12 Questions
What causes the middle zone of a flame to appear luminous?
Carbon particles emitting yellow light
What happens to the carbon particles in the middle zone of a flame that causes it to appear as smoke and soot?
They leave the flame as smoke and soot
Why is the middle zone of a flame considered moderately hot?
Due to the presence of unburnt gas particles
What is the purpose of Activity 6 mentioned in the text?
To show how carbon particles form in the luminous zone of a flame
In which part of the candle flame are unburnt carbon particles found?
Middle luminous zone
What causes the circular blackish ring to form on the glass slide placed in the luminous zone of a candle flame during Activity 6?
Unburnt carbon particles settling on it
What is the main characteristic of the innermost zone of a candle flame?
Lacks oxygen and appears black
Which part of the candle flame contains unburnt wax vapour?
Innermost zone
In which zone of a candle flame is there enough air for complete burning of vapour?
Middle zone
Why does the innermost zone appear black in a candle flame?
Due to the presence of unburnt wax vapour and lack of oxygen
What conclusion can be drawn from observing the burning of wax vapour in a glass tube introduced into the dark inner zone of a candle flame?
Presence of wax vapour in the dark inner zone
What happens when a lighted matchstick is brought near the greyish-white vapour coming out from a glass tube inserted into the dark inner zone of a candle flame?
The vapour catches fire and burns at the end of the glass tube
Study Notes
Characteristics of a Candle Flame
- The middle zone of a flame appears luminous due to the presence of incandescent carbon particles.
- In the middle zone, carbon particles are not fully oxidized, resulting in the formation of smoke and soot.
- The middle zone is considered moderately hot because it has a lower temperature than the outer zone.
Activity 6 and the Luminous Zone
- The purpose of Activity 6 is to observe the formation of a circular blackish ring on a glass slide placed in the luminous zone of a candle flame.
- The circular blackish ring is formed due to the deposition of unburnt carbon particles from the luminous zone onto the glass slide.
Zones of a Candle Flame
- The innermost zone of a candle flame is characterized by a lack of oxygen, resulting in incomplete combustion.
- Unburnt wax vapour is found in the innermost zone of a candle flame.
- The outer zone of a candle flame has enough air for complete burning of vapour.
Observation of the Dark Inner Zone
- The innermost zone appears black due to the lack of oxygen, which prevents complete combustion.
- Observing the burning of wax vapour in a glass tube introduced into the dark inner zone of a candle flame reveals that the vapour ignites when it comes into contact with oxygen.
- When a lighted matchstick is brought near the greyish-white vapour coming out from a glass tube inserted into the dark inner zone of a candle flame, it ignites, indicating the presence of unburnt wax vapour.
Learn about the different zones of a candle flame, from the innermost zone lacking oxygen to the outermost zone of complete combustion. Understand the characteristics and composition of each zone.
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