Yellow-orange color fire. Why does fire come in different colors, what determines the color of the flame

Light a candle and carefully examine the flame. You will notice that it is not uniform in color. The flame has three zones (Fig.). Dark zone 1 is at the bottom of the flame. This is the most cold zone compared to others. The dark zone is bordered by the brightest part of the flame 2. The temperature here is higher than in the dark zone, but the most heat at the top of the flame 3.

To ensure that different flame zones have different temperatures, you can conduct such an experiment. Place a splinter (or match) into the flame so that it crosses all three zones. You will see that the splinter is more charred where it hits zones 2 and 3. This means that the flame is hotter there.

To all the answers I will add one more detail that is used by chemists. There are several zones in the flame structure. The one that is inner, blue, the coldest (relative to other zones) is the so-called restoration flame. Those. reduction reactions can be carried out in it (for example, metal oxides). Top part, yellow-red is the hottest zone, also called oxidizing flame. It is here that the oxidation of substance vapors with atmospheric oxygen occurs (if, of course, we are talking about an ordinary flame). It is possible to carry out appropriate chemical reactions in it.

The color of the fire depends on the chemical elements that burn during combustion, for example, if you want to see a blue light, then it appears when burning natural gas, and is conditioned carbon monoxide, which gives this shade. Yellow flames appear when sodium salts decompose. Wood is rich in such salts, so an ordinary forest fire or household matches burn with a yellow flame. Copper gives the flame green tint. With a high copper content in the combustible substance, the flame has a bright green color, almost identical to white.

Green color and barium, molybdenum, phosphorus, and antimony also give its shades to fire. Selenium colors the flame blue, and boron colors the flame blue-green. The red flame will give lithium, strontium and calcium, purple potassium, a yellow-orange tint comes out when sodium burns.

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The color of the flame depends on its temperature, as well as on the composition of the substance that burns:

4300K ​​- white-yellow, the brightest light;

5000K - cool white color;

6000K - white with light blue

8000K - blue-blue - the lighting quality is worse.

12000K purple

So, in fact, the hottest flame of a candle is from the bottom, and not from the top, as Maxim26ru 325 said, and the temperature at the tip of the flame is higher only due to the presence of gravity on Earth - convection currents arise, as a result of which the heat rushes vertically upward.

The color of fire depends directly on the temperature of the flame, and the temperature, in turn, releases a substance that will give a certain color in its spectrum. For example:

Carbohydrate dates are blue in color;

Boron - Blue-green;

Zhlto- Orange color release sodium salts

Green color comes from the release of copper, molybdenum, phosphorus, barium, antimony

Blue is selenium

Red from excretion of lithium and calcium

Purple date potassium

At first, as Alexander Antipov said, yes, the color of the flame is determined by its temperature (if I’m not mistaken, it was proven by Planck). And then the material of what is burning accumulates in the flame. Atoms different elements are able to absorb quanta with a certain energy and emit them back, but with an energy that depends on the nature of the atom. Yellow is the color of sodium in the flame. Sodium is found in any natural organic material. A yellow capable of drowning out other colors - this is a feature of human vision.

Well, it depends what kind of fire it is. It can be any color, depending on the burning substance. And this blue-yellow flame is from its heating. The further the flame is from the burning substance, the more oxygen there is. And the more oxygen, the hotter the flame and therefore lighter and brighter.

In general, the temperature inside the flame is different and changes over time (depending on the influx of oxygen and combustible substance). Blue color means that the temperature is very high up to 1400 C, yellow means the temperature is slightly lower than when blue flame.

The color of the flame may vary depending on chemical impurities.

For many centuries, fire has played very important role In human life. Without it it is almost impossible to imagine our existence. It is used in all areas of industry, as well as for cooking, warming the home and promoting technological progress.

Fire first appeared in the Early Paleolithic era. Initially it was used in the fight against various insects and attacks by wild animals, and also provided light and warmth. And only then the flames of fire were used in cooking, making dishes and tools. So fire entered our lives and became “ an indispensable assistant» person.

Many of us have noticed that flames can vary in color, but not many know why the fire element has a variegated color. Typically, the color of a fire depends on what chemical is being burned in it. Due to the exposure to high temperature, all the atoms of the chemicals are released, thus giving the hue to the fire. It was also carried out a large number of experiments, which will be written about in this article below, in order to understand how these substances affect the color of the flame.

Since ancient times, scientists have made efforts to understand what chemicals burn in a flame, depending on what color the fire takes.

We can all see a light with a blue tint when cooking at home. This is predetermined by highly combustible carbon and carbon monoxide, which gives the light its blue tint. Sodium salts, which are endowed with wood, give the fire a yellow-orange hue, which burns with an ordinary fire or matches. If you sprinkle the stove burner with regular salt, you can get the same color. Copper gives fire its green color. At very high concentration copper, the light has a very bright shade green, which is virtually identical to colorless white. This can be observed if you sprinkle copper shavings on the burner.

Experiments were also carried out with an ordinary gas burner and various minerals in order to establish their constituent chemical substances. To do this, carefully take the mineral with tweezers and bring it to the fire. And, based on the shade that the fire took, one can draw conclusions about the various chemical additives that are present in the element. Minerals such as copper, barium, phosphorus, molybdenum give a green tint, and boron and antimony give blue-green color. Also in Blue colour Selenium gives the flame. A red flame is obtained by adding lithium, strontium and calcium, a purple flame is obtained by the combustion of potassium, and a yellow-orange color is produced by sodium.

To study various minerals and determine their composition, a Bunsen burner is used, invented in the 19th century by Bunsen, which produces a colorless flame that does not interfere with the course of the experiment.

It was Bunsen who became the founder of the method for determining chemical composition substances according to color palette flame. Of course, before him there were attempts to conduct such experiments, but such experiments were not successful, since there was no burner. He introduced different burners into the fiery element chemical components on wire made of platinum, because platinum does not in any way affect the color of the fire and does not give it any shade.

At first glance, it may seem that there is no need for any complex chemical research; bring the component to the fire - and you can instantly see its composition. However, not all so simple. In nature, substances in pure form are very rare. As a rule, they include a considerable range of different impurities that can change color.

Therefore, using characteristic properties molecules and atoms emit light of a certain color range– a method was created for determining the chemical composition of substances. This method of determination is called spectral analysis. Scientists are studying the spectrum that the substance emits. For example, during combustion, it is compared with the spectra of known components, and thus its chemical composition is established.

Description:

Wetting a copper plate in hydrochloric acid and bringing it to the burner flame, we notice an interesting effect - coloring of the flame. The fire shimmers with beautiful blue-green shades. The spectacle is quite impressive and mesmerizing.

Copper gives the flame a green tint. With a high copper content in the combustible substance, the flame would have a bright green color. Copper oxides give an emerald green color. For example, as can be seen from the video, when wetting copper hydrochloric acid the flame turns blue with a greenish tint. And calcined copper-containing compounds soaked in acid color the flame azure blue.

For reference: Barium, molybdenum, phosphorus, and antimony also give green color and its shades to fire.

Explanation:

Why is the flame visible? Or what determines its brightness?

Some flames are almost invisible, while others, on the contrary, shine very brightly. For example, hydrogen burns with an almost completely colorless flame; the flame of pure alcohol also shines very weakly, but a candle and a kerosene lamp burn with a bright luminous flame.

The fact is that the greater or lesser brightness of any flame depends on the presence of hot solid particles in it.

Fuel contains carbon in greater or lesser quantities. Carbon particles become heated before they burn, which is why the flame gas burner, a kerosene lamp and a candle shines - because it is illuminated by hot carbon particles.

Thus, it is possible to make a non-luminous or weakly luminous flame bright by enriching it with carbon or heating non-combustible substances with it.

How to get multi-colored flames?

To obtain a colored flame, not carbon is added to the burning substance, but metal salts that color the flame in one color or another.

The standard method of coloring a faintly luminous gas flame is to introduce metal compounds into it in the form of highly volatile salts - usually nitrates (salt nitric acid) or chlorides (salts of hydrochloric acid):

yellow- sodium salts,

red - strontium, calcium salts,

green - cesium salts (or boron, in the form of boronethyl or boronmethyl ether),

blue - copper salts (in the form of chloride).

IN Selenium colors the flame blue, and boron colors the flame blue-green.

This ability of burning metals and their volatile salts to impart a certain color to a colorless flame is used to produce colored lights (for example, in pyrotechnics).

What determines the color of a flame (in scientific language)

The color of a fire is determined by the temperature of the flame and what chemicals it burns. The high temperature of the flame allows atoms to jump for some time to a higher temperature. energy state. When the atoms return to their original state, they emit light at a specific wavelength. It corresponds to the structure of the electronic shells of a given element.

Blacker than black

Figure 1 - Model of a completely black body.

Light entering through the hole will be completely absorbed after repeated reflections, and the outside of the hole will appear completely black. Even if we paint the cube black, the hole will be blacker than the black cube. This hole will be completely black body. IN literally words, the hole is not a body, but only clearly demonstrates we have a completely black body.
All objects emit heat (as long as their temperature is above absolute zero, which is -273.15 degrees Celsius), but no object is a perfect heat emitter. Some objects emit heat better, others worse, and all this depends on various conditions environment. Therefore, a black body model is used. A completely black body is ideal heat emitter. We can even see the color of a completely black body if it is heated, and the color we will see, will depend on what temperature We let's heat it up absolutely black body. We have come close to the concept of color temperature. Look at Figure 2.

Figure 2 - The color of an absolutely black body depending on the heating temperature.

A) There is an absolutely black body, we don’t see it at all. Temperature 0 Kelvin (-273.15 degrees Celsius) - absolute zero, the complete absence of any radiation.
b) Turn on the “super-powerful flame” and begin to heat up our absolutely black body. The body temperature, through heating, increased to 273K.
c) A little more time has passed and we already see a faint red glow of a completely black body. The temperature increased to 800K (527°C).
d) The temperature rose to 1300K (1027°C), the body acquired bright red color. You can see the same color glow when heating some metals.
e) The body has heated up to 2000K (1727°C), which corresponds to an orange glow. Hot coals in a fire, some metals when heated, and a candle flame have the same color.
f) The temperature is already 2500K (2227°C). The glow at this temperature becomes yellow. Touching such a body with your hands is extremely dangerous!
g) White color - 5500K (5227°C), the same color of the glow of the Sun at noon.
h) Blue color of the glow - 9000K (8727°C). In reality, it will be impossible to obtain such a temperature by heating with a flame. But such a temperature threshold is quite achievable in thermonuclear reactors, atomic explosions, and the temperature of stars in the universe can reach tens and hundreds of thousands of Kelvin. We can only see the same blue tint of light, for example, in LED lights, celestial bodies or other light sources. The color of the sky in clear weather is approximately the same color. Summarizing all of the above, we can give a clear definition of color temperature. Colorful temperature is the temperature of a black body at which it emits radiation of the same color tone as the radiation in question. Simply put, 5000K is the color that a blackbody becomes when heated to 5000K. The color temperature of orange is 2000K, which means that a completely black body must be heated to a temperature of 2000K for it to acquire an orange glow.
But the color of the glow of a hot body does not always correspond to its temperature. If the flame gas stove in the kitchen blue-blue color, this does not mean that the flame temperature is above 9000K (8727°C). Molten iron in its liquid state has an orange-yellow hue, which actually corresponds to its temperature, which is approximately 2000K (1727°C).

Color and its temperature

Figure 3 - Color temperature of xenon automobile lamps.

Figure 4 - Color temperature of fluorescent lamps.

On Wikipedia I found numerical values ​​for the color temperatures of common light sources:
800 K - the beginning of the visible dark red glow of hot bodies;
1500-2000 K - candle flame light;
2200 K - incandescent lamp 40 W;
2800 K - 100 W incandescent lamp (vacuum lamp);
3000 K - incandescent lamp 200 W, halogen lamp;
3200-3250 K - typical film lamps;
3400 K - the sun is at the horizon;
4200 K - fluorescent lamp (warm white light);
4300-4500 K - morning sun and lunchtime sun;
4500-5000 K - xenon arc lamp, electric arc;
5000 K - sun at noon;
5500-5600 K - photo flash;
5600-7000 K - fluorescent lamp;
6200 K - close to daylight;
6500 K - standard source of daytime white light, close to midday sunlight; 6500-7500 K - cloudy;
7500 K - daylight, with a large share of scattered light from a clear blue sky;
7500-8500 K - twilight;
9500 K - blue clear sky on the north side before sunrise;
10,000 K is an “infinite temperature” light source used in reef aquariums (anemone blue tint);
15,000 K - clear blue sky in winter;
20,000 K - blue sky in polar latitudes.
Color temperature is source characteristics Sveta. Any color we see has a color temperature and it doesn’t matter what color it is: red, crimson, yellow, purple, violet, green, white.
Works in the field of studying the thermal radiation of a black body belong to the founder of quantum physics, Max Planck. In 1931, at the VIII session of the International Commission on Illumination (CIE, often written as CIE in the literature), it was proposed color model XYZ. This model is a chromaticity diagram. The XYZ model is shown in Figure 5.

Figure 5 - XYZ chromaticity diagram.

The X and Y numeric values ​​define the color coordinates on the chart. The Z coordinate determines the brightness of the color, it is in this case is not involved, since the diagram is presented in two-dimensional form. But the most interesting thing in this figure is the Planck curve, which characterizes the color temperature of the colors on the diagram. Let's take a closer look at it in Figure 6.

Figure 6 - Planck Curve

The Planck curve in this figure is slightly truncated and “slightly” inverted, but this can be ignored. To find out the color temperature of a color, you simply need to extend the perpendicular line to the point of interest (color area). The perpendicular line, in turn, characterizes such a concept as bias- degree of color deviation to green or purple. Those who have worked with RAW converters know such a parameter as Tint - this is the offset. Figure 7 displays the color temperature adjustment panel in RAW converters such as Nikon Capture NX and Adobe CameraRAW.

Figure 7 - Panel for setting color temperature for different converters.

It's time to look at how the color temperature is determined not just of an individual color, but of the entire photograph as a whole. Take, for example, a rural landscape on a clear sunny afternoon. Who has practical experience in photography, knows that the color temperature at solar noon is approximately 5500K. But few people know where this figure came from. 5500K is the color temperature the whole stage, i.e. the entire image under consideration (picture, surrounding space, surface area). Naturally, an image consists of individual colors, and each color has its own color temperature. What you get: blue sky (12000K), foliage of trees in the shade (6000K), grass in a clearing (2000K), various kinds vegetation (3200K - 4200K). As a result, the color temperature of the entire image will be equal to the average value of all these areas, i.e. 5500K. Figure 8 clearly demonstrates this.

Figure 8 - Calculation of the color temperature of a scene shot on a sunny day.

The following example is illustrated in Figure 9.

Figure 9 - Calculation of the color temperature of a scene filmed at sunset.

The picture shows a red flower bud that seems to be growing from wheat cereal. The picture was taken in the summer at 22:30, when the sun was setting. This image is dominated by a large amount of yellow and orange color tones, although there is a blue tint in the background with a color temperature of approximately 8500K, and there is also an almost pure white color with a color temperature of 5500K. I took just the 5 most basic colors in this image, matched them to a chromaticity chart, and calculated the average color temperature of the entire scene. This is, of course, approximately, but true. There are a total of 272816 colors in this image and each color has its own color temperature. If we calculate the average for all colors manually, then in a couple of months we will be able to get a value that is even more accurate than I calculated. Or you can write a program to calculate and get an answer much faster. Let's move on: Figure 10.

Figure 10 - Calculation of color temperature of other lighting sources

The hosts of the show programs decided not to burden us with color temperature calculations and made only two lighting sources: a spotlight emitting white-green bright light and a spotlight that shines with red light, and the whole thing was diluted with smoke... oh, well, yes - and they installed a presenter bring to Front. The smoke is transparent, so it easily transmits the red light of the spotlight and becomes red itself, and the temperature of our red color, according to the diagram, is 900K. The temperature of the second spotlight is 5700K. The average between them is 3300K. The remaining parts of the image can be ignored - they are almost black, and this color does not even fall on the Planck curve on the diagram, because the visible radiation of hot bodies begins at about 800K (red color). Purely theoretically, one can assume and even calculate the temperature for dark colors, but its value will be negligible compared to the same 5700K.
And the last image in Figure 11.

Figure 11 - Calculation of the color temperature of a scene taken in the evening.

Photo taken summer evening after sunset. The color temperature of the sky is located in the region of the blue color tone on the diagram, which, according to the Planck curve, corresponds to a temperature of approximately 17000K. Green coastal vegetation has a color temperature of about 5000K, and sand with algae has a color temperature of about 3200K. The average value of all these temperatures is approximately 8400K.

White balance

Figure 12 - Modes for setting white balance in a photo camera (video camera).

It should be said right away that the white color of objects can be obtained if use source Sveta with color temperature 5500K(this could be sunlight, photoflash, other artificial illuminants) and if the ones themselves are considered objects white (reflect all visible light radiation). In other cases, the white color can only be close to white. Look at Figure 13. It shows the same XYZ chromaticity diagram that we recently looked at, and in the center of the diagram there is a white dot marked with a cross.

Figure 13 - White dot.

The marked point has a color temperature of 5500K and, like true white, it is the sum of all the colors of the spectrum. Its coordinates are x = 0.33 and y = 0.33. This point is called equal energy point. White dot. Naturally, if the color temperature of the light source is 2700K, the white point is not even close, what kind of white color can we talk about? There will never be white flowers there! In this case, only highlights can be white. An example of such a case is shown in Figure 14.

Figure 14 – Different color temperatures.

White balance– this is setting the value color temperature for the entire image. At correct installation you will receive colors that match the image you see. If the resulting image is dominated by unnatural blue and cyan color tones, it means that the colors are “not warmed up enough”, the color temperature of the scene is set too low, it needs to be increased. If the entire image is dominated by a red tone, the colors are “overheated”, the temperature is set too high, it is necessary to lower it. An example of this is Figure 15.

Figure 15 – Example of correct and incorrect color temperature settings

The color temperature of the entire scene is calculated as average temperature all colors given image, so in the case of mixed light sources or very different color tone colors, the camera will calculate average temperature, which is not always true.
An example of one such incorrect calculation is shown in Figure 16.

Figure 16 – Inevitable inaccuracy in setting color temperature

The camera cannot perceive sharp differences in brightness individual elements images and their color temperature are the same as human vision. Therefore, to make the image look almost the same as what you saw when you took it, you will have to manually adjust it according to your visual perception.

This article is more intended for those who are not yet familiar with the concept of color temperature and would like to learn more. The article does not contain complex mathematical formulas and precise definitions of some physical terms. Thanks to your comments, which you wrote in the comments, I made small amendments to some paragraphs of the article. I apologize for any inaccuracies.

In most cases, the flame of a fireplace or fire is yellow-orange due to the salts contained in the wood. By adding certain chemicals, you can change the color of the flame to better suit a special event or to simply admire the changing colors. To change the color of the flame, you can add certain chemicals directly to the fire, make paraffin cakes with chemicals, or soak the wood in a special chemical solution. Despite all the fun that creating colored flames can give you, be sure to take extra care when working with fire and chemicals.

Steps

Selecting the right chemicals

Select the color (or colors) of the flame. Although you have the opportunity to choose from a whole range of various shades flames, you need to decide which ones are most important to you so that you can select the appropriate chemicals. The flame can be made blue, turquoise, red, pink, green, orange, purple, yellow or white.

Determine the chemicals you need based on the color they create when burned. To color the flames desired color, you need to select suitable chemicals. They must be powdered and not contain chlorates, nitrates or permanganates, which form harmful by-products when burned.

• To create a blue flame, use copper chloride or calcium chloride.
• To make the flame turquoise, use copper sulfate.
• To obtain a red flame, take strontium chloride.
• To create a pink flame, use lithium chloride.
• To make the flames light green, use borax.
• To obtain green flame, take alum.
• To create orange flame, use sodium chloride.
• To create a flame purple take potassium chloride.
• To obtain a yellow flame, use sodium carbonate.
• To create a white flame, use magnesium sulfate.

1. Buy the right chemicals. Some of the flame coloring agents are common household chemicals and can be found at grocery, hardware, or garden stores. Other chemicals can be purchased at specialty chemical stores or purchased online.

   • Copper sulfate is used in plumbing to kill tree roots that can damage pipes, so you can look for it in hardware stores.
   • Sodium chloride is a common salt, so you can buy it at the grocery store.
   • Potassium chloride is used as a water softener, so it can also be found in hardware stores.
   • Borax is often used for laundry, so it can be found in the detergents some supermarkets.
   • Magnesium sulfate is contained in Epsom salt, which you can ask around in pharmacies.
   • Copper chloride, calcium chloride, lithium chloride, sodium carbonate and alum should be purchased from chemical stores or online retailers.

Making paraffin cakes

1. Melt the paraffin in a water bath. Place a heatproof bowl over a pan of gently simmering water. Add a few pieces of paraffin wax to the bowl and let them melt completely.

   • You can use purchased lump or jar paraffin (or wax) or leftover paraffin from old candles.
   • Do not heat paraffin over an open flame, otherwise you may start a fire.

2. Add the chemical to the paraffin and stir. Once the paraffin has completely melted, remove it from the water bath. Add 1–2 tablespoons (15–30 g) chemical reagent and stir thoroughly until a homogeneous mixture is obtained.

   • If you don't want to add chemicals directly to the paraffin, you can pre-wrap them in used absorbent material and then place the resulting package in the container you are going to fill with paraffin.

3. Let the paraffin mixture cool slightly and pour it into paper cups. After preparing the paraffin mixture with the chemical, let it cool for 5-10 minutes. While the mixture is still liquid, pour it into paper muffin cups to make wax cakes.

   • For cooking paraffin cakes You can use either small paper cups or egg cartons.

4. Allow the paraffin to harden. After the paraffin is poured into the molds, let it sit until it hardens. It will take about an hour to cool completely.

   Throw the paraffin cake into the fire. When the paraffin cakes have hardened, remove one of them from the packaging. Throw the cake into the hottest part of the fire. As the wax melts, the flame will begin to change color.

   • You can add several paraffin cakes with different chemical additives to the fire at once, just place them in different places.
   • Paraffin cakes work well for fires and fireplaces.

Treatment of wood with chemicals

1. Gather dry and light materials for the fire. These materials will suit you wood origin, like wood chips, lumber scraps, Pine cones and brushwood. You can also use rolled newspapers.

2. Dissolve the chemical in water. Add 450 g of the selected chemical for every 4 liters of water, use for this plastic container. Stir the liquid thoroughly to speed up the dissolution of the chemical. For achievement best results Add only one type of chemical to the water.

   • You can also use a glass container, but avoid using metal containers, which may react with chemicals. Be careful not to drop or break glass containers in use near a fire or fireplace.
   • Be sure to wear safety glasses, a mask (or respirator), and latex gloves when you prepare a chemical solution.
   • It is best to prepare the solution for outdoors, as some types of chemicals may stain the work surface or produce harmful fumes.
3. Be sure to use protective equipment, including safety glasses and gloves when creating colored flames.

Warnings

• Handle all chemicals with care and follow the instructions on their containers. Even completely harmless substances (like table salt) in high concentrations can cause skin irritation and chemical burns.
• Keep hazardous chemicals in sealed plastic or glass containers. Keep children and pets away from them.
• When adding chemicals directly to your fireplace, first make sure there is good ventilation to prevent your home from filling with harsh chemical fumes.
• Fire is not a toy and should never be treated as such. It goes without saying that the fire is dangerous and can quickly get out of control. Be sure to keep a fire extinguisher or a container with enough water on hand.