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EXTRACTION AND PROPERTIES OF HALOGENS
PLAN

1.TEXT

2.DICTIONARY

3.QUESTION

4.GRAMMAR EXERCISES

5. PEDAGOGICAL TECHNOLOGY

6.GAME

7.REFERENCES

TEXT
Extraction and properties of halogens Elements of the seventh main group of the periodic table: fluorine, chlorine, bromine, iodine - are called halogens. Halogen atoms are characterized by the presence of seven electrons in the outer energy shell. Because all halogens are highly prone to electrons, they are strong oxidants in the free state, so they react violently with hydrogen and metals, as well as various complex substances that can be oxidized, e.g.

2FeCI2 + 3CI2 = 2FeCI3 H2S + J2 = 2HJ + S

As the sequence number of halogens increases, their oxidizing activity decreases. Therefore, one halogen can displace another halogen from its compounds: for example, chlorine, bromine and iodine, and bromine can displace iodine. Negatively charged ions of halogen are reductants. As the sequence number of halogens increases, their reversibility increases.

Halogens show positive valence in their compounds with oxygen and other metals. The maximum positive valence of chlorine, bromine, and iodine is seven, while fluorine does not have a positive valence. Negative valence compounds of halogens are more stable than positive valence compounds. The aggregate state of free halogens varies depending on their sequence number. At room temperature, fluorine is an almost colorless gas, chlorine is a green-yellow gas, bromine is a red-brown liquid, and iodine is a dark purple solid crystalline substance. Free halogens have a very pungent odor. All of them, even a small amount, severely irritate the mucous membranes of the respiratory tract, throat and nose, so it is necessary to be very careful when working with them and to conduct the experiment in a tubular cabinet. Halogens are sparingly soluble in water. Halogens are more soluble in organic solvents - alcohol, ether, benzene, gasoline, chloroform and carbon (IV) sulfide than in water. For example, iodine is 600 times better soluble in carbon (IV) sulfide than in water. Methods for the free extraction of halogens are based on the oxidation of their negatively charged ions. The larger the sequence number of the halogen, the easier it is to oxidize, the easier it is to obtain halogen free. Hydrogen compounds of halogens -hydrogen halides are a pungent-smelling gas that dissolves well in water.00 One volume at C is about 500 volumes of hydrogen chloride soluble in water. Aqueous solutions of hydrogen halides have acidic properties. The most important of the halide acids is hydrochloric acid (HCl). Commercially concentrated hydrochloric acid with a density of 1.19 g / cm3 contains about 37% HCl. Halogens exhibit positive oxidation states in all oxygenated compounds. All oxygenated compounds of chlorine are among the strongest oxidants. When chlorine is passed through water, a solution containing hypochloric acid and hydrochloric acid is formed together with chlorine:

CI2 + H2 O = HCIO + HCI

If chlorine is passed through an alkaline solution, KCIO and KCI are formed when chloride and hypochloric acid salts, for example, CI2 are passed through a KOH solution. A liquid (Javel water) containing a mixture of these salts decolorizes dyes.Experiments on chlorine and its compounds

Note: All experiments with free halogens, halides and other concentrated acids should be carried out very carefully in a pipe cabinet. Immediately expose a person who has been poisoned by chlorine or bromine vapor to the open air and give him a 2-3% ammonia solution. If liquid bromine splashes on the body, wipe the area thoroughly with a dry cotton ball and then wash with a 10% soda solution. Extraction of chlorine. Under the influence of hydrochloric acid on different oxidants, take three test tubes for the preparation of chlorine, put in the first one crystals of KMnO4, the second of PbO2, the third of K2Cr2O7 crystals and place 1 ml of concentrated (d = 1.19g / cm) hydrochloric acid in each of them. Find out the release of chlorine by its smell (with gusto) and color. If the reaction is slow, heat the solutions slightly. (note: after each experiment, add a small amount of sodium thiosulfate solution to the chlorine-releasing solution and wash the solution immediately). Write the reaction equations for obtaining chlorine, taking into account the transition of manganese and lead to the divalent state, chromium to the trivalent state in the above reactions. Given that water is also required for the reaction between chlorine and sodium thiosulfate, write the reaction equations, assuming the formation of sulfur, hydrochloric acid, sodium sulfate as reaction products, and determine the oxidizers and reductants in these reactions. Draw diagrams of the transfer of electrons from one substance to another. Place 5 g of manganese (IV) oxide in a vortex flask, using a dropper funnel, and add a concentrated HCl solution (d = 1.19 g / cm3). Collect the released chlorine in cylinders or conical flasks with a capacity of 50-100 ml. Once the jars are filled with chlorine, cover their mouths with a glass plate and store for further experiments. After all the containers have been filled with chlorine, disassemble the chlorinated instrument in a tubular cabinet and wash it, write the equations of the chlorine removal reactions.

Oxidizing properties of chlorine

a) Combustion of metals in chlorine. Insert a smaller thin copper wire or copper shavings into an iron spoon, heat in a gas flame, and quickly pour it into one of the chlorinated jars obtained in the previous experiment. Observe the interaction of copper with chlorine. When the reaction is complete, close the mouth of the container and remove to cool. Write the reaction equation. Once the dish has cooled, add a little water to it and shake. Observe the color of the copper salt solution. And explain why. Write the reaction equation.

b) Cut a small piece of sodium metal, wipe it dry with filter paper and put it in an iron spoon and keep it on the gas flame. After the sodium has melted, pour the spoon into a jar filled with chlorine. Observe the combustion of sodium in chlorine. Write the reaction equation. c) The effect of chlorine on metals. Take a little dried red phosphorus in an iron spoon and burn it in a flame, then quickly pour it into a jar filled with chlorine. Observe the combustion of phosphorus in a chlorine atmosphere. Write the reaction equation, determine which chlorine and phosphorus are oxidizing and which are reducing.
Extraction and properties of hydrogen chloride Add a little salt to the test tube, place 2-3 ml of concentrated sulfuric acid on it. Cover the test tube with a stopper and lower the end of the tube to the bottom of the test tube. Put a cotton ball in the mouth of the test tube. 1 _heat the test tube a little. When white smoke appears in solution 2, remove it from the instrument, close the mouth with a finger and turn it over and immerse it in a bowl of water, opening the solution under water. Explain the reason for the rise in water level in the test tube. Close the mouth of the test tube under water again with your finger and take it out of the water, check the solution formed in the solution using the indicator. Write the equation of the reaction in which HCl is formed. Extraction and properties of chlorinated lime. a) Put 3-4 g of calcium hydroxide in a glass of 100-200 ml, put 15-20 ml of water on it and shake. Heat the resulting mixture to 300C, add chlorine to it and observe the formation of a precipitate of chlorinated lime. Write the reaction equation b) Filter the sediment and divide it into two parts. Place hydrochloric acid on a piece of paper and determine the odor of chlorine and write the reaction equation. Dissolve the second part in water, place the fuchsin solution on top of it and observe the discoloration of the solution. Differences of chloride ion from other anions. Take three test tubes and pour 5-6 drops of sodium chloride solution into one, sodium carbonate solution into the other, and sodium sulfite solution into the third. Add 3-4 drops of silver nitrate solution to each solution. Sediment is formed in all three solutions. Add 8-10 drops of nitric acid solution to the precipitates. Which of the sediments is soluble in nitric acid? Write the molecular and ionic equations of the reactions. Test questions to reinforce the topic 1. How many milliliters of (37%) hydrochloric acid solution (d = 1.19) are needed to obtain 2.8 liters of chlorine measured under normal conditions? 2. Calculate the number of liters of chlorine formed under normal conditions and the percentage concentration of caustic soda in the solution when 10 kg of a 30% solution of Osh salt is completely electrolyzed. 3. Is the chlorine released by heating an excess of manganese (IV) oxide in hydrochloric acid obtained to dissolve 2 moles of hydrogen chloride in water enough to convert 28 g of iron into iron (III) chloride? 4. Why do salts of hypochloric acid have bleaching properties, while salts of hydrochloric acid do not have such properties?

Extraction of bromine and iodine.

a) Mix a few crystals of KBr with a little MnO2 and add the mixture to the solution. Add a few drops of concentrated sulfuric acid solution to it and heat slightly. what is observed Write the reaction equations.

b) Conduct a similar reaction with the KJ solution and observe the formation of a purple vapor of iodine. Write the reaction equation.

Oxidizing properties of bromine. a) Add a small amount of magnesium, zinc or aluminum powder to the test tube with brominated water and shake the test tube. Observe the discoloration of bromine water and explain the cause. Write the reaction equation. b) Add 2-3 ml of bromine water to the solution and add 3-4 drops of hydrogen sulfide water and shake vigorously. What is observed? Write the reaction equation.

Iodine extraction. Put 2-3 crystals of potassium iodine and as much manganese (IV) oxide in a dry crucible. Add 1-2 drops of concentrated sulfuric acid. Cover the crucible with a lid or watch glass and place it on the asbestos net and heat it gently for 3-4 minutes on the burner flame. Observe the iodine crystals formed on the crucible lid or watch window after cooling. Write the reaction equation.

The effect of iodine on starch. Add 5-6 drops of freshly prepared starch paste to the solution and add one drop of iodized water to it. observe the change in color of the solution. Does brominated and chlorinated water color starch like iodine?

Solubility of iodine. Take 1 ml of distilled water, add iodine crystals and shake well. Is iodine soluble in water? Then, add a smaller crystal of potassium iodide. Shake the solution. How can the increase in the solubility of iodine in potassium iodine (when added) be explained? Write the equation of the interaction of iodine with potassium iodide. Evaporation of iodine.

Put iodine crystals in a dry solution. Gently heat the test tube and observe the evaporation of the iodine. Note the small iodine crystals that appear in the upper cold part of the test tube walls. What process is called iodine evaporation.

Extraction of hydrogen iodide. Mix 10 g of finely ground iodine and 1 g of well-dried red phosphorus in a dry flask fitted with a dropper funnel. Pour a little water into the funnel and drop it into the mixture of iodine and phosphorus in the tube. Collect the resulting hydrogen iodide in a dry solution and form a solution of iodide acid by dissolving hydrogen chloride in water and by dissolving hydrogen iodide in water. Test the solution formed in the solution using an indicator and save it for the next experiment. Write the reaction equation, taking into account that the reaction proceeds in two stages.

Properties of iodic acid. Divide the iodide acid solution obtained in the previous experiment into three solutions. Add to one of the solutions a solution of AgNO3, to another a solution of (CH3COO) 2Pb or Pb (NO3) 2, and to a third a solution of a little H2SO4 and KMnO4. Halogenide ions: Qualitative reactions for CI-, Br-, J-. Take three test tubes and add 5-6 drops of AgNO3 solution to one of them with NaCl, the other with KBr, and the third with KJ solutions. What is observed? Write the molecular and ionic equations of the corresponding reactions.

Test questions to reinforce the topic

1. How much iodine can be extracted from 1 ton of chili nitrate containing 0.2% NaJO3?

2. In the laboratory, bromine can be obtained using the following redox reactions:

a) KBr + MnO2 + H2SO4- -Br2-. . .

b) KBr + KbrO3 + H2SO4-Br2 +. . .

3. Write the redox reactions that take place with the formation of iodine.

a) FeCl3 + KJ -J2 + b) KI + CuSO4 -J2 + CuI + v) KJ + NaClO + H2SO4-