Molar mass of the mixture. Problems on gas laws

Bitumen stains on a car’s paintwork are a real problem that needs to be dealt with in a timely manner. The body becomes especially actively contaminated with resin with the onset of warm weather, when road workers begin their favorite “pothole repair”.

It’s good if the spots are small and they flew off their own wheels. The example in the photo shows a more severe case. The car was left near the hole. The road workers filled it with tar and left. According to the law of meanness, it was during this period of time that another car rushed past and landed its wheel directly into a fresh tar puddle. There were stains on the doors, sills, fender, windows and a little on the roof...

What and how to remove bitumen stains?

The cheapest, most accessible and completely safe remedy for effective fight with resin on the car body - kerosene. You can buy it in construction stores. It is usually found in bottles among solvents. By the way, they can also be used to remove bitumen contaminants. But solvents are more expensive than kerosene.

As an alternative, car enthusiasts use other means that happen to be at hand in the garage. It's about about gasoline, diesel fuel and, of course, about WD-40 (or similar). All these liquids also do an excellent job with resin, but, again, they cost more than kerosene.
In addition to the solution for dissolving bitumen stains, you will also need car shampoo. Traces of kerosene will need to be washed off, and plain water can't handle this. To protect the paintwork in the future, it is recommended to treat the body with special wax.
For cleaning you will also need a piece of thick foam rubber, clean rags and a kerosene container.

The process of removing bitumen stains begins with the fact that they must be generously moistened with the product that has been chosen. Rubbing hard with a rag won't help. The main task is to dissolve the hardened resin.
After wetting, stains should be easily wiped off with a rag soaked in kerosene. It is not advisable to rub vigorously, as there is a risk of dulling the varnish layer.

If some stain does not give in, it is better to return to it in a few seconds, when it has dissolved better.
After these activities, take a clean rag and use it to wipe dry all remaining tar and kerosene. The treated area is carefully inspected. If some spots are missed, the process is repeated.

After removing bitumen contaminants, you must thoroughly wash the car body. A standard car shampoo can deal with greasy traces of kerosene without any problems. On the topic described, many car owners will find the following simple recommendations useful:

Bitumen stains should be removed promptly. The longer the resin sits on the paintwork, the more difficult it is to remove.
Do not rub bitumen stains vigorously. The key to success lies in dissolution, not mechanical action.
Do not rush to buy a “special” product for removing bitumen stains from a car store. Its effectiveness is comparable to kerosene, and the price can be ten times higher.
To protect your paintwork in the future, use wax regularly. Resin, dirt, dust, and bird droppings stick to them worse.
Do not attempt to clean the resin with overly aggressive solvents. This may damage the paintwork.

Results

In general, removing bitumen stains is quite simple task, which does not require a lot of time, effort and money. The most important thing is not to put off this event for too long.

The greatest threat to car coatings is bitumen resin. She not only spoils appearance car, but can also damage the paintwork. And in order not to have to resort to expensive paintwork renewals, it is necessary to get rid of bitumen stains in a timely and correct manner. The main thing is to choose the right product and follow the instructions for removing contaminants.

Where do bitumen stains appear on the car body?

Asphalt laid on the road surface is a multi-component material. The adhesive is bitumen, a resinous substance that becomes a black viscous substance when heated. As it cools, it hardens again and firmly adheres to the surface it hits.

In the summer hot weather bitumen gets very hot and almost always has a soft consistency. It clings to the wheels of a car driving along the roadway, and then, flying off, lands on the body. Heat and heating - no the only reason formation of resinous contaminants. Existing routes are often renovated, which also involves bitumen.
The softened resin “settles” on the body vehicle and freezes. It forms a thin black film, which is quite difficult to remove in the future. Vehicles with light-colored paintwork suffer the most damage. If bitumen stains are not removed in a timely manner, it will not be possible to do this without harm to the paintwork.

What means can get rid of bitumen on paintwork?

A variety of compounds are used to remove bitumen stains. On sale you can find a huge number of products that promise to cope with resin without any problems. Not all of them meet the declared quality. There are also those that can damage the paint layer on the body. When purchasing a product, you should focus not only on price, but also on quality, and choose only a proven product.
Compositions for removing resin can be special or universal. The first ones are intended exclusively for removing bitumen from paintwork. Universal formulations are products that are intended for wide range works They contain both active surface components and chemical additives and alcohols. Such products do not always cope with bitumen stains, since the resin can become firmly embedded in the paintwork, so preference is given to special products.

Available means

Universal products are suitable for removing fresh and small bitumen contaminants. Almost every car enthusiast has them in his garage and is always available for use.

Gasoline and diesel fuel

They remain the most popular and sought-after means in the fight against bitumen stains. Unlike many universal products, they can also deal with old stains, but require a lot of effort. You have to make many passes to achieve the desired effect.
The main disadvantage of using kerosene is the presence unpleasant odor, as well as a greasy coating that remains after washing off the resin. In addition, this universal product is truly active, so it often removes paintwork along with bitumen. Therefore, when trying to remove serious stains, it is better to give preference to more delicate professional products.

White spirit

Similarly, it is better to use kerosene with caution and not for those bitumen stains that have already “eaten into” the paintwork. It removes fresh resin just fine. The advantage of the product is that it can be used at home. If the stains are small and not very old, they are removed as follows:

The car is washed thoroughly. It is better to use a special shampoo for the car. Thanks to this, it is possible to avoid scratches and completely wash away dirt and dust.
Wait for the paintwork to dry and only then begin to treat the tar stains. A cotton or foam swab is dipped into the solvent, wait about 5 minutes and begin to carefully wipe off the bitumen contamination.

You can't put in the effort. When “White spirit” does not give the desired result, it means that the resin will have to be washed with special (professional) means or contact a workshop.

Additional products and solvents

Alcohol or regular nail polish remover solvents, of course, can also help remove resin, but only fresh and in small quantities. Such products will not help with old and large stains. They are absolutely powerless in such cases, but they will help remove dirt when, for example, you return from a trip and find resin stuck to the body.

Professional compositions

They differ from universal ones in their improved composition. Professional products contain oil fractions that remove bitumen and tar contamination, as well as other special additives. The disadvantage is excessive aggressiveness. They require careful adherence to instructions and work experience. If you plan to use such a product, it is better to first test the product on a small area.
Among the most popular professional formulations that are recommended for use at home are the following:

Mazbit Turbo made in USA;
"Profam-3500", produced in Russia;
Cleaner with fresh citrus scent No. 7535, made in Sweden;
Teer Entferner, which is produced in Germany;
TurtleWaks, proven in the fight against bitumen stains.

Among the latest developments You should pay attention to synthetic clay, which is similar to plasticine, removes not only bitumen, but also other contaminants, and is also very delicate, without damaging paint and varnish. You can also use a special auto scrub, which is made of rubberized material in the form of a napkin, circle or mitten.

Important nuances for removing bitumen stains

To get rid of resin and not damage your car’s paintwork, you must follow certain rules:

always read and adhere to the instructions supplied with the product;
wash and clean the body before removing bitumen;
allow the surface to dry thoroughly before cleaning the paintwork from resinous stains;
apply the product from above so that it flows down evenly;
let the composition “stand” for the time specified in the instructions;
volatile agents, which include all solvents, should be applied in small doses;
It is better to remove stubborn stains with a brush or brush, working the area point by point;
Be sure to wash your car with car shampoo and clean water, since all bitumen removers leave a greasy residue.

Bitumen should always be removed fresh. This will avoid the problem of removing old resin.

To minimize the risk of damage to the paintwork, it is necessary to use only proven and safe means for removing bitumen stains. In addition, the procedure should not be delayed. The longer the resin is on the body, the more difficult it is to remove. In some cases, it is no longer possible to save the paintwork.

It is recommended to avoid areas where repair work has recently been carried out or where there are bitumen puddles. If this is not possible, it is necessary to reduce the speed of the vehicle to a minimum. This will reduce the likelihood of bitumen appearing on the body, but after the trip you should definitely inspect the car for stains. You should check not only the paintwork, but also the wheels. When bitumen remains on the latter, as the car moves further, it will become soft and fall on the car.
You should not neglect protective agents - polishes, films for the bumper and hood, polishes, waxes and others. They allow you to quickly and easily get rid of any contaminants, including bitumen.

Bitumen (tar, mountain tar) is an organic compound applies in road construction or production of insulating materials.Removing road potholes in hot weather leads to bitumen getting onto the car body.

The thinner the rock tar, the more dangerous it is for the car. It penetrates into the paintwork (hereinafter referred to as paintwork). Removing bitumen stains from a car is possible. Eatseveral ways, helping to preserve the paintwork in its original form.

Fresh spots

Black drops, drips and splashes of bitumenspoil the appearance of the car. There are special compounds for removing bitumen from the vehicle body. When purchasing chemicals, they are guided by the age of the stains, and not by the size of the stains.

How to remove tar (review of the best compounds):

LIQUI MOLY Teer Entferner is developed based on a combination of solvents for removing resins from the body. Can be used for paintwork and glossy surfaces. LIQUI MOLY Teer Entferner dissolves resin, paint and tar residues well. Application: shake the can and spray to dirty areas, wait 3 minutes and delete bitumen with a soft cloth.
Cleaner with fresh citrus scent No. 7535 has proven itself well. Produced by a Swedish factory. Means allows you to clean car parts (fenders, body, headlights) from tar efficiently and in 1 minute. Possesses gentle effect on paintwork. Doesn't fit for old and dried formations. Apply for 1 minute. Remove remaining tar with a soft cloth.
Turtle Wax Bug & Tar Remover is made in the UK. The stain remover is used to remove bitumen from car bodies. Turtle Wax Bug & Tar Remover, unlike similar compounds, held on a vertical plane. Not harms paintwork. Application of the drug: spray on the body of the car, wait 1 minute, remove the remaining tar with a rag.
Tar stain cleaner “Agate” is sold in a volume of 500 ml.They remove resin, fat and oil contaminants. Sold as a spray.
Doctor Wax DW5628 penetrates deeply into cracks and micropores of paintwork. The cleaner quickly removes even non-visible, but chemically active pockets of contamination. Doctor Wax DW5628 not only removes tar from the pores, it creates a protective coating.
WD-40 removes fresh resin droplets. Use if special chemicals are not at hand.

Bitumen reacts with the paintwork, leaving marks on it. If contact lasts for a long time, dirt cannot be removed; the body will have to be painted.

Dried spots

Fresh bitumen stains can be easily removed. After drying, the resin can be removed using professional means.

Among the best cleansing compounds highlight:

Profoam Kangaroo 5000 removes rock tar, insect marks and road grime. Comfortable when applied, it penetrates to the very base of dried bitumen in 30 seconds. To remove bitumen stains shake Profoam Kangaroo 5000 spray can, apply from a distance of 30 cm. Wait 30 seconds and use the cleaner again. Wipe stained area of soft cloth
Cleaner with fresh citrus scent No. 7230 and No. 7535 analogues. Used on old stains.Cleaner with fresh citrus scent No. 7230 is considered the best among similar compositions.
Grass anti-bitumen is designed to remove oil products, bitumen stains and rubber traces. The spray does not need to be diluted; it is used in concentrated form. Antibitumen is sprayed onto the contamination and left for 10 minutes. Remove the tar with a soft cloth, then wash the car with water.
Wurth is an industrial universal cleaner.Dissolves well, sealant and oil residues. For sale in an aerosol volume 500 ml. It's cheap.
Astrohim spray, similar to Profoam Kangaroo 5000, penetrates into the deep layers of dried tar. Has a complex special additives that allow you to remove old stains. Astrohim is a strong chemical that begins to act immediately after use. There are no aggressive substances in the composition, the cleaner does not damage paintwork.
Autoprofi – the cheapest remedy, no less effective. Before use, shake the can, apply to the surface, wait 3 minutes and remove with a sponge., without waiting for it to dry.

Heavier Remove hardened dirt from the car rather than fresh dirt. You have to gradually dissolve the thick layer of hardened bitumen with a cleaner.

Features of use

Remove bitumen stains from cars completely Can , using professional formulations according to the instructions.

The right way uses:

Wash the car with special shampoo. Dry the body.
Lightly moisten the resinous spots with water.
Try to remove some of the dirt with a rag.
Apply purchased cleaner.Leave as directed, rinse with water.
Repeat until not a trace remains of tar contamination.
Protect car with wax, polish or other similar product.

Using professional solutions without following the instructions will result in the paint dissolving.

Available means

If you use household chemicals it doesn’t work, you can remove bitumen stains with helpers means.

Diesel fuel, acetone, margarine and other substances will help solve the problem, but longer than professional products.

How to use them:

Diesel fuel cheap and effective. Wear gloves and handle car body. After removing bitumen stains, wash car at a car wash or at home Karcher and soapy water. Diesel fuel is replaced by kerosene/gasoline.
White spirit is a premium solvent. Use as a last resort,dissolves paint coatings.
The use of acetone is highly discouraged. It removes road tar along with paintwork. If you act carefully, you can clean the body. Remove with acetone Dried bitumen is not allowed.
Margarine will soften road tar ifremove wet resin. Apply with a ragto dirty places wait until the tar will dissolve. This will take from 1 to 3 hours. Carefully delete the remains with a clean cloth.Wash carefully so as not to damage the paintwork.
Vegetable oil is used similarly to margarine. It helps remove only fresh stains.
Abrasive clay is economical, removes resins well. First, then a block of clay is kneaded into a cake and used to clean the wet area.

Solvent and turpentine are also used among available means. You will have to work hard to wipe it off; a matte stain may remain on the body.

The car must be protected from such pollution. Protective compounds help with this. They can be applied independently or in a workshop.Gives the best resultwax polishes.The bitumen will be removed at a car wash if you cannot clean the body yourself.

Average molecular weight is a conventional value and refers to such a homogeneous gas in which the number of molecules and total mass equal to the number of molecules and the mass of the gas mixture.

If the value of the gas mixture constant is known, then

Replacing the gas constants R 1, R 2, ..., R n with their values from the Clapeyron equation, we obtain an expression for the average molecular weight if the mixture is specified by mass fractions:

(3-8)

If the mixture is specified by volume fractions, then, as follows from equation (3-6),

Since That

The average molecular weight of a mixture of gases is equal to the sum of the products of the volume fractions and the molecular weights of the individual gases that make up the mixture.

Partial pressures

The partial pressure of a gas can be determined through mass fractions from the Clapeyron equation, if the basic gas parameters are known:

(3-10)

To find the partial pressure of each gas when specifying the mixture by volume fractions, you can use the Boyle-Mariotte law, from which it follows that at a constant temperature

(3-11)

The partial pressure of each gas is equal to the product of the total pressure of the mixture of gases and its volume fraction.

Equation (3-11) is usually used in technical calculations and when testing thermal installations. Volume fractions gases are determined special devices- gas analyzers.

Specific enthalpy, i.e. enthalpy per 1 kg, is denoted by the letter i and is, by definition, complex function kind

The enthalpy differential di is the elementary amount of heat involved in the process at constant pressure. All the heat in the process at constant pressure is spent on enthalpy changes:

(5-15)

From equation (5-12) it follows that

(5-16)

Enthalpy is greater than external heat by the amount of work vdp, which is represented on the pv diagram by the elementary area abed (Fig. 5-11). Obviously, the entire square. ABCD is given by

, which is called available, or useful, work.

The change in enthalpy is completely determined by the initial and final states of the working fluid and does not depend on intermediate states. The change in gas enthalpy in cycles is zero, i.e.

Since enthalpy is a function of the main parameters of the state, di is the total differential of this function for any independent variables characterizing the state gas;

(5-17)

The change in enthalpy in all processes occurring between two points A and B will be the same (Fig. 5-12).

The physical meaning of enthalpy will be clear from the following example. A weight weighing t kg is placed on a moving piston in a cylinder containing 1 kg of gas (Fig. 5-13). Piston area /; internal energy of the working fluid and. The potential energy of the weight is equal to the product of the mass t of the weight t and the height S. Since the gas pressure p is balanced by the mass of the weight, its potential energy can be to express it differently:

The product /S is the specific volume of the gas. From here

The product of pressure and volume is the work that must be expended to introduce a gas of volume v into external environment with pressure p. Thus, work pv is the potential energy of the gas, depending on the forces acting on the piston. The greater these external forces, the greater the pressure p and the greater the potential energy of pressure pv.

If we consider the gas in the cylinder and the piston with a load as one system, which we will call an extended system, then the total energy E of this system consists of the internal energy of the gas and potential energy piston with a load equal to pv:

From this it is clear that enthalpy i is equal to the energy of the extended system - the body and environment. This is the physical meaning of enthalpy.

Enthalpy values for vapors, gases and gas mixtures are given in technical and reference literature. Using these data, it is possible to determine the amount of heat involved in the process at constant pressure. Enthalpy received great value and application in calculations of heating and refrigeration units and, as a parameter of the state of the working fluid, significantly simplifies thermal calculations. It allows [the use of graphical methods in the study of all kinds of thermodynamic processes and cycles.

It is especially advisable to use enthalpy when p and T are taken as the main parameters. This can be clearly seen if enthalpy i is compared with internal energy And. At v = const, the equation of the first law of thermodynamics dq = = du + pdv turns into dq v = du, or q v - u 2 -u 1 and at p = const q p = i 3 - i 1.

Enthalpy ideal gas," just like the internal energy, is a function of temperature and does not depend on other parameters. Indeed, for an ideal gas

therefore (since both terms depend only on temperature), i = f(T).

Then, by analogy with internal energy, we will have

that is, in any process of changing the state of an ideal gas, the derivative of the change in enthalpy with respect to temperature will be a complete derivative.

Numerical values of enthalpies ideal gases are given in the appendix, table. XIII.