Structure of flame - class-VIII

A flame consist of three zones. These are the Innermost zone, middle zone, outer zone. The three zones of a flame have different colours and different temperature.

Dark zone is directly above the wick and wax gets vaporized at this region but does not undergo burning.

The material which vaporizes on burning is capable of producing flame.

Barium gives light green or apple green colour in flame test. This is the preliminary test for detecting Barium in any salt mixture.

The Invisible-zone of the flame is also called as non-luminous zone which is the zone of complete combustion. Due to complete combustion the zone become hottest zone of the flame.

Type of flame depends upon the amount of oxygen available for burning of the fuel. If oxygen is present in sufficient amount it is called as oxidizing flame but oxygen is not available in sufficient amount it is called as reducing flame.

A flame is produced when a substance undergoes combustion. The ability to burn is called combustibility.

A circular blackish ring on the glass plate kept over the candle flame indicates the luminous zone. The candle flame consists of mainly 3 zones depending on the temperature i.e the outer zone ( hottest among all, blue in colour, complete combustion occurs here and is the non-luminous part of the flame), middle zone ( moderately hot, yellow in colour, partial combution), inner zone (least hot and black in colour, and is the luminous part).

The luminous zone of a flame contains unburnt carbon particles that glow, emitting a yellow light.

Flame color determines the rate of combustion and thus the temperature difference producing a different color flame. In LPG the blue zone is the zone of complete combustion of fuel. So, the amount of soot decreases and the temperature is highest as high heat is released.

The correct match is:- (a) - (ii), (b) - (iii), (c) - (i)
Hottest zone of candle flame $ \rightarrow $ Non-luminous zone.
Yellow zone of candle flame $ \rightarrow $ Incomplete combustion zone.
Black innermost zone of the candle flame $ \rightarrow $ Zone of unburunt wax vapours.

The hottest part of a Bunsen flame is just above the tip of the primary (inner) blue cone, where complete combustion occurs.

A candle flame is a luminous flame because the wax vapors do not burn completely, leaving glowing carbon particles that produce a yellow light.

Coal burns directly without getting vaporised. So it does not produce flame. It burns with a glow.

The hottest part of a candle flame are actually the blue, almost invisible area near the base. Where oxygen is drawn in and blue or white part around the edge. In this area flame meets the oxygen-rich air all around it. The flame get progressively cooler as you move in from the outside edge toward the wick.

The colour and temperature of a flame are dependent on the nature of the fuel involved in the combustion.

The flame consist of three zones: 

The outermost zone in the candle flame is the hottest zone owing to the fact that complete combustion has taken place in this region.

Artificial ruby and sapphires are manufactured from alumina to which 1.5% of magnetic iron oxide and 0.5% of titanium oxide has been added, the mixture is fused and crystallised in an oxy-hydrogen flame. It is a reducing flame.

The outermost portion that is blue.

Candles produce light by releasing heat. A candle flame consists of three zones. Each zone has different temperatures and colors.

• The first zone is called the Outer zone
• The second zone is called the Middle zone
• The third zone is called the Inner zone

The outer zone is blue in color, due to complete combustion,. This zone is the hottest zone.

The middle one is in yellow color, which is the bright part of the flame. It is moderately hot and partial combustion of fuel takes place.

The least hot region of the flame is innermost zone. This inner zone is black in color due to the presence of unburnt wax vapors.