On the Internet you can find many designs for homemade chemical heating pads for fishermen and tourists. The operation of the heating pad is based on a chemical reaction involving water, salt, aluminum and copper sulfate. A heating pad is used to warm numb fingers when fishing. You can use it to warm up cold food.
It must be admitted that the reagents are not cheap now, it may be easier and more profitable to take a catalytic heating pad, one refill is enough for 6-8 hours of operation, after 200-300 uses the platinum element is simply changed. But, according to the author of the development we are considering, the Chinese catalytic heating pad has its drawbacks. If you come across a weak one, the catalyst will last for a week. In addition, this heating pad is temperature sensitive. In the outer pocket the body cools down, the fuel stops evaporating and the heating pad without fuel stops producing heat. She is capricious in this regard. Even the case doesn't help. And if you take it with frozen hands, it will cool down very quickly.

The author of the video tutorial first demonstrates the mechanism of operation of a chemical heating pad. To do this, he took copper sulfate bought in a store and ground it in a coffee grinder. However, he had to grind the vitriol only to demonstrate the operation of the device, since large crystals crack when heated. Copper sulfate was calcined in order to increase the initial temperature of the solution, so as not to wait a few extra minutes before the reaction began, but you can do without this.

What aluminum is used in the heating pad? Food foil. Width 28 cm, length 20 cm, thickness 14 microns. The ratio of copper sulfate and kitchen salt is 2:1. A bamboo skewer is glued into the cork using hot glue.

In the experiment it is very cold water. The mixture is heated to room temperature due to the dissolution of anhydrous copper sulfate. Shake the bottle with the mixture to speed up the chemical reaction. The foil on the skewer will heat the liquid in the bottle evenly. During the reaction, hydrogen and heat will be released, which will speed up the reaction. The pressure in the bottle must be monitored and the hydrogen must be constantly released. Aluminum dissolves and copper is released from the solution. If no gas is released within a minute, the reaction is over. In principle, you can even boil water, but the bottle will not withstand such heat.

And now about how not to make a chemical heating pad.

Wanting to reduce reaction time to a minimum, the author of the video decided to increase the aluminum contact area. For this purpose, he crushed aluminum plates. Next, as usual, I put salt and copper sulfate in the bottle in the required proportions. Filled it with water. Stirred. I threw in the aluminum blank and screwed on the lid. Having opened the lid slightly to vent the hydrogen, he received a charge of dirty hot liquid on himself.

Watch the video experiment showing the chemical reaction behind the heating pad and how to make one yourself. Well, if you want to see immediately “what the violation of technology resulted in,” that is, about the dangers of chemical heating pads, then from the moment 3:41.

Features of the heating pad made from copper sulfate proposed by the author.

A similar recipe has been floating around the internet for decades, but it all boils down to mixing salts, adding sawdust, aluminum and water. And yet not
it is clear how to regulate the reaction speed, the temperature of the heating pad and how to remove the released gases. The author chose a simple path. A short but active chemical reaction produces heat that holds the salt mixture. This allows you to save reagents and keep the temperature in a comfortable range.
As the heating pad cools, you can add new portions of aluminum.

The rate of a chemical reaction depends on the concentration, temperature, and surface area of ​​the reactants. Therefore, aluminum is in the form of foil, and not wire, pipes, corners and other things. Because The concentration of salts decreases during the reaction, then there should be an excess of salts. The solubility of copper sulfate in 100 grams of water at 25 degrees Celsius is 23 grams. I don’t recommend taking more than 4 times the amount because... During the reaction, copper is released in the form of a fine powder, which thickens the salt solution and prevents the circulation of the solution. Copper sulfate was calcined in order to increase the initial temperature of the solution, so as not to wait a few extra minutes before the reaction began, but you can do without this.

The wooden skewer is designed to sink the foil bundle and isolate it from the walls of the bottle. Otherwise, the foil becomes covered with many bubbles and floats. In this case, all the heat is released in the upper part of the bottle, which leads to strong heating and deformation of the walls. In the case of a skewer, gas bubbles cause the liquid to circulate, so it is not necessary to constantly shake the bottle and release gas. It’s enough just to let the bottle sit for a couple of minutes without tightening the cap. The army works on the same principle.
flameless food heaters.

The other is a safe heating pad with a very interesting operating principle.

Making a chemical heating pad

On a winter hike or traveling through the northern regions, it is so nice to warm up from an external heat source. But a fire can only be lit at a rest stop or during a long stay, but what to do while on the move? This might help chemical heating pad, which is necessary attribute in sets for survival.

Of course, it can be purchased in specialized stores, but it will not cost as cheap as we would like, so it is better to stay at homemade device. Depending on how you want to use it: to warm your hands, body under clothes, or as a heating pad for a sleeping bag, you select the container in which the chemical reaction will take place.

There are several ways to make a chemical heating pad, but we will focus on the three most common. First, let's decide on the ingredients that I depicted in the picture.

Method 1 (older)

For the first method you will need: 20 g of ordinary salt (NaCl), 40 g of copper sulfate (CuCl), a piece of aluminum wire and 30 g sawdust. It is advisable to grind the vitriol and salt to a crystal size of no more than 1 mm (if they are larger).

Add sawdust to the mixture of salt and copper sulfate and mix thoroughly. Bend the aluminum wire into a spiral and place it in a jar or bottle (preferably glass). Pour the prepared mixture on top so that the level is 1 cm below the neck. To get it into working condition, just add 50 ml of water to the container, which will start the reaction and raise the temperature of your heating pad to 60°C in 3-4 minutes.

To understand the principle of operation, I will give the formula of the chemical reaction:

CuSO 4 +2NaCl → Na 2 SO 4 +CuCl 2

It is the formation of copper chloride that leads to the release of part of the heat, but the main heat arises when it interacts with aluminum wire:

2Al+3 CuCl 2 → 2AlCl 3 +3Cu

Sawdust does not take part in the chemical reaction. By absorbing water, they act as a kind of reaction retardant, which significantly extends the operating time of the heating pad. In addition, wood has low conductivity, which allows it to accumulate heat and release it gradually. In a closed container, heat is retained for up to 2 hours.

For modern realities, glass containers- this is something rare. Much easier to find plastic container suitable shape and volume. In this case, make sure that the wire does not touch the plastic, as it may warp when heated.

Method 2

This design of a chemical heating pad is in demand among tourists who spend winter nights in tents. They take it with them in their sleeping bag and place it in their bosom to keep warm before going to bed.

To make it, you will need a thick waterproof bag (experienced take 2 - one in one), into which a mixture of 5 g of CuCl powder, 5 g of aluminum powder and 5 tablespoons of sawdust is poured. It is enough to add 40 ml of water to such a mixture to start a chemical reaction with the release of heat.

Method 3

This method is in many ways similar to the first. Only in this case we do not use sawdust.

First, take a piece of aluminum foil 20x30 cm. Fold it in half (10x30 cm) and roll it into a tube around a wooden barbecue skewer. After this, glue the skewer to the lid of the plastic bottle with a glue gun. This way the heating foil will not touch the plastic walls.

We take table salt and copper sulfate powder in a ratio of 1:2 and pour them into the bottle. To start the reaction, add water to the container. During the reaction, heat and hydrogen will be released, which will have to be released from time to time. Aluminium foil will dissolve, so the bottle must be shaken periodically. You will know about the end of the reaction, and therefore the cessation of heat generation, when gas evolution on the foil ceases.

As you can see, the methods I have given have their pros and cons, so choose the one that suits you best for hiking and local conditions survival.

With the onset of autumn and winter, cold weather comes to Japan. And although snow is rare in Tokyo, the temperature remains around ten degrees Celsius, and even lower at night. At the same time, in the houses there is no central heating, the walls are thin, and the window glazing is single-layer. All these factors lead to the fact that living in such houses in winter becomes somewhat problematic, and even impossible to live comfortably. Why do you think they sell heated toilet attachments in Japan? That's it! And if earlier the Japanese heated their homes with a hearth with a live fire, now in ordinary apartments This is impossible and inconvenient. In Russia, the heating issue is solved simply - batteries, but in Japan, for the most part, there are no batteries, but there are many other ways to bring comfort to winter existence.

Consider the following sources of heat in enclosed spaces.

1. Gas heaters.
2. Oil heaters.
3. Kerosene heaters.
4. Electric heaters.
5. Halogen heaters.
6. Electric carpets.
7. Air conditioners.
8. Ionizers-dryers.
9. Sleeping bag.
10. Girl in bed.
11. Ofuro and water heating pad.
12. Chemical heaters.

Each method has its pros and cons. In general, there are two main methods of active heating, namely by heating the surrounding air and directly transferring heat to objects. TO the last type include halogen heaters, and all others belong to the first. In Japan, the power and model of the heater are selected based on the area of ​​the tatami room and the tasks it must perform. For example, do you need to heat the entire room or just some part of it? Almost all heating equipment is equipped with temperature indicators and automatic on/off timers, and more expensive models can operate in support mode certain temperature or turn on at certain specified hours.

Gas heaters.
Gas heaters operate on the principle of combustion natural gas, which is supplied to them through a hose from the home gas network. Gas price in Tokyo is about 117 yen per cubic meter and gas is very popular in Japan; water is heated in showers and in the kitchen using gas water heaters; food is cooked on gas.

Gas inlets are built into the walls of the rooms, a hose is connected to them, and the other end is connected to a gas heater. Such a heater will allow you to heat large areas; the power of conventional models reaches 4 kilowatts at prices of about 18 yen per hour of operation per kilowatt of output power. The disadvantage is the inability to freely move the heater around the apartment. Moreover, in Russia such a heater is useless due to the lack of appropriate gas inlets. Moreover, gas heater during operation, it consumes oxygen, reducing its amount in the heated room, and we will return to this point a little lower.

Oil heaters.
Oil heaters are also widely known in Russia, and work on the principle of electrically heating the oil inside the tank.

They consume only electricity, heat up very slowly, but at the same time they have the most large area heating elements, that is, maximum heat transfer per unit of power. They are silent, do not burn oxygen during operation, and are one of the most effective ways heating the home, but also consume a lot of electricity. In addition, they are not at all exotic, like, for example, the next type.

Kerosene heaters.
Kerosene heaters create heat by burning kerosene supplied from special built-in tanks. Kerosene is poured into them manually. Kerosene itself can be bought at gas stations or in supermarkets, and in winter there is a tank that drives along the streets and you can buy it there.

This liquid fuel costs about half as much as electricity, and its consumption greatly depends on the operating mode and model of the heater. There are those who consume 16 yen per hour, giving 900 watts, and there are those who give 2300 watts for 18 yen. Five liters of fuel is enough for approximately 70 hours of operation. One of the advantages is the high mobility of such a heater. No hoses or wires required, you can place it anywhere comfortable spot. Some models also have stove capabilities - you can, for example, boil tea or heat up food. The kerosene stove can be taken to Russia and smoked there. Of the minuses - when starting and stopping (or the possible old age of the device), you can smell kerosene, you need to pour kerosene into the tanks (and smell its smell), as well as have a supply of it. It is not electricity that is always there. But the main disadvantage is the significant burning of oxygen, which, in a poorly ventilated room, can lead to headaches in the morning and general weakness. The Japanese themselves, who heat with kerosene, regularly ventilate the room. By the way, there are models with air intake from outside, but this requires special installation and chiseling the wall.

Electric heaters.
Electric heaters of the classical type work on the principle of heating high-resistance elements from a current passing through them and then transferring heat from them to the air. They may have a metal reflector, and some models are equipped with a fan that disperses warm air around the room.

However, models sold in Japan are oriented only at local 100-110 volt voltage. Electricity prices are 22 yen per kilowatt, from here you can calculate the financial costs of heating. It is believed that one kilowatt of power is sufficient to warm up one workplace, i.e. in eight hours you will run up eight kilowatts or 176 yen. Multiplying by 30 days we get 5280 yen per month.

Halogen heaters.
Halogen heaters are a variant of electric heaters, but heat is transferred to objects not by heating the air, but by infrared radiation directly to objects. When you turn on such a heater, you will immediately feel warmth, but only where its radiation hits.

They are lightweight and silent, and can often automatically rotate on the stand within a certain angle, but whatever doesn't hit it will remain cold. No, of course, over time the entire room will warm up, but you will have to wait a long time and gathering in a circle around such a heater is somewhat more difficult than around a gas heater. On the other hand, such a heater is silent and does not burn oxygen.

Electric carpets.
These products run on electricity and are sewn inside the fabric. heating elements. Such carpets have different areas; you can not only sit on them, but also place chairs, a table, and some models can even be washed.

However, it is believed that sleeping on a source of low-frequency electromagnetic radiation is not good for health; moreover, such rugs lead to a decrease in humidity in the apartment, which can also have a negative effect on the body. In particular, sleeping in a constantly upward flow (warm air from the carpet will rise to the ceiling) can lead to flaky skin, and dehydration can put additional stress on the kidneys. There are also electric blankets - thinner and lighter than electric carpets. Typically, they are used in combination with regular blankets. This group also includes a kotatsu - a table with a built-in stove and a “fringe” of blanket around the perimeter.

Air conditioner.
IN winter time An air conditioner can heat the air, but you cannot expect it to be super efficient. Regular home model(not to be confused with large ones for institutions) heats the air only a few degrees and the colder it is outside, the less efficient (after all, the air is taken from there). Consumes quite a lot of electricity and is noisy.

Ionizer dryer.
This is a device for ionizing air and reducing humidity in a room. Inside there is a water tank into which atmospheric moisture condenses. This is not a heating device, but it can raise the temperature in a small room by several degrees, while making a loud noise.

Sleeping bag.
Even though it seems ridiculous, a good sleeping bag is in a great way keeping warm at night. The human body itself is a source of heat, you just need to preserve it. If tourists sleep in sleeping bags in winter, with significant negative temperatures, then indoor use is very simple. All models of sleeping bags have two temperature characteristics - comfortable and extreme temperature, you need to choose according to what is comfortable.

An important fact remains that “heating” with a sleeping bag does not require additional costs for electricity or gas. Moreover, you can open the windows at night and ventilate the room, which will have a beneficial effect on your health. The downside is that it will take some psychological effort to get out of the bag on a cold morning when the water in the cups in the kitchen freezes. In this case, it is recommended to immediately run to a hot shower and then dress warmly. If someone is not satisfied with the sleeping bag normal looking, industry offers unusual options, for example in the form of a bear skin. You’ll fall asleep in one of these in the woods without a tent, and in the morning you’ll scare someone. Nice, right?

Girl in bed.
A logical continuation of the previous option, it is distinguished by higher heat transfer and additional psychological (and possibly physical) comfort, however, the option is difficult to “operate”, “set up”, and in general it is a rare success to find it. If we talk about students of language schools, then their accommodation is predominantly same-sex and it is important, in the pursuit of warmth, not to slide into complete achtung.

Ofuro and water heating pad.
Ofuro is a deep bathtub with hot water, which is taken both for warming up and for relaxation. A shower cannot replace ofuro.

Taking ofuro before bed and then diving into bed will help you fall asleep quickly. The disadvantages are the consumption of water and time. If you put it in a two-liter water bottle hot water(at least 75 degrees) and put it under the blanket, it will help keep you warm until the morning.

Chemical heaters.
These are small plates applied to the body or clothing. After activation of such a plate, a chemical reaction occurs inside with the release of heat. The heat is released slowly and you can get burned unnoticed.

Which heating method you choose is up to you and depends on your lifestyle and finances. For those who spend most of their time outside the home, a sleeping bag and ofuro will be enough. Homebodies need a powerful source of heat because sedentary work only increases the feeling of cold.

Gerasimenko Elena

The work “Thermochemical reactions in the creation of a chemical heating pad” examines practical use theoretical material about chemical reactions.

The choice of the problem of interest is justified. The ability to create a “chemical heating pad” at home from inexpensive scrap materials can be very useful in extreme natural conditions.

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Municipal secondary education state-financed organization average
secondary school No. 19 MO Korenovsky district

Scientific and practical conference for schoolchildren “Eureka”

"Thermochemical reactions in the creation
chemical heating pad"

Completed by a student of class 11 A of MOBU secondary school No. 19Municipal district Korenovsky district

Gerasimenko Elena Mikhailovna Head teacher of chemistry Bobrovskaya L.F.

Korenovsk

year 2014

annotation

The work “Thermochemical reactions in the creation of a chemical heating pad” examines the practical application of theoretical material about chemical reactions.

The choice of the problem of interest is justified. The ability to create a “chemical heating pad” at home from inexpensive scrap materials can be very useful in extreme natural conditions.

Availability analyzed Supplies. The thermal effects of reactions are calculated using standard enthalpies of formation of substances.

In her work, the student carried out experiments using new laboratory equipment Mishab, on the basis of which she calculated the ash effects of reactions and established the most effective reactions.

The result of the work was formulated recipes and recommendations for creating “chemical heating pads” in an understandable and accessible form.

The work has practical application and deserves attention.

Introduction.

In the cold season, people whose activities involve performing certain
tasks on the street, there is always a desire to warm up. But this is not always the case
conditions. The problem can be solved by using heating pads.

In my work, I decided to explore the problem of creating a chemical heating pad. The heating pad can be reusable. For reusable “warmers”, crystalline salt hydrates, which can be stored supercooled for a long time, are best suited. There are similar heating pads on sale, filled with crystalline sodium acetate hydrate SNZS0 (Zha-ZN20. This salt melts in its own water of crystallization at 58 ° C. The salt, placed in a plastic bag, is melted in boiling water and then the melt can be cooled to room temperature and below without crystallization ( hypothermia). Then it is enough to crumple the bag - and crystallization begins with the release of heat. This process can be repeated many times."

I was more interested in the possibility of creating a real chemical heating pad, which works due to exothermic reactions occurring in it. These heating pads are disposable, which is convenient because after use they can be thrown away or recycled.

I managed to find several recipes for such warmers. The goal of my work was to choose the most convenient, reliable, accessible, cheap and effective recipe, testing and testing it in practice.

. .) ^ > * 1 3

During my work, I studied the theory of thermochemical reactions, calculated the thermal effect of the selected reactions, and conducted experiments with the selection of different recipes.

Study plan

In the study of chemistry we become acquainted with thermochemical reactions, which occur with the absorption or release of heat. Energy stored in substances in the form chemical bonds, is released during the formation of new substances. In chemical production, this energy is used to heat reagents or produce vapors or heat water.

The thermal effects of chemical reactions are necessary for many technical calculations.

The effect of certain exothermic reactions can be used to create a customized portable heater.

The goal of the work was to investigate some chemical reactions to create a thermochemical heating pad. For this purpose, some experiments were carried out using the most available reagents.

I want to explore the problem of using the energy of chemical reactions in miniature individual heating systems “hot water bottles”. For this it is necessary:

1. Study the issue and determine whether there are similar heating pads;
2. Select the most suitable reactions for creating chemical heating pads;
3. Select the most efficient reactions in terms of calorific value during a chemical comparative experiment;
4. Choose the most convenient form for filling and application.

1. Thermochemical reactions.

Thermochemistry -- a section of chemical thermodynamics, the task of which is to determine and study the thermal effects of reactions, as well as to establish their relationships with various physicochemical parameters. Another task of thermochemistry is to measure the heat capacities of substances and determine their heats of phase transitions.

Thermochemical equations

Thermochemical equations of reactions are equations in which near the symbols chemical compounds are indicated states of aggregation of these compounds or crystallographic modification and the numerical values ​​of thermal effects are indicated on the right side of the equation.

The most important quantity in thermochemistry is the standard heat of formation (standard enthalpy of formation). Standard heat (enthalpy) of formation complex substance is called the thermal effect (change in standard enthalpy) of the reaction of the formation of one mole of this substance from simple substances in standard condition. The standard enthalpy of formation of simple substances in this case is taken equal to zero.

In thermochemical equations, it is necessary to indicate the aggregative states of substances using letter indices, and the thermal effect of the reaction (TR) must be written separately, separated by a comma. For example, the thermochemical equation

4Ш 3 (g) + 30 2 (g) -+ 2Н 2 (g) + 6Н 2 0 (g), DN=-1531 kJ

shows that this chemical reaction is accompanied by the release of 1531 kJ of heat, at a pressure of 101 kPa, and refers to the number of moles of each substance that corresponds to the stoichiometric coefficient in the reaction equation.

In thermochemistry, equations are also used in which the thermal effect is related to one mole of the formed substance, using fractional coefficients if necessary.

Hess's law

Thermochemical calculations are based on Hess's law: The thermal effect (TE) of a chemical reaction (at constant P and T) depends on the nature and physical state of the starting substances and reaction products and does not depend on the path of its occurrence.

Corollaries from Hess's law:

1. The thermal effects of the forward and reverse reactions are equal in magnitude and opposite in sign.
2. The thermal effect of a chemical reaction (TR) is equal to the difference between the sum of the enthalpies of formation of the reaction products and the sum of the enthalpies of formation of the starting substances, taken into account the coefficients in the reaction equation (that is, multiplied by them)."

Hess's law can be written as the following mathematical expression:

∆ N in =∑(∆ N 0 reaction products) - ∑(∆ H 0 reagents)

Using data on standard enthalpies, I will calculate the thermal effect of reactions for chemical heating pads.

1. Recipes for chemical heating pads.

1. compound : One of the simplest chemical heating pads contains calcium oxide CaO ( quicklime), which reacts with water to form calcium hydroxide:

CaO + H 2 0 = Ca(OH) 2.

The reaction is accompanied by heat release. The temperature of the heating pad can reach 70-80°C.

1. compound : Another type of chemical heating pad uses the interaction of metals (in the form of shavings) and salts. A completely dry mixture of iron (Fe) shavings with copper salts (for example, CuCl 2 ) can be stored for quite a long time, and when water is added, the temperature immediately rises to almost 100°C due to the reaction:

F e + CuC1 2 = F eC1 2 + Cu.

At the same time, a heating pad in which copper chloride CuC1 2 turns into ferric chloride F еС1 2 , retains heat for about ten hours.

1. compound : Equipment: aluminum wire, copper sulfate, table salt, sawdust, water.

2A1 + ZSi S 0 4 - A1 2 (S 0 4 ) 3 + ZSi.

Sodium chloride is added to intensify the process; chlorine ions accelerate and facilitate the reaction with aluminum. Against the background of this reaction, there is probably also a reaction of aluminum with water, such as

2А1 + 4Н 2 0 => 2А10(0Н) + ЗН 2.

1. compound : To make a chemical heating pad, it is better to use copper chloride powder and aluminum filings. Mix 5-6 g of copper chloride with the same weight of aluminum sawdust and add 5-6 tablespoons of well-dried sawdust to the mixture. Pour the resulting mixture into a plastic bag. The heating pad begins to work when 30-40 ml of water is poured into the bag. Copper chloride, dissolving in water, reacts with aluminum:

ZSiS12+2A1=2A1S13+ZSi.

The reaction is accompanied by the release of heat. The sawdust acts as a "diluent" to prevent the reaction from proceeding too quickly.

1. compound : a mixture of potassium permanganate and iron powder in a steel cylinder. It was invented by the Japanese during World War II. Weighed about two hundred grams. As soon as you added a little water, this mixture began to warm up. The heating pad worked for up to 20-30 hours, and it outside temperature did not exceed sixty degrees, that is, it could not burn the skin. One such heating pad was enough to warm an adult.
2. compound : A flat polypropylene bag in which the oxidation of iron dust with atmospheric oxygen occurs, forming rust and generating heat. The mixture also includes water, salt (works as a catalyst), Activated carbon(distributes heat evenly), vermiculite (serves as a heat accumulator) and cellulose (filler). The heating pad is disposable, starts working after opening the sealed package (to ensure oxygen access) and is capable of providing heat for several hours.
3. compound : You can also add oxalic or citric acid(crystalline hydrates), which increases heat output. Such heating pads allow you to obtain temperatures from 100 to 300°C. To start them, a small amount of water is introduced into the reaction mixture of calcium oxide and oxalic acid crystal hydrate; during the reaction, the water released during neutralization will react with calcium oxide.

. - « ■ (IV /1 V*

CaO + H20 = Ca(OH)2 + 10.6 kcal

Ca(OH)2 + H2C204*2H20 = CaC204 + 4H20 + 31kcal

1. compound: MORE EFFECTIVE composition chemical heating pads are a mixture of iron filings, potassium permanganate, coal and sand. Coal and sand serve as reaction retardant fillers. Heat is released as a result of adding water to this mixture.

The resulting reaction when water is added to the mixture is:

4Ee + 2H20 + 302=2(Ee203»H20) + 390.4 kcal

Such a mixture, placed in a housing, allows you to maintain a temperature of 100°C for 10-12 hours. An individual heating pad of this type is a rubberized bag filled with the specified composition with a neck for pouring water.

1. compound: And the best disposable chemical heating pad (namely a chemical heating pad, since a reusable heating pad has nothing to do with chemistry) is a mixture of iron and copper filings with salt. It fills with water and starts to warm up.

CaO + H 2 0 = Ca(OH) 2

DN° 298 = DN° 2 98 (Ca(OH) 2 ) -(DN 0 2 98 (CaO) + DN 0 2 9 8 (H 2 O))= -985.1-(-635.1-285.83)= = -64.17 kJ/mol

Ee + CuC1 2 = HeC1 2 + Cu

DN° 298 = DN 0 2 98 (ReS1 2) - DN°29 8 (SiS1 2 ) = -341.7+205.85 =135.85 kJ/mol2A1 + ZSi804 = A12(80)3 + ZSi

DN° 298 = DN 0 298(A12(8O)3) - DN° 298 (Ci804)*3= -3441.8 -(3*(- 770.9))=-1129.12А1 + 4Н20 => 2АУ(ОН) + ЗН2 DN° 298 = DN°2 98 (A10(0N))*2 - DN° 298 (N20)*4 =

ZSiS12+2A1=2A1S13+ZSi.

DN° 298 = DN° 298 (A1S13)*2 - DN°298(SiS1 2 )*3-585,2 *2 - (-205,85 *3) = - 552,45

4. Experiment.

For determination of practical outputheat of different reactions, I will conduct an experiment. IN

under the same conditions I will observe the heatcreative ability of mixtures and cooling time.

Conclusion, the greatest heat output is observed when aluminum interacts with

copper chloride. Based on this mixture, the heating pad will work most effectively, but you need to select the proportions of the reagents

5.0 determination of the thermal effect of the reaction 5 grams of CuC were added to 50 g of water l 2 *2 N 0 and some aluminum powder. By

change in water temperature d e la thermal effect of reaction.

b. Recipe for a chemical heating pad

To create chemical greeks, you need to prepare a mixture.

For 1 tablespoon of copper sulfate, take 1 tablespoon of salt and add 1 teaspoon of aluminum powder. The temperature of the heating pad will rise to 100° and

gradually decrease.

Conclusion.

Thanks to the experiments carried out, it was concluded that the most optimal way to create a thermochemical heating pad is the reaction of replacing a metal from a salt with a stronger metal.

The main task practical work was to create a portable heater from available reagents, which would be used in the cold season and serve as a heating pad in camping conditions.

To create the heating pad, some reactions were carried out:

1. .Interaction of copper chloride (||) with aluminum

A mixture of copper chloride, coal and sawdust is prepared. I poured in aluminum powder. Added water. Using the device it was measured Maximum temperature heating (100°C) and time to lower the temperature to 22°C (approximately 1.5 -2 hours)

1. .Interaction of copper chloride (||) with iron

I prepared a mixture of copper chloride (dry), coal and sawdust. Added iron powder. Added water. Using the device, I found out that the substances interact poorly. The temperature rose from 25°C to 35°C, and lasted no more than 40 minutes.

1. Lime slaking

Calcium oxide was taken for the reaction. Added water. The reaction did not occur (most likely due to long-term storage, calcium oxide has turned into calcium carbonate).

Based on the experiments conducted, it was concluded that to create a heating pad, the most optimal reaction is the displacement of metal salts by a more active metal.

Experience has shown that many exothermic reactions occur aggressively, with violent gas release, with a small thermal effect and are not suitable for creating a thermochemical heating pad.

Bibliography:

FindPatent.RU2012-2013

Chemical salt applicators - convenient devices for a warming or cooling compress. And if at home, salt warmers can be replaced electrical appliances, then you simply can’t do without them on a hiking trip.

Types of salt warmers

A chemical heating pad is a container filled with supersaturated saline solution, which is in equilibrium in the inactive state. U different manufacturers The exact composition of the mixture may vary.

All autonomous salt applicators existing on the market can be divided into two large groups:

• disposable;
• reusable.

Disposable heating pads have a simpler composition. Externally, these are small rag or rubber cases, usually rectangular shape, which contain a dense dry mass. When activated, this mass heats up.

A reusable chemical heating pad is a more complex design. The body for it is made of rubber. Inside the case, in addition to the solution, there is a special trigger, which is responsible for starting the crystallization process. This device may also have an additional microfiber cover and an electronic starter.

Why are salt applicators better than analogues?

Compared to other autonomous heaters, chemical ones have several advantages:

• They can be purchased at any travel equipment store. Reusable heating pads are also sold in pharmacies and baby supply stores.
• These devices are portable. They are small in size.
• Unlike the same gasoline portable heating pads, salt ones do not smell anything during operation.
• They are easy to use.
• Chemical heating pads are safe even for small children, as they are hypoallergenic and airtight.
• There is no need to purchase additional filters or replacement parts.
• They are durable. The shelf life of disposable applicators is 2-3 years, while reusable ones can be used for up to 1000 uses.

How much does a reusable chemical heating pad cost? The price for an autonomous heater of any type is affordable. A disposable heating pad costs 20-50 rubles. And prices for reusable devices depend on the country of manufacture, the size and shape of the heating pad, but usually range from 300-2000 rubles.

Indications for use

When treated with dry heat, blood vessels dilate. Because of this, blood circulation improves. Therefore there is a whole range medical indications, in which the doctor may prescribe heating with an autonomous chemical applicator:

• arrhythmia;
• heart failure;
• menstrual cramps;
• headache;
• osteochondrosis;
• arthritis;
• arthrosis;
• rhinitis;
• frontal sinusitis;
• sinusitis;
• angina;
• frostbite;
• leg pain;
• other colds.

But a warm compress cannot be used if:

• acute inflammatory processes;
• pustular skin lesions;
• allergic skin reactions;
• fever;
• for pain and spasms of unknown origin.

And when, on the contrary, it is necessary to slow down blood circulation, a chemical heating pad is used for cooling. Indications for this are:

• bruises and contusions;
• nosebleeds;
• muscle and tendon strains;
• high body temperature;
• rush of blood to the head;
• the first hours after injury;
• recovery period after surgery.

But a cold chemical heating pad is contraindicated for shock, collapse and cramping pain in the abdomen.

For ease of use, manufacturers make reusable applicators of different designs. Mattresses and collars are best for warming up large plots body: lower back, neck and joints. And special knee pads have a shape and ties that are convenient for attaching to the knee. There are warmers in the form of insoles for shoes or pads for the nose and face.

How to make a heat compress correctly?

Activation of the applicator in the “heating” mode depends on what type it belongs to.

The disposable heating pad must be removed from its packaging, then kneaded thoroughly. But at the same time, you should not open the bag with the filler. After this, the applicator should be left on outdoors for a while. After 5-10 minutes it will become warm. This means that the chemical heating pad is ready for use. You can put it in your pocket or shoes and use it to warm your hands and feet for 3-4 hours. Do not allow the heating pad to come into contact with a naked body.

Reusable applicators are activated using a special trigger, which usually looks like a trigger stick:

1. The trigger must be bent by squeezing the heating pad or pressing a special button. This will start the crystallization reaction.
2. After this, the heating pad needs to be slightly kneaded in your hands and applied to the diseased organ, so that as it warms up it takes on the desired anatomical shape. A few minutes after switching on, the solution will become solid.
3. To avoid burns on the body, the applicator should not touch bare skin. Therefore, it is better to put it in a special case or wrap it in a towel.
4. To prevent the device from moving, you need to remain calm for the entire time you receive the compress.

The operating time of a reusable heating pad in an active state is about 30-90 minutes. After this it needs to be restored.

Rules for cooling with a salt applicator

For a cold compress, a reusable one is also used. Instructions for use are simple: the inactive applicator is put in the refrigerator for half an hour, after which it is immediately ready for use.

This heating pad will keep cold three times longer than regular ice. And in addition to cold compresses to the body, it can also be used to cool equipment and food products. Similar salt applicators are used when transporting products.

In this case, you cannot:

• Place a heated active heating pad in the refrigerator. Temperature changes can cause it to break.
• Cool the applicator in freezer. At subzero temperatures, the solution inside it crystallizes, hardens and becomes unusable.

Disposal and restoration of the heating pad

Immediately after use, a disposable chemical heating pad is disposed of with household waste, and a reusable heating pad is disposed of only after the solution inside it has expired. Until reusable heating pad can be restored after each use. To do this you need:

1. Wait until it finishes heating and begins to cool.
2. Wrap the heating pad in a plain cloth.
3. Place in boiling water for 5-20 m.
4. Drain and let dry.
5. Place in a dark, dry place at room temperature until next use.

If necessary, the reusable heating pad can be reused immediately.

Babies often experience colic and teething. And while exploring the world, small children can accidentally hurt themselves. Therefore, a device with which a child can be given a cooling or heating compress in a matter of minutes is so valuable when caring for children.

Self-contained applicators for children are available in a special design. They have a bright and colorful appearance, which makes them look like toys. Such heating pads, in addition to traditional compresses, use:

• for heating the stroller while walking;
• to warm the crib before bed.

Any salt product is absolutely safe thanks to its sealed packaging. In this case, the device does not cause allergies and takes the shape of the body.

Using a heating pad for cosmetic procedures

Steam your facial skin before applying a nourishing mask. It will also treat minor pimples and relax the facial muscles after a hard day at work, which will have a beneficial effect on overall well-being and smooth skin. The instructions for using it for cosmetic purposes will help you to do this procedure. The instructions for using it for cosmetic purposes are very simple and do not differ from the rules for using a regular heat compress.

To do this, you need to activate it and apply it to your face in the area of ​​interest. To prevent the heating pad from burning your skin as it heats up, you can additionally wrap the device in gauze or a towel. The main thing is that both the heating pad itself and the towel are clean, since during the compress, an infection can be introduced into the enlarged pores.

But it is best to buy a special device that has suitable size and anatomical shape. Included with the applicator for cosmetic procedures There is a convenient microfiber cover.

Will heating pads help on a camping trip?

When going fishing, hunting or just relaxing in nature, you definitely need to take several self-contained heating pads with you. They will be useful for:

• warm the sleeping bag;
• warm your hands in your pockets;
• warm and dry your feet.

To use the chemical ones you just need to activate the applicators and put them in your shoes. Either disposable heating pads or reusable devices in the form of insoles are best suited for this purpose.

But heating in this way can only be done locally. If general hypothermia of the body has been allowed, then the compress should be abandoned, since in this case the blood flow will rush to the heated organ, depriving the rest of normal blood circulation. Which will lead to even more freezing.

Knowing how to use a chemical heating pad, you can have time to provide first aid in case of injury and warm up even during winter fishing.