White smoke is produced after the candle is extinguished, what is white smoke?

Under normal circumstances, when paraffin wax is burned, the volatile paraffin particles will be heated and burned due to the presence of flames, but black smoke will be produced because they are not completely burned. When blowing out, the temperature drops, so the small particles do not burn because they do not reach the burning point, so white smoke is generated!

It is paraffin vapor, which is flammable, and after blowing out the candle, the white smoke is lit with a match, and the candle can be rekindled].

It's paraffin. Candles are usually made of paraffin wax. It is produced from the wax-containing fraction of petroleum by cold pressing or solvent dewaxing.

Paraffin is a mixture of several higher alkanes, mainly n-dodosecane (C22H46) and n-octadecane (C28H58), containing about 85 carbon elements and 14 hydrogen elements. Stearic acid (C17H35COOH) is also often added to candles to improve softness. When the candle burns, the products of the combustion of n-docosane and stearic acid are carbon dioxide and water.

The chemical equation for the reaction is as follows: 2C22H46 + 67O244CO2 + 46H2O C17H35Cooh + 26O218CO2 + 18H2O].

The wax volatilizes when heated, and then condenses tiny wax droplets in the air].

The candle burns again because the composition of the white smoke is paraffin, which supports combustion. ]

White smoke is produced when the candle is just extinguishedSolid microparticles produced by paraffin vapor when exposed to condensation

The main component of the candle is paraffin, the melting and boiling point of paraffin wax is very low, when the candle begins to burn for a while, the paraffin wax is directly liquefied or condensed in the air in the process of sublimation, forming small particles or droplets, at this time the hot air gradually rises, forming the white smoke we see.

The principle of candle lighting

When the candle is lit, the flame that initially burns is smaller and gradually larger, and the flame is divided into three layers (outer flame, inner flame, and flame center). The flame core is mainly candle vapor, and the temperature is the lowest; The internal flame paraffin burns inadequately, the temperature is higher than that of the flame core, and it contains carbon particles.

The outer flame is in full contact with the air, the flame is the brightest, the combustion is sufficient, and the temperature is the highest. Therefore, when a matchstick is quickly placed flat into the flame and taken out after about 1 second, the part of the matchstick that touches the outer flame turns black first.

Carbon dioxide.

Carbon dioxide gas is a part of the composition of the atmosphere (accounting for the total volume of the atmosphere, which is abundant in nature, and its production routes are mainly as follows:

1. Organic matter (including animals and plants) can release carbon dioxide in the process of decomposition, fermentation, decay and deterioration.

2. Carbon dioxide should also be released during the combustion of oil, paraffin, coal and natural gas.

3. Petroleum and coal will also release carbon dioxide in the process of producing chemical products.

4. All manure and humic acid can also release carbon dioxide during fermentation and maturation.

5. All animals must inhale oxygen and exhale carbon dioxide during breathing.

The white smoke produced when the candle is first extinguished is a small paraffin wax particle formed by the solidification of paraffin vapor.

Start by scoring what fog is and what smoke is. Fog is a phenomenon formed by liquid particles suspended in the air; Whereas, smoke is formed by solid particles suspended in the air. So the white smoke you are talking about should be a phenomenon caused by the condensation of paraffin vapor into solid particles and then suspended in the air.

Paraffin vapor solidifies into particles.

Paraffin vapor, how can it be water vapor?

There are two variations of wax burning:

1. The first is physical change: solid wax is heated and liquefied and then vaporized into wax gas molecules that are dispersed in the air.

2. Then there is the chemical change: the gaseous wax molecules are mixed with oxygen to undergo a redox reaction to produce CO2 and water (when completely combusted).

The main component of the candle is carbon oxides, which react with the oxygen of the air during combustion to produce water and carbon dioxide. When scientists observe the whole process of candle burning, they find that the mass of water and carbon dioxide produced after the candle is burned is exactly equal to the sum of the mass of the candle and the mass of oxygen consumed when the candle is burned.

The two upstairs said that it was a mess, look at me, the white smoke produced by the burning of the candle is a physical change, the white smoke is a small particle of solid paraffin, that is to say, no other substances are generated, it belongs to a physical change, the paraffin burning is melted into a liquid by the solid, and the white smoke produced when the liquid is heated and vaporized, and the candle can be re-burned, and the burning is the steam of the paraffin, and the vapor of the paraffin wax condenses into a solid paraffin small particles after being blown out, becoming smoke, so the candle is extinguished to produce white smoke, It is a physical change.

After extinguishing, the vaporized paraffin solidifies to form small white particles, which is the white smoke seen. Candles, a tool for daily lighting, are mainly made of paraffin wax, and in ancient times, were usually made from animal fat. Combustible glows.

The candle burning we see is not the burning of the paraffin solid, but the ignition device ignites the cotton wick, and the heat released melts the paraffin solid, and then vaporizes to generate paraffin vapor, which is combustible.

The white smoke produced when the candle goes out is small white particles formed by the solidification of paraffin. There are two changes in the combustion of wax, the first is the physical change: the solid wax is heated and liquefied and then vaporized into wax gas molecules that are dispersed in the air; Then there is the chemical change:

The gaseous wax molecules are mixed with oxygen to undergo a redox reaction to produce CO2 and water. The main component of the candle is carbon oxides, which react with the oxygen of the air during the combustion process to produce water and carbon dioxide. When scientists observed the whole process of burning a candle, they found that the mass of water and carbon dioxide produced after the candle burned was exactly equal to the sum of the mass of the candle and the mass of oxygen consumed when the candle burned.

The moment the candle is extinguished, the temperature drops suddenly, and the solid particles of wax formed by the condensation of gaseous wax form white smoke (smoke is solid). The main raw material of candles is paraffin, which is prepared from the wax-containing fraction of petroleum by cold pressing or solvent dewaxing, and is a mixture of several higher alkanes, mainly n-dodosecane and n-octadecane. Candles are easy to melt, less dense than water, and difficult to dissolve in water.

It melts into a liquid state when heated, colorless and transparent, and is light and slightly volatile when heated, and can smell the unique smell of paraffin. When cold, it solidifies into a white solid form with a slight special odor. For more information on what is the white smoke produced when a candle goes out, go to see more.

1) Carbon dioxide can make the clarified lime water turbid, blow out the candle and immediately cover the white smoke with a beaker stained with clarified lime water, the purpose of which is to verify the hypothesis a, the white smoke is the carbon dioxide generated when burning;

2) Blow out the candle and immediately put a piece of dry and cold glass on the white smoke, there is no water mist on the glass sheet, indicating that the white smoke is not water vapor;

3) blow out the candle, immediately light the white smoke with the burning wooden strip (do not touch the wick), and find that the candle is re-lit, indicating that the white smoke is flammable, which proves the correctness of hypothesis c; And because neither water vapor nor carbon dioxide can be burned, the hypothesis ab is also proved to be incorrect

So the answer is: 1) a;

2）b；3）c；ab；Neither water vapor nor carbon dioxide can be burned