We begin this academic year with the study of a new branch of physics devoted to thermal phenomena. Thermal phenomena include heating and cooling of various bodies, melting, evaporation, boiling, melting of substances, etc. The words “warm”, “cold”, “hot”, familiar to us for a long time, mean the thermal states of bodies. The quantity characterizing the thermal state of bodies is temperature.
Features of the movement of particles that make up bodies Repetition. Answer the questions: 1. The main provisions of the MKT (and their experimental confirmation) 2. What is diffusion? How does the diffusion process take place? 3. What explains the increase in the diffusion rate with increasing temperature?
Thermal movement. Temperature Thermal motion is the random movement of the molecules of a substance. In liquids and gases, molecules move randomly, colliding with each other. In solids, thermal motion consists in oscillations of particles around the equilibrium position. The temperature of the body depends on the speed of movement of molecules. The faster the molecules move, the higher the temperature of the body. Let us pay attention to the fact that thermal motion differs from mechanical motion in that a lot of particles participate in it and each one moves randomly.
Source of Temperature Information We know from experience that different bodies can be heated to different degrees. However, the sensation of heat and cold is a subjective factor. Let's check it out experimentally. ! ? ! Conclusion: with the help of sensations it is impossible to judge the temperature!
Thermometer So, we have a problem: we need to find such a sign or such a property of bodies that would clearly indicate how the body is heated. Such a sign may be the expansion of bodies when heated. The more heated the body, the greater its volume, the more intense the chaotic movement of molecules and atoms. A device that uses this property of bodies is a thermometer. From the Greek "therme" - heat and "metreo" - I measure. A liquid thermometer is a device whose principle of operation is based on the use of the property of thermal expansion of a liquid. Depending on the temperature range, the liquid thermometer is filled with mercury, ethyl alcohol and other liquids. Any thermometer shows its own temperature. To determine the temperature of the environment, the thermometer must be placed in this environment and wait until the temperature of the device stops changing, taking a value equal to the temperature of the environment.
Celsius temperature scale The Celsius temperature scale was proposed in 1742 by the Swedish scientist A. Celsius and named after him. The temperature of melting ice is taken as zero degrees Celsius, and the boiling point of water at normal atmospheric pressure (760 mm Hg) is taken as 100 degrees. The interval between these temperatures is divided into 100 equal parts, each 1 degree Celsius (1°C).
Temperature scales In practice, other temperature scales are used, such as the Kelvin scale and the Fahrenheit scale. The relationship between the Celsius scale and the Kelvin scale can be seen in the figure. To measure temperature, various substances (mercury, alcohol) are used, which change their volume with a change in temperature.
The physical meaning of temperature What is the physical meaning of temperature? To do this, you need to answer the question, how does cold water differ from hot? Warm water is made up of the same molecules as cold water. Experience on diffusion in hot and cold water shows that the higher the temperature, the greater the penetration of one substance into another. Diffusion is caused by the movement of molecules. Since diffusion occurs faster in hot water, it means that the speed of movement of molecules in it is higher.
The physical meaning of temperature In a body with a higher temperature, molecules move faster on average. The temperature of a substance is determined not only by the average speed of the molecules, but also by their mass. Temperature is a measure of the average kinetic energy of the particles of a body.
Laboratory work: "Measurement of body temperature" The purpose of the work: to establish the relationship between body temperature and an increase in the kinetic energy of molecules. Equipment: thermometer. Workflow 1. Hold the thermometer in your fist so that you can see the temperature value on the scale. 2. Watch the rise of the mercury (alcohol) column. Answer in writing the following questions: 1. Why does the column of mercury (alcohol) rise up? 2. When will the column of mercury (alcohol) stop? 3. What does a thermometer measure? 4. Can the thermometer be removed from the medium whose temperature is being measured? Why? 5. What can be said about the magnitude of the kinetic energy of mercury (alcohol) molecules when the column is raised? 6. What device did you use to determine body temperature? 7. What is the division value of this instrument? 8. What is the minimum (maximum) temperature that can be measured with this instrument?
Interesting to know * Various mammals have a normal temperature of 35 to 40.5 °C; * Temperature of birds 39.5 - 44 °С; The highest air temperature on Earth is 58 °C, the lowest is 3 °C; The surface temperature of the Sun is about 6000°C; At a temperature of 42 ° C, the blood does not absorb oxygen from the air, and a person dies from oxygen deficiency. The natural temperature of the human body cannot be lower than 34°C. Artificially, it is sometimes lowered to 26 ° C and then the body falls into a state of suspended animation. Life processes in it slow down. Instead of 16 breaths per minute, a person takes only 4, the pulse drops from 70 to 25 beats per minute. Bears, badgers and many other animals are in a state of suspended animation in winter.
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Presentation on the topic: Thermal movement. Temperature
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slide number 2
Description of the slide:
Thermal movement. Temperature We begin this academic year with the study of a new branch of physics devoted to thermal phenomena. Thermal phenomena include heating and cooling of various bodies, melting, evaporation, boiling, melting of substances, etc. The words “warm”, “cold” have long been familiar to us , "hot" mean the thermal state of the bodies. The value characterizing the thermal state of the bodies is the temperature.
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Features of the movement of particles that make up bodies Repetition. Answer the questions: The main provisions of the MKT (and their experimental confirmation) What is diffusion? How does the diffusion process take place? What explains the increase in the diffusion rate with increasing temperature?
slide number 4
Description of the slide:
Thermal movement. Temperature Thermal motion is the random movement of the molecules of a substance. In liquids and gases, molecules move randomly, colliding with each other. In solids, thermal motion consists in oscillations of particles around the equilibrium position. The temperature of the body depends on the speed of movement of molecules. The faster the molecules move, the higher the temperature of the body. Let us pay attention to the fact that thermal motion differs from mechanical motion in that a lot of particles participate in it and each one moves randomly.
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Description of the slide:
Source of Temperature Information We know from experience that different bodies can be heated to different degrees. However, the feeling of heat and cold is a subjective factor. Let's check this in practice. ! ? ! Conclusion: with the help of sensations it is impossible to judge the temperature!
slide number 6
Description of the slide:
Thermometer So, we have a problem: we need to find such a sign or such a property of bodies that would clearly indicate how the body is heated. Such a sign may be the expansion of bodies when heated. The more heated the body, the greater its volume, the more intense the chaotic movement of molecules and atoms. A device that uses this property of bodies is a thermometer. From the Greek "therme" - heat and "metreo" - I measure. A liquid thermometer is a device whose principle of operation is based on the use of the property of thermal expansion of a liquid. Depending on the temperature range, the liquid thermometer is filled with mercury, ethyl alcohol and other liquids. Any thermometer shows its own temperature. To determine the temperature of the environment, the thermometer must be placed in this environment and wait until the temperature of the device stops changing, taking a value equal to the temperature of the environment.
slide number 7
Description of the slide:
Celsius temperature scale The Celsius temperature scale was proposed in 1742 by the Swedish scientist A. Celsius and named after him. The temperature of melting ice is taken as zero degrees Celsius, and the boiling point of water at normal atmospheric pressure (760 mm Hg) is taken as 100 degrees. The interval between these temperatures is divided into 100 equal parts, each 1 degree Celsius (1°C).
slide number 8
Description of the slide:
Temperature scales In practice, other temperature scales are used, such as the Kelvin scale and the Fahrenheit scale. The relationship between the Celsius scale and the Kelvin scale can be seen in the figure. Various substances (mercury, alcohol) are used to measure temperature, which change their volume with temperature.
Description of the slide:
The physical meaning of temperature In a body with a higher temperature, molecules move faster on average. The temperature of a substance is determined not only by the average speed of the molecules, but also by their mass. The temperature is a measure of the average kinetic energy of the particles of the body.
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Description of the slide:
Laboratory work: “Measuring body temperature” Purpose of work: establishing a relationship between body temperature and an increase in the kinetic energy of molecules. Equipment: thermometer. Progress of work1. Hold the thermometer in your fist so that you can see the temperature value on the scale.2. Watch the rise of the column of mercury (alcohol). Answer the following questions in writing: 1. Why does the column of mercury (alcohol) rise? When will the column of mercury (alcohol) stop?3. What does a thermometer measure?4. Can the thermometer be removed from the environment whose temperature is being measured? Why?5. What can be said about the magnitude of the kinetic energy of mercury (alcohol) molecules when the column is raised?6. What device did you use to determine body temperature?7. What is the division value of this device? 8. What is the minimum (maximum) temperature that can be measured with this instrument?
slide number 12
Description of the slide:
It is interesting to know * Various mammals have a normal temperature from 35 to 40.5 ° C; * Temperature of birds 39.5 - 44 ° C; The highest air temperature on Earth is 58 ° C, the lowest - - 88.3 ° C; Temperature the surface of the Sun is about 6000 ° C; At a temperature of 42 ° C, the blood does not absorb oxygen from the air, and a person dies from oxygen deficiency. The natural temperature of the human body cannot be lower than 34°C. Artificially, it is sometimes lowered to 26 ° C and then the body falls into a state of suspended animation. Life processes in it slow down. Instead of 16 breaths per minute, a person takes only 4, the pulse drops from 70 to 25 beats per minute. Bears, badgers and many other animals are in a state of suspended animation in winter.
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Along with water and alcohol, Braga contains other substances, many of which are harmful to the body. Fortunately, their boiling point is higher or lower than that of ethyl alcohol, so fractional distillation (separation into fractions) can prevent most of the dangerous impurities from entering the finished product. We will consider methods that allow you to select the correct amount of tails and heads of moonshine, which will positively affect the quality of the distillate.
Attention! The information is relevant only for a conventional moonshine still, consisting of a distillation cube and a refrigerator in the form of a coil, it is also possible to have a steamer. For devices with dephlegmators and other devices that simulate the operation of a distillation column, the parameters for selecting tails and heads may differ from those described here. I advise you to clarify this point with the designers of the circuit, manufacturers or equipment sellers. I do not consult on commercial models of devices.
The amount of harmful impurities depends on the raw materials, water, yeast, temperature, fermentation duration, design of the moonshine still and distillation technology. Even in mash according to the same recipe, the concentration of harmful substances can change every time, but at home, analysis of the composition of the mash is impossible, so approximate values \u200b\u200bare taken as a basis.
"Head" moonshine(also called "pervach" or "pervak") - the initial fraction with a sharp unpleasant odor. Contains the most dangerous impurities: methyl alcohol (many in grain and fruit mash), acetone, acetaldehyde and others. Due to the fact that the boiling point of harmful substances is lower than that of ethyl alcohol, they come out first during distillation, therefore, it is possible to prevent them from entering the main product.
In everyday life, pervach is considered the highest quality moonshine, because it is strong and quickly intoxicates. In fact, this is a poison in its purest form, its use causes toxic poisoning, which is often confused with intoxication.
Heads are the strongest The moonshine head should not be drunk or used for rubbing. This fraction can go exclusively for technical needs, but because of the unpleasant smell, in most cases it is simply poured out.
"Body"- drinking part, the main goal of the moonshiner (the second name is "heart"). In theory, it contains only ethyl alcohol and water, but in practice there are always other impurities in the “body”, since during distillation it is purely physically impossible to divide the yield into clear fractions, to one degree or another different substances with close boiling points are always mixed, the yield is obtained " lubricated."
For complete decomposition into fractions, rectification is needed, thanks to which pure ethyl alcohol can be obtained. The disadvantage of the method is that, along with harmful impurities, substances responsible for the organoleptic properties of the drink are removed.
This means that after rectification, the taste and smell of moonshine from different raw materials (sugar, grains and fruits) will be the same, since only ethyl alcohol will remain in the drink.
It should be remembered that the harm and benefits of many substances in the distillate are relative. For example, fusel oils cause the liver to activate before alcohol begins to act, this protects the body from the harmful effects of alcohol.
A study by Vladimir Pavlovich, a professor at the Narcology Research Institute of the Ministry of Health of the Russian Federation, proved that rectified alcohol (vodka) causes alcohol addiction many times faster than distillates - whiskey, cognac, tequila, etc. About 70% of dependent people are vodka alcoholics. The purer the poison (in our case, ethyl alcohol), the faster the addiction develops.
The correct separation of moonshine into fractions during distillation on a classic moonshine still allows you to remove almost all harmful substances, but leave those that are responsible for the aroma and taste of the drink, which cannot be done during rectification.
"Tail" moonshine- the third fraction, in addition to ethyl alcohol, contains fusel oils, which give an unpleasant odor, taste and cloudy color. The boiling point of fusel oil is higher than that of ethyl alcohol, therefore, in order to separate the tail of moonshine, it is enough to stop collecting the main product - the “body” in time.
Although after distillation a lot of ethyl alcohol remains in the “tails” (up to 40%), the ingress of other substances along with it spoils the quality of moonshine, which is why it is so important to finish the distillation on time.
Tailings can be recycled, but usually not worth the energy spent. Unlike "heads", "tails" are recyclable, they can be added to a new batch of mash (immediately before distillation) or cleaned in a distillation column. Distilling the “tails” a second time on a moonshine is useless, this will not improve the quality!
The question of how much to select "heads" and "tails" is a compromise between the quantity and quality of moonshine. Further, we will use the "golden mean" - parameters that have been tested by more than one generation of moonshiners. You can change them at your discretion both in one direction and in the other. Further, I will pay attention not to specific numbers, but to methods of calculation.
How to select the head of moonshine
First, the mash is brought to a boil. When the first drops appear, the power is reduced to a minimum, then the heating is gradually increased again so that the device enters the operating mode. Performance depends on the design and power of the stove, there are no average parameters here. It is considered normal when the moonshine comes out cold (the temperature is approximately equal to the temperature of the cooling water). This is what you should strive for.
Head separation methods:
1. By sugar. The simplest, but at the same time effective method. Suitable if the sugar content of the mash or the amount of added sugar is known. In fruit or grain mash, sugar content is determined by a special device - a vinometer (hydrometer-saccharometer) before adding yeast.
For example, there are 5 liters of mash with a sugar content of 20%, which means that the total sugar content is 1 kg (5 * 0.2 = 1). The calculation assumes that 1 liter of solution by weight is equal to 1 kilogram, in practice this is not the case, but the error itself has little effect on the result, and the calculation simplifies significantly, so I advise you not to "bother".
60-100 ml heads are taken from 1 kg of sugar. It is advisable to divide this amount into two distillations, taking 30-50 ml of yield during the first distillation and the same amount during the second.
2. For pure alcohol. It is not always possible to find out the sugar content before fermentation begins. In this case, the first distillation is done without cutting off the “heads”, then the amount of absolute alcohol is measured. For example, if you get 6 liters of distillate with a total strength of 63%, then it contains 3.78 liters of pure alcohol (6 * 0.63 = 3.78). To simplify the calculations, we take the ethyl strength as 100%, although absolute alcohol can only be obtained in laboratory conditions.
During the second distillation, the head fraction is cut off at the rate of 8-15% of the amount of pure alcohol. In our example, this is 0.567 liters (3.78 * 0.15 = 0.567).
One of the varieties of this method is the selection of 1% of the heads of the mash volume, but due to various reasons related to fermentation and sugar concentration, this method cannot be considered accurate, it is better to focus on absolute ethyl.
3. By smell. Suitable for experienced distillers who can identify moonshine heads by an unpleasant odor.
The distillate leaving the apparatus is periodically sniffed, rubbing a couple of drops in the palms, when the pungent smell disappears, they begin to select the “body”. In this way, it is good to check the correctness of calculations based on sugar or alcohol.
4. By temperature. Due to the design features of moonshine stills and the different composition of impurities, this method does not always work well in practice. I recommend using it only as a last resort. I bring it for review.
The evaporation temperature of the “heads” is 65-68°C. During distillation, when the temperature reaches 63°C (the thermometer must be at the inlet to the refrigerator), the heating power is sharply reduced in order to smoothly reach the above temperature range. Then the “heads” are taken away while drops come out of the apparatus. When the output stops, raise the temperature to 78°C and select the "body" to a temperature of 85°C. The values are approximate and may differ depending on the device!
How to separate tails in moonshine
Evidence of the appearance of tails is the fall of the fortress in the jet to 30-45 degrees. In order not to miss this moment, it is desirable towards the end of the distillation to collect the moonshine coming out of the apparatus into a flask or a small jar, in which it is easy to measure with an alcohol meter (the liquid temperature must be 20 ° C). If the strength is high enough, pour the distillate into a common container and substitute the jar again.
During the first distillation (especially fruit and grain brews), you can collect the "body" until the degree of distillate falls below 30%. At the same time, moonshine sometimes becomes cloudy, but that's okay, the second distillation, in which the beginning of the tails is considered to be 40% fortress, will fix the problem.
Most moonshiners prefer to consider everything that has a fortress below 40 degrees as tails of moonshine. If there is no alcohol meter, moonshine is taken until it burns in a spoon.
When the yield strength falls below the minimum, the distillation is stopped by stopping the heating, or they continue to collect tailings up to 15-20%, but this wastes energy and time, which in most cases does not justify itself.
In the manufacture of moonshine, the temperature of the mash during distillation is of paramount importance. Without exaggeration, the quality of moonshine and the integrity of the moonshine still depend on how correctly the temperature regime is observed. Bringing the mash to a boil too quickly can even explode the alembic. You can achieve the desired result through trial and error. But it is more reasonable to use the information already collected and ready-made advice.
Composition of raw materials
Braga is a water-alcohol solution, which, in addition to alcohol and water, contains impurities of essential oils, aldehydes and other compounds. The point of distillation is to extract as much ethyl alcohol as possible from this solution. The most complete separation of ethyl alcohol from the mash allows distillation with separation into fractions. There are several fractional distillation methods. Correct temperature control is optimal and proven.
Distillation temperature
The separation of moonshine into fractions is based on the difference in boiling points of the compounds included in the mash. At a pressure of 760 mm Hg. Art. the boiling point of ethyl alcohol is 78.3°C, of water is 100°C. The rest of the substances included in the mash boil before alcohol or later. Consider, in a detailed example, at what temperature to drive moonshine.
Range 0-68°C
At the beginning of the distillation, the distiller is brought to an operating power of 63°C. Then the heating is reduced so that the temperature of the mash smoothly reaches 65–68 ° C. With moderate heating, the wash will linger for a while at this level, and will not slip through it. At this stage, the following liquid compounds boil:
- acetaldehyde - 20°C;
- formic ethyl ether - 54°C;
- formic methyl ester - 57 ° C;
- methyl alcohol - 65 ° C.
These harmful and poisonous compounds are called "heads", and the process of their separation is called the selection of heads. It is not recommended to use them even for technical needs.
Range 78-85°C
After the selection of heads, it is recommended to replace or clean the steamer. We put a new container and start collecting the "body" of moonshine. This is the purpose of the entire distillation, in fact, ethyl alcohol. To drive it out, we gradually increase the temperature of the mash to 78 ° C, approaching the beginning of the boiling of ethyl. The higher the concentration of alcohol in the wash, the faster it will evaporate. The exit of the body continues up to 85°C. We try to keep the mash in this temperature range as long as possible.
Above 85°C
Heating the distillation cube to 85 degrees, you can increase the heating and quickly separate the "tails". There is still a small amount of alcohol left in the moonshine still. But it is dissolved in a mixture of acetic and formic acids, butyric ethyl ether, amyl alcohol and other fusel compounds with a boiling point above 100°C. They are often referred to simply as "sivuha". The only option for their further use is to add to the new mash for the next distillation.
Distillation without a thermometer
In conditions where the distiller is made by hand and is not equipped with a thermometer, you can do without temperature readings.
Goal selection
In this case, double distillation is required. The first stage is carried out without crushing into fractions. Upon completion, measure the volume of raw alcohol in liters and the strength in degrees. To calculate how much pure alcohol is in Braga, you need to multiply these data by each other. 12-15% of the amount of pure alcohol is occupied by the heads, which must be taken into a separate container during the second distillation.
The second process for calculating heads is based on the sugar content of the mash. Measurements are carried out at the stage of preparation of the wort before the addition of yeast. For each kilogram of sugar added, 100 ml of heads must be selected.
Collection of moonshine body
The next step after the release of the heads will be the collection of alcohol distillate. It continues until the raw strength drops to 40°C. Technology without the use of an alcohol meter suggests setting fire to moonshine. As long as the combustion reaction is accompanied by a blue flame, the main fraction continues. stop burning.
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