Class 9 Record Experiment 3

 EXPERIMENT – 3 

Aim
To carry out the following chemical reactions and classify them as physical or chemical changes.

1. Iron with copper sulphate solution in water.

2. Burning of magnesium ribbon in air.

3. Zinc with dilute sulphuric acid.

4. Heating of copper sulphate.

5. Sodium sulphate with barium chloride in the form of their solutions in water.

Theory

1. Physical Change: When there is no change in the composition of a substance and no change in chemical nature of the substance, such change is called as physical change.

2. In physical change, the interconversion of state takes place. For example,
   

3. 

4. Chemical Change: It is a change which brings change in the chemical properties of matter and a new substance is obtained. For example, burning of oil, fuel.

5. In a chemical change – heat is evolved or taken in, formation of bubbles, gas, fumes takes place, there is a change in colour of the reactants when they form a product.

The chemical reactions are of four types:

1. Combination reaction: Two elements/compounds combine to form a single product.

2Mg (s)+ O2 (g) → 2MgO (s)

CaO (s) + H2O (l) → Ca(OH)2 (aq)

2. Decomposition reaction: When a compound decomposes/breaks due to energy, heat, light or electricity to form simpler substance.

3. Displacement reaction: It takes place when more reactive metal reacts with the salt of less reactive metal and displaces it to form a new compound.

4. Double displacement reaction: In this reaction when two salts are mixed together in solution form then exchange of ions takes place and a new product is obtained.
   E.g.

Materials Required
Test tubes, test tube stand, test tube holder, a pair of tongs, Bunsen burner.

Chemicals Required
Iron filings, copper sulphate solution, magnesium ribbon, zinc granules, dilute sulphuric acid, sodium sulphate and barium chloride solutions and copper sulphate crystals.

Procedure

Iron with copper sulphate solution in water

Burning of magnesium ribbon in air

Zinc with dilute sulphuric acid.


Reaction: Zn(s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g) 

Heating of copper sulphate salt

Reaction of sodium sulphate and barium sulphate solutions.

Precautions

1. Use all the chemicals in very less quantity.

2. Use test tube holder for heating.

3. Clean magnesium ribbon with sand paper and use fire tongs for holding magnesium ribbon.

4. Handle the acids and alkalies carefully