To investigate the combustion of metals in oxygen

Aim :
To investigate the combustion of metals in oxygen

Procedure :
1.    A piece of  5 cm magnesium ribbon is cleaned with sandpaper.
2.    The magnesium ribbon is held with a pair of tongs and lit in the Bunsen burner.
3.    It is quickly placed into a gas filled with oxygen.
4.    Any changes that occurs are recorded.

The white powder formed is magnesium oxide.


Magnesium oxide is formed.

 
 
 
 
 
 
Special thanks to ace_0106 for typing the procedure.

Experiment 3.2: To Study Redox Reaction in terms of Displacement Reaction of a Metal from its Salt Solution

Aim :
To study the redox reaction in terms of displacement reaction of a metal from its salt solution.

Procedure :
1.    A strip of zinc plate and a strip of copper plate are cleaned with sandpaper.
2.    The zinc plate is then immersed in the copper(II) sulphate solution (test tube P) and the copper plate is immersed in silver nitrate solution (test tube Q).
3.    The mixture is left aside for half an hour.
4.    The changes that take place on the zinc plate, the copper plate, and in the copper(II) sulphate solution and the silver nitrate solution are recorded.

Special Thanks to ace_0106 for typing the procedures.

*Test tube P
Zinc plate in copper(II) sulphate solution.

Copper metal is deposited on the zinc plate. The blue colour fades as the concentration of Cu2+ ions decreases.


*test tube Q
The shining silver metal is precipitated on copper plate.



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Experiment 3.3: To Study the Displacement Reaction Between Halogens and Halide Ions

Aim :
To study the displacement reactions between halogens and halide ions

Procedure :
1.    A test tube is filled with 2 cm3 of potassium bromide, KBr solution.
2.    2 cm3 of chlorine water is added to the potassium bromide solution. The mixture is shaken gently.
3.    2 cm3 of 1,1,1,-trichloromethane (CH3CCl3) is then added to the misture obtained in step 2. The mixture is then shaken vigorously.
 4.    The test tube is allowed to stand for a few minutes and the colour of the 1,1,1,-trichloromethane layer is recorded.



5.    Steps 1 to 4 are repeated using the following mixtures.

a)    Chlorine water and potassium iodide, KI solution
b)    Liquid bromine and potassium chloride, KCl solution
c)    Liquid bromine and potassium iodide solution
d)    Iodine solution and potassium bromide solution
e)    Iodine solution and potassium chloride solution


A special thanks to ace_0106 for typing the procedures.



Br2 + KCl  no displacement occur.


Activities 2.6 To Prepare Ethyl Ethanoate

Aim :
To study the chemical properties of ethanoic acid (reaction between ethanoic acid and alcohol)   

Procedure :
1.    2 cm3 of ethanoic acid is poured into a test tube.
2.    4 cm3 of pure ethanol is added to the ethanoic acid.
3.    By using a dropper, four drops of concentrated sulphuric acid are added slowly and carefully to the mixture. The resulting solution is shaken gently.
(Precaution : concentrated sulphuric acid is very corrosive !!!)

4.    The reaction mixture is heated slowly and carefully until it boils. The test tube is shaken continuously.
5.    The contents of the test tube is poured into a beaker half-filled with water.
6.    The odour, colur and solubility of the organic product is obtained and recorded.

The distillate is a colourless liquid and with a fragrant odour. The liquid is insoluble in water and floats on water.
•    organic product (ester)- ethyl ethanoate

Activities 2.4 To Investigate the Properties of Ethanol

Aim :
To investigate the properties of alcohol

Procedure :
(A) Combustion of ethanol in air

1. About 1 cm3 of ethanol is added to an evaporating dish.
2. The ethanol is ignited using a lighted wooden splint.
3. The flammability of ethanol and the nature of the flame is observed.


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(B) Oxidation of ethanol

1. The boiling tube is filled with approximately 5 cm3 of potassium dichromate(VI) solution, K2Cr2O7.
2. About 5 cm3 of dilute sulphuric acid is added to the potassium dichromate(VI) solution.
3. About 5 cm3 of ethanol is added to the acidified potassium dichromate(VI) solution.

4. A rubber stopper fitted with a delivery tube is inserted into the boiling tube. The delivery tube is inserted into a test tube placed in a beaker half-filled with ice cold water.

5. The mixture of ethanol and acidified potassium dichromate(VI) ios boiled slowly. The distillate is collected in the test tube.


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6. The distillate is tested with a piece of blue litmus paper.
A colourless distillate is obtained.
The property of the distillate is acidic. It turns blue litmus paper red.

The orange colour of acidified potassium dichromate(VI) turns green.
The distillate has a vineger smell. Ethanoic acid is produced.

(C) Dehydration of ethanol

1. About 2 cm3 of ethanol is put into a dry test tube.
2. A small amount of glass wool is inserted into the test tube to absorb the ethanol.
3. Some porcelain chips are placed in the middle section of the test tube.

4. The test tube is closed with a rubber stopper fitted with a delivery tube. Another test tube is filled with water and inverted into a beaker.
5. The porcelain chips are heated strongly. The Bunsen burner flame is then shifted to the glass wool to vaporise the ethanol absorned in it.
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6. The gas released is collected in two set test tubes.The following tests are carried out on the gas collected.

A) The flammability of the gas
B) The reaction of the gas with liquid bromine

Experiment 1.2 To Study the Effect of Concentration on the Rate of Reaction

Aim :
to study the effect of concentration on the rate of reaction between sodium thiosulphate solution and dilute sulphuric acid

Procedure :
1. 50cm3 of 0.2 mol dm-3 sodium thiosulphate solution is measured out using a 100 cm3 measuring cylinder. The solution is then poured into a clean dry conical flask.



2. The conical flask is placed on a pice of paper with a cross “X” marked on it.

3. 5 cm3 of dilute sulphuric acid is measured out by using a 10 cm3 measuring cylinder.
The acid is then quickly poured into sodium thiosulphate solution. The stopwatch is started
immediately.

4. The reaction mixture is swirled once and the cross “X” is viewed from above.
A yellow precipitate will appear slowly in the conical flask.

5. The stopwatch is stopped as soon as the cross disappears from view and the time taken is
recorded.

6. Steps 1 to 2 are repeated with different mixtures of sodium thiosulphate solution and the
distilled water as shown in the following table.

Experiment                              1    2   3   4  5
Volume of Na2S2O3 / cm3      50  40 30 20 10
Volume of water / cm3             0   10 20 30 40
Volume of H2SO4/ cm3           5    5   5  5   5


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Special Thanks to ace_0106 for typing the procedure.

Experiment 1.3 To Study the effect of Temperature on the Rate of Reaction

Aim :
To investigate the effect of temperature on the rate of reaction between sodium thiosulphate solution and dilute sulphuric acid



Procedure :
1. 50 cm3 if 0.1 mol dm-3 sodium thiosulphate solution is poured into a dry, dry conical flask.
2. The temperature of the sodium thiosulphate solution is measured with a thermometer.
3. The conical flask is placed on a white paper marked with a cross “X”.



4. 5 cm3 of 1 mol dm-3 sulphuric acid is quickly poured into the sodium thiosulphate solution.
5. The stopwatch is started immediately and the conical flask is swirled gently.

6. The cross “X” is viewed from above. The stopwatch is stopped as soon as the cross disappears from view and the time taken is recorded.

7. The solution in the conical flask is poured out. The conical flask is washed thoroughly and dried. 50 cm3 of 0.1 mol dm-3 sodium thiosulphate solution is poured into the conical flask.
8. The solution is heated over a wire gauze until the temperature reaches about 45˚C.

9. The hot conical flask is placed over a white paper marked with a cross “X”.
10. 5 cm3 of 1 mol dm-3 sulphuric acid is measured out using a 10 cm3 measuring cylinder.
11. When the temperature of sodium thiosulphate solution falls to 40˚C, the sulphuric acid is quickly poured into the thiosulphate solution.
12. The stopwatch is started immediately and the conical flask is swirled gently.

13. The cross “X” is viewed from the top and the time taken for the cross to disappear from the view is recorded.
14. Steps 7 to 13 are repeated at a higher temperature of 50˚C, 55˚C and 60˚C respectively.




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Special thanks to ace_0106 for typing the procedures.

Experiment 1.4 To study the effect of a catalyst on the rate of decomposition of hydrogen peroxide

Aim :
To study the effect of a catalyst on the rate of decomposition of hydrogen peroxide

Procedure :
1. A test tube is hald-filled with hydrogen peroxide.
2. A glowing splint is placed at the mouth of the test tube to test for the gas evolved.
3. The changes that take place inside the test tube and on the glowing splint are recorded.
4. 0.5 g if manganese(IV) oxide, MnO2, is added to the hydrogen peroxide and shaken. The changes that take place in the test tube and on the glowing splint are recorded.

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Special thanks to ace_0106 for typing the procedures.