Designation of electrical dissociation. Electrolytic dissociation: equal, peace, constant, reactions. Classification of speeches in dissociation
Electrolytic dissociation of acids
When acid, salt, and bases differ in water, they dissociate into positively and negatively charged ions (cations and anions). Significantly characteristic are signs of dissociation of electrolytes in the skin class of spoluk.
Acids, as you remember, are formed from Hydrogen and acid excess, bound by a covalent polar bond. At the front of the paragraph on the example of the separation of hydrogen chloride, the world was looked at, as if the molecules of the water polar bond is transformed into an ionic one, and the acid is decomposed into cations of Hydrogen and chloride-ones.
Thus, from the point of view of the theory of electrical dissociation of Arrhenius,
Acids are electrolytic, during dissociation of which, cations of Hydrogen and anions of acid excess are dissolved.
Similar to chloride acid, the dissociation of other acids, for example, nitrate, proceeds:
During the dissociation of a sulphate acid molecule, the number of cations in Hydrogen outweighs the number of anions in the acid excess - sulfate ions. The charge of the anion is equal to -2 (in the formulas of ions write "2-"):
The names of the anions that are dissolved in the dissociation of acids are avoided by the names of acid excesses. The stench is pointed at the tables of rozchinnosti on the endpapers.
It is easy to remember that various anions are dissolved in the dissociation of various acids, but there is only one type of cations - cations Hydrogen H +. Later, the very cations of Hydrogen are characterized by the characteristic power of acids - sour relish, change in the preparation of indicators, reactions with active metals, basic oxides, bases and salts.
Rich basic acids dissociate step by step, adding ions to Hydrogen sequentially, one by one. For example, in the case of sulfate acid, the following processes occur:
As can be seen from the induction of equal dissociations of a richly basic acid, anions, which are settled at the first stage of dissociation at the first stage, revenge ions on Hydrogen. The name is shown in the name of anions: HSO - hydrogen sulfate-ion.
The electrolytic dissociation of orthophosphate acid takes place in three stages:
Totally equal dissociation of orthophosphate acid may look like:
In this way, the skin rich basic acid in the form of sprats of anions and all the stench is present at the same time.
Bring respect, that some equals of dissociation should have two-way arrows. What stinks mean, you know in the next paragraph.
Electrolytic dissociation of bases
Substations are composed of cations of the metal element and hydroxide anions. With the dissociation of the bases, the ions pass from the roots. The number of hydroxide ions, which are dissolved during dissociation, is equal to the charge of the metal element ion. In this manner, from the point of view of the theory of electrical dissociation
Substantiate - ce elektrolity, yak dissociation on the cations of the metal element and hydroxide-anions.
Let's take a look at the dissociation of the basics on the basis of the dissociation of sodium and barium hydroxides:
When the bases are dissociated, anions of the same type are established - hydroxide-ions, which signify all the characteristic power of differences in meadows: building change in the presence of indicators, reacting with acids, acid oxides and salts.
Electrolytic dissociation of salts
Salts made with cations of a metal element and anions of an acidic excess. With varying salts in water, ions pass from the roots.
Salts are electrolytic, which dissociate into cations of a metal element and anions of an acidic excess.
Let's look at the dissociation of salts from the butt of dissociation of potassium nitrate:
Similarly, dissociate those other salts, for example, calcium nitrate and potassium orthophosphate:
In the equation of dissociation of salts, the charge of the cation for the absolute value is the most important degree of oxidation of the metal element, and the charge of the anion is the sum of the degrees of oxidation of the elements in the acid excess. For example, cuprum(P) sulfate breaks down into ions
and ferum(SH) nitrate - on ioni
The charge of the cations of the metal elements in the majority of the falls can be assigned to the Periodic Table. Charge the cations of the metal elements in the head subgroups, ring out the number of the group in which the element is mixed:
The metal elements of the secondary subgroups sound to make up the sprat of ions, for example, Fe 2 +, Fe 3 +.
Charges of acidic excesses are easier to assign for the number of ions to Hydrogen in the warehouse of the acid molecule, as they were in the 8th class. A charge of some acidic excesses is induced at the tables of rozchinnosti on the endpapers.
Respect that in equal dissociations of acids, bases and salts, the total charge of cations and anions is to be brought to zero, the shards of speech are electrically neutral.
The stage of dissociation increases the possibility of using acidic and basic salts. Acid salts avenge ions to Hydrogen, like acid. That is why salts are called sour. And in the main salts there are hydroxide-ions, like in the bases.
At the first stage of dissociation of sulfate acid, hydrogen sulfate ion HSO- is dissolved, which causes acidic salts: NaHSO 4 (sodium hydrogen sulfate), Al (HSO 4) 3 (aluminum hydrogen sulfate) and in. На першій стадії дисоціації сульфатної кислоти утворюється гідрогенсульфат-іон HSO-, завдяки чому існують кислі солі: NaHSO 4 (натрій гідрогенсульфат), Al(HSO 4) 3 (алюміній гідрогенсульфат) та ін. Orthophosphate acid is also characterized by acid salts K 2 HPO 4 (potassium hydrogenorthophosphate) or KH 2 PO 4 (potassium dihydrogenorthophosphate).
Для ортофосфатної кислоти також характерні кислі солі K 2 HPO 4 (калій гідрогенортофосфат) або KH 2 PO 4 (калій дигідрогенортофосфат).
In roses, acid salts dissociate in two stages:
У розчинах кислі солі дисоціюють у дві стадії:
Acid salts are less characteristic of rich-basic acids, stink shards dissociate more often. Кислі солі характерні лише для багатоосновних кислот, оскільки вони дисоціюють східчасто. The only wine is a monobasic acid - fluoride. Єдиним винятком є одноосновна кислота – флуоридна. Water-soluble links in the presence of H 2 F 2 particles and fluoride acid can adjust the acidic strength of the KHF 2 warehouse.
Завдяки водневим зв\u0027язкам у розчині цієї кислоти присутні частинки H 2 F 2 і флуоридна кислота може утворювати кислу сіль складу KHF 2 .
Deyakі nerazchinnі hydroxide dissolve cations, in which є hydroxide-ion. Деякі нерозчинні гідроксиди утворюють катіони, в яких є гідроксид-іон. For example, aluminum should be stored at the warehouse for the AlOH 2+ cation, why is it necessary to use the warehouse AlOHCl 2 (aluminum hydroxochloride). Наприклад, алюміній міститься у складі катіону AlOH 2+ , завдяки чому існує сіль складу AlOHCl 2 (алюміній гідроксохлорид). Such strength is called the main one.
Таку сіль називають основною.
Key Idea
Ключова ідея
Control nutrition
Контрольні питання
100. Give the purpose of acids, bases and salts from the point of view of the theory of electrical dissociation.
100. Дайте визначення кислот, основ та солей з точки зору теорії електролітичної дисоціації.
101. Why is the dissociation of rich basic acids similar to monobasic acids? 101. У чому особливість дисоціації багатоосновних кислот, порівняно з одноосновними? Explain on the example of sulfate acid.
поясніть на прикладі сульфатної кислоти.
Task for mastering the material
Завдання для засвоєння матеріалу
102. As a result of the dissociation of an acid molecule, an ion with a charge of 3- has dissolved. 102. В результаті дисоціації молекули кислоти утворився іон із зарядом 3-. How many ions did Hydrogen get?
111. During the dissociation of any nitrate, 1 mole of cations with a charge of 2+ was dissolved. How many speeches of nitrate-ionov settled down with whom?
112. Fold the formula and write down the equal dissociation of ferum(II) sulfate and ferum(III) sulfate. What do the salts excite?
113. Induce, after one butt, the level of dissociation of salts in a similar way to the schemes (the letter M denotes a metal element, and X is an acidic excess): a) MX ^ M 2+ + X 2-; b) MX 3 ^ M 3+ + 3X -;
c) M 3 X ^ 3M + X 3-; d) M 2 X 3 ^ 2M 3 + + 3X 2-.
114. In retail, ions K +, Mg 2 +, NO-, SO4 -. Have you repaired some speeches? Provide two options for prompting.
115*. To store the equal dissociation of quiet electrolytes, if they dissolve chloride ions: CrCl 3 , KClO 3 , BaCl 2 , Ca(ClO) 2 , HClO 4 , MgOHCl.
Tse material of the assistant
The nature of the retailer's molecules plays the same role of electrical dissociation as the macroscopic power of the retailer - its dielectric penetration (scheme of electrical dissociation).
Dissociation pіd melting hour
In the midst of high temperatures, they begin to repair the crystal lattice, the kinetic energy moves, and such a moment has come (at the melting temperature of the speech), if it is possible to outweigh the energy between the ions. The result of this is the disintegration of speech into ions.
Classical theory of electrical dissociation
The classical theory of electrical dissociation was created by S. Arrhenius and W. Ostwald in 1887. Arrhenius did not take into account the physical theory of design, not protecting the interaction between electricity and water, and taking into account that the designs have free ions. Russian chemists I. A. Kablukov and V. A. Kistyakovsky were asked to explain the electrical dissociation of the chemical theory of development of D. I. Mendeliev, they brought it that when the electrolyte is separated, there is a chemical interaction with water, after which the electrolyte dissociates into ions.
The classical theory of electrolytic dissociation is based on the assumptions about the inconsistent dissociation of the divided speech, which is characterized by the dissociation step α, so that electrolyte molecules often break up. Dynamic equality between non-dissociated molecules and ions is described by the law of volatile masses. For example, the electrical dissociation of the binary electrolyte KA is similar to the type:
The dissociation constant is determined by the activities of cations, anions and non-dissociated molecules in the following order:
Significance to deposit due to the nature of the speech and the retailer, as well as the temperature, can be determined by experimental methods. Steps of dissociation ( α ) may be covered for any concentration of electrolyte for additional support:
,de - the average coefficient of activity of the electrolyte.
Weak electricity
Weak electricity- chemical compounds, the molecules of which in highly diluted varieties are slightly dissociated into ions, which are in dynamic alignment with non-dissociated molecules. To weak electrolytes lie more organic acids and rich organic bases in water and non-aqueous varieties.
Weak electrolytes є:
- Mayzhe all organic acidic water;
- active inorganic acids: HF, HClO, HClO 2 , HNO 2 , HCN, H 2 S, HBrO, H 3 PO 4 , H 2 CO 3 , H 2 SiO 3 , H 2 SO 3 and in;
- deyakі malokrozchinnі hydroxide metal: Fe(OH) 3 , Zn(OH) 2 and in.
Stronger electricity
Stronger electricity- chemistries, the molecules of which in breeding varieties are practically more dissociated into ions. The level of dissociation of such electrolytes is close to 1. To strong electrolytes, there are rich inorganic salts, inorganic acids and bases in water roses, as well as in retailers, which may have a high dissociation property (alcohols, amides and others).
The classical theory of electrolytic dissociation is stagnant only to the dilution of weak electrolytes. Strong elec- tricity in breeding dissociations is practical for the most part, and there is no evidence of the equality between ions and non-dissociated molecules. Vіdpovіdno to yavlen, hanging in the 20-30s. 20 st. V. K. Semenchenko (SRSR), N. B'errum (Denmark), R. M. Fuoss (USA) and others, in the case of strong electrolytes at medium and high concentrations, ion vapor and collapsible aggregates are established. Current spectroscopic data show that an ion pair is formed from two ions of an opposite sign, that they are in contact (contact ion pair) or separated by one or a decalcom molecules of a retailer (separated ion pair). All bets are electrically neutral and do not take part in the transferred electricity. Poorly diluted differences of strong electrolytic compounds between solvated ions and ionic pairs can be approximately characterized, similarly to the classical theory of electrolytic dissociation, the dissociation constant (or the turning value - the aco constant). Tse allows you to win the quest for more equalization for the development of a higher level of dissociation, based on experimental data.
In the simplest types (large monatomic singly charged ions), the approximate values of the dissociation constant in the breeding of strong electrolytes can be calculated theoretically, while showing a purely electrostatic interaction between ions in an uninterrupted medium - a retailer.
Apply strong electrolytes: deacid acids (HClO 4 , HMnO 4 , H 2 SO 4 , HCl, HBr; HI), hydroxides of tidal earth metals (NaOH, KOH, Ba(OH) 2); more salts.
Div. also
Posilannya
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Wonder what is "Electrolytic dissociation" in other dictionaries:
electrical dissociation- dissociation r Nar. speeches at rozchinі chi rozmeltі elektrolіtіv. Topics metallurgy EN electrolytic dissociation … Dovіdnik technical translation
ELECTROLYTIC DISSOCIATION- div... Great Polytechnical Encyclopedia
The latest or partial disintegration of the molecules of the divided speech into ions in the aftermath of interaction with the retailer. Obumovlyuє ionna conductivity of rozchinіv elektrolitіv. Great Encyclopedic Dictionary
electrical dissociation- - Povniy or chastkovy disintegration of divided speech into ioni. Foreign chemistry: assistant / A. V. Zholnin ... Chemical terms
Electrolytic dissociation- a new or partial disintegration of the molecules of the divided speech as a result of interaction with the retailer; umovlyuє іonnu prіdnіstі razchinіv elektrolitіv. [Terminological dictionary for concrete and concrete. FSUE "NIC… Encyclopedia of terms, designation and explanation of everyday materials
Electrolytic dissociation- ELECTROLYTIC DISSOCIATION, a new or frequent disintegration of the divided speech into and after the interplay with the retailer. Zumovlyuє elektroprovіdnіst elektrolitіv. … Illustrative encyclopedic dictionary
Abo ionization. Encyclopedic dictionary F.A. Brockhaus and I.A. Efron
The latest or partial disintegration of the molecules of the divided speech into ions in the aftermath of interaction with the retailer. Zumovlyuє ionnu conductivity of rozchinіv elektrolitіv. * * * ELECTROLYTIC DISSOCIATION ELECTROLYTIC DISSOCIATION, again… Encyclopedic dictionary
electrical dissociation- elektrolitinė disociacija statusas T sritis chemija apibrėžtis Istirpintos medžagos virtimas jonais jai sąveikaujant su tirpiklio molekulėmis. atitikmenys: English electrolytic dissociation eng. electrical dissociation… Chemijos terminų aiskinamasis žodynas
electrical dissociation- elektrolitinė disociacija statusas T sritis fizika atitikmenys: engl. electrolytic dissociation vok. elektrolytische Dissoziation, f rus. electrical dissociation, f pranc. dissociation electrolytique, f … Fizikos terminų žodynas
Books
- Type a table. Chemistry. 8-9 grade (20 tables), . Initial album from 20 arkushivs. Valence. Budov of the atom, Isotopes. Electronic configurations of atoms. Adoption of covalent and ionic chemical bonds. Types of crystal lattices.
Electrolytes and non-electrolytes
From the lessons of physics, it is clear that the construction of some speeches in buildings conducts an electric stream, and others - not.
Speech, rozchini such as conducting an electric strum, are called electrolytes.
Speech, reasons for not conducting an electric strum, are called non-electrolytes. For example, do not conduct an electric strum.
Electrolytic dissociation and association
Why do electricians need to conduct an electric strum?
Swedish teaching S. Arrenius, showing the electrical conductivity of various speeches, deyshov 1877. to visnovka, which is the reason for electrical conductivity ioniv, which are settled when the electricity is separated from the water
The process of disintegration of electrolyte on ion is called electrical dissociation.
S. Arrhenius, who had reached the point of understanding the physical theory of design, did not worry about the relationship between electricity and water, and he respected that the designs had free ions. On the view of the new Russian chemist I. A. Kablukov and V. A. Kistyakovsky worked to explain the electrical dissociation of the chemical theory of D. I. Mendeliev was brought up that when the electric power was changed, the chemical interaction of the divided speech with water was introduced, so that the odors were dissolved into ions. The stench was respected, that they are not free, not naked, but hydrated, dressed in a fur coat with water molecules.
Water molecules dipoles(two poles), the shards of atom and water are staggered under a cut of 104.5°, which makes the molecule form a cut shape. The water molecule is shown schematically below.
As a rule, it is easier to dissociate speeches from ionic sound and, vіdpovidno, with an ionic crystal lattice, shards of stench are formed from ready-made ions. Behind their separate dipoles, the waters are oriented in opposite directions by charged terminals towards positive and negative ions in the electrolyte.
Between the ions of the electrolyte and the dipoles of the water, the forces of mutual gravity are blamed. As a result, the bonds between the ions are weaker and there is a transition of the ions from the crystal to the difference. It is obvious that the sequence of processes that occur during the dissociation of speeches with an ionic sound (salts and lunas) will be as follows:
1) orientation of molecules (dipoles) of water near the ions of the crystal;
2) hydration (interaction) of water molecules with ions of the surface sphere of the crystal;
3) dissociation (decomposition) of the crystal electrolyte on the hydration of the ion.
A simpler process can be imagined for the help of an offensive equal:
Similarly, they dissociate and electricity, in molecules of some covalent bonds (for example, molecules of HCl chloride, see below); only in the same direction under the influx of dipoles, the water turns the covalent polar bond into an ion; the sequence of processes, which are carried out at the same time, will be like this:
1) orientation of water molecules towards the poles of electrolyte molecules;
2) hydration (interaction) of water molecules with electrolyte molecules;
3) ionization of electrolyte molecules (transformation of a covalent polar bond into an ionic one);
4) dissociation (decomposition) of electrolyte molecules on ion hydration.
The process of dissociation of hydrochloric acid can be simplified as follows:
Slid vrakhovuvaty, scho in terms of electrolytic hydration ion, chaotic collapse, can shut up and reunite with each other. This reversal process is called association. Association among people is observed in parallel with dissociation, so in equal reactions put the sign of reversibility.
The powers of the hydrated ions are being challenged by the non-hydrated powers. For example, non-hydrated ion middi Cu 2+ - white in anhydrous crystals sulfate midi (II) and may have a blackish color, if hydrated, then the interactions with water molecules Cu 2+ nH 2 O. water molecules.
Stages of electrical dissociation
In the case of electrolytes, it is charged with ions of the present molecule. Therefore, the range of electrolytes is characterized stage of dissociation, which is denoted by the Greek letter a ("alpha").
The value of the number of particles that broke up into ions (N g), up to the total number of separate particles (N p).
The degree of dissociation of the electrolyte is determined by the last path and is observed in parts of several hundred. If a = 0, then the dissociation is daily, and if a = 1, if it is 100%, then the electrolyte will be more disintegrated into ions. Different kinds of electricity can be different to the world of dissociation, i.e., the steps of dissociation can lie in the nature of the electrolyte. It will also lie in concentration: with the expansion of the difference between the steps of dissociation, it will increase.
Behind the stage of electrical dissociation, electricity is divided into strong and weak.
Stronger electricity- tse elektroliti, yakі when different in water, it is practical to dissociate on ioni. Such electrolytes have a significant degree of dissociation of the right one.
Up to strong electrolytes one can see:
1) mustard salts;
2) strong acids, for example: H 2 SO 4 HCl, HNO 3;
3) services, for example: NaOH, KOH.
Weak electricity- tse elektroliti, yakі when separated from the water, may not dissociate into ions. Such electrolytes have a dissociation level of zero.
Weak electrolytes can be seen:
1) weak acids - H 2 S, H 2 CO 3, HNO 2;
2) aqueous solution of ammonia NH 3 H 2 O;
4) active salts.
Dissociation constant
In the cases of weak electrolytes, after their inconsistent dissociation, they are restored dynamically equal between non-dissociated molecules and ions. For example, for optic acid:
It is possible to zastosuvat until tsієї rivnovagi the law of inflammatory mast and write down the viraz constants of rivnovagi:
The equalization constant, which characterizes the process of dissociation of a weak electrolyte, is called dissociation constant.
The dissociation constant characterizes the strength of the electrolyte (acids, bases, water) dissociate into ions. The greater the constant, the easier it is for the electrolyte to fall into ions, and also, they are the strongest. The values of dissociation constants for weak electrolytes are found in dovіdniki.
The main provisions of the theory of electrical dissociation
1. When separated in water, the electricity dissociates (disintegrates) into positive and negative ions.
Іoni- this is one of the forms of the basis of a chemical element. For example, atoms of sodium metal Na 0 interact energetically with water, satisfying at that meadow (NaOH) and water H 2 but they do not satisfy such products with sodium Na +. Chlorine Cl 2 has a yellow-green color and a strong smell, brittle, and chlorine Cl ion - bezbarvnі, not brittle, relieved the smell.
Іoni- either positively or negatively charged particles, on which atoms or groups of atoms of one or dekilkoh chemical elements are transformed as a result of the transfer or arrival of electrons.
At retailers, they are awkwardly shifting at retailers directly.
Behind the warehouse they go to just- Cl - , Na + i folding- NH 4 +, SO 2 -.
2. The reason for the dissociation of electrolyte in water sources is the first hydration, because the interaction of electrolyte with water molecules breaks the chemical bond in newcomers.
As a result of such interdependence, hydration is established, so that it is associated with water and ion molecules. Also, for the obviousness of the water shell, they are divided into hydrated(At rozchinah and crystallogidratah) і non-hydrated(In anhydrous salts).
3. Under the action of an electric struma, positively charged ions collapse to the negative pole of the struma - cathode and are called cations, and negatively charged ions collapse to the positive pole of the struma - anode and are therefore called anions.
Later, there is one more classification of ions. by the sign of their charge.
The sum of charges of cations (H +, Na +, NH 4 +, Cu 2+) is the same as the sum of charges of anions (Cl -, OH -, SO 4 2-), after which the difference of electrolytes (HCl, (NH 4) 2 SO 4, NaOH, CuSO 4) become electrically neutral.
4. Electrolytic dissociation - the process of werewolves for weak electrolytes.
The order of the process of dissociation (disintegration of electrolyte into ions) proceeds and the reversal process - association(Z'ednannya ioniv). Therefore, in equal electrical dissociation, replace the sign of equality with the sign of negotiability, for example:
5. Not all electricity in the same world dissociate into ions.
Deposit according to the nature of the electrolyte and its concentration. The chemical powers of the differences in electrolytics are determined by the powers of the ions, like the stench of dissociation.
The dominance of the differences of weak electrolytes is surrounded by molecules and ions, which have settled into the process of dissociation, which are in dynamic equalization one by one.
The smell of optic acid and the presence of the presence of CH 3 COOH molecules, the sour taste and the change of infection are indicators of the appearance of the presence in the range of H + ions.
The dominance of differences in strong electrolytes is determined by the dominance of ions, as they are established for their dissociations.
For example, the powerful power of acids, such as a sour relish, changes in the presence of indicators and other indicators, including the presence of cations in water (more precisely, ions in oxonium H 3 O +). Zagalni power meadows, such as softness on the dotik, change of indica- tors and other. due to the presence of hydroxide-ions in OH - in their ranges, and the power of salts - due to the breakdown of them into metal cations (or ammonium) and anions of acidic excesses.
Appropriate for the theory of electrical dissociation all reactions in aqueous solutions of electrolytes and reactions between ions. Tsim umovleny vysoko shvidkіst richness of chemical reactions in rozchiny elektrolitіv.
Reactions that occur between ions are called ionic reactions, A equalization of these reactions - ionim equals.
Reactions of ion exchange in water can occur:
1. Non-negotiable, until the end.
2. Back, then run at the same time at two opposite straight lines. The reactions of exchange between strong electrolytes in different ways proceed to the end, or are practically irreversible, if they, united one by one, make speeches:
a) indistinct;
b) low dissociation (weak electricity);
c) gaseous.
Let's look at some examples of molecular and short-term ionic lines:
The reaction is irreversible one of the її products is a non-distinct speech.
Neutralization reaction is non-reversible, because K. A little dissociated speech is established - water.
The reaction is irreversible, because CO 2 gas and low dissociation speech - water.
Even in the middle of the speeches and the middle of the products of the reaction, weak electricity or little speech, such reactions are werewolves, so they don’t run until the end.
In turnaround reactions, jealousy is swayed by the adoption of the least dissociated speeches.
For example:
Rivnovaga zmіshchuєtsya in the case of the adoption of a weak electrolyte - H2O.
If speeches are strong, they are strong electrolytes, which, when mixed, do not settle indistinct or poorly dissociated speeches or gases, such reactions do not proceed: when mixed, they settle sumish ions.
Dovіdkovy material for passing the test:
periodic table
Table of retail
Theory of electrical dissociation zaproponuvav Swedish teachings S. Arrhenius in 1887 roci.
Electrolytic dissociation- the breakdown of electrolyte molecules with solutions in a variety of positively charged (cations) and negatively charged (anions) ions.
For example, octova acid dissociates like this in water:
CH 3 COOH⇄H + CH 3 COO - .
Dissociation is placed before the turnaround processes. Ale different electrics dissociate differently. Steps to deposit in the nature of the electrolyte, its concentration, the nature of the retailer, the natural minds (temperature, vice).
Steps of dissociation α - the ratio of the number of molecules, which broke up into ions, to the total number of molecules:
α=v'(x)/v(x).
The steps can be changed from 0 to 1 (depending on the duration of the dissociation up to the final completion). Significantly in vіdsotkah. It appears as an experimental path. With the dissociation of the electrolyte, there is an increase in the number of particles in the difference. The degree of dissociation shows the strength of the electrolyte.
Separate strongі weak electricity.
Stronger electricity- ce electricity, the degree of dissociation which exceeds 30%.
Medium power electrolytes- tse tі, stupіn disotsіаtsії yakої podіlyaє in the boundaries vіd 3% to 30%.
Weak electricity- the degree of dissociation in the water 0.1 M difference is less than 3%.
Apply weak and strong electrolytes.
The strongest elec- tricity in breeding plants is more likely to fall on them, that is. α \u003d 1. But experiments show that dissociation cannot be more advanced 1, it can be closer, but not more important 1. Not good dissociation, but yes.
For example, let me have some kind of z'ednanny α = 0.7. Tobto. According to the theory of Arrhenius, 30% of the molecules “float” in a variety of ways, which were not produced. And 70% did it for free. And the electrostatic theory gives a further definition of the concept: if α = 0.7, then all molecules are dissociated into ions, but ions are more than 70% more, and 30%, which are missing, are connected by electrostatic interactions.
There are stages of dissociation.
The stages of dissociation lie not only in the nature of the retailer and speech, which vary, but also in the concentration and temperature.
Equal dissociation can be applied to such a look:
AK ⇄ A- + K + .
The first stage of dissociation can be expressed as follows:
With an increase in concentration, the difference between the steps of dissociation of electrolyte drops. Tobto. the value of the step for a particular electrolyte has ceased to be the value of the constant.
Oskіlki dissociation - the process of werewolves, then the equalization of the quickness of the reaction can be written as follows:
If dissociation is equally important, then the speed will improve and as a result it will be taken the equalization constant(Dissociation constant):
To deposit due to the nature of the retailer and temperature, but not to deposit due to the concentration of the products. It can be seen from the equation that the more non-dissociated molecules, the smaller the value of the dissociation constant of the electrolyte.
Rich basic acids dissociate stepwise often, and skin steps may have a constant value of dissociation.
As a dissociated bugatobasic acid, the first proton is more easily split, and when the charge of the anion increases, it grows more heavily, and the proton is split richer. For example,
The dissociation constants of phosphoric acid on the skin layer of the skin are highly permeable:
I - stage:
II - stage:
III - stage:
At the first stage, phosphoric acid is an acid of medium strength, and the other is weak, at the third - even weak.
Apply the constants of rіvnovagi of deyakyh dezchinіv elektrolitіv.
Let's look at the example:
As if it were possible for them to bring in metal copper, then at the moment of jealousy, the concentration of ions in the midi is due to a greater, lower concentration of silver.
Ale constant may be lower value:
AgCl⇄Ag + +Cl - .
What can we say about those who, at the time of reaching the rіvnovaga, had even a little chloride srіbla.
The concentration of metal midi and silver is entered into the equalization constant.
Ionny dobutok vodi.
Hover tables have data:
Call the constant Qiu ionny vitvir vodi, yak deposit less than temperature. Vdpovidno to dissociation for 1 ion H + falls one hydroxide-ion. In pure water, the concentration of these ions is the same: [ H + ] = [Oh - ].
Zvіdsi, [ H + ] = [Oh-] = = 10-7 mol/l.
If you add a third-party speech to the water, for example, hydrochloric acid, then the concentration of ions in the water growth, the aleionic addition of water in the concentration will not fall.
And if you add a meadow, then the concentration of ions will increase, and the amount of water will decrease.
Concentration and interrelationships: more than one value, then less than another.
Acidity difference (pH).
The acidity of the differences is expressed by the concentration of ions H+. In sour media pH<10 -7 моль/л, в нейтральных - pH\u003d 10 -7 mol / l, in puddles - pH> 10 -7 mol/l.
The acidity of the difference is expressed through the negative logarithm of the concentration of ions in water, called її pH.
pH = -lg[ H + ].
Vzaimozv'yazok between a constant and a stage of dissociation.
Let's take a look at the example of dissociation of optic acid:
We know the constant:
Molar concentration W=1/V, we can imagine that in equal time we take it:
Qi equal є by the law of breeding W. Ostwald, zgіdno z kakim the dissociation constant of the electrolyte can not be deposited in the form of a divorce.
This lesson of devotions to the topics "Electrolytic dissociation". At the process of cultivating these, you will understand the essence of some amazing facts: why the difference in acids, salts and luzhiv is to conduct an electric jet; Why is the boiling temperature of the difference between the electrolyte and the difference between the difference between the electric and non-electronic.
Chemical sound.
Lesson:Electrolytic dissociation
The theme of our lesson is Electrolytic dissociation". We will try to explain the amazing facts:
Why rozchini acids, salts and meadows conduct an electric jet.
Why is the boiling temperature of the difference between the electrolyte and the concentration will be higher, the lower boiling temperature is the difference between the electrolyte and the concentration.
Svante Arrhenius
In 1887, the swedish physicist - chemist Svante Arrhenius, doslіdzhuyuchi elektroprovіdnіnіst vodnyh razchinіv, vyslovіn pripuschenja, scho in such razorіnі speech rozdayutsya on zarjazhenі particles - іoni, yakі can pass to elektrodіv - negatively charged cathode and positively charged anode.
This is the cause of the electric strum in rozchiny. Tsey process otrimav name electrical dissociation(The last translation is splitting, laying out under the influx of electricity). Such a name also conveys that dissociation comes under the influence of an electric stream. Further investigations showed what is wrong: and they are onlycarriers of charges in a variety of ways, it is not necessary for him to pass throughrozchin strum chi nі. With the participation of Svante Arrhenius, the theory of electrolytic dissociation was formulated, which is often named after the honor of this scientist. The main idea of \u200b\u200bthis theory lies in the fact that the electricity under the retailer's deed miraculously falls into ions. I themselves tsі іоnіy є vіdіami vіdpovіdat for elektroprovіdnіst razchiny.
Electric strum - ce straightening ruh vіlny charged particles. You already know what rozchiny and melting of salts and luzhіv elektroprovіdnі, that is why they are formed not from neutral molecules, but from charged particles - ions. When melted, they melt free carriers of electrical charge.
The process of disintegration of speech into free ions in the course of its dispersal is called electrical dissociation.
Rice. 1. Scheme of decomposition into ions of sodium chloride
The essence of electrolytic dissociation lies in the fact that they become free under the influx of a water molecule. Fig.1. The process of disintegration of the electrolyte on ion is to be carried out for the help of a chemical equalization. Let's write down the equal dissociation of sodium chloride and calcium bromide. With the dissociation of one mole of sodium chloride, one mole of sodium cations and one mole of chloride - anions are dissolved. NaCl⇄ Na + + Cl -
With the dissociation of one mole of calcium bromide, one mole of calcium cations and two moles of bromide - anions are dissolved.
CaBr 2 ⇄ Ca 2+ + 2 Br -
Give respect: Since the formula of the electrically neutral part is written in the left part of the equation, then the total charge of the ions is to be equal to zero.
Visnovok: during dissociation of salts, cations of metal and anions of acid excess are dissolved.
Let's take a look at the process of electrical dissociation of meadows. Let's write down the equal dissociation of potassium hydroxide and barium hydroxide.
During the dissociation of one mole of potassium hydroxide, one mole of potassium cations and one mole of hydroxide anions are dissolved. KOH⇄ K + + Oh -
During the dissociation of one mole of barium hydroxide, one mole of barium cations and two moles of hydroxide anions are dissolved. Ba(Oh) 2 ⇄ Ba 2+ + 2 Oh -
Visnovok: during electrolytic dissociation of meadows, metal cations and hydroxide - anions are dissolved.
Indistinct at the water base practical do not give up electrolytic dissociation So, as near the water, the stench is practically indistinguishable, and when heated, they spread out, so the melting of them is not possible.
Rice. 2. Budov molecules of chlorine water and water
Look at the process of electrolytic dissociation of acids. Molecules of acids are fixed by a covalent polar bond, hence, acids are not made up of ions, but rather of molecules.
Vikaє nutrition - how is the acid dissociated, i.e., how are the free charged parts established in acids? It appears that they settle down in acid concentrations on their own when they are dissolved.
Let's look at the process of electrolytic dissociation of chlorine water in water, but for this we will write down the water and chloride molecules. Fig.2.
The offending molecules are fixed by a covalent polar bond. The electron gap of the chlorine water molecule is shifted to the chlorine atom, and the water molecule is shifted to the acid atom. The water molecule dissolves the water cation into the chlorine water molecule, with which the hydroxonium H3O + cation is dissolved.
In equal reactions of electrostatic dissociation, it is necessary to protect the light of the hydroxonium cation - it seems that the water cation is established.
Todi equal dissociation of chlorine water looks like this:
HCl⇄ H + + Cl -
During dissociation of one mole of chlorine water, one mole of water cation and one mole of chloride-anion are dissolved.
Stage dissociation of sulfuric acid
Look at the process of electrolytic dissociation of sulfuric acid. Sulfuric acid dissociation stepwise, in two stages.
I-I stage of dissociation
At the first stage, one cation is introduced into the water and the hydrosulfate anion is dissolved.
II - I stage of dissociation
At the other stage, further dissociation of hydrosulfate - anions takes place. HSO 4 - ⇄ H + + SO 4 2-
This stage is reversed, so that sulfate - ions are established - they can take water cations to themselves and turn into hydrosulfate - anions. Tse is shown by the reverse sign.
Іsnuyu acid, yakі navіt at the first stage dissociate not exactly - such acids are weak. For example, carbonic acid H 2 3 .
Now we can explain why the boiling temperature of the difference between the electrolyte will be higher, the lower temperature of the boiling point will be the difference between the non-electronic.
When the molecules of the speech are separated, they interact with the molecules of the retailer, for example - water. The more particles of different speech are in one volume of water, the higher the boiling temperature. Now it is clear that in the same obsyagi the authorities have repaired equal amounts of speech-electrolyte and speech - non-electrolyte. The electrolyte in the water will break up into ions, which means that the number of particles will be larger, lower at the time of separation of non-electrolyte. In this way, the presence of free particles in the electrolyte explains why the boiling temperature will increase the difference between the electrolyte and the lower boiling temperature will change the difference between the non-electronic.
Bringing a bag to the lesson
At this time, you have recognized that the differences in acids, salts and electrical conductors, so that when they are differentiated, charged parts - ions are established. This process is called electrical dissociation. During the dissociation of salts, metal cations and anions of acidic excesses are dissolved. During the dissociation of meadows, metal cations and hydroxide anions are dissolved. During the dissociation of acids, cations of water and anions of acid excess are dissolved.
1. Rudzitis G.Y. Inorganic and organic chemistry. Grade 9: handyman for lighting installations: basic rіven/G. Є. Rudzitis, F.G. Feldman. M: Enlightenment. 2009 119s.:il.
2. Popel P.P.Chemistry: 8th class: a handyman for the central lighting of the initial deposits / P.P. Popel, L.S. Krivlya. -K.: IC "Academy", 2008.-240 p.: Іl.
3. Gabrielyan O.S. Chemistry. Grade 9 Podruchnik Vidavnitstvo: Bustard.: 2001. 224s.
1. No. 1,2 6 (p.13) Rudzitis G.Є. Inorganic and organic chemistry. Grade 9: handyman for lighting installations: basic rіven/G. Є. Rudzitis, F.G. Feldman. M: Enlightenment. 2009 119s.:il.
2. What is electrical dissociation? Speech, what kind of classes lie down to electrolits?
3. Speech, what type of connection with electrolytes?
