14.4 Halides. Iodine.

Uses of halogens and its compounds. Laboratory work ?7. Properties of halogens and qualitative analysis of halide-ions you will:determine the halide ions in given solutionsexplain the uses of chlorine for water disinfection and advantages, disadvantages of this processdetermine the biological role of halogens and their compounds; Why silver bromide AgBr (yellow precipitate) used in photography?   HalidesThe halogens react with metals to produce salts called metal halides (F-, Cl-, Br-, I-). Important fluoride salts:CaF2 – fluorspar – widely distributed mineral used as a flux in steelmaking and the production of HF.HF – hydrogen fluoride – colorless, extremely toxic gas, used to make F2, organic fluorine compounds, and polymers.

Also used in the aluminum manufacture and glass etching. Fluorspar mineralImportant chloride salts:NaCl – sodium chloride – used in food industry, in the manufacture of chlorine, sodium, hydrochloric acid, sodium hydroxide and soda. KCl – potassium chloride – important potassium fertilizer ZnCl2 – zinc chloride – used in electrogalvanizing, in agriculture as pesticide, in cosmetics as skin creamCaCl2 – calcium chloride – used for refrigeration of plants, ice and dust control on roads, to preserve some foods as salt, added to liquids for removing water.NaCIO – sodium hypochlorite and Ca(CIO)2 calcium hypochlorite – oxidizing agents, used to  bleach wood pulp and textiles and to disinfect swimming pools, foods, and sewage. NH4CIO4 – ammonium  perchlorate – a strong oxidizing agent, used in the space shuttle as fuel.

KClO4 – potassium perchlorate – for using in explosives and fireworks. Bottles of Clorox bleachImportant bromide salts:AgBr – silver bromide is very sensitive to light. When they are exposed to sunlight, they are easily reduced to the metallic silver.

As a result of this property, they are used to produce photographic films.Important iodide salts:KI – potassium iodide – added to table salt to prevent thyroid disease, used in chemical analysis    IodineThe word iodine is derived from the Greek word “iodos”, meaning “violet color”. It is the first halogen found in nature. Iodine has a black metallic luster and it is formed as dark-colored crystals. It sublimes easily by releasing violet vapor, which is poisonous and has an unpleasant odor.The solubility of iodine in water at 25°C is only 1.3 x 10–3 mol/L. It can dissolve in organic solvents such as CCl4 and C2H5OH.

Iodine is used to detect starch because it turns blue when it comes in contact with starch. 732264289 For starch test used iodine solution Diatomic iodine molecule   173594078It is extracted from seawater and sodium iodate (NaIO3) in Chile saltpeter in nature:2NaIO3 + 12HCl(conc) ? I2(s) + 5Cl2(g) + 2NaCl + 6H2O NaIO3+ 3H2SO4(dil) + 5NaI  ? 3I2(s) + 3Na2SO4+ 3H2OIn the laboratory, elemental iodine is produced by passing chlorine gas through solutions of iodine salts.2NaI(aq) + Cl2(g)  ? 2NaCl(aq) + I2(s)A deficiency of iodine in the body causes goiter. Healthy woman and female with enlarged thyroid gland   705416050The solutions of iodine in alcohols are used as an antiseptics in medicine. The compound iodoform (CHI3) is used as antiseptic in dentistry and it is a good solvent for phosphorus, P4. Uses of halogens and its compoundsFluorine is used in the manufacture of polymers such as Teflon.

F2 is component of freon gas (CCl2F2) used in refrigerators. Hydrofluoric acid (HF) is the only acid may react with SiO2; it is used to decorate glassware. Chlorine is used for bleaching wood pulp (required for the manufacture of paper and rayon), bleaching cotton and textilesin the extraction of gold and platinum in the manufacture of dyes, drugs and organic compounds such as CCl4, CHCl3, DDT, refrigerants, etc. in sterilising drinking water Chlorine is used for the preparation of poisonous gases such as phosgene (COCl2), tear gas (CCl3NO2), mustard gas (ClCH2CH2SCH2CH2Cl). On April 22, 1915, German forces introduced the use of lethal chlorine gas at Ypres, Belgium.

Bromine is used in agriculture as drugs, in the manufacture of films and drug industry. Used to protect engines from knocking. Added to fuel-oil.Iodine is usedas an antiseptic (tincture of iodine) in medicine. to detect starch.      in halogen lamps in car headlights.                                                          Laboratory work ?7. Properties of halogens and qualitative analysis of halide-ions IntroductionThe halogens are elements of Group 17 of the Periodic table.

This experiment illustrates some of the trends and similarities within the compounds of this group. Materials: silver nitrate AgNO3 solution, KCl solution, NaBr solution, KI solution, chlorine water, lead nitrate Pb(NO3)2 solution, NaCl solution, KBr solution, test tubes, teat pipette, burner, test tube holder.Procedure: Test 1. Silver nitratePut a little potassium chloride solution in a test-tube and add five drops of silver nitrate solution. Leave in the light for a few minutes.Put a little sodium bromide solution in a test-tube and add five drops of silver nitrate solution. Leave in the light for a few minutes.Put a little potassium iodide solution in a test-tube and add five drops of silver nitrate solution.

Leave in the light for a few minutes.Test 2. Chlorine waterAdd a few drops of a solution of chlorine to sodium bromide solution.Add a few drops of a solution of chlorine to potassium iodide solution.Test 3. Lead nitratePut approximately 5 ml of lead nitrate solution into a boiling tube, then add five drops of sodium chloride solution to a boiling tube and heat till it boils. Put approximately 5 ml of lead nitrate solution into a boiling tube, then add five drops of potassium bromide solution to the boiling tube and heat till it boils.Put about 5 ml of lead nitrate solution into a boiling tube, then add five drops of potassium iodide solution to a boiling tube and heat till it boils.

Place all 3 tubes in a beaker of cold water to cool. Safety: Wear eye protection. Wear disposable gloves. Avoid skin contact.

Wash hands after use. Observation and questions:Note your observations. …..

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……………………………………What can you say about the products of salts and salt reactions? Explain.Write the ionic and net ionic reaction equations for the experiment.Ionic equations : ………………………………………………………………………………………………………………………………………Net ionic equations : ………………………………………………………………………………………………………………………………………Write colors of precipitates.1. Write the products of electrolysis of the given substances.Molten potassium bromideLithium chloride solution2. Write the reaction equations for the following reaction schemas.KCl ? HCl ? Cl2 ? Br2 ? HBrO ? HBr ? KBrHCl ? NaCl ? Cl2 ? NaClO ? NaClO3KMnO4 ? I2 ? HIO3 ? KIO3 ? KI ? I2 ? NaIO3SiO2 ? SiF4 ? HF ? NaF 3.   During the electrolysis of NaCl solution, a total of 20.16 L gas is obtained at STP. According to the given information, find the masses of each substance produced in this process.4. If 67.2 L HBr gas (at STP) is completely dissolved in 25% NaOH solution (1 kg), find the mass percentages of all species in the final solution.5. If 47.6 g of KBr is produced at the end of the reaction of potassium with bromine, how many grams of bromine are consumed?halides – ???????????? / ??????????flux – ???? / ?????fluorspar – ????????? ???? / ?????????? ???? goiter – ????????, ?????? / ??? tear gas – ??? ?????????? ??? / ???????????? ???mustard gas – ?????, ???? ???? / ????????? ???, ?????

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