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EXPERIMENT-1

CHEMICAL REACTIONS

AIM:

To perform and observe the following reactions and classify them into:

(i) Combination reaction (action of water on quick lime)

(ii) Decomposition reaction (action of heat on ferrous sulphate crystals)

(iii) Displacement reaction (iron nails kept in copper sulphate solution)

(vi)Double decomposition reaction (reaction between sodium sulphate and barium chloride)

APPARATUS REQUIRED:

1. A rack of at least six clean test tubes and a boiling tube (hard glass test tube)

2. Two 100 cc beakers

3. A test tube holder

CHEMICALS REQUIRED:

1. Small pieces of quicklime (CaO) in crystal form and not in powder form

2. Ferrous sulphate crystals

3. Copper sulphate solution

4. Iron filings

5. Sodium sulphate solution

6. Barium chloride solution

7. Distilled water

8. Acidified potassium dichromate paper

1. (A) PROCEDURE
i) Take a clean and dry 100 cc beaker and in it. Place small pieces of quick lime. ii) Fill a dropper with water and pour about 5 cc of it in the beaker. Make your observations.

(B) OBSERVATIONS:

i) As soon as the water comes in contact with the quick-lime, it starts crumbling producing a sort of crackling noise. It gives off steamy vapour. ii) The beaker on touching is found very hot.

(C) CONCLUSIONS:

i) The reaction between quick-lime and water is exothermic in nature. That is the reason why steamy fumes are given out. The reaction can be represented by the following equation:

CaO (s) + H2O (l) ( Ca(OH)2 (aq) + heat(∆)

The reaction is a combination reaction.

2. (A) PROCEDURE

i) Take some ferrous sulphate crystals in a dry and clean boiling tube. ii) Introduce the boiling tube into the non-luminous flame, such that the mouth of tube is facing away from you. iii) Tiny droplets of a colorless liquid settle near the neck of the test tube and heating further a colourless gas is evolved iv) Test the gas with acidified potassium dichromate paper. v) Note the color of the residue of the boiling test tube. (B) OBSERVATIONS:

i) Crystals of ferrous sulphate are light green in color. ii) When boiling tube is gently heated, steamy fumes are given out which condense on the cooler parts of the boiling tube iii) On strongly heating, a white powdery mass changes to reddish brown colour and colorless gas smells like burning sulphur is formed. iv) Acidified potassium dichromate paper changes from orange to green. (C) CONCLUSIONS:

i) When the boiling tube is gently heated, it decomposes into ferric oxide, sulphur dioxide and sulphur trioxide and water of crystallization is lost as shown in the given equation. 2FeSO4.7H2O(s) ( Fe2O3 (s) + SO2(g) + SO3(g) + 14H2O(l) (light green) (reddish brown) (colorless) (colorless) (water of crystallization )

It is a decomposition reaction.

3. (A) PROCEDURE

i) Pour some copper sulphate solution in a test tube. ii) Take some iron filings and put them in the copper sulphate solution. (B) OBSERVATIONS:

i) When the filings surface is covered with brick red deposit. ii) The blue color of copper sulphate solution changes to greenish colour (C) CONCLUSIONS:

i) The reaction between iron and copper sulphate solution is a displacement reaction. In this reaction, the more active metal iron, displaces the less active metal (Cu2+ ions) from its salt solution (CuSO4). The chemical reaction is represented as follows: CuSO4(aq) + Fe(s) ( FeSO4(aq) + Cu(s)

(blue) (silver grey) (light green)...
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