For a chemical reaction to take place some chemical change must occur. So, here is the activity to demonstrate a chemical reaction:

Step-1: Take a magnesium ribbon around 2cm long by rubbing it with sand paper.

Step-2: Hold it with tongs.

Step-3: Burn the ribbon and collect the ash in a watch glass which is white in pair.

Precaution must be taken while performing the experiment to keep the burning ribbon far away from eye. The experiment should be under some expert supervision.

In the activity we observed that magnesium ribbon burns with a white flames and changes into white powder. This powder is magnesium oxide.

There was a change in state, change in colour, change in temperature all of these are chemical changes and this proves that chemical reaction takes places here in which magnesium was converted into magnesium dioxide.