Extinguishing candles with your bare hands may seem like a nice act, but why doesn't it burn us?
Let's start by understanding the principle of how a candle burns. There are several factors essential for the combustion of candles: paraffin and oxygen. The combustion process consists of the solid paraffin in the wick of the lit candle first melting and then vaporizing. Vaporized paraffin reacts violently with oxygen in the air to produce light and heat. Therefore, solid paraffin will not react when placed in air. And when people quickly pinch the flame, they push out the surrounding air and cut off the oxygen. The combustion stops immediately without the participation of oxygen, so it will not continue to release heat and damage our fingers. This is one of the reasons.
The second is the structure of the candle flame.The flame is mainly divided into three parts: the outer flame, the inner flame, and the flame core. The temperature decreases more and more from the outside towards the inside, because the further inwards one goes, the less complete the combustion is and the innermost part is already paraffin vapor. When a person pinches the flame of a candle with their hands, they pinch it directly from the root to the center of the flame. In a short time, it almost does not touch the high temperature external flame or anything else. In other words, the time when it touches the outer flame is extremely short. We had already put out the candle before we could burn ourselves, so we didn't get burned.
And we can see that oxygen is an essential element of combustion. Except in special circumstances, the combustion of most substances requires a large quantity of oxygen. Therefore, when noWhen putting out a fire, our first concern is to isolate the oxygen. This is the most effective and safest way. For example, when a pan catches fire, pouring water on it will not extinguish the flames, but will instead cause greater danger. At this time, just hold the cover on the oil pan to cut off the oxygen, and the oil pan will be able to extinguish the fire immediately. Another example is our commonly used fire extinguishing tool: a fire extinguisher, which sprays a large amount of carbon dioxide to quickly isolate the fire from the oxygen in the air, thereby achieving the goal of extinguishing the fire. 'fire. However, it should be noted that everything is special. Magnesium can also burn in carbon dioxide, so specific issues need to be analyzed in detail.
How many layers does a candle flame have? Which layer has the highest temperature?
The productss of burning a candle are carbon dioxide and water.
When a candle burns, the products of combustion are carbon dioxide and water. Its chemical expression is C25H52+O2→(ignition) CO2+H2O. The combustion phenomenon in an oxygen cylinder is that the flame emits bright white light, releases heat, and water mist appears on the cylinder wall.
The simple proof experiment is as follows:
Light the candle, cover a cold, dry beaker over the candle for 5 minutes, then quickly invert the beaker and find that the inside The wall of the beaker becomes blurry and water droplets form. Explain that burning a candle produces water. Add a small amount of clear limewater to the beaker and shake it. The clear limewater is observed to become cloudy, indicating that the candle is burning to produce carbon dioxide.
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Precautions for using candles:
1. Candles should be stored in a cool, dark, dry place. or direct sunlight will melt the surface of the candle, which will affect the fragrance dispersion degree of the candle, resulting in insufficient fragrance dispersion when lit.
2. Don’t blow out candles with your mouth! This will not only damage the candle, but also produce black smoke, turning the wonderful aroma of the scented candle into smoke. You can use a candle extinguisher to extinguish the candle, or use a candle extinguisher hook to immerse the candle wick in the wax; oil
3. Keep the lit candle out of reach of children and pets; protect your furniture. It will become hot after burning for 3 hours, so try not to place it on the furniture for a long time.period. time ; its cover can be used as a heating pad.
Baidu Encyclopedia: Candle - Principle
3 layers, the outer layer is the highest.
(1) Inner layer. Dark blue flame, due to insufficient oxygen supply, incomplete combustion, lowest temperature and reducing effect. It is called the flame core or the reduction flame.
(2) Intermediate layer. Dark red or light yellow flame, brilliant. The temperature is higher than the inner layer. This is called the inner flame.
(3) Outer layer. Colorless, due to sufficient oxygen supply, complete combustion, highest temperature and oxidation. It is called external flame or oxidation flame.
It can be divided into flame core, inner flame and outer flame. The flame temperature increases from the inside to the outside.
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The flame of a candle is caused by heat which causes the flow of air to rise. The airflow gently circulates around the candle flame and gathers it into one point. If the air is mixed with the gas beforehand, the temperature of the flame is much higher and the shape is much more regular, a cone with a little blue.
In any case, the shape of the flame is linked to gravity, in particular the fact that hot air is less dense than cold air and therefore rises upwards. In weightlessness, this “convection” effect no longer works, and the shape of the flame is more spherical.
Fire can bring many benefits to humans, but it can also cause serious harm if used carelessly. The three conditions for generating a flame are combustible materials, oxidants and temperature reaching the ignition point (but some substances do not necessarily have bneed oxygen to burn, such as active magnesium metal which can burn in carbon dioxide and nitrogen).
Baidu Encyclopedia - Flame