On swidkіst reaction vplyvayut. Lesson "Sharpness of a chemical reaction. Factors that are added to the severity of a chemical reaction". Backwardness of chemical reactions

The speed of the reaction to deposit depends on the nature and concentration of the reacting substances, temperature, pressure, the presence of a catalyst and that power, the degree of detail of the solid phase, the degree of light quanta and other factors.

1. Nature of reactive speeches. Under the nature of the reactive speeches, the nature of the chemical bond in the molecules of the reagents is understood. The development of links and the establishment of new links determine the value of the stability constant, and, by the same token, add to the process of overshooting the reaction.

The magnitude of Energia Akivatsії є Tim factor, for the first kind of good acquisition of the price of recycling recycling on the Schwidkіst reaches: Yakscho Energia Akivatiya Mala, Schwidkіt Takovo Recariya Great, Fort, SIM REACTAKII OBMINU OBMINUT PRESSIBLE MITTєVO, BELIEVE BY SHVIDCOSTY REPAKS IN PERUM RADIKALIV; as the energy of activation is great, the speed of such a reaction is small, for example, there are many reactions between speeches with covalent chemical bonds, between gas-like speeches.

2. Concentration of reactive speeches. Kіlkіsnu characteristics of the fallowness of the dryness of the reaction in the form of concentration is set chinnyh mas law (Guldberg and Vaazi, 1867): the speed of the chemical reaction is directly proportional to the concentration of the reactants, the elements at the stage, equal to the stoichiometric coefficients of the equal reaction.

For the reaction aA + bB \u003d cC + dD, the mathematical viraz to the law of incombustible masses can look like:

υ =k [A] a [B] b or υ \u003d k C A a C B b,

de v - Fluidity of chemical reaction; [BUT], [IN] or BEHIND, W W– molar concentrations of reacting speeches; a, b – stoichiometric coefficients of reactive speeches; k- Coefficient of proportion.

Name similar virazi kinetic equals of reactions . Proportionality coefficient k in a kinetic equal name speed constant . The fluidity constant is numerically superior to the fluidity of the reaction at concentrations of reacting speeches of 1 mol/l; k deposit due to the nature of the reacting speeches, temperature, method of expressing the concentration, but not to deposit depending on the concentration of the speeches that react.

For heterogeneous reactions of the concentration of hard speeches in equal hardness are not included, oskіlki reaction ide less on the surface of the phases. For example, the kinetically equal reaction of the fire of the fire C (tv) + O 2 (g) \u003d CO 2 (g) looked like: υ =k [Pro 2].

The sum of indications in the concentration steps of reagents in a kinetic equal reaction is called order of chemical reaction . The order of the given speech ( private order ) is shown as an indication of the level at the concentration of speech. For example, the extreme order of the reaction: H 2 + I 2 \u003d 2HI do two, private orders of water and iodine are equal to one, because υ=k · · .

3. Temperature. The degree of coldness of the reaction depends on the temperature van't Hoff's rule (1884): when the skin temperature rises by ten degrees, the reaction increases by about 2-4 times. Mathematical Virase Van't Hoff Rules:

υ 2 = υ 1 γ∆t/10

de υ 1 і υ 2 - Quickness of reaction at t 1 and t 2 ; ∆t\u003d t 2 - t 1; γ is a temperature coefficient, which shows how much time the reaction speed increases for a temperature increase of 10 ºС.

The dependence of the constant of the fluidity of the reaction with temperature is expressed by Arrhenius (1889):

k \u003d A e - E / RT

de E – activation energy, cal/mol; J/mol; e is the basis of the natural logarithm; A - post_yna, yak to lie in the temperature; R - Postiyna gas.

The influence of temperature on the speed of the reaction is explained by the fact that at elevated temperatures there is a sharp (in geometric progression) increase in the number of active molecules.

4. On top of the reactive speech and vise. IN heterogeneous reactions interactions of speech bubbles appear on the surface of the phase separation, that the greater the area of the surface, the greater the speed of the reaction. In times of increased surface glare, it shows an increased concentration of reactive speech.

On the speed of reactions for participation gas-like speeches, pouring change vise. A change or an increase in the pressure to produce up to major changes is obligatory, and the shards of the number of speeches do not change at that, the concentration of speeches that react will change.

5. Catalyst. One of the methods for accelerating chemical reactions and catalyses, which is used for additional introduction of catalysts, which increases the speed of the reaction, but does not show up afterward. The mechanism of the catalyst is to change the activation energy of the reaction, tobto. to a change in the difference between the average energy of active molecules and the average energy of the molecules of the outer speeches. The speed of the chemical reaction in your own will increase. As a rule, the term " catalyst » zastosovuyut until quiet speeches, yakі zbіlshuyut quickness of the chemical reaction. Speech, which changes the speed of reaction, is called inhibitors .

Catalysts take an uninterrupted fate in the process, but after the end of it, they can be seen from the reactionary sum of the left number. Catalysts are characterized selectivity , then. zdatnіst spit on the passage of the reaction in the song directly, to that from the very same vihіdnyh rechovina can be taken away different products in the fallow of vicarious catalyst.

Special space is occupied by biocatalysts –enzymes , which are proteins. Enzymes are poured on the basis of strictly singing reactions, so that the selectivity can be even higher. Enzymes speed up reactions in millions and trillions at room temperature. As the temperature rises, the stench wastes its activity, the shards cause the denaturation of proteins.

There are two types of catalysis: homogeneous catalysis , if the catalyst and speech are in the same phase, heterogeneous , If the catalyst and speech are in different phases, then. reactions run on the surface of the catalyst. The catalyst does not swell the station equal to the system; It is worth noting that the equivalence shows a minimum isobaric-isothermal potential (Gibbs energy), and the equivalence constant may have the same value as the presence of a catalyst, and without it.

Dia of a homogeneous catalyst I believe in the fact that I react with one of the last speeches with the approved intermediate half, yak, at my own hand, enter into a chemical reaction with the other speech, giving the bazhan reaction product that "catalyst". Thus, with a homogeneous catalyzation of the process, there are several stages, but with lower activation energies for the skin stage, lower for a direct non-catalytic process.

Let speech A react with speech B, satisfying the half of AB:

The reaction proceeds from an insignificant swirl. When adding a catalyst K reactions proceed: A + K = AK and AK + B = AB + K.

Having added qi two equals, we take: A + B = AB.

An example of a reaction that proceeds through the participation of a homogeneous catalyst can be the reaction of oxidation of sulfur oxide (IV) to sulfur oxide (VI): without a catalyst: SO 2 + 0.5O 2 = SO 3;

with NO 2 catalyst: SO 2 + NO 2 \u003d SO 3 + NO, NO + 0.5 O2 \u003d NO 2.

Dia of a heterogeneous catalyst It depends on the fact that the gas molecules (or any) are adsorbed on the surface of the catalyst crystal, which leads to a redistribution of the electronic gap in the adsorbed molecules and a weakening of the chemical bond in them right up to the complete dissociation of the molecule into atoms. Significantly easier in the interplay of adsorbed molecules (atoms) of reacting speeches among themselves. The larger the surface, the more efficient catalyst. As heterogeneous catalysts, metals (nickel, platinum, palladium, copper), crystalline aluminosilicate zeolite, Al 2 O 3 , Al 2 (SO 4) 3 and in. are widely used.

The reverse of chemical reactions.

Chemically zealous

All chemical reactions can be divided into werewolves and non-reversible by looking at the turnover. Werewolves reactions are called that occur simultaneously at two opposite directions; irrevocable – reactions that run practically to the end in one straight line.

Signs practical irreversibility reaction є:

1) vision of gas: Na 2 CO 3 + 2HCl \u003d 2NaCl + H 2 O + CO 2;

2) precipitation: BaCl 2 + Na 2 SO 4 = BaSO 4 ↓ + 2NaCl;

3) the adoption of a little dissociative speech (weak electrolyte):

NaOH + HCl \u003d NaCl + H 2 O;

4) seeing a great amount of energy:

H 2 + Cl 2 \u003d 2HCl + Q (the reaction proceeds with a vibe).

Most chemical processes are turnarounds, tobto. behind the silence of the minds themselves, direct and reverse reactions flow. The mill of the reverse process, with some kind of direct and reverse reaction, is called chemical zealous. I will become a necessary sign of the chemical (thermodynamic) equivalence of the system - immutability - at the hour for the tasks of the best minds. Chemistry is more dynamic to wear a dynamic character: some of the other speeches enter into the reaction, the same is established after the hemorrhagic reaction. The system is pragne to a minimum of free energy, which is guarded by the station of jealousy. Chemіchnі rіvnovagi hіvchayutsya hіmіchnі іvnovagi іn chastіshe vyvchayutsya іn stіynym tysk і tematurі.

The skin is crumbly and chemically rіvnovag is characterized by its constant – the equalization constant K p. For system aA+bB ↔ cC+dD

quickness of direct reaction: υ pr\u003d k 1 [A] a [B] b;

swidkіst zvorotnoї reaction: υ arr\u003d k 2 [C] s [ D ]d.

Zastosovuyuchi law dyuchyh mas to direct and salvage reactions of the reverse process otrimuyut viraz for rozrahunke constants of chemical equivalence:

K P \u003d k 1 /k 2 \u003d [C] c [D] d / [A] a [B] b,

de do r – constant of chemical equivalence (deposit according to the nature of the rivers, temperature and pressure); [A], [B], [M], [D] – equal molar concentrations of reactive speech, mol/l; a, b, c, d – stoichiometric coefficients of reactive speeches.

At the station, it is necessary to increase the concentration of the products of the reaction to the concentration of the final speech gradually, moreover, the concentration of the skin speech is taken in steps, which increases the number of moles of the speech, to take part in the reaction.

The value of the chemical reactivity constant characterizes the extent of overshooting the reverse reaction. The greater the value of K P, the more the reaction proceeds, the more the reaction of the products is established.

For example, for the 2NO + O 2 ↔ 2NO 2 system, the chemical constants are equal: KR = 2/2.

In times heterogeneous reactions in virazes, the constants are equal to less than the concentration of quiet speeches, as in the gas phase. For example, the reactions CO 2 + Z ↔ 2CO constant equals may look like: K P = 2 /.

For reactions that occur between gas-like speeches, the equalization constant can be expressed through the partial pressure of reacting speeches. In the meantime, the equalization constant K P can be expressed through activity a reactive speeches. For ideal Calculate the coefficients of activity equal to one, activity equal to molar concentrations. The equalization constant K R of the chemical reaction is related to the standard variable Gibbs energy equal to:

∆G 0 T = – RTlnK p = – 2.3RTlgK p .

Officials, what to add to the constant of jealousy: the main factor that contributes to the equalization constant, є the nature of reactive speeches, mіtsnіst khіmіchnyh zv'yazkіv v spolukakh. The second factor that determines the value of the constant of equality is to serve temperature. fallow the constants of equalization in terms of temperature are expressed equal:

lnK P = – ∆H/RT + ∆S/R

The constant of equality does not lie in the presence of partial pressures and the concentration of reacting speeches. The change is only added to the change in the position of the equal and the steps of the transformation of speeches. Steps of transformation speeches – changing the quantity of speech from the equal sum to the final quantity of speech.

Mechanisms of overcoming of chemical transformations and yogo stability of development of chemical kinetics. Chemical processes run at the hour with different speeds. Yakіs vіdbuvayutsya shvidko, mayzhe mittєvo, for the passage of others needed to finish the trival hour.

In contact with

Quickness of reaction- swidk_st, with which the reagents are sifted (their concentration changes) or the products of the reaction are settled in one obsyag.

Officials, zdatnі vplyvat on swidkіst chemical reaction

For those who are quick to react chemically, the following factors can be added:

speech concentration;
the nature of the reagents;
temperature;
the presence of a catalyst;
vice (for reactions in a gaseous medium).

In this way, changing the songs of the mind through the chemical process, you can stick to those who are weakly running through the process.

In the process of chemical interaction, parts of reacting speeches stick together one by one. The number of such zbіgіv is proportional to the number of particles of speech in the total sum that reacts, and therefore it is proportional to the molar concentrations of the reagents.

Chinni Mas Law signifies the staleness of the dryness of the reaction in the form of molar concentrations of speeches, as in mutuality.

For an elementary reaction (A + B → ...), this law is expressed by the formula:

υ = k W A W B,

de k is the speed constant; A і B - molar concentrations of reagents, A і B.

If one of the reacting speeches is found in a solid state, then the interactions occur on the surface of the phase separation, at the link with zim the concentration of solid speech is not included until it is equal to the kinetic law of mass, which is to be found. For the understanding of the physical sensitivity of the density constant, it is necessary to take Z, A and C equal to 1. Therefore, it became clear that the density constant is the most accurate of the reaction at concentrations of reagents, equal to one.

The nature of the reagents

Since chemical bonds of reactive speeches are destroyed in the process of interchange and new bonds of products in the reaction are established, the nature of the bonds plays a great role, which takes part in the reaction of the molecules of reactive speeches.

Surface area of reagent dot

Such a characteristic, like the area of the surface of the solid reagents, is significant for the duration of the reaction. Detailing the hard speech allows you to increase the area of the surface of the dot of the reagents, and also, to speed up the process. The area of dotik rozchinnyh speeches is easy to expand the speeches.

Reaction temperature

With an increase in temperature, the energy of the frequency, which is collapsing, with growth, obviously, that with the increase in temperature, the chemical process itself will slow down. As a prime example of how the increase in temperature affects the process of speech interaction, one can use the data in the tables.

Table 1

For a kіlkіsnogo description of how the temperature can influence the swidkіst vzaєmodії rechovina, vikoristovuyut van't Hoff's rule. Van't Hoff's rule lies in the fact that when the temperature rises by 10 degrees, it accelerates by 2-4 times.

The mathematical formula that describes the van't Hoff rule looks like this:

De γ – temperature coefficient of fluidity of the chemical reaction (γ = 2-4).

A little more accurately describe the temperature stagnation of the constant of Arrhenius' fluidity:

De R - universal gas steel, A - multiplier, which is determined by the type of reaction, E, A - activation energy.

Activation energy is called such energy, as a molecule can come, so that chemical transformation occurs. This is like an energy barrier, which will need to be overcome by the molecules that stick together in the reactionary bond, for re-arranging the bonds.

The energy of activation is to lie in the name of the famous officials, and to lie in the nature of speech. Activation energy values up to 40 - 50 kJ/mol allow speeches to react one by one actively. However, the activation energy exceeds 120 kJ/mol, then speeches (for normal temperatures) will react even more correctly. Change the temperature to change the number of active molecules, that is, molecules that have reached the energy of greater, lower activation energy, and also, building to chemical transformations.

Dia of the catalyst

To call speech a catalyst, to speed up the process, but not to enter the warehouse of yoga products. Cataliz (an early transition of the chemical transformation) is subdivided into homogeny, heterogeneous. If the reagents and the catalyst are transferred to the same aggregate mills, then catalysis is called homogeneous, if different, then heterogeneous. Mekhanizm dії katal_zatorіv raznomanіtnі і dоsіt foldіnі. In addition, the next thing to note is that the catalysts are characterized by vibrancy. So that same catalyst, speeding up one reaction, may not change the speed of another.

vice

If the reformed take the fate of the gas-like speech, then for the speed of the process, the change of the vice in the system . Tse vіdbuvaetsya to that, For gas-like reagents, change the pressure to produce a change in concentration.

Experimental determination of the stability of the chemical reaction

It is experimentally possible to determine the speed of the course of a chemical transformation, taking into account the data about those, how the concentration of speech changes in a single hour, which enter into a reaction, or a product. Methods for collecting such data are subdivided into

chemistry,
physical and chemical.

Chemical methods are simple, accessible and accurate. With this additional help, they determine the concentration of reagents and products without intermediary zameryayuchi. In the case of a different reaction, to control it, as the reagent is stained, samples are taken. After what is indicated in the sample reagent. Zdiisnyuyuchi svіdbіr samples through equal intervals of time can take data about changing the amount of speech in the process of vzaєmodії. Most often vikoristovuyut so see the analysis, like titrimetry and gravimetry.

As the reaction runs smoothly, if you take a sample, you should be sure. Tse it is possible to grow for additional cooling, harsh removal of the catalyst, It is also possible to expand the production or transfer one of the reagents to a non-reaction mill.

Methods of physical and chemical analysis in modern experimental kinetics are more often observed, less chemical. With this help, it is possible to predict a change in the concentration of speech in a real hour. In case of any reaction, there is no need to take a sample and select a sample.

Physico-chemical methods are based on the world of physical power, like to lie in a place in the system of the singing half and change with the hour. For example, if the reactions take the same fate as the Gazi, then such power can be squeezed. Also, the electrical conductivity, the indicator of brokenness, the spectrum of the slurry of speeches are vimiryuyut.

In the previous divisions, some aspects of kinetics were looked at, and now the hour has come to pick up the big bags: why should the quickness of the reactions be deposited and how can they be controlled.

(a) The nature of the reagents. The food was not clearly discussed, but implicitly my yogo was stuck around constantly. Is speech molecular or non-molecular? It is rich in what it means, if the reaction is homo-or heterogeneous. Balance the activity of oxides in carbon and silicon: if CO 2 is consumed in the meadow, in contact with OH- ions, a skin molecule appears, and in SiO 2 in the same situation, only the surface of the crystal is in contact with the meadow, so there is no use for that part the quickness of the reaction is inconspicuously less. Yaka mіtsnіst zv'azku? It pours in the energy of activation. The oxide activity of the atoms in the sour is rich, the lower atoms in chlorine, and in the molecule of the sour the bonds are richly mesnish, so wine is less active. What is the polarity of the calls? It adds to the mutual orientation of molecules and the mechanism of opening the bond. What is the geometry of the structure? Chi is friendly won for reaction? You can add і frequency multiplier, і activation energy.

Under the camp of reagents, there are odors: there are stinks in the independent phase, or in different ways, as the nature of the retailer: HCl (gas), HCl (aqueous) and HCl (in benzol) - all three different speeches; for hard speeches - defectiveness of the structure, the state of the surface, the presence of a house there.

(b) Temperature. Weep it up to the level of Arrhenius, but it’s also necessary to check the temperature of the cob, and then change the reaction afterward (div. below p. g).
(c) The presence of "outside" speeches, so as not to take the fate of the total equal reaction. The stinks can be catalysts, inhibitors, initiators, inert third-party particles that make it easier to shave off the Lantzug reaction, catalytic otters, etc. speechovina, yakі vzaєmodіyut іz catalysts and pozbavlyayut yoga activity. In heterogeneous processes, stench is added to the defectiveness of the reagents and products and the speed of diffusion through the ball to the product (like they are chromium in the oxide layer). The retailer also pours into the camp of the reagents, but it may be insured at the record level (div. p. a).
(d) The nature of the products. The product can be a catalyst. For heterogeneous reactions, it is of paramount importance that the product does not close the surface of the contact and is possible through new diffusion. In reactions that are limited by the germ of light, the primary role is played by the activation energy of the first microcrystal product.
(e) Concentration of reagents. Іstotna seldom there, de є razchiny, vplyaє zgіdno іz law dії mas, but it is not required to forget about її change at the hour, but for heterogeneous reactions - and at space.
(e) Phase contact area. Іstotna is less than heterogeneous reactions, at its own trace of memory about the possibility of closing the products of the reaction.
(f) Influx of non-thermal forms of energy. On hіmіchnі reaktsії mozhut vplivati opromіnennya svіtlom abo ultrafіoletovimi (UV) abo rentgenіvskimi Promen (їh vivchaє fotohіmіya) radіoaktivne opromіnennya (radіatsіyna hіmіya) elektrichny rozryad y gases (plazmohіmіya) transmission Strum through elektrolіt (elektrohіmіya) mehanіchny vpliv (mehanohіmіya) . Your injection may be twofold.
1) Speedy mimic processes. For example, the Lantzug reaction of water with chlorine can be vibrated with clarification, heating without clarification, and with an electric discharge; the interplay of calcium oxide and silicon during heating is mimicry, and grinding the summish is more likely to speed up the process, destroying the product and creating defects in the structure.

Photochemistry of cicava tim, which allows vibrating to activate one of the many parallel processes. For which vicorist quanti, the energy of which h exactly matches the energy of dissociation either of the destruction of the same molecules or of the first few molecules of the molecules. However, other molecules of other cells are not activated. Heating and rubbing activates all speech without discrimination.

2) The creation of processes, if not to go. Just like the energy of the old dzherel, the movement of the energy of Gibbs G is seen. Albeit for the energy conversion of either an electric discharge, it is possible to vibrate the dissociation of the oxygen molecule O 2 2O, and the subsequent reaction O + O 2 O 3 is already there itself.

Similarly, the distribution of electric power: 2H 2 O \u003d 2H 2 + O 2 ide mivolіl, more than rahunok elektroenergії vіd zvnіshny dzherel.

Possibility or impossibility of such reactions is determined by the amount of energy, which is introduced: if the energy of a quantum (or the voltage on the electric power plant) is less than the required value - the reaction does not go, it is independent of the number of quanta or the strength of the strum. The frequency of such reactions is determined by the frequency of the energy input: in photochemistry - by the number of quanta per hour, with electricity - by the power of the stream. In addition, in the case of electrolysis, the material of the electrode is important, which can give a catalytic effect (select one of the decile processes or galvanize otherwise), and the speed of diffusion in electrolyte. You can, for example, think so, that during electrolysis, the distribution of sulfuric acid occurs in the process 2H 2 SO 4 \u003d H 2 + H 2 S 2 O 8, although it is thermodynamically more efficient for the distribution of water.

(g) Mass of reagents, size and shape of judge, quality of thermal insulation. The form of this rozmir sudini is strongly influenced by the kinetics of Lantzug reactions, since on the walls there are urvish lancers. If the reaction is exothermic, then it is even more important that the heat rises in the right middle, or leads to the heating of the reaction system. In the rest of the day (great mass and good thermal insulation) the process is self-reinforcing and self-indulgent. As the reaction progresses, the reaction accelerates, and as you see it, more energy is seen, the temperature moves even more, and so on. A solitary wheat grain is practically not oxidized, and a large grain of grain is often self-engaged. That is why, when harvesting in the elevators, the grain is regularly aired through the air.

Podіbne posterіgaєtsya and in case of catalytic expansion of water peroxide. On the other hand, the reaction is not much quicker, but at any time it heats up and the quickness of the reaction grows sharply.

(3) Vice For reactions for the participation of gases, the pressure is adjusted to change the concentration (div. p. e) appropriately to the level of the gas. For systems without gases, it is less expensive, but in solid-phase processes, it is possible to improve the contact of the particles and thereby speed up the reaction.

For the reaction aA + bB \u003d cC + dD, the mathematical viraz to the law of incombustible masses can look like:

υ =k [A] a [B] b or υ \u003d k C A a C B b,

υ 2 = υ 1 γ∆t/10

The dependence of the constant of the fluidity of the reaction with temperature is expressed by Arrhenius (1889):

k \u003d A e - E / RT

de E – activation energy, cal/mol; J/mol; e is the basis of the natural logarithm; A - post_yna, yak to lie in the temperature; R - Postiyna gas.

Let speech A react with speech B, satisfying the half of AB:

The reaction proceeds from an insignificant swirl. When adding a catalyst K reactions proceed: A + K = AK and AK + B = AB + K.

Having added qi two equals, we take: A + B = AB.

with NO 2 catalyst: SO 2 + NO 2 \u003d SO 3 + NO, NO + 0.5 O2 \u003d NO 2.

Distributed: Chemistry

Meta: Actualization and knowledge about the frequency of chemical reactions, the prevalence of the frequency of homogeneous and heterogeneous reactions in various factors.

Ownership: Na 2 S 2 O 3 (0.25n), H 2 SO 4 (2n), stopwatch, two burettes, distilled water, flask with concentrated aqueous ammonia, platinum drіt, two test tubes with H Cl . A piece of granulated tin, a piece of zinc, a second watch.

I Etap lesson - introductory.

The teacher reminds the topic of the lesson, explaining the yoga method and teaching the students how to eat until discussed:

What is called swidkistyu in mechanics?
Introduce butts of chemical reactions from different swedishness.
Navіscho vyvchati swidkіst, z kakoy protіkayut khіmіchnі yavischa?

II stage of the lesson - Explanation of the new material.

Concepts about mobility and the mechanisms of chemical reactions are called chemical kinetics. The frequency of chemical reactions changes at the boundaries. Some reactions are practically mitigated, for example, the interaction of water with sour when heated. Quite often rust on metal objects, products of corrosion on metals.

In this case, it is impossible, obviously, to be between daily and succinct remarks about “Shvidki” and “complete” reactions. It is necessary to characterize such an important understander, like the speed of a chemical reaction (V x. P.)

Speed of chemical reactions - change in the concentration of one of the reacting speeches in one hour

C (mol/l) – concentration of speeches,

t (s) - hour, V. x. p (mol / l) - the speed of the chemical reaction.

Looking at the kinetics of chemical reactions, the next thing to remember is how to deposit in the aggregate mill products and reagents. The products and reagents, taken together, satisfy the so-called physical-chemical system. The structure of the same parts of the system, which may have the same chemical warehouses and power and water-reinforcement in other parts of the system, is called the surface distribution phase. For example, crystals of kitchen salt were brought in near the glass with water, then at the first moment a two-phase system is established, as if it were transformed into a single-phase system after the separation of salt. Sumish gases for normal minds are single-phase (water and alcohol) or rich-phase (water and benzene, water and mercury). Systems that are formed in one phase are called homogeneous, And the systems that can replace the sprat of phases - heterogeneous. Vidpovidno to what in chemistry introduced the concept of homogeneousі heterogeneous reactions. The reaction is called homogeneous, as the reagents and products form one phase:

HCI+NaOH=NaCL+H2O

In a heterogeneous reaction, the reagents and products are found in different phases:

Zn+2HCL=ZnCL2+H2

In times, as reagents, products form different phases (Zn is solid, ZnCL2 is different, and H2 is gas).

As the reaction proceeds between speeches in a heterogeneous system, then the speeches that react do not stick among themselves in their entirety, but only on the surface. In connection with cym, the designation of the frequency of the heterogeneous reaction:

The frequency of a heterogeneous reaction is determined by the number of moles of speech in the result of a reaction in one hour on a single surface

- Changing the amount of speech (reagent or product), mol.

- Interval hour - s, min.

Officials who pour in swidkist reaction

1. The nature of reactive speeches. The teacher shows the proof:

At two test tubes, pour 1 ml of HCL. In one we put a piece of granulated tin, in the other - a piece of zinc of the same size. Learn to equalize the intensity of seeing bulbs to gas, to equalize the interrelationship of HCL with zinc and tin, to splinter biscuits about the influx of the nature of the reactive speeches on the swidkistity of the reaction.

2. Concentration of reactive speeches.

Dosvid - Interaction of sodium thiosulfate with sulfuric acid.

a) Spend a link to the yakіsny dosvіd. For this, pour 1 ml of sodium sulfuric acid into a test tube and add sodium and add 1-2 drops of sulfuric acid. Significantly, after a certain hour, opalescence will appear, and further away, a cloudy rozchina in the form of a free sirka:

Na2S2O3+H2SO4=Na2SO4+SO2 + S+H2O

An hour to pass through the cracking until the litter cloudiness, to lie down in the dryness of the reaction.

b) In three numbered test tubes, pour 0.25 N from the burette. sodium thiosulfate: 1 ml for a Persian, 2 ml for a friend, 3 ml for a third. To the first test tube, add 2 ml of water from the burette, to the other - 1 ml of water. In this order, mental concentration will be: in test tube No. 1 - C; in test tube No. 2 - 2C; in test tube No. 3 - 3С.

In test tube No. 1 with sodium thiosulfate, add 1 drop of sulfuric acid, shake it for mixing, turn on the stopwatch instead. Indicate the hour from the beginning of the expansion until the litter appears opalescence.

Repeat until test tubes No. 2 and No. 3, add also 1 drop of sulfuric acid and the hour of the reaction.

After carrying out the check on the future chart of the fallowness of the concentration of the reaction of the concentration of the reacting speeches, then on the abscissa axis it shows the mental concentration of sodium thiosulfate, on the axis of the ordinates the concentration of the reaction. (The schedule can be prepared ahead of time).

Learn to analyze the graph and analyze the visnovki about the staleness of the dryness of the reaction to the concentration of the reacting speeches.

Influx of the concentration of reagents on the degree of chemical interaction is manifested by the basic law of chemical kinetics.

The speed of chemical reactions that proceed in a homogeneous medium at constant temperature is directly proportional to the concentration of reacting substances, the products of which are at the stage of their stoichiometric coefficients

= k[A]n [B]m

Price equalization - kinetic equalization of speed. [ A], [B] (mol/l) is the concentration of the outward speeches; n, m- Coefficients in equal reactions; k- speed constant.

Physical change of the speed constant ( k):

yakscho [ A] = [B] = 1 mol/l => = k 1 n 1m. , tobto. = k. Tse shvidk_st ts_єї reactions in standard minds.

No. 1. 2H 2 (g) + O 2 (g) -> 2H 2 O (g)

= k 2

How to change the frequency of the reaction, how to increase the concentration of skin from external speeches in 2 times?

1 = k(2) 2 (2);

2 and 2 - new concentrations of outgoing speeches.

1 = k 4 2 2

1 = 8k 2 .

Possibly equal to equals (1) – swidth increased in 8 times.

№ 2. 2Сu (solid) + Pro 2 (g) 2СuO (solid)

= k 2 however, the concentration of solid speech is excluded from equal - it is impossible to change - a constant value.

Cu (tv.) => [Сu] = const

= k,

3. Temperature.

Great influence on the speed of chemical reactions is given by temperature

van't Hoff formulated the rule: p increase in temperature on the skin 10 about 3 to produce an increase in the speed of the reaction by 2-4 times (the value is called temperature coefficient of reaction).

As the average temperature rises, the number of molecules, their energy, and the number of particles increase insignificantly, then a part of the “active” molecules moves sharply, which in effective closures constitutes an energy barrier of the reaction.

Mathematical influence

de? t2,? t1 is the sensitivity of the reaction in case of end-of-life t 2 t 1 temperatures;

Apply: how many times do you have more rapid chemical reaction at t pro: 50 -> 100 pro, yaxcho = 2?

2 = 1 2 100 –50 10 ; 2 = 1 2 5

so that the speed of the chemical reaction is increased by 32 times.

4. Catalyst

One of the most effective contributions to the fluidity of chemical reactions is the selection of catalysts. As you already know the school course of chemistry, catalysts- Tse speeches that change the speed of the reaction, and themselves, until the end of the process, are invariable, both for the warehouse and for the mass. Otherwise, it seems that at the moment of the reaction itself, the catalyst takes an active part in the chemical process, like the reagents, but until the end of the reaction between them, the principle of influence is vindicated: the reagents change their chemical warehouse, transforming into a kind of product, and the catalyst looks like a catalyst.

Most of all, the role of the catalyst is played by the increased speed of the reaction, although the active catalysts do not speed up, but improve the process. The phenomenon of accelerated chemical reactions catalysis, and uplifting - inhibition.

Cataliz is an important branch of chemistry and chemical technology. You knew about the active catalysts, cultivating the chemistry of nitrogen and sirks. The teacher demonstrates the proof.

As soon as you see it, to avenge the concentrations of water and ammonia, place the flask in front of the heated platinum drіt, it will get hot and spend an hour at the station of the red hardening. Ale de todi take the energy that raises the high temperature of platinum? Everything is simply explained. In the presence of platinum, ammonia interacts with sour again, the reaction is more exothermic (H-900 kJ):

4NH 3 (G) + 5O 2 \u003d 4NO (G) + 6H 2 O (G)

While the reaction is going on, initiated by platinum, the heat that is seen is raising the temperature of the catalyst to a high level.

ІІІ Stage of the lesson - Consolidation of the material

Rozrahunkov's head

In two of the same boats, they took 10 s: in the first one - 22.4 l of H 2 . Where is the speed of the chemical reaction greater? How many times?
For 10 s, the concentration of the external speech changed from 1 mol/l. up to 0.5 mol/l. Calculate the average number of responses.
Why is the temperature coefficient of the reaction more stable, even if at t pro: 30 -> 60 the pro speed of the reaction increased by 64 times?

IV Stage of the lesson - Homework

Head 1

How many times in growth do you have a reaction between carbon oxide (II) and sour, so that the concentration of your speeches will increase the loss?

Manager 2

At how many times in growth does the chemical reaction rate at a temperature increase of 40 ° C, so the temperature factor of the rate of reaction rate is 3?

Manager 3

Theory (behind the abstract)

List of references

Gorsky M.V. Learning the basics of global chemistry - M .: Prosvitnitstvo, 1991.
Dorofiev A.M., Fedotova M.I. Workshop on inorganic chemistry. L.: Chemistry, 1990.
Tretyakov Yu., Metlin Yu.G. Fundamentals of global chemistry. - M.: Prosvitnitstvo, 1985.
Ulyanova G.M. Chemistry class 11 St. Petersburg "Parity", 2002.
Makarenya A.A. Repeatable chemistry - M .: "Vishcha school" 1993.
Varlamova T.M., Krakova A.I. Zagalna that inorganic chemistry: Basic course. - M.: Rolf, 2000.