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Show that non-metallic oxides are acidic in nature

Materials Required

  • Powdered Sulphur
  • Water
  • Glass tumbler/Gas jar
  • Lid
  • Watch glass
  • Deflagrating Spoon
  • Spirit lamp
  • Lighter
  • Red and Blue litmus papers

 

The Procedure

Real lab procedure

  • Take a small amount of sulphur using the deflagrating spoon.
  • Introduce the spoon with burning sulphur into a glass tumbler/jar containing some water. 
  • Caution: Take care that the spoon should not dip in the water. 
  • Cover the tumbler/jar with a lid to stop the escape of gas produced during the burning of sulphur. 
  • Remove the spoon after some time. 
  • Shake the covered tumbler well to dissolve the gas in water.
  • Transfer the solution to the watch glass.
  • Dip one by one red and blue litmus papers in the solution and observe the change in the colour of the litmus papers. 

Simulation procedure

  • Drag and drop the lighter towards the spirit lamp to burn it. 
  • Click the bottle cap to open the sulphur bottle. 
  • Drag and drop the deflagrating spoon towards the bottle containing sulphur to collect the sulphur powder from the bottle. 
  • Drag and drop the deflagrating spoon containing sulphur powder towards the spirit lamp to burn the sulphur powder. 
  • Drag and drop the deflagrating spoon towards the gas jar containing water.
  • Click on the gas jar lid to close it. 
  • Click on the glass lid to open the gas jar and remove the spoon and close the gas jar again. 
  • Click on the gas jar to shake it well to get the sulphur gas get dissolved completely.
  • Click on the lid to open the gas jar. 
  • Drag and drop the gas jar towards the watch glass to pour the water onto it. 
  • Drag and drop the red litmus paper onto the watch glass.
  • Drag and drop the blue litmus paper onto the watch glass.  
  • Click the reset button to redo the experiment. 

 

Observation

  • There is no change in the colour of red litmus paper.
  • Blue litmus paper turns red.

 

Conclusion

  • The non-metallic oxide after dissolving in water shows acidic character. Sulphur on burning in air forms sulphur dioxide gas, which dissolves in water and form sulphurous acid.

    Sulphur + Oxygen (from air) → Sulphur dioxide                                                  

    S + O2 → SO2

    Sulphur dioxide + Water → Sulphurous acid

    SO2 + H2O → H2SO3

  • Sulphurous acid turns the colour of blue litmus paper red.

 

Precautions

  • Do not take too much sulphur to burn. It pollutes the air.
  • Handle chemicals and hot surface carefully.