Question

yo are provided with magnesium ribbon and sulphur powder. explain with the help of an activity that metal oxides are basic and non-metal oxides are acidic in nature.

Answer 1

We take the magnesium ribbon, and heat it over flame using tongs. An ash is produced due to formation of magnesium oxide. Take this ash in a test tube and dissolve in water. We see it dissolves partially. Divide the solution in two parts and test with blue and red litmus, one by one. When blue litmus is added to magnesium oxide solution, there is no change in colour. On adding red litmus solution, the colour changes to blue. We know that only basic substances turn red litmus to blue. Since magnesium oxide solution turns red litmus to blue, it is basic in nature.

2 Mg(s) + O₂(g)$\to$ 2 MgO (s)
MgO (s) + H₂O (l)$\to$ Mg(OH)₂ (aq)

Similarly we burn sulphur powder taken in a combustion spoon , over flame. After some time sulphur will start burning. When sulphur starts burning, introduce the spoon in a glass jar and allow the sulphur to burn inside the gas jar. Sulphur burns in the air of gas jar to form a pungent smelling gas, sulphur dioxide. After all sulphur has burnt remove the combustion spoon from the gas jar and cover it with a lid. The gas jar now contain sulphur dioxide gas. We now introduce a moist blue litmus paper inside the jar. The colour changes from blue to red. This confirms that sulphur dioxide is acidic in nature.


S(s) + O₂(g)$\to$ SO₂ (s)
SO₂ (s) + H₂O (l)$\to$ H₂SO₃ (aq)