The Bunsen burner flame has distinct regions with different temperatures. The flame consists of:

• Region 1 (innermost blue cone): This is the unburnt gas mixture zone. It is relatively cool because combustion has not started here.
• Region 2 (dark inner cone): This is the reduction zone where incomplete combustion occurs. It has a moderate temperature.
• Region 3 (outer blue cone): This is the oxidation zone where complete combustion occurs. It is the hottest region due to efficient burning.
• Region 4 (outer faint mantle): This is the outer mantle where combustion is less efficient, and it is cooler than the oxidation zone.

The hottest part is region 3 (the tip of the inner blue cone) because it is where the primary combustion happens with sufficient oxygen, reaching temperatures up to $1500°C$.

Related Topics

Combustion: A chemical process where a substance reacts with oxygen to produce heat and light. In a Bunsen burner, methane (or other gas) undergoes combustion: $\mathrm{CH}4+2O2\to \mathrm{CO}2+2H2O$.

Flame Structure: Flames have zones based on temperature and combustion efficiency. The oxidation zone is always the hottest due to exothermic reactions.

Key Formulae

Heat of combustion: $\Delta H=-Q$, where $Q$ is the heat released. Maximum heat is released in the oxidation zone.