Make up the equations o f the reactionss

F₂ + H₂ =

F₂ + H₂O =CaF₂ + H₂SO₄ =

SiO₂ + HF =

F₂ + NaOH =

MnO₂ + HCl =

KMnO₄ + HCl =

KMnO₄ + KCl + H₂SO₄ =

K₂Сr₂O₇ + HCl =

NaCl + H₂SO₄ =

Cl₂ + H₂O =

Cl₂ + KOH =

Cl₂O + H₂O =

Cl₂ + KOH

KClO₃ + H₂C₂O₄ =

KClO₃ + SO₂ + H₂SO₄ =

ClO₂ + H₂O =

ClO₂ + O₃ =

Cl₂O₆ + H₂O =

KClO₃

KClO₃ + H₂SO₄ =

HClO₄ + P₂O₅ =

Cl₂O₇ + H₂O =

Experimental section

1. Materials and equipment: crystalline manganese (ІV) oxide, potassium permanganate, potassium dichromate, sodium chloride, ammonium chloride, calcium chloride, ammonium - iron (ІІ) sulphate (Mohr's salt), calcium hypochlorite - chloride, potassium chlorate, potassium perchlorate, solutions of sulfuric acid, potassium iodide, sodium fluoride, sodium chloride, lead acetate, sodium hydroxide, concentrated hydrochloric and sulfuric acid, exsiccator, 100 mls flask, litmus paper, 100 mls beakers, test tubes, glass rods.

2. Chemical properties of fluorine, chlorine and their compounds

2.1. Put 3-4 crystals of manganese (ІV) dioxide into a test tube, add 1 ml of concentrated hydrochloric acid and heat up (carry out the experiment in a ventilating hood). What is observed? Cover an aperture of the test tube with a paper strip, moistened with solution of potassium iodide. What is observed? Give the equations of the relevant reactions.

2.2. Put 3-4 crystals of potassium permanganate into a test tube, add 1 ml of concentrated hydrochloric acid and heat up (carry out the experiment in a ventilating hood). What is observed? What gas is evolving? How can it be proved? Give the equations of the relevant reactions.

2.3. Put 3-4 crystals of potassium dichromate into a test tube, add 1 ml of concentrated hydrochloric acid and heat up (carry out the experiment in a ventilating hood). What is observed? What gas is evolving? How can it be proved? Give the equations of the relevant reactions.

2.4. Cover a glass plate with a layer of lampwax at slight heating. After lampwax solidifies, draw or write something on a plate with a nail, scratching lampwax to glass. Moisten a picture with hydrofluoric acid. In 15-20 minutes wash out a plate and delete lampwax. What is observed? Give the equations of the relevant reactions.

2.5. Put 1 g of crystalline sodium chloride into a test tube, add 1-2 mls of concentrated sulfuric acid and cautiously heat up (carry out the experiment in a ventilating hood). Collect the evolving gas in a dry test tube by the method of air replacement. Then close the aperture of the test tube with collected gas by a finger, upturn the test tube, plunge it in exsiccator with water and take away the finger. What is observed? Why? Close the test tube under water with a finger again and take it out of water. What is formed in the test tube? How can it be proved? Give the equations of the relevant reactions.

2.6. Put 2-3 g of crystalline substances into three test tubes: sodium chloride into the first, ammonium chloride into the second, calcium chloride into the third one, add 3-4 drops of concentrated sulfuric acid and heat up slightly (carry out the experiment in a ventilating hood). What is observed? Put wet litmus paper into the apertures of the test tubes, not touching their walls. What is observed? Put a glass rod wetted with concentrated ammonia solution into the apertures of test tubes. What is observed? Give the equations of the relevant reactions.

2.7. Place 3-4 drops of 0,5N solution of sodium fluoride into each of two test tubes and add 1-2 drops of 0,5N solutions: of calcium chloride into the first, of lead acetate into the second one. What is observed? Make a conclusion on the solubility of obtained fluorides.

2.8. Put 2-3 crystals of ammonium - iron (ІІ) sulphate FeSO₄ (NH₄)₂SO₄·6H₂O (Mohr's salt) into a test tube and add 2-3 drops of distilled water. Shake the test tube, so that the crystals dissolve and add to a solution 2-4 drops of 1 M sodium hydroxide solution. Note the colour of a precipitate, which was formed. Add 3-5 drops of sodium hypochlorite solution to the test tube and shake the test tube. What is observed? How does the colour of the precipitate change? Why? Give the equations of the relevant reactions.

2.9. Put 3-4 crystals of dry calcium hypochlorite - chloride (bleaching or lime chloride) into a test tube, add 3-5 drops of 0,5N lead acetate solution and heat up slightly. What is observed? How and why does the colour change? Give the equations of the reaction.

2.10. Put 3-4 crystals into two test tubes: of potassium chlorate into the first, of potassium perchlorate into the second and add 7-8 drops of water. Are salts dissolving well? Then add 3-4 drops of 0,5N solution of potassium iodide and 3-4 drops of diluted sulfuric acid into each test tube. What is observed? Compare obtained results and explain them. Do the reactions take place in both cases? Why?

Laboratory work 6

BROMINE, IODINE

Themes for home preparation

Structure of atoms, oxidation state of bromine and iodine. Occurence in nature, obtaining. Physical and chemical properties of bromine and iodine. Interaction with water and alkalies. Polyiodides.

Change of physical and oxidation-reduction properties in a range of halogens.

Hydrogen bromide and hydrogen iodide, their obtaining and properties. Hydrobromic and hydroiodic acid, their properties. Comparation of acid-base and reducing properties in a range of hydrohalogenic acids.

Oxides of bromine and iodine, their obtaining, properties. Hypobromous and hypoiodous acids, bromic and iodic, perbromic and periodic acids (ortho-iodic) acids, their obtaining, properties. Salts of these acids. Comparation of acid-base properties, stability, oxidation-reduction properties of oxygen-containing acids of halogens.

Interhalogenic compounds.

Questions and tasks

1. How and why does the oxidising activity in a range of halogens change? Give examples of the relevant reactions.

2. How and why does the character of proceeding reactions of interaction of halogens with hydrogen change?

3. How and why do the strength, acid-base and reducing properties of hydrohalogenic acids change? Give the equations of the relevant reactions.

4. How does bromine react with chlorine water, cold and hot alkali solutions? Give the equations of the relevant reactions.

5. How is hypoiodous acid received? Give the equations of the relevant reactions. What are the chemical properties of hypoiodous acid, which substances are formed at its thermal decomposition?

6. How and why do the strength, stability and oxidising properties of acids in a range HOCl - HOBr - HOI change? How can these acids be obtained? Give the equations of the relevant reactions.

7. How and why do acid-base and oxidation-reduction properties of acids in a range HClO₄ - HBrO₄ - HIO₄ change?

8. How and why do acid-base properties of acids in a range HIO - HIO₃ - HIO₄ change?

9. What volume of 6% solution potassium bromate (= 1,04 g/cm³) is necessary to oxidise 50 mls of the solution, containing 0,75 mol/l of iron (II) sulphate in the presence of excess amount of sulfuric acid?

10. What volume of the 5% solution of iodic acid (= 1,02 g/cm³) is necessary for complete removing of iodine from 40 mls of the 8% solution of hydroiodic acid (= 1,06 g/cm³)?