Question

(b) What happens when an iron needle is dipped in a copper sulphate solution?
(c) With the help of an experiment explain that the burning of magnesium ribbon i
chemical change.​

Answer 1

1. When an iron nail is dipped in copper sulphate solution, a brown coating of copper is formed in the surface of iron and the colour of copper sulphate solution changes from blue to pale green. The reaction shows that iron is more reactive than copper because it displaces copper from the copper sulphate solution

2.

• AIM : To show that burning of magnesium ribbon is a chemical change.
• MATERIAL REQUIRED : Magnesium wire , tongs , burner
• Procedure :

1. Take a strip of magnesium ribbon and hold it with the help of tongs.

2. Introduce it into the flame of the burner.

• OBSERVATION :

Magnesium ribbon burns with dazzling light and white substance is formed which is magnesium oxide. This happen due to following reaction :-

• CHEMICAL REACTION :

2Mg ( s ) + O₂ ( g ) --------------> 2MgO ( s )

• CONCLUSION :-

Burning of magnesium in presence of oxygen to form magnesium oxide is a combination reaction and an exothermic process because heat and light are produced.