Laboratory work 1
Main classes of inorganic compounds and types of chemical reactions.
Themes for home preparation
Oxides and hydroxides. Bases and acids. Neutral, acidic, basic and double salts. Classification, chemical properties, obtaining, use. Principles of classification of inorganic compounds. Generic link between main classes of inorganic compounds.
Questions and tasks.
1. What are oxides? Give their classification.
2. Explain properties of basic oxides. Complete the equations of possible reactions:
Na2O + H2O = CaO + HCl =
NiO + H2O = CaO + CO2=
3. What oxides are acid oxides? What are their characteristic properties? Complete the equations of the reactions.
SO3 + CaO =
SO3 + NaOH =
CO2 + Ca(OH)2 =
4. What oxides are amphoteric oxides? What are their characteristic properties? Complete the equations of the reactions.
ZnO + HCl = ZnO + KOH =
5. How can the following conversions be done:
CaO Ca(OH)2 NiO Ni(OH)2
6. Give the classification of salts. Complete the equations of the reactions.
H2SO4 + NaOH = H2SO4 + 2NaOH =
In what case is the neutral salt formed, in what case is the acidic salt formed and why?
7. What are acidic salts? Give their characteristic properties. Complete the equations of the reactions.
BaSO4 + H2SO4 = NaHCO3 + NaOH =
CaCO3 + H2O + CO2 =
8. What salts are called basic salts? What are the methods of obtaining and characteristic properties of those salts? Complete the equations of the reactions and explain their proceeding.
MgCl2 + NaOH =
MgCl2 + 2KOH =
Mg(OH)Cl + HCl =
9. Give the characteristic features of chemical reaction proceeding. Give examples.
10. Complete equations of the reactions and determine the type of each reaction:
Hg(NO3)2
+
KOH = KHCO3
Cr(OH)3 + KOH = Al(OH)Cl2 + HCl =
ZnCl2
+ ZnO = K2CO3
+ Cr2O3
P2O3 + H2O = FeO + Cr2O3
NaOH + V2O5 = Zn + NaOH + H2O =
BaO + H2O = P2O5 + Ca(OH)2 =
Mg + H2SO4(diluted) = CaH2P2O7 + Ca(OH)2 =
Mg + H2SO4(concentrated) = MgCl2 + Mg(OH)2 =
Na2S + H2S = Si + KOH + Н2О =
KOH + Br2 = KCrO2 + HCl =
H3PO4 + NH3 = Mg3(PO4)2 + H3PO4 =
NO2 + Ca(OH)2 = NaAl(SO4)2+KOH(excess) =
11. Make up equations of reactions of neutral salts obtaining from acid and basic salts:
КHSO4, Sn(OH)Cl, Fe(OH)Cl2,
KHS, CaH2P2O7, [NiOH]2SO4,
NaHCO3, Ba(HSO4)2, Bi(OH)2NO3,
Sr(OH)Cl2, Al(OH)2Cl, Mg(OH)Cl.
12. What salts can be formed when the following acids and hydroxides react:
Bi(OH)3 + H2SO4 = Ba(OH)2 + H3PO4 =
Fe(OH)3 + HCl = NaOH + H2MoO4 =
Sn(OH)2 + HCl = Cr(OH)3 + H2SO4 =
Al(OH)3 + H2SO4 = Cr(OH)2 + HNO3 =
13. Complete equations of the reactions of complex compounds forming:
AgCl + NH3 = CoCl2 + NH3 =,
taking into consideration that coordination numbers of Ag+ and Co2+ are equal to 2 and 6 respectively. Find the charge of all the parts of complex compounds and write down the schemes of their dissociation.
14. Write down the equations of the double replacement reactions:
K3[Fe(CN)6] + FeCl2 = K4[Fe(CN)6] + FeCl3 =
Experimental section
1. Materials and equipment: magnesium band, metallic tin, calcium oxide, phosphorus oxide, copper oxide, sodium sulphite, sodium carbonate, crystalline iron chloride (III), sodium chloride and nickel chloride (II), solutions of phenolphthalein, methyl orange, copper sulphate, zinc sulphate, aluminium sulphate, nickel sulphate, iron chloride, cobalt chloride, barium hydroxide, hydrochloric acid, ammonia solution, barium chloride, ammonium-iron sulphate, potassium hexacyano(III)ferrate, concentrated solutions of sodium silicate, sodium hydroxide, potassium rhodanate, litmus paper, gas-generating device, 100-ml chemical beakers, test tubes, glass rods.
2. Preparing of basic oxides and their interaction with water and acids.
2.1. Burn the piece of magnesium band, holding it with pincers. Protect eyes from the bright light. Write down the equation of reaction of white powder forming after magnesium burns out.
Moisten the magnesium oxide MgO in the test tube with water, add 2 – 3 drops of phenolphthalein and heat. Write down observations and give the equation of reaction.
Gradually add diluted hydrochloric acid solution to obtained solution with precipitate until phenolphthalein becomes colourless. What happens with the precipitate? Write down equation of the reactions.
2.2. Moisten the pieces of calcium oxide CaO in the test tube with water and add 2 – 3 drops of phenolphthalein. What proves that the reaction proceeds? Give equation of the reactions.
Gradually add diluted hydrochloric acid solution to obtained solution with precipitate until phenolphthalein becomes colourless. Write down the equation of reaction.
2.3. Moisten the powder of copper oxide CuO in the test tube with water and add 2 – 3 drops of phenolphthalein. Does the colour of phenolphthalein change in this case? Does this oxide dissolve in water? What do basic oxides of metal dissolve in water, forming bases?
Fig. 15.1. Gas generating
device: 1 –reaction vessel; 2 – stopper with gas-discharging
tube
3. Obtaining of acid oxides and their interaction with water and bases.
3.1. Place 2 – 3 g of sodium carbonate in the reaction vessel of the gas-generating device (see fig. 15.1.), add small amount of hydrochloric acid solution and immediately close the vessel with stopper provided with gas discharging tube. Pass the evolving gas through the test tube with distilled water, to which a few drops of methyl orange were added beforehand. Carry out the investigation in the ventilating hoods. How does the colour of solution change and why? Write down the equations of the reactions.
Add a few drops of alkali solution to the obtained solution until the indicator changes its colour. What will happen? Write down equation of the reactions.
3.2. Carry out the experiment 3.1, taking the sodium sulphite instead of sodium carbonate. Write down the equations of the reactions.
3.3. Put a small amount of phosphorous oxide Р2О5 on the glass spreading rod and moisten it with water in the beaker. Determine the reaction of solution with litmus paper. How and why has the colour of indicator changed? Add drop by drop the base solution to the obtained solution until the colour of indicator changes. Write down the equations of the reactions.
4. Obtaining of neutral, acidic and basic salts and their interaction with acids, alkalis and other salts.
4.1. Pour about 10 ml of KOH solution in the beaker and add 1 – 2 drops of phenolphthalein. Notice the colour of the solution. Then gradually add small quantities of hydrochloric acid solution from the burette. After each portion is added, stir the solution and continue to add acid until the solution becomes colourless. Why has the solution become colourless? Write down equation of the reactions. What property is the most characteristic for bases? Why do all the bases have common properties?
4.2. Pour some solution of barium hydroxide to the test tube and pass the carbon dioxide from the gas-generating device through the solution. What can you observe? Write down equation of the reactions.
Continue passing carbon dioxide СО2 through the precipitate of obtained neutral salt until it dissolves completely. Why does the precipitate dissolve? Write down equation of the reactions. What salts are called acidic? How can they be obtained?
Add the solution of barium hydroxide Ва(ОН)2 base to the obtained solution of acidic salt Ba(HCO3)2. Give equation of the reactions. What properties do acidic salts have? How do they dissociate into ions?
4.3. Add drop by drop the solution of base to 4 – 5 ml of cobalt neutral salt cocl2. Observe the formation of precipitate of basic cobalt salt Co(OH)Cl.
Divide the obtained precipitate into two test tubes. Continue to add the solution of base to the first one until pink colour of cobalt hydroxide Со(ОН)2 appears and add the solution of acid to the second. Write down equation of the reactions.
4.4. Place 2 – 3 ml of such 1 M solutions in three test tubes: copper sulphate in the first one, nickel sulphate in the second one and iron (III) chloride in the third. Add 2 - 3 ml of KOH solution to each test tube. What can you observe? What proves the proceeding of reactions? Give the equations of the reactions in molecular and ionic form. Derive a general conclusion on methods of base forming.
4.5. Pour 5 ml of concentrated solution of Na2SiO3 salt to the test tube and add 2 – 2.5 ml of hydrochloric acid. Stir the liquid thoroughly with the glass rod and observe the forming of jellies of silica acid н2sio3. Write down equation of the reactions.
4.6. Add 2 – 3 drops of barium chloride solution to the sodium sulphate solution. Write down your observations. Explain why those salts react one with the other.
Carry out some more double replacement reactions. For this purpose, prepare two beakers, each with 10 ml of sodium silicate na2sio3 solution. Add 2 – 3 crystals of iron (iii) chloride and nickel (ii) chloride to each solution. Observe the growth of the semi-transparent precipitates of corresponding silicates. Write down equation of the reactions.
Laboratory work 2