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Experiment:To show the hottest part of the Bunsen burner flames

Answer Text:
Experiment:To show the hottest part of the flame.
Apparatus:
- Bunsen burner, match stick
Procedure
- A matchstick is placed at the top of the bunsen burner chimney using a pin.
- A bunsen burner is lit and adjusted to get a nonluminous flame.
- The match stick is observed fro sometime for any changes.
- If no observable changes are made, the matchstick is then slowly raised towards the blue zone and observed keenly.
Observations.
- The matchstick did not ignite while it was at the bottom of the flame (resting on top of the chimney).
- It ignited as it was being raised towards the outer pale blue zone.
Explanations.
- The bottom of the flame (just on top of chimney) corresponds to the almost colourless zone.
- This zone contains unburnt gases, hence no burning occurs and is thus least hot to cause ignition of the matchstick.
- As the matchstick is raised upwards it moves past the greenish blue zone (where there is partial combustion) then to the outer pale blue zone where there is complete combustion and hence most heat.
- The heat in this region is adequate to cause ignition of the matchstick.
Conclusions.
- The outer pale blue zone is the hottest part of the nonluminous flame, and is thus the correct position to place an object during heating.