Flames come from burning gases

The idea

A flame is produced only when gaseous substances burn; a luminous flame is seen when atoms of the gaseous substance are heated and glow, and the colour produced is characteristic of each element.

Flame and glow

In an 'angithi', burning charcoal sometimes just glows red and gives out heat, with no flame. A candle and an LPG stove burn with a flame.

What do you think decides whether something burns with a flame?

• Whether gaseous substances are burning
• Whether it is hot enough to boil water
• Whether it is made of carbon

Flame or glow?

Open every tab.

Flames need gases

A flame is the glow of burning gases. A solid like charcoal can glow red and give out heat without a flame.

A flame is produced only when gaseous substances burn. A luminous flame is seen when the atoms of the gaseous substance are heated and glow, and the colour produced is characteristic of each element.

Notes

A flame is produced only when gaseous substances burn. A luminous flame is seen when atoms of the gas are heated and glow, and the colour is characteristic of each element.

Check yourself

A piece of charcoal glows red without a flame. Why?

Why does wood burn with a flame in the beginning?

What gives a luminous flame its colour?

Incomplete combustion gives soot. What is soot?

• It is too cold to burn. Charcoal is hot enough to glow red and give out heat. No gaseous substance is burning, so there is no flame.
• It contains no carbon. Charcoal contains carbon, which burns. A flame needs gaseous substances to burn.
• A flame is produced only when gaseous substances burn — correct. Yes!
• Volatile substances in it vapourise and burn — correct. Yes!
• The wood turns directly into charcoal. The book says the volatile substances vapourise and burn with a flame in the beginning.
• The wood is made of carbon dioxide. Wood is not made of carbon dioxide. Its volatile substances vapourise and burn.
• The colour of the container. The colour comes from the glowing atoms of the burning gaseous substance.
• The atoms of the gaseous substance glow, and each element has its own colour — correct. Yes!
• The size of the flame. The colour is a characteristic property of the element, not the size of the flame.
• Carbon dioxide. Carbon dioxide is a gas formed by complete burning. Soot is carbon.
• Water. Water is formed when a compound containing hydrogen burns. Soot is carbon.
• Carbon — correct. Yes!