Lab Manual: Types of Reactions & Changes | Lab Manuals for Class 9 PDF Download

Objective

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

• Iron with copper sulphate solution in water.
• Burning of magnesium ribbon in air.
• Zinc with dilute sulphuric acid.
• Heating of copper sulphate.
• Sodium sulphate with barium chloride in the form of their solutions in water.

Theory

• 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.
• In physical change, the interconversion of state takes place. For example,
  
• 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.
• 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.
  Reactants ⟶ Products
  A + B ⟶ C(Chemicalreaction)

The chemical reactions are of four types:

• Combination reaction: Two elements/compounds combine to form a single product.
  A + B ⟶ C
  2Mg(s) + O₂(g) ⟶ 2MgO(s)
  CaO(s)+H₂O(l) ⟶ Ca(OH)₂(aq)
• Decomposition reaction: When a compound decomposes/breaks due to energy, heat, light or electricity to form simpler substance.
  
• 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.
  E.g.
  Sodium sulphate + Barium chloride ⟶ Barium sulphate + Sodium chloride
  

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

Reactions of Fe + CuSO₄

Burning of magnesium ribbon in air

 Reaction of Mg + O₂ 

Reaction: 

Zinc with dilute sulphuric acid

Reactions of Zn + H₂SO₄ 

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

Heating of copper sulphate salt

Reaction of heat on CuSO₄ crystals.

Reaction: On heating CuSO₄.5H₂O crystals

On adding water to white powder of anhydrous copper sulphate

Reaction of sodium sulphate and barium sulphate solutions

Reaction of Na₂SO₄ + BaCl₂

Reaction:

Precautions

• Use all the chemicals in very less quantity.
• Use test tube holder for heating.
• Clean magnesium ribbon with sand paper and use fire tongs for holding magnesium ribbon.
• Handle the acids and alkalies carefully.