Make up the equations of the reactions
Ca + H2O =
Mg
+ H
=
Be + NaOH + H2O =
Mg + HNO3 (diluted) =
Sr + H2 =
CaH2 + H2O =
CaC2 + H2O =
Ca + N2 =
Ba3N2 + H2O =
Sr + O2 =
BaO + O2 =
CaO + H2O =
Be(OH)2 + NaOH =
BaCO3
Ba(HCO3)2
Ca(HCO3)2 + Ca(OH)2 =
CaSO4 + Na2CO3
Experimental section
1. Materials and equipment: маgnesium shaving, dust of magnesium, crystalline magnesia, calcium oxide, magnesium chloride, calcium chloride, barium chloride, solutions of phenolphthalein, hydrochloric acid, soda, calcium chloride, nitrate strontium, barium chloride, test tube, microspatula.
2. Chemical properties alkaline earth metals
2.1. Take the cut of a magnesium strip with pincers and burn it. Protect eyes from a bright light. Write down the equations of reaction of a white dust formation after combustion of magnesium.
2.2. Put 1-2 microspatulas of magnesia Mg into a test tube, moisten it with water, add 2-3 drops of phenolphthalein and heat. Write down observations and give the equation of the reaction.
Gradually add a solution of diluted hydrochloric acid to received solution with precipitate until the decoloration of phenolphthalein. What occurs with the precipitate? Write down the equations of the reaction.
2.3. Put 1-2 microspatulas of calcium oxide into a test tube, moisten with water and add 2-3 drops of phenolphthalein. What proves that the reaction has taken place? Give the equation of the reaction.
Gradually add a solution of diluted hydrochloric acid to received solution with precipitate until the decoloration of phenolphthalein. Give the equation of the reaction.
2.4. Put some magnesium powder into a test tube and add water. Does the reaction proceed? Heat the mixture in a test tube at the burner to boiling. What is observed? Cool a solution and add 1-2 drops of phenolphthalein. How is the indicator coloured? Why?
2.5. Put 4-5 drops of a neutral litmus solution and 5-6 drops of distilled water into each of three test tubes. Then put into the test tubes 1-2 crystals of salts: magnesium chloride into the first, calcium chloride into the second, barium chloride into the third. What is observed? What salt is hydrolysed? Give the equation of the hydrolysis.
2.6. Put 5-6 drops of 0,1 M soda solution into each of three test tubes and add 4-5 drops of 0,1 M solution: of calcium chloride into the first, of strontium nitrate into the second, of barium chloride into the third. What is observed? What substances precipitate? Give the equations of the relevant reactions. Add 5-6 drops of diluted hydrochloric acid to each test tube. Write down the observations.
Laboratory work 5
FLUORINE, CHLORINE
Themes for home preparation
General characteristic of halogens. Fluorine. A structure of atom, oxidation state. Occurring in nature, obtaining. Properties of fluorine. Fluorine as an oxidising agent. Hydrogen fluoride, its obtaining and properties. Hydrofluoric acid, peculiarities of its dissociation. Fluorides and hydrofluorides.
Fluoride of oxygen, obtaining and properties. Application of fluorine and of its compounds.
Chlorine. A structure of atom, oxidation state. Occurring in nature, obtaining. Physical and chemical properties of chlorine. Hydrogen chloride, obtaining and properties. Hydrochloric acid, its properties. Chlorides.
Compounds of chlorine with oxygen. Interaction of chlorine with water and alkalies. Oxides of chlorine, their obtaining, stability, interaction with water and alkalies. Oxygen-containing acids of chlorine: hypochlorous, chlorous, chloric, perchloric; methods of obtaining, properties of acids and their salts. Change of stability, base-acidiс and oxidising properties in a range of oxygen-containing acids of chlorine.
Questions and tasks
1. What electronic configurations have atoms of halogens? What oxidation states and valences can they have in compounds? Why fluorine differs significantly from other halogens?
2. How and why do the physical properties in a range F - Cl - Br - I change?
3. How and why do the oxidising properties in a range F - Cl - Br - I change? Can halogens in a free state be reducing agents in chemical reactions? Give the equations of the relevant reactions.
4. How is fluorine received in industry?
5. How is hydrogen fluoride received? Why has it the highest boiling point of all halogen hydrides? How do hydrogen fluoride dissociate in water solution? Why can not hydrofluoric acid be stored in glassware?
6. What causes the opportunity of metals hydrofluorides formation?
7. How do fluorine and chlorine react with alkali solution? What is the reason of difference of these reactions proceeding?
8. How does chlorine react with cold and hot alkali solution? Why are different products formed in these reactions? What is lime chloride, how is it received?
9. Calculate the рH of 0,01 M sodium hypochlorite solution.
10. What reactions can hypochlorous acid be decomposed by? What conditions do they require?
11. How is chlorous acid received? What properties this acid has?
12. How are chloric and iodic acids received? Give the equations of the relevant reactions.
13. How do strength, stability and oxidising properties of acids change in a range HOCl - HClO2 - HClO3 - HClO4?
14. What amount of calcium fluoride, which contains 97,5 % of main substance, and how many litres of a 98% solution of sulfuric acid (= 1,84 g/cm3) are necessary to obtain 1 kg of fluorine hydride?
15. What volume of concentrated hydrochloric acid, which contains 39 % HCl (= 1,2 g/cm3), is necessary for reaction with 0,1 mol of KMnO4?
16. What volume of chlorine at the temperature of 0° and at the pressure of 104 kPa is necessary for complete interaction with 10 l of the 3,75% solution of barium hydroxide (= 1,04 g/cm3)?