No, there are only a few elements that have a subscript of 2 in their standard states. They all exist as diatomic molecules have a subscript of 2. You should memorize these-it will be to your advantage. User login Username. Create new account Reset your password. Unanswered Questions how to find the balanced equation of calcium chloride dehydrate and potassium hydroxide.
Calculate the acetate ion concentration in a solution prepared by dissolving 1. In an experiment, 0. Calculate the relative molecular mass of the vapour. How to solve the rate of an iodine clock reaction? As the chloride ion, Cl-, it is also the most abundant dissolved ion in ocean water. Isotopes Chlorine has isotopes with mass numbers ranging from 32 to There are two principal stable isotopes, 35 Cl In the subsurface environment, 36 Cl is generated primarily as a result of neutron capture by 35 Cl or muon capture by 40 Ca.
The half-life of this hydrophilic nonreactive isotope makes it suitable for geologic dating in the range of 60, to 1 million years. Additionally, large amounts of 36 Cl were produced by irradiation of seawater during atmospheric detonations of nuclear weapons between and The residence time of 36 Cl in the atmosphere is about 1 week. Thus, as an event marker of s water in soil and ground water, 36 Cl is also useful for dating waters less than 50 years before the present.
Even higher concentrations of chloride are found in the Dead Sea and in underground brine deposits. Most chloride salts are soluble in water, thus, chloride-containing minerals are usually only found in abundance in dry climates or deep underground. Common chloride minerals include sodium chloride, potassium chloride, and potassium magnesium chloride hexahydrate. Over naturally-occurring organic chlorine compounds are known.
Industrially, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. The production of chlorine results in the co-products caustic soda sodium hydroxide, NaOH and hydrogen gas H 2. These two products, as well as chlorine itself, are highly reactive. Chlorine can also be produced by the electrolysis of a solution of potassium chloride, in which case the co-products are hydrogen and caustic potash potassium hydroxide.
The "rocking" cells used have been improved over the years. Today, in the "primary cell", titanium anodes formerly graphite ones are placed in a sodium or potassium chloride solution flowing over a liquid mercury cathode. When a potential difference is applied and current flows, chlorine is released at the titanium anode and sodium or potassium dissolves in the mercury cathode forming an amalgam.
The mercury is then recycled to the primary cell. The mercury process is the least energy-efficient of the three main technologies mercury, diaphragm and membrane and there are also concerns about mercury emissions. It is estimated that there are still around mercury-cell plants operating worldwide. In Japan, mercury-based chloralkali production was virtually phased out by except for the last two potassium chloride units shut down in In the United States, there will be only five mercury plants remaining in operation by the end of Diaphragm cell electrolysis In diaphragm cell electrolysis, an asbestos or polymer-fiber diaphragm separates a cathode and an anode, preventing the chlorine forming at the anode from re-mixing with the sodium hydroxide and the hydrogen formed at the cathode.
This technology was also developed at the end of the nineteenth century. There are several variants of this process: the Le Sueur cell , the Hargreaves-Bird cell , the Gibbs cell , and the Townsend cell The cells vary in construction and placement of the diaphragm, with some having the diaphragm in direct contact with the cathode.
The salt solution brine is continuously fed to the anode compartment and flows through the diaphragm to the cathode compartment, where the caustic alkali is produced and the brine is partially depleted. But diaphragm cells are not burdened with the problem of preventing mercury discharge into the environment.
Membrane cell electrolysis Development of this technology began in the s. The electrolysis cell is divided into two "rooms" by a cation permeable membrane acting as an ion exchanger. Saturated sodium or potassium chloride solution is passed through the anode compartment, leaving at a lower concentration.
Sodium or potassium hydroxide solution is circulated through the cathode compartment, exiting at a higher concentration. A portion of the concentrated sodium hydroxide solution leaving the cell is diverted as product, while the remainder is diluted with deionized water and passed through the electrolysis apparatus again. Other electrolytic processes Although a much lower production scale is involved, electrolytic diaphragm and membrane technologies are also used industrially to recover chlorine from hydrochloric acid solutions, producing hydrogen but no caustic alkali as a co-product.
Furthermore, electrolysis of fused chloride salts Downs process also enables chlorine to be produced, in this case as a by-product of the manufacture of metallic sodium or magnesium.
Due to the extremely corrosive reaction mixture, industrial use of this method is difficult and several pilot trials failed in the past. Nevertheless, recent developments are promising. Another earlier process to produce chlorine was to heat brine with acid and manganese dioxide. The manganese can be recovered by the Weldon process. In the latter half of the 19th century, prior to the adoption of electrolytic methods of chlorine production, there was substantial production of chlorine by these reactions to meet demand for bleach and bleaching powder for use by textile industries; by the s the UK, as well as supporting its own then not inconsiderable domestic textile production was exporting 70, tons per year of bleaching powder.
This demand was met by capturing hydrochloric acid driven off as a gas during the production of alkali by the Leblanc process, oxidising this to chlorine originally by reaction with manganese dioxide , later by direct oxidation by air using the Deacon process in which case impurities capable of poisoning the catalyst had first to be removed , and subsequently absorbing the chlorine onto lime. Small amounts of chlorine gas can be made in the laboratory by putting concentrated hydrochloric acid in a flask with a side arm and rubber tubing attached.
Manganese dioxide is then added and the flask stoppered. The reaction is not greatly exothermic. As chlorine is denser than air, it can be collected by placing the tube inside a flask where it will displace the air. Once full, the collecting flask can be stoppered.
Another method for producing small amounts of chlorine gas in a lab is by adding concentrated hydrochloric acid typically about 5M to sodium hypochlorite or sodium chlorate solution. Industrial production Large-scale production of chlorine involves several steps and many pieces of equipment. The description below is typical of a membrane plant. The plant also simultaneously produces sodium hydroxide caustic soda and hydrogen gas.
Maintaining a properly saturated solution with the correct purity is vital, especially for membrane cells. Many plants have a salt pile which is sprayed with recycled brine. Others have slurry tanks that are fed raw salt. Chlorine Cl 2 is among the ten highest volume chemicals manufactured in the United States. It is produced commercially by electrolysis of sodium chloride brine.
Chlorine is used in industry and in household cleaning products. Chlorine was also the first poison gas to be used as a weapon during World War I. Chlorine has a variety of uses. It is used to disinfect water and is part of the sanitation process for sewage and industrial waste. During the production of paper and cloth, chlorine is used as a bleaching agent. It is also used in cleaning products, including household bleach which is chlorine dissolved in water.
Chlorine is used in the preparation of chlorides, chlorinated solvents, pesticides, polymers, synthetic rubbers, and refrigerants. Given the ubiquity and volume of chlorine in industrial and commercial locations, widespread exposures could occur from an accidental spill or release, or from a deliberate terrorist attack.
Because chlorine is a gas at room temperature, exposure occurs via inhalation. People may also be exposed to chlorine through skin or eye contact, or through ingestion of chlorine-contaminated food or water. The health effects of chlorine are primarily due to its corrosive properties. The strong oxidizing effects of chlorine cause hydrogen to split from water in moist tissue, resulting in the release of nascent oxygen and hydrogen chloride which produce corrosive tissue damage.
The oxidation of chlorine may also form hypochlorous acid, which will penetrate cells and react with cytoplasmic proteins to destroy cell structure. The health effects resulting from most chlorine exposures begin within seconds to minutes. The severity of the signs and symptoms caused by chlorine will vary according to amount, route and duration of exposure. Inhalation: Most chlorine exposures occur via inhalation.
Chlorine's odor provides adequate early warning of its presence, but also causes olfactory fatigue or adaptation, reducing awareness of one's prolonged exposure at low concentrations. At higher levels of exposure, signs and symptoms may progress to chest tightness, wheezing, dyspnea, and bronchospasm. Severe exposures may result in noncardiogenic pulmonary edema, which may be delayed for several hours.
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