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What products are formed when a candle burns? Comparison of physical properties and analysis of combustion products of candles made of various materials. Making candles

Lesson format: research with elements of interdisciplinary integration.

You cannot change someone by passing on ready-made experience.
You can only create an atmosphere conducive to human development.
K. Rogers

The purpose of the lesson: look at the candle flame and at the candle itself through the eyes of a researcher.

Lesson objectives:

Begin the formation of the most important method of understanding chemical phenomena - observation and the ability to describe it;

Show during practical work the significant differences between physical and chemical reactions;

Update background knowledge about the combustion process, taking into account the material learned in the lessons of other academic disciplines;

Illustrate the dependence of the candle combustion reaction on the reaction conditions;

Begin developing the simplest methods for conducting high-quality reactions to detect candle combustion products;

Develop cognitive activity, observation, broaden horizons in the field of natural science and artistic and aesthetic knowledge of reality.

Lesson steps:

I Organizing time. Teacher's opening speech.

Candle? - a traditional lighting device, which is most often a cylinder made of solid combustible material (wax, stearin, paraffin) serving as a kind of reservoir solid fuel, brought in molten form to the flame by a wick. The ancestors of candles are lamps; bowls filled with vegetable oil or fusible fat, with a wick or just a sliver for lifting fuel into the combustion zone. Some peoples used wicks inserted into raw fat (even the carcass) of animals, birds or fish as primitive lamps. The first wax candles appeared in the Middle Ages. Candles for a long time were very expensive. To illuminate a large room, hundreds of candles were required; they smoked, blackening the ceilings and walls. Candles have come a long way since their creation. People have changed their purpose and today people have other light sources in their homes. But, nevertheless, today candles symbolize a holiday, help create a romantic atmosphere in the house, calm a person, and are an integral part of the decor of our homes, bringing comfort and coziness into the house. A candle can be made from pork or beef fat, oils, beeswax, whale oil, and paraffin, which is obtained from oil. Today it is easiest to find candles made from paraffin. We will conduct experiments with them today.

II Updating students' knowledge.

Briefing. Safety regulations

Conversation:

Light a candle. You will see how the paraffin begins to melt near the wick, forming a round puddle. What process is taking place here? What happens when a candle burns? After all, paraffin simply melts. But where does the heat and light come from then?

What happens when a light bulb comes on?

Students' answers.

Teacher:

When paraffin simply melts, there is no heat or light. Most of paraffin burns, turning into carbon dioxide and water vapor. Because of this, warmth and light appear. And the heat melts part of the paraffin, because it is afraid of hot things. When the candle burns out, there will be less paraffin left than there was at first. But when an electric light bulb burns, heat and light are also released, but the light bulb does not get smaller? The burning of a light bulb is not a chemical, but a physical phenomenon. It does not burn on its own, but converts electricity into light and heat. As soon as you turn off the electricity, the light goes out. All you have to do is light the candle, and then it burns itself.

And now our task is to look at the candle flame and at the candle itself through the eyes of a researcher.

III Studying new material.

Experiment “Structure of a candle”

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
1. Considered a paraffin and wax candle. 2. Separate the wick.	A candle consists of a rod and a wick of tightly twisted threads in the center of a column.	The base of the candle is wax or paraffin. The wick is a kind of capillary through which the melt of the candle mass enters the combustion zone. The wicks are woven from cotton threads. Wax candles should have a loosely woven wick made of thick fibers; for all other candles, the wicks are made of tightly woven threads. This is due to the viscosity of the candle mass in the molten state: viscous wax requires wide capillaries, while easily moving paraffin, stearin and fats require thinner capillaries, otherwise the candle will begin to smoke heavily due to excess combustible material.

Experience “Study of the physical and chemical processes that occur when a candle burns”

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
1.Light a candle.	1. Burning a candle. If you bring your palms to the flame, you feel warmth.	1.Candle is a source of heat, because The combustion process of gaseous paraffin is exothermic.
2. We studied the sequence of the candle burning process. We observed the phase transformations that occur with the candle.	2. The paraffin begins to melt near the wick and changes from a solid state to a liquid state, forming a round puddle.	2. When a candle burns, phase transformations of paraffin (physical phenomena), osmotic phenomena, and chemical transformations are observed.
3. We observed the cotton wick and found out its role in the burning of a candle.	3. The candle does not burn along the entire wick.	Liquid paraffin wets the wick, ensuring its combustion. The paraffin itself does not burn. The cotton wick stops burning at the level where liquid paraffin appears. 3. The role of liquid paraffin is to prevent the wick from burning quickly, to promote it long burning

. Liquid paraffin near the fire evaporates, releasing carbon, the vapor of which supports combustion. If there is enough air near the flame, it burns clearly.

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
Melted paraffin extinguishes the flame, so the candle does not burn along the entire wick.	Experiment “Study of the structure of a candle flame. Detection of combustion products in a flame. Observation of flame heterogeneity” 1.Light a candle placed in a candlestick. They let it burn well. The candle flame has an oblong shape. IN	different parts The flames have different colors. In a calm candle flame, 3 zones are distinguished. The flame has a somewhat elongated appearance; at the top it is brighter than at the bottom, where the middle part is occupied by the wick, and some parts of the flame, due to incomplete combustion, are not as bright as at the top. The ascending air flow gives the flame an oblong shape: because the flame that we see is extended to a considerable height by the influence of this current of air.
2. We took a thin, long sliver of wood, which we held horizontally and slowly passed it through the widest part of the flame, not allowing it to catch fire and smoke heavily.	The sliver leaves a mark left by the flame. There is more soot above its outer edges, more soot above the middle.	The part of the flame that is directly adjacent to the wick consists of heavy paraffin vapor - it appears to be blue-violet in color. This is the coolest part of the flame. The second, brightest part is created by hot paraffin vapor and coal particles. This is the hottest zone. The third, outer layer contains the most oxygen and glows weakly. Its temperature is quite high, but somewhat lower than the temperature of the light part. It seems to be cooled by the surrounding air.
3. Take a piece of white thick cardboard, hold it horizontally in your hand, and quickly lower it from above onto the flame of a burning candle.	The top side of the cardboard becomes scorched from the flame.	A ring-shaped scorch has formed on the cardboard because... The center of the flame is not hot enough to char the cardboard.
The flame has different temperature zones.	4. A glass rod was brought into the candle flame. The candle flame is yellowish-orange in color and glows.	Soot forms on the surface of the glass rod. The luminous nature of the flame is due to the degree of oxygen consumption and the completeness of combustion of paraffin, the condensation of carbon and the glow of its heated particles.
Soot indicates incomplete combustion of paraffin and the release of free carbon.	5. The dry test tube was secured in a holder, turned upside down and held over the flame of an alcohol lamp.	The walls of the test tube fogged up. Water droplets form on the walls of the test tube.

Water is a product of candle combustion.

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
1.Light a candle.	Experiment “Studying the dependence of the height of a candle flame on the length of the wick”	The candle wick lights up, the candle flame is high.
Liquid paraffin wets the wick, ensuring its combustion. The paraffin itself does not burn.	The size of the flame changed, it decreased in size. The flame descends down the wick to the molten paraffin and fades. It burns longer at the top. The part of the paraffin closest to the wick melts from the heat.	Drops of liquid paraffin are attracted to each other less strongly than to the wick, and are easily drawn into the smallest cracks between the threads.

This property of a substance is called capillarity.

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
Experiment “Proof of candle burning in air oxygen” 1. Place a burning candle (thin, small, attached with plasticine) in the middle of the plate.	Colored water was added to the plate (to hide the bottom), and the candle was covered with a cut glass. Water starts to get under the glass	The candle gradually goes out. The candle burns as long as there is oxygen in the glass. As oxygen is consumed, the candle goes out. Due to the vacuum that has formed there, the water rises.

Combustion is a complex physical and chemical process of interaction between the components of a combustible substance and oxygen, occurring at a fairly high speed, releasing heat and light.

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
Experiment “The influence of air on the combustion of a candle. Watching the flame of a burning candle"	They brought a lit candle to the slightly open door. 1. Place a candle on the floor. 2. Carefully stand on a stool near the slightly open door, holding a lit candle at the top of the door. 1.The flame is deflected towards the room.	2. The flame deviates towards the corridor.
Warm air at the top flows out of the room, while at the bottom the cold air flows inward.	3.Top the candle over so that the fuel flows onto the wick.	The candle will go out

The flame has not had time to heat the fuel enough for it to burn, as happens at the top, where the fuel enters the wick in small quantities and is fully exposed to the flame.

Experiment “Study of the smoke of an extinguished candle”

WHAT THEY WERE DOING?	WHAT DID YOU OBSERVE?	CONCLUSIONS
Experiment “Qualitative reaction for detecting candle combustion products” 1. Lime water was poured into a glass.		The candle stub was placed on a wire to make it easier to lower it into the glass.
Lime water can be prepared as follows: take a little quicklime, stir it in water and strain through blotting paper. If the solution turns out cloudy, you need to strain it again until it is completely clear. 2. Light a candle stub and carefully lower it to the bottom of an empty glass.	They took out the candle, lit it and put it back into the jar. The cinder burns for a while and then goes out.	The glass contains a colorless and odorless gas that does not support combustion and prevents the candle from burning. This is carbon dioxide - CO 2. .
3. Add lime water to a glass.	The water in the glass becomes cloudy.	When a candle burns, carbon dioxide is produced. Carbon dioxide makes lime water cloudy.

IV Consolidation of the studied material.

Frontal survey:

List the sequence of processes in which a candle burns.

What phase transformations are observed when a candle burns?

What is the combustible material of a candle?

What is a cotton wick used for?

What phenomenon allows liquid paraffin to rise to a certain height?

Where is the hottest part of the flame?

Why does the candle length decrease?

Why does the candle flame not go out, although during combustion substances are formed that do not support combustion?

Why does a candle go out when we blow on it?

What conditions are necessary for a longer and better burning candle?

How can you put out a candle? What properties are these methods based on?

What is the qualitative reaction to carbon dioxide?

Teacher:

Consideration of the structure and combustion of a candle convincingly illustrates the complexity of the most trivial everyday objects around us, testifies to how inseparable sciences such as chemistry and physics are. A candle is such an interesting object of study that the topic cannot be considered exhausted.

At the end of our lesson, I would like to wish you that, like a candle, you radiate light and warmth for those around you, and that you are beautiful, bright, and necessary, like the candle flame that we talked about today.

V Homework.

1. Assignment for those wishing to carry out research work at home:

Take for experience any thing that has a zipper. Open and close the zipper several times. Remember your observations. Rub a paraffin candle onto a zipper, for example, on a sports jacket. (Don't forget to ask your mom for permission when you take the jacket for the experiment). Has the movement of the zipper changed?

Answer the question: “Why do they sometimes rub zippers with a candle?”

(The substances from which the candle column is made (stearin, paraffin) are a good lubricant that reduces friction between the fastener links.)

2. Assignment for those wishing to carry out research work at home.

Take 3 candles of different composition, made of paraffin, wax, stearin. You can buy candles in the store, or you can make them yourself. (Ask Mom or Dad to watch the experience with you.) Wait until dusk, place the candles close to each other and light them. Fill in the table as you observe the burning candles.

References.

1. Faraday M.., History of a candle, M., Nauka, 1980.

During the combustion process, a flame is formed, the structure of which is determined by the reacting substances. Its structure is divided into areas depending on temperature indicators.

Definition

Flame refers to gases in hot form, in which plasma components or substances are present in solid dispersed form. They carry out transformations of physical and chemical type, accompanied by glow, release of thermal energy and heating.

The presence of ionic and radical particles in a gaseous medium characterizes its electrical conductivity and special behavior in an electromagnetic field.

What are flames

This is usually the name given to processes associated with combustion. Compared to air, gas density is lower, but high temperatures cause gas to rise. This is how flames are formed, which can be long or short. Often there is a smooth transition from one form to another.

Flame: structure and structure

To determine the appearance of the described phenomenon, it is enough to light it. The non-luminous flame that appears cannot be called homogeneous. Visually, three main areas can be distinguished. By the way, studying the structure of the flame shows that various substances burn with the formation various types torch.

When a mixture of gas and air burns, a short flame is first formed, the color of which is blue and purple shades. The core is visible in it - green-blue, reminiscent of a cone. Let's consider this flame. Its structure is divided into three zones:

1. A preparatory area is identified in which the mixture of gas and air is heated as it exits the burner opening.
2. This is followed by the zone in which combustion occurs. It occupies the top of the cone.
3. When there is insufficient air flow, the gas does not burn completely. Carbon divalent oxide and hydrogen residues are released. Their combustion takes place in the third region, where there is oxygen access.

Now we will separately consider different combustion processes.

Burning candle

Burning a candle is similar to burning a match or lighter. And the structure of a candle flame resembles a hot gas flow, which is pulled upward due to buoyancy forces. The process begins with heating the wick, followed by evaporation of the wax.

The lowest zone, located inside and adjacent to the thread, is called the first region. It has a slight glow due to a large amount of fuel, but a small volume of oxygen mixture. Here, the process of incomplete combustion of substances occurs, releasing which is subsequently oxidized.

The first zone is surrounded by a luminous second shell, which characterizes the structure of the candle flame. A larger volume of oxygen enters it, which causes the continuation of the oxidation reaction with the participation of fuel molecules. Temperatures here will be higher than in the dark zone, but not sufficient for final decomposition. It is in the first two areas that when droplets of unburned fuel and coal particles are strongly heated, a luminous effect appears.

The second zone is surrounded by a low-visibility shell with high temperature values. Many oxygen molecules enter it, which contributes to the complete combustion of fuel particles. After the oxidation of substances, the luminous effect is not observed in the third zone.

Schematic illustration

For clarity, we present to your attention an image of a burning candle. Flame circuit includes:

1. The first or dark area.
2. Second luminous zone.
3. The third transparent shell.

The candle thread does not burn, but only charring of the bent end occurs.

Burning alcohol lamp

For chemical experiments, small tanks of alcohol are often used. They are called alcohol lamps. The burner wick is soaked with the liquid poured through the hole. liquid fuel. This is facilitated by capillary pressure. When the free top of the wick is reached, the alcohol begins to evaporate. In the vapor state, it is ignited and burns at a temperature of no more than 900 °C.

The flame of an alcohol lamp has a normal shape, it is almost colorless, with a slight tint of blue. Its zones are not as clearly visible as those of a candle.

Named after the scientist Barthel, the beginning of the fire is located above the burner grid. This deepening of the flame leads to a decrease in the internal dark cone, and out of the hole comes middle section, which is considered the hottest.

Color characteristics

Various radiations are caused by electronic transitions. They are also called thermal. Thus, as a result of combustion of a hydrocarbon component in air, a blue flame is caused by the release H-C connections. And when C-C particles are emitted, the torch turns orange-red.

It is difficult to consider the structure of a flame, the chemistry of which includes compounds of water, carbon dioxide and carbon monoxide, and the OH bond. Its tongues are practically colorless, since the above particles, when burned, emit radiation in the ultraviolet and infrared spectrum.

The color of the flame is interconnected with temperature indicators, with the presence of ionic particles in it, which belong to a certain emission or optical spectrum. Thus, the combustion of certain elements leads to a change in the color of the fire in the burner. Differences in the color of the torch are associated with the arrangement of elements in different groups of the periodic system.

Fire is examined with a spectroscope for the presence of radiation in the visible spectrum. At the same time, it was found that simple substances from the general subgroup also cause a similar coloration of the flame. For clarity, sodium combustion is used as a test for this metal. When brought into the flame, the tongues turn bright yellow. Based color characteristics highlight the sodium line in the emission spectrum.

It is characterized by the property of rapid excitation of light radiation from atomic particles. When non-volatile compounds of such elements are introduced into the fire of a Bunsen burner, it becomes colored.

Spectroscopic examination shows characteristic lines in the area visible to the human eye. The speed of excitation of light radiation and the simple spectral structure are closely related to the high electropositive characteristics of these metals.

Characteristic

The flame classification is based on the following characteristics:

• aggregate state of burning compounds. They come in gaseous, airborne, solid and liquid forms;
• type of radiation, which can be colorless, luminous and colored;
• distribution speed. There is fast and slow spread;
• flame height. The structure can be short or long;
• nature of movement of reacting mixtures. There are pulsating, laminar, turbulent movement;
• visual perception. Substances burn with the release of a smoky, colored or transparent flame;
• temperature indicator. The flame can be low temperature, cold or high temperature.
• state of the fuel - oxidizing reagent phase.

Combustion occurs as a result of diffusion or pre-mixing of the active components.

Oxidative and reduction region

The oxidation process occurs in a barely noticeable zone. It is the hottest and is located at the top. In it, fuel particles undergo complete combustion. And the presence of oxygen excess and combustible deficiency leads to an intense oxidation process. This feature should be used when heating objects over the burner. That is why the substance is immersed in the upper part of the flame. This combustion proceeds much faster.

Reduction reactions take place in the central and lower parts of the flame. It contains a large supply of flammable substances and a small amount of O 2 molecules that carry out combustion. When introduced into these areas, the O element is eliminated.

As an example of a reducing flame, the process of splitting ferrous sulfate is used. When FeSO 4 enters the central part of the burner torch, it first heats up and then decomposes into ferric oxide, anhydride and sulfur dioxide. In this reaction, reduction of S with a charge of +6 to +4 is observed.

Welding flame

This type of fire is formed as a result of the combustion of a mixture of gas or liquid vapor with oxygen from clean air.

An example is the formation of an oxyacetylene flame. It distinguishes:

• core zone;
• middle recovery area;
• flare extreme zone.

This is how many gas-oxygen mixtures burn. Differences in the ratio of acetylene and oxidizing agent lead to different types flame. It can be of normal, carburizing (acetylenic) and oxidizing structure.

Theoretically, the process of incomplete combustion of acetylene in pure oxygen can be characterized by the following equation: HCCH + O 2 → H 2 + CO + CO (one mole of O 2 is required for the reaction).

The resulting molecular hydrogen and carbon monoxide react with air oxygen. The final products are water and tetravalent carbon oxide. The equation looks like this: CO + CO + H 2 + 1½O 2 → CO 2 + CO 2 +H 2 O. This reaction requires 1.5 moles of oxygen. When summing up O 2, it turns out that 2.5 moles are spent per 1 mole of HCCH. And since in practice it is difficult to find ideally pure oxygen (often it is slightly contaminated with impurities), the ratio of O 2 to HCCH will be 1.10 to 1.20.

When the oxygen to acetylene ratio is less than 1.10, a carburizing flame occurs. Its structure has an enlarged core, its outlines become blurry. Soot is released from such a fire due to a lack of oxygen molecules.

If the gas ratio is greater than 1.20, then an oxidizing flame with an excess of oxygen is obtained. Its excess molecules destroy iron atoms and other components of the steel burner. In such a flame, the nuclear part becomes short and has points.

Temperature indicators

Each fire zone of a candle or burner has its own values, determined by the supply of oxygen molecules. The temperature of the open flame in its different parts ranges from 300 °C to 1600 °C.

An example is a diffusion and laminar flame, which is formed by three shells. Its cone consists of a dark area with a temperature of up to 360 °C and a lack of oxidizing substances. Above it is a glow zone. Its temperature ranges from 550 to 850 °C, which promotes thermal decomposition of the combustible mixture and its combustion.

The outer area is barely noticeable. In it, the flame temperature reaches 1560 °C, which is due to natural characteristics fuel molecules and the speed of entry of the oxidizing agent. This is where the combustion is most energetic.

Substances ignite under different temperature conditions. Thus, magnesium metal burns only at 2210 °C. For many solids the flame temperature is around 350°C. Matches and kerosene can ignite at 800 °C, while wood can ignite from 850 °C to 950 °C.

The cigarette burns with a flame whose temperature varies from 690 to 790 °C, and in a propane-butane mixture - from 790 °C to 1960 °C. Gasoline ignites at 1350 °C. The alcohol combustion flame has a temperature of no more than 900 °C.

• 1. Smoking will occur when there is insufficient oxygen content in the combustion atmosphere. I don’t know how to do it, maybe. add water vapor.
  2. In a large jar, the oxygen did not burn out completely, but some percentage of it remained, so the left candle burned longer than ideal.
• Michael,
  1. An exact solution is needed for the first question. The general direction of thought is correct - combustion with a lack of oxygen, but it didn’t work out that way for me. I tried just covering the jar with a lid, the flame just gradually went out, and that was it. There is no smoking.
  2. I don’t think there will be any oxygen left in the big jar. The flame causes strong mixing throughout the entire volume. Hot carbon dioxide rises up - cools down from the can - falls down. Plus, its density is 1.5 times greater than that of air, so it will also sink down.
• Apparently, some of the carbon dioxide has gone down from the 3 liter bottle. Most likely, the experiment will be successful if the jar is sealed with a piece of plastic cover and turn over before covering with cardboard.
  P.S.
  CO2 = 46
  Air = 29
  Total difference is 1.5 times
  You can light a candle, for example, by a chemical reaction of potassium permanganate with sulfuric acid
  KMnO4 + H2SO4 (conc.)
  the resulting oxide, when interacting with paraffin, will ignite it
• As for the procedure: I think the answers should have been hidden so that the “second” ones would not see the answers of the “first”, so that there would be no disputes - it’s a competition, after all

  Essentially: there’s nothing else in my head, there’s no way to surf the Internet right now...

• Mikhail, openness of comments is normal. The first correct answer still counts.
  There is no need to scour the Internet, there is more logic and basic knowledge physics and chemistry. And, of course, imagine all the nuances of the experiment in your head.
• On the second question: – “Why does the left candle burn for so long?” for some reason there is still no comment about the intensity of combustion, if you look at the video it is noticeable that when burning with big amount carbon dioxide
  gas flame is smaller.
  Regarding the first question, there is an assumption that perhaps the candle will smoke when the wick is long, i.e. the wick burns and burns oxygen around it.
• Sergey, I agree. It is very difficult to make a quantitative assessment here. Who said that the flame of both candles burns equally intensely? By eye, they seem to be the same, but maybe one consumes more oxygen than the other. And secondly, the flame attenuation processes themselves. As a result, it turns out that we can only give a qualitative assessment (“yes, the left candle burns less”), but not a quantitative assessment.

• Andrey

  4 August 2010, 06:01

  Regarding the combustion. The candle “eats” not all the oxygen, but very little. I had a need to organize an oxygen-free atmosphere, and I was just thinking of making it a candle, but I read on the cave-dwelling forums that if a candle goes out in a closed cave, it means there is only a couple of percent less oxygen. Well, there’s only two or three percent carbon dioxide there, or what? I do not remember.
  Well, besides, there is such a thing as convection. Carbon dioxide is heavier than air and collects from below, while the air above is thus somewhat richer in oxygen. This is what allowed the candle to burn longer
  I can’t tell you how to make it smoke, offhand, you have to play around with it.
• Andrey, I didn’t understand how the idea about convection and the fact that “Carbon dioxide is heavier than air and collects from below, while the air above is thus somewhat richer in oxygen.”. If there is strong convection from the flame, as I wrote above, then everything inside the jar is quickly mixed, and it doesn’t matter where everything is collected.

  Anatoly, you can also bring any object into the middle zone of the flame, where incomplete combustion occurs. Then the soot is deposited on the object. This is how glass is smoked. You can also see this here:

  Here you can clearly see how the rod and the plastic bag are smoked.

  I’m still waiting for the last correct answer, where the excess oxygen could have come from in the closing jar. Hint: think in terms of thermal expansion of gases.

• (got it because the pressure in the bank began to drop)
• Regarding the first question, I think there is already an answer. It is necessary to do some kind of manipulation so that incomplete oxidation occurs: it could be, for example, an object brought to the surface - the vapor of burning paraffin will cool sharply, without having time to burn completely (this is still a cold object). If I'm not mistaken, it looks like it might work out with the addition of some chemical substances onto the candle wick.
  Regarding the second point:
  In general, the combustion of a candle in this case can be considered as an inertial link of the nth order. In the very simple case, if the rate of oxygen combustion is directly proportional (although it can be proportional to the square, cube... concentration). In this case, the less oxygen in the can, the slower it burns. IN general case VCO2(t)=K1*e^(–k2/t). This non-linear equation for carbon dioxide explains why, with 0.5 liters of “clean” air, a candle will burn twice as long as with 2.5 liters - it’s just that the combustion will be very intense at first and almost 2 liters of air are used in the first 10 seconds and as in the second case, only 0.5 liters will remain, which will burn out for another 30 seconds.

• esfir

  January 2, 2014, 06:37

  Quote: “Wax candles must have a loosely woven wick from thick fibers; for all other candles, the wicks are made from tightly woven threads. This is due to the viscosity of the candle mass in the molten state: viscous wax requires wide capillaries, and easily moving paraffin, stearin and fats require thinner capillaries, otherwise due to excess combustible material the candle will begin to smoke heavily."
  Option: place a piece of loose rope into the paraffin melted near the wick.
• I noticed that it starts to smoke when the wick is slightly moistened, i.e. The heating temperature of the wick itself is below average when burning dry wicks. The flame itself, naturally, has normal temperature, because oxygen burns, and the wick only supports the combustion. You have to spit on your finger, run it along the wick and set it on fire - it will smoke
• All this is very interesting. But, "great minds", can you answer another question? While the candle is burning, it has no smell. And that's okay, because pure water and carbon dioxide are odorless. But! Once you put out the candle, you will get strong bad smell! Incomplete combustion produces the same water, pure carbon C and CO instead of CO2, but C and CO are also odorless. Then why does it stink so much when we put out a candle?

• January 5, 2017, 06:15

  Pavel, as I understand it, it smells like the products of incomplete combustion of paraffin. That is, at the moment the candle is extinguished, there should be a fairly large range of all sorts of molecular compounds.

Introduction……………………………………………………………………………………………………………………………………..… …..1

ILiterature review

1. The history of the creation of the candle……………………………………………………………………………………………………………2

   Types of candles……………………………………………………………………………………………………………………………………...3

   Soap making……………………………………………………………………………………………………………….…..4

IIexperimental part

2.1 Physical analysis of candles………………………………………………………………………………………………………….………..5

2.2 Where is the hottest part of the candle?………………………………………………………………………………….…….6

2.3 What burns in a candle? ……………………………………………………………………………………………………………..6

2.4 Chemical analysis of candle combustion products………………………………………………………….…….6

IIIManufacturing and practical use candles

3.1 Making candles…………………………………………………………………………………………………………..7

3.1.1 Wax candle

3.1.2 Paraffin candle

3.1.3 Stearic suppository

3.2 Obtaining soap from stearin…………………………………………………………………………………………8

Conclusions………………………………………………………………………………………………………………………………… …..8

Conclusion

Bibliography

Applications

Introduction

Although candles have long been replaced by electric lamps, they are still in use and create a festive mood during the holidays. New Year, and sometimes help out during an unexpected power outage. Currently, candles can be found in the most various colors and forms. They are used for decorative purposes, for scenting rooms, and for measuring time. Candles have also found their use in religion. Church candles and candles in Buddhism have a thin, elongated shape and are made of wax. Many famous artists used the theme of candles, the play of light and shadow in their work. Boris Pasternak wrote the famous poem “Winter Night”, written in 1946, the main character of which is a candle. So magical and attractive, known to man since ancient times, they have becomethe topic of my project.

The relevance of research: Candles originated in ancient times, but even now they are still popular: they create a festive mood for the New Year and save us during an unexpected power outage. Despite the fact that a candle is the most common item for us, we know little about it.

Research objectives:

Analyze scientific literature on this topic

Compare the physical properties of candles from various materials

Find out where the hottest part of the flame is and what exactly is burning in the candle.

Conduct a chemical analysis of combustion products of candles made from various materials

Make candles of various materials with your own hands

Make soap

I Literature review

1.1 History of the creation of the candle.

Candles were invented by man a long time ago, but for a long time they were used only in the homes of rich people and were expensive. The combustible material for a candle can be: lard, stearin, wax, paraffin, spermaceti or another substance with suitable properties (fusibility, flammability, solid). The prototype of a candle is a bowl filled with oil or fat, with a sliver of wood as a wick (later, fiber or fabric wicks were used). Such lamps gave off an unpleasant odor and produced a lot of smoke. First candles modern design appeared in the Middle Ages and were made from fat (most often) or wax. Wax candles have long been very expensive. To illuminate a large room, hundreds of candles were required; they smoked, blackening the ceilings and walls. In the 15th century, beeswax slowly began to increase in popularity as a combustible material for candles. IN XVI-XVII centuries American colonists invented the production of wax from some local plants, and candles produced in this way temporarily gained great popularity - they did not smoke, did not melt as much as tallow ones, but their production was labor-intensive, and their popularity soon faded. The development of the whaling industry in the late 18th century brought the first major changes to the candle-making process because spermaceti (a waxy oil obtained from the top of the sperm whale's head) became readily available. Spermaceti burned better than fat and did not smoke, and in general was closer to beeswax in properties and benefits. Most of the inventions that influenced the candle making industry relate to 19th century. In 1820, the French chemist Michel Chevrolet discovered the possibility of isolating a mixture of fatty acids from animal fats - the so-called. stearin. Stearin, otherwise sometimes called stearic wax due to wax-like properties, turned out to be hard, tough and burned without soot and almost odorless, and the technology for its production was not expensive. And as a result, soon stearin candles almost completely replaced all other types of candles, and mass production was established. Around the same time, the technology of impregnating candle wicks was mastered. boric acid, which eliminated the need to frequently remove the remaining wick (if not removed, it could extinguish the candle). Closer to the beginning of the 20th century, chemists were able to isolate petroleum wax - paraffin. Paraffin burned cleanly and evenly, giving off virtually no odor (the only strong smell was the smoke produced when extinguishing the candle, but this smell was not very unpleasant), and it was cheaper to produce than any other combustible substance for candles known at that time. Its only drawback was low temperature melting (compared to stearin), due to which the candles tended to float before they burned, but this problem was solved after they began to add harder and more refractory stearin to the paraffin. Even with implementation electric lighting For quite a long time at the beginning of the 20th century, paraffin candles were just gaining popularity, this was facilitated by the rapid development oil industry while. Over time, their importance in lighting changed to decorative and aesthetic.

Today, paraffin candles are almost the only type among candles. Candles are made from a mixture of highly purified (snow-white or slightly transparent) paraffin with a small amount of stearin, or from low-purified (yellow) paraffin, both with and without the addition of stearin. The former are more aesthetically pleasing and less odorous, the latter do not float so much. Occasionally, candles are made from unrefined paraffin (red-yellow) without additives, which float very much and are therefore not in demand.

1.2 Types of candles

When making candles the following are used:

Paraffin - waxy mixture saturated hydrocarbons(mineral wax) composition from C 18 N 38 to C 35 N 72 . It has low chemical activity and is poorly soluble in water. The product of petroleum distillation is the most popular material for candles, and in one form or another is included in most candles. In the 19th century, stearin significantly replaced it as a candle material.

Beeswax - a natural product produced by bees. Simple lipids (esters of higher fatty acids and higher high molecular weight alcohols). Beeswax consists mainly of the ester of palmitic acid and myricyl alcohol. The wax is very stable, insoluble in water, but soluble in gasoline, chloroform, and ether. Beeswax candles burn longer and brighter than paraffin candles and are preferred by connoisseurs because they are natural. Due to the higher cost of wax candles, candles are often not made entirely from beeswax, but rather it is added to other materials to extend the burning time of the candle and imitate the natural aroma. The wax used for candles comes in different types.

Stearin - stearic acid with an admixture of palmitic, oleic and other saturated and unsaturated fatty acids. It is added to paraffin so that it shrinks more and when it cools, candles cast from it are easier to remove from the mold. Stearine also prevents candles from melting. For some time, stearin was the main material for making candles until they learned to extract paraffin from crude oil.

Glycerol - used in a mixture with gelatin and tannin. Glycerin candles are completely transparent; they can be given any color using different dyes. Inside a glycerin candle you can place various compositions of colored paraffin, which gives the candle extraordinary decorative properties.

Fat , for example beef. In some countries, due to the fight against obesity, they are trying to find other uses for this fat other than food. Sodium nitrate (up to 5%) and potassium alum (up to 5% by weight) are usually added to fat suppositories. Candles burn cleanly, without smoke or soot.

1.3 Soap making

Soap was invented much earlier than gunpowder and paper, no one knows when and no one knows by whom. It happened for the first time when melted fat, dripping from roasting meat, fell onto wood ash. The fat was immediately partially hydrolyzed, forming fatty acids that combined with sodium and potassium salts in the ash. These compounds were actually soap. This is the first surfactant. On scientific basis soap production was started at the beginningXIXcentury. This was facilitated by numerous studies of the French chemist M. Chevral in the field of fat chemistry. Chevreul established that the basis of any soap is fats. chemical compounds glycerol with higher fatty acids. In the middleXIXcenturies, chemists could accurately name the composition of all soaps obtained and used. Since then, soap production has not undergone fundamental changes. The cleansing effect of soap is a complex process. The molecule of the salt of a higher carboxylic acid has a polar ionic part (-COONa) and a nonpolar hydrocarbon radical. The polar part of the molecule is soluble in water (hydrophilic), and the non-polar part is soluble in fats and other low-polar substances (hydrophobic). Under normal conditions, particles of fat or oil stick together, forming aquatic environment separate phase. In the presence of soap, the picture changes dramatically. The non-polar ends of the soap molecule dissolve in the oil droplets, while the polar carboxylate anions remain in aqueous solution. As a result of the repulsion of like charges on the surface of the oil, it is divided into tiny particles, each of which has an ionic shell of COO anions - . The presence of this shell prevents the particles from coalescing, resulting in the formation of a stable oil-in-water emulsion. Emulsification of fat and grease containing dirt is responsible for the cleansing effect of soap.

II experimental part

2.1 Physical analysis of candles

For physical analysis, we took candles from various materials and compared their properties.

Observations

Wax candle

Paraffin candle

Stearic suppository

Appearance candles

Yellow-brown solid

Solid matter is dirty white

White solid

Candle burning time

Burns longer

Burns less

Burns longer

Presence of odor when burning

Gives off a faint honey smell

No

No

Soot formation during combustion

Smokes less

Smokes more

Smokes less

Flame brightness

Almost the same

Candle melting when burning

Floats less

Floats more

Floats less

2.2 Where is the hottest spot of the flame?

At first glance it seems to be in the very center. We checked this by holding a sheet of paper over the middle of the candle flame, across it. There should be no drafts in the room so that the flame is even and does not fluctuate.

Research results

A charred ring-shaped area appeared on the paper. It was narrower the higher the paper was held, and it turned into a solid spot at the level of the upper third of the flame - this is where its hottest place is located. This seemingly strange result turns out to be quite obvious if we remember that oxygen is necessary for combustion. It enters the flame only from the periphery, and only there does the combustion reaction occur. Therefore, the temperature of the flame in its different parts is different.

2.3 What burns in a candle

Probably the material from which it is made (paraffin, stearin or wax). But if we turn a burning candle over, the material will flow along the wick and, instead of flaring up, extinguish it. So what burns in a candle? We carefully blew out the candle, breathing lightly on it. A thin stream of bluish smoke trailed from the wick. They brought a match to her.

Research results

The flame along this stream from a distance of 1-2 centimeters jumped to the wick and the candle lit up again. What we mistook for smoke was paraffin vapor (stearin or wax) - it is they that burn in the candle. The molten paraffin material (stearin or wax) rises through the wick, like water through a thin capillary. The flame of a match evaporates it and ignites the vapor. The wick serves only as a “pipeline” supplying fuel to the “firebox” - the tongue of the flame.

2.4 Chemical analysis of candle combustion products

Soot detection: We fixed the glass slide in the holder, brought it into the area of ​​the dark cone of a burning candle and held it for 3 seconds. They quickly raised the glass and examined the lower plane. dark spot will indicate the presence of soot.

Water detection: The dry test tube was secured in a holder, turned upside down and held over a flame until it fogged up. A fogged wall of the test tube will indicate the formation of water.

Carbon dioxide detection: 2 ml of lime water was added to the same test tube. The formation of carbon dioxide was determined by the cloudiness of the lime water.

Research results

Combustion products

Wax

Paraffin

Stearic

Soot

+

+

+

Water

+

+

+

Carbon dioxide

+

+

+

Combustion reaction equations

Wax candle 2 C 15 H 31 COOC 31 H 63 + 139 O 2 =94 CO 2 + 94 H 2 O

Paraffin candle 2C 16 H 34 +49 O 2 =32 CO 2 + 34 H 2 OC 17 H 36 + 26 O 2 =17 CO 2 + 18 H 2 O

Stearic suppository C 17 H 35 COOH+ 26O 2 =18O 2 + 18H 2 O

III Manufacturing and practical application various types candle

3.1 Making candles with your own hands

3.1.1 Wax candle

A wax candle was made from beeswax. Beeswax can be purchased from honey sellers. For production, we chose the “twisting” method: the wick is pulled horizontally and evenly covered with wax, softened in warm water. When the workpiece reaches the desired thickness, they begin to roll it on a smooth board with a flat board to give it future candle cylindrical shape. Then the candle is cut from the bottom and its top is pulled out.

3.1.2 Paraffin candle

Since it is not possible to obtain paraffin on your own, to make a paraffin candle the right size We took a ready-made paraffin candle and made a new one from it using the casting method. To do this, we made a mold and secured the wick in it. The mold can be made from any material that can withstand heating up to 50 degrees. The walls of the mold were smeared with dishwashing liquid and allowed to dry. The paraffin, heated in a water bath to a liquid state, was carefully poured into the mold and allowed to cool. The slower a paraffin candle cools, the less likely it is to crack. After cooling completely, carefully remove the candle from the mold.

3.1.3 Stearic suppository

First, we obtained a concentrated soap solution. To do this, the soap was ground on a grater. Soap shavings were placed in a container, water was added and heated, stirring with a wooden stick, until completely dissolved. After this, while still heating and stirring the solution, vinegar was poured in. After adding acid, a white mass immediately floated to the surface. This is stearic acid. Reaction mixture must have an acidic reaction, otherwise not all soap will react with the acid. Therefore, acid must be taken in excess. The reaction of the medium was easily checked using litmus paper. After the mixture cooled, the stearin was collected on the surface. The resulting liquid under the stearin is a solution of sodium sulfate or sodium acetate. The stearin was scooped out with a spoon and washed with water to remove excess acid. We dried the mass and wrapped it in a cloth. Stearin is ready! A stearin candle can be made in a mold by securing the wick in it in advance and pouring melted stearin into the mold. You can also prepare a candle by dipping, then you don’t need a mold. A wick is dipped into the melted stearin (you can take a thread from a wick for kerosene gas or a kerosene stove). I take out the wick, and when the stearin hardens on it, I put it back into the solution. This operation is repeated several times until the candle of the required thickness grows on the wick. Reaction equation for producing stearin from soap:C 17 H 35 COONa+ CH 3 COOH= C 17 H 35 COOH+ CH 3 COONa

3.2 Making soap from a candle

We took several pieces of stearin candle. Melt the stearin in a water bath and add a saturated soda solution. A solid white mass immediately formed. This is sodium stearate, that is, soap itself. The mixture was heated for several minutes to allow the reaction to take place as completely as possible. Then we substituted the form ( Matchbox) and poured the resulting mass. After the soap has cooled, remove it from the mold. Reaction equation for producing soap from stearin: 2C 17 H 35 COOH+ Na 2 CO 3 =2 C 17 H 35 COONa+ H 2 O+ CO 2 .

Conclusions:

Analyzed and studied scientific literature on this topic

I compared the physical properties of candles made from various materials: wax and stearin candles have the best physical properties.

The hottest part is found at the top third of the candle flame. The reason a candle burns is not the combustion of the material, but the formation of vapors during combustion.

Based chemical analysis combustion products, I found out that they all form soot, water and carbon dioxide, i.e. they are organic substances.

I made candles from various materials with my own hands.

I made soap from a stearin candle.

Conclusion

Wax and stearin candles have the best physical properties: they not only smoke and float less, but also burn longer. U paraffin candles there is an advantage in cost (they are slightly cheaper than wax and stearic ones), which is why they are the most common in our country. The most burning part is located at the level of the upper third of the flame, and what burns in a candle is not the material from which it is made, but the vapors formed during combustion. When burned, all candles produce soot, water and carbon dioxide, i.e. they are organic substances.

Bibliography

Michael Faraday "The Story of a Candle" 1982

Gabrielyan O.G. "Chemistry. 8th grade" Moscow 2002

Gabriel O.G. "Chemistry. 10th grade" Moscow 2014

Magazine “Science and Life”, article “The candle was burning on the table” No. 6, 2014

Magazine "Young Chemist Club", article "Soap from a candle and a candle from soap"

Magazine "Chemistry and Life", article "While the candles are burning"

The candle was burning on the table...

Research team headed by academician Russian Academy natural sciences S.G. Semenov, without any bias towards folk experience, studied the effect of burning a candle. And here are the conclusions and recommendations of the experts that the academician talks about.

Some people are doing well in life. The candle he placed burns with a “high flame”; no swells are formed. But as soon as nervousness or some kind of mental trouble arises in a person’s inner world, the candle begins to “cry” and influxes flow through it.

If a flow line runs along a newly placed candle from top to bottom, this means that a curse has fallen on the person. Two lines - two curses. As a rule, there are no more than three lines.

If a burning candle is moved clockwise in front of a person from the head, and it begins to smoke black smoke, this means that the internal organs in this place are blocked by disease and they must be treated until the candle stops smoking.

The candle should be held with one side facing the person. If influxes form on his part, he himself is to blame for his illnesses. If it’s the opposite, it means that the disease was “ordered” for him. And if a “tear” rolls down the candle on the left or right, then it is obvious: there is an energetic struggle between a person and someone else. If the “tear” is black, it means that the person is in a state of negative energy.

Using a candle, you can diagnose not only a person’s condition, but also their home. On the days of the new moon and full moon, it is good to carry a candle flame along the doorposts so that it does not touch them closely: the fire will destroy the bad energy accumulated in the house. The candle should be carried clockwise. This way you will remove the memory of the past from yourself and the room and give life the opportunity to go in a new way. Where the candle begins to crackle and smoke as you walk around the room, you need to move it clockwise until the crackling and smoke stop.

Space cleansing rituals are difficult to explain from a scientific point of view. They belong rather to the area of ​​esotericism or borderline psychology. But what matters to us is what produces results. Moreover, even a certain amount of skepticism in such activities does not prevent you from feeling the changes that follow after performing the ritual. But it is better if you take it seriously and focus your attention on the goal you want to achieve.

You can use the following ritual to increase energy, safety and security in your home. Stand by front door. Relax. Feel your breath, your arms, legs, the temperature of the surrounding air. Concentrate only on your feelings. Stay in this state for as long as your intuition tells you.

When you feel like you are “floating away” a little, clearly and concisely formulate instructions for your subconscious. For example: “May my home be a cup full of love, joy and inspiration.” There is no need to repeat this phrase several times.

Then light the candle in the glass lamp. Look into the center of the flame and imagine that this light is expanding and you find yourself in the center of a flickering sphere of light. Hold the candle at the center of your chest, connecting the power of the flame with your power and intention. Lift the candle up, inviting the light to “come into your home,” then lower it to the center of your chest, move it to the left and right. You create a cross - a symbol of protection and strength.

Go around the whole house, performing this ritual wherever you consider it necessary. It’s better if everything happens spontaneously, without tension and extraneous thoughts.

To attract happiness and prosperity to the house, Epiphany and Easter candles are lit - those that you purchased in the church for Epiphany and Easter. And the Thursday candle brought on Maundy Thursday has, but popular belief, the ability to destroy the spells of sorcerers and drive away witches. It is usually used to burn crosses on the doorposts and windows so that evil spirits do not visit the home.

Contemplation of fire is a very ancient ritual. Behind it is finding peace of mind. Fire is the most powerful element that protects a person from the influence of evil spirits and is a mediator between the human and the divine. The flame of a candle cleanses the body and soul of a person from energy “dirt”, including those caused by damage and the evil eye.

If something is bothering you, light a candle and sit quietly, looking at its fire and telling her - you can mentally, but better out loud - about what is bothering you. this moment. All negative things will burn away in the candle flame, you will feel lighter and freer, as if you have dropped a heavy load.

Because candles emit light, their power lies in the visual experience. To choose the appropriate color of a candle and enhance the magical power of your desire, you need to remember that each color has a certain energetic effect.

WHITE CANDLES are usually used in prayers and ceremonies; they symbolize light, purity and enlightenment.

A BLACK CANDLE in some cases can symbolize divinity (together with a white candle symbolizing God).

RED CANDLES are used in rituals aimed at sending love or establishing a relationship with a lover who is far from home (red candles promote passion, and PINK CANDLES symbolize tender and calm relationships between lovers, innocence).

GREEN CANDLES are used in rituals of dedication to the native land, animals and plants, as well as rituals for abundance and prosperity.

BROWN CANDLES are used if, with the help of a ritual, they want to have success in all matters in the future. They are also used to heal the native land and strengthen connections with it.

BLUE CANDLES are used in rituals aimed at getting rid of high self-esteem and increasing creative activity.

PURPLE CANDLES are used in prayers and meditation, the purpose of which is to increase extrasensory abilities. They can also be used to calm a person.

YELLOW CANDLES are used to improve mood, luck and achieve stability in financial matters.

ORANGE CANDLES are used in prayers and rituals aimed at increasing vitality and self-confidence.
If you cannot choose a candle of a suitable color, then use a white one.

Newspaper "Magic", Donetsk