Question

give reasons for the changing of colourless concentrated sulphuric acid to glow in adding a small piece of copper to it

Answer 1

Answer:

Explanation:

Lab Procedure:  

SI No. Experiment Observation Inference

1  Take a piece of magnesium ribbon and rub it with  sand paper to remove dirt from its surface. It looks silvery white. Colour of magnesium metal is silvery white.

2 Hold the magnesium ribbon with the help of a pair of tongs, light the magnesium and collect the ash of burnt ribbon in a china dish. It burns brilliantly and a white ash is left behind. Magnesium burns in air to form Magnesium oxide (MgO).

3  Take a moist red litmus paper and bring it in contact with the white ash of MgO. Red litmus paper turns blue. MgO is basic in nature.

Inferences:

Magnesium is a silvery white metal that burns in air and utilizes atmospheric oxygen from air to form magnesium oxide.

Magnesium oxide changes the colour of red litmus paper to blue. This reaction shows that magnesium oxide is basic in nature.

The formation of magnesium oxide is a direct combination reaction of two elements: magnesium and oxygen. Magnesium oxide is entirely different from the reactants magnesium and oxygen. So, this reaction is a chemical change.

Precautions:

The surface of magnesium ribbon should be properly cleaned with sand paper.

The white ash of magnesium oxide should not be touched.

Magnesium ribbon should be held by a pair of tongs while burning it.

It is better to use sun glasses to protect eyes from dazzling light of burning magnesium ribbon.