of salts, and nothing was known about the constitutional features of bases that enabled them to do
The concept of the atom originated in Greek philosophy around six hundred B.C. with the question: ¡§What is the world made of ?¡¨ (Sachs, 9). Thales first suggested that ¡§water [is] the basic building block of the world¡¨, and air, sand, and stone could be different forms of one fundamental substance (web page). Yet, Anoimenes believed ¡§mist or air was the cornerstone of matter¡¨ (Clagett, 49). These ancient thinkers made simple and direct assertions about matter. Later, the idea of the atom was conceived and developed by Leucippus and Democritus in the fifth century B.C. and concluded that there must be ¡§parts which are partless¡¨ such as sand, stone, water, or even a ¡¥void¡¦ which have the continuous and coherent appearance of a pure object though are not ¡¥true¡¦ structures (Young, 18).
In 1841, he founded the Chemical Society of London, of which he was the first president. His study in the field of colloids (a type of homogenous mixture) led to the discovery of dialysis and his earning of the name �the father of colloid chemistry.�
It is a transparent, colorless, viscous, oily liquid. It is tasteless and odorless when cold and have a faint odor of petroleum when heated. It is practically insoluble in 95% ethyl alcohol, glycerin and water. It is soluble in benzene, acetone, carbon disulfide, chloroform, ether and petroleum ether. It is miscible with volatile oils and fixed oils except castor oil (74).
Preservatives are a substance used to preserve foodstuffs, wood, or other materials against decay. Preservatives can be man- made or natural. There are many types of preservatives. There are sorbates(200-203), benzoates(210-218), sulphites(220-228), and propionates(280-283). Nitrates can be classified too as preservatives(249-250). The numbers are a way of simplifying and organizing different types of preservatives.The preservatives are labeled on the labeling sticker. Benzoates have two versions of itself. Potassium benzoate and sodium benzoate. “Potassium benzoate (E212), the potassium salt of benzoic acid, is a food preservative that inhibits the growth of mold, yeast and some bacteria.”(Wikipedia March 31, 2016). It is found in mostly acidic
Prehistoric time: King Hammurabi knew metal were recorded and listed them in conjunction with heavenly bodies, in 1700 B.C. on his rule over Babylon. Then Democritus of ancient Greece proclaimed the atom was the simplest unit of matter and that matter is composed of all atoms, in 430 B.C. A few years in 300 B.C. Aristotle believed that there were only four elements, fire, earth, water, and air. That matter is made up of all these elements and they had four properties, hot cold, dry, and wet. They each believed in these things and even tried to prove that they were right.
in an airtight container and process it in such a way that the four main