Make up the equations of the reactions

K + H₂O =

Na + H₂ =

Li + N₂ =

Li + C =

KO₂ + CO₂ =

KOH + O₃ =

KO₃ + CO₂ =

Na₂O₂ + Na =

NaN₃ + NaNO₃ =

K₂O + H₂O =

LiOH

NaCl + C + CaCO₃ =

NaCl + NH₃ + CO₂ + H₂O =

Li + O₂ =

Na + O₂ =

K + O₂ =

Na₂O₂ + H₂O =

Na₂O₂ + CO₂ =

KO₂ + H₂O =

Experimental section

1. Materials and equipment: metallic sodium, crystalline sodium peroxide, solutions of phenolphthalein, sulfuric acid, potassium iodide, lithium chloride, sodium chloride, potassium chloride, porcelain casserole, porcelain crucible, glass funnel, test tubes, microspatula.

2. Chemical properties of alkali metals

2.1. Receive a small piece of sodium from laboratory assistant, dry it with a filter paper from kerosene (it is usually kept under layer of such non-polar organic solvent), and place it in a crucible. Heat a crucible in the ventilating hood. What is it observed?

After cooling transfer the contents of the crucible with the help of a microspatula to a test tube; add 5-6 drops of diluted sulfuric acid and 2-3 drops of 0,1 N potassium iodide solution. What is observed? Give the equations of the relevant reaction.

2.2. Place some water in a porcelain casserole. Receive from laboratory assistant a small piece of sodium, dry it with a filter paper from kerosene, throw it in the porcelain casserole and cover with a glass funnel. What is observed? After completion of the reaction add 1 drop of a phenolphthalein solution to the solution in the cup. What is observed? Why? Give the equations of the relevant reaction.

2.3. Put 1-2 microspatulas of crystalline sodium peroxide into a test tube and add some water. What gas evolves as a result of the reaction? How it can be proved?

2.4. Take nichrome wire with an eye on the end, wash it thoroughly in a solution of hydrochloric acid then put it in a solution of lithium salt and bring to a colourless flame of the burner. What can you observe? Do the same with salts of sodium and potassium.

Laboratory work 4

S - ELEMENTS of ІІ GROUP

Themes for home preparation

Structure of atoms and oxidation state. Occurring of metals in nature, their properties. The relation to the action of water and acids, non-metals (hydrogen, nitrogen, carbon, oxygen).

Oxides, their interaction with water. Hydroxides, obtaining, solubility in water, acidic and basic properties. Unslaked and slaked lime.

Barium peroxide. The most important salt of elements. Sulphates and their solubility.

Carbonates and acid carbonates. Change of properties of metals and their compounds in a range beryllium - radium. Water hardness and methods of its elimination. Application of elements and their compounds. Idea on astringents.

Questions and tasks

1. What methods of s-elements of ІІ group obtaining are known? Indicate conditions and give the equations of the relevant reactions.

2. How and why does the reactivity of metals in the range Be - Mg - Са - Sr - Ba change? Give the equations of the relevant reactions.

3. What volume of hydrogen at the temperature of 27^о and at the pressure 99,7 kPа can be received as result of interaction of 21 kgs of calcium hydride with water?

4. Why do solubility and acid-basic properties vary in a range of hydroxides Ве(OH)₂ - Mg(OH)₂-Са (OH)₂-Sr(OH)₂ - Ba(OH)₂? What are the peculiarities of beryllium hydroxide properties?

5. What is unslaked lime, slaked lime natron (натронная?) and chloride lime? How can they be obtained?

6. Using values of solubility product, determine the direction of equilibrium shift in the following reactions:

а) CaCO₃ + Na₂SO₄  Na₂CO₃ + CaSO₄;

б) BaCO₃ + Na₂SO₄ Na₂CO₃ + BaSO₄.

7. What is cement and how is it obtained? What chemical transformations occur when cement slurry solidifies?

8. What is a hardness of water? What compounds cause water hardness?

9. What hardness is referred as temporary, and what - as constant? What chemical methods is it possible to use for removing temporary and constant water hardness? Give the equations of the relevant reactions.