What Form Of Energy Is Transformed In A Burning Candle?


Have you ever wondered what is the science behind a burning candle, or imagine what is happening as you light a candle, well it is simple energy is simply being transformed to give you light.

In this article, we would be explaining the process involved in a burning candle, how matter changes from one form to the other.

Law Of Conservation Of Energy – Burning Candle

This law states that matter can change from one form of energy to another, it could be reversible.

In a burning candle when you light up the candle, it’s a form of energy that is chemical and when it burns it changes to heat and light energy(radiant).

It is a chemical reaction between the hydrocarbons in the candle wax and air(oxygen) to liberate energy (heat & light)

All of the light that a candle emits comes from a chemical reaction known as combustion, in which wax (made from carbon-based chemicals, usually derived from petroleum) reacts with air(oxygen) to form a colorless gas called carbon dioxide.

Water is also formed as vapor. Since wax never burns perfectly clean, some smoke is also produced.

The smoke is an aerosol (tiny particles of solid, unburned carbon from the wax mixed with the vapor) and often leaves a black carbon residue on the walls or ceiling above where the candle burns.

Steam forms in the blue part of the candle flame, where the wax burns cleanly and with plenty of oxygen; smoke forms in the bright, yellow part of the flame, where there is not enough oxygen for complete combustion.

Candles don’t burn by themselves. It takes energy to start the chemical combustion reaction that makes the wax burn. The initial energy needed to start a chemical reaction is called activation energy. It can be obtained with a burning match.

Rate Of Combustion Of A Burning Candle

The candle flame is considered a laminar diffusion flame. A diffusion flame implies that the fuel (the candle wax in the form of various hydrocarbons) and the oxygen (from the air) necessary for combustion enter the reaction zone (here the wick) separately.

The mixing of fuel and oxygen is due to convection and diffusion: The liquid fuel rises through the capillaries into the wick.

Here it evaporates due to the high temperature of the flame. The hot gas rises upwards and mixes with the surrounding air by diffusion.

In addition, cooler air enters the lower part of the flame by convection. Here it also mixes with the gaseous fuel. The combustion reaction preferably starts in the flame zone above the wick.

Small candles with small wicks will burn for 7-9 hours on 28 grams of wax used.

Larger candles with larger wicks use up wax faster. Larger wicks can be expected to burn 5-7 hours per 28 grams of wax used.

Temperature Of Candle Flame

Note that the exact temperatures vary greatly depending on many different factors, particularly the type of wax the candle is made of, as well as the ambient temperature (air) and the amount of oxygen present.

→Wick: 400°C (750°F).

→Blue/white outer edge of the flame (and also the blue cone underneath flame where the oxygen enters): 1400°C (2550°F).

→Yellow central region of the brightest part of the flame: 1200°C (2190°F).

→Dark brown/red inner part of the flame: 1000°C (1830°F).

→Red/orange inner part of the flame: 800°C (1470°F).

→Body of the candle: 40–50°C (104–122°F).

→Melted wax on top of the candle: 60°C (140°F).

Perhaps surprisingly, the brightest part of the flame is not the hottest part, The hottest part of a candle flame are the blue, almost invisible area at the base where the oxygen enters, and the blue/white part at the edge where the flame meets the oxygen-rich air around it.

The flame becomes progressively cooler as it moves from the outer edge to the wick.

The cooler areas are darker and colored orange, red, or brown. Most of the heat of the flame is transferred to the tip, where a large volume of gas burns constantly and convection constantly lifts the hot gases upward. If you want to heat something with a candle, hold it near the tip.

Do Burning Candles Cause Pollution

Yes, but some pollute more than others. In a candle, the flame burns a mixture of hydrocarbons in the air (oxygen and nitrogen), so in addition to steam and carbon dioxide, it also emits small amounts of carbon monoxide, nitrogen dioxide, and quite a few “particulate matter” (soot, unburned carbon particles).

In the case of air pollution, what matters is usually your exposure (how many pollutants you inhale, in total, over a period of time).

If you light candles singly and only occasionally, they are unlikely to cause enough indoor air pollution to worry about; other sources of air pollution, both inside and outside your home, are likely much more significant. But if you burn a lot of candles and sit in the smoke for long periods of time, you should think twice.




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