what colour will a bunsen flame be when the air hole is open?

When the air hole on a Bunsen burner is open, the flame is a blue non- luminous flame.

Quick Scoop

• With the air hole open , extra oxygen mixes with the gas.
• This gives complete combustion and produces a hot blue flame.

• The blue flame is hotter, cleaner (no soot), and often called the “roaring blue flame” in lab guides.

In short: open air hole → blue, hot, non-luminous flame.

TL;DR: What colour will a Bunsen flame be when the air hole is open? It will be blue.

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