Hydrochloric acid electrolyte or not. The electrolytes are
- (Greek). A liquid body decomposed by an electric (galvanic) current. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. ELECTROLYTE A liquid subject to decomposition by galvanic current. ... ... Dictionary of foreign words of the Russian language
electrolyte- a, m. electrolyte m. electro + gr. lytos is degradable. specialist. Chemical substance(in melt or solution), capable of decomposing into its constituent parts when passing through it electric current. battery electrolyte. BASS 1. Throwing ... ... Historical dictionary gallicisms of the Russian language
electrolyte- A solution in which, when an electric current passes through it, the decomposition of a substance occurs, which leads to the appearance of an electric current. The electrolyte is the basis of accumulators and batteries. [Hypertext encyclopedic Dictionary on… … Technical Translator's Handbook
ELECTROLYTE- ELECTROLYTE, a solution or molten salt capable of conducting electricity and used for ELECTROLYSIS (during which it decomposes). Current in electrolytes is conducted by charged particles IONS, not electrons. For example, in lead ... ... Scientific and technical encyclopedic dictionary
ELECTROLYTE- ELECTROLYTE, electrolyte, husband. (from the word electric and Greek lytos dissolved) (physical). A solution of a substance capable of being broken down into its component parts by electrolysis. Dictionary Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov
electrolyte- noun, number of synonyms: 1 catholyte (1) ASIS Synonym Dictionary. V.N. Trishin. 2013 ... Synonym dictionary
Electrolyte- Electrolytes are substances, solutions and alloys of which, with other substances, electrolytically conduct galvanic current. A sign of electrolytic conductivity, in contrast to metallic, should be considered the ability to observe chemical ... ... Encyclopedia of Brockhaus and Efron
electrolyte- - a substance whose aqueous solution or melt conducts an electric current. General chemistry: textbook / A. V. Zholnin ... Chemical terms
ELECTROLYTE- a substance whose aqueous solution or melt conducts an electric current (see), resulting from electrolytic (see). This E., also called (see) the second kind, differ from metals (conductors of the first kind), in which the transfer ... Great Polytechnic Encyclopedia
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Instruction
The essence of this theory is that when melted (dissolved in water), almost all electrolytes decompose into ions, which are both positively and negatively charged (which is called electrolytic dissociation). Under the influence of an electric current, negative (“-”) towards the anode (+), and positively charged (cations, “+”), move towards the cathode (-). Electrolytic dissociation is a reversible process ( reverse process is called molarization.
The degree (a) of electrolytic dissociation is dependent on the electrolyte itself, the solvent, and their concentration. This is the ratio of the number of molecules (n) that have decayed into ions to total number molecules introduced into the solution (N). You get: a = n / N
Thus, strong electrolytes are substances that completely decompose into ions when dissolved in water. Strong electrolytes, as a rule, are substances with highly polar or ionic bonds: these are salts that are highly soluble, strong acids (HCl, HI, HBr, HClO4, HNO3, H2SO4), as well as strong bases (KOH, NaOH, RbOH, Ba( OH)2, CsOH, Sr(OH)2, LiOH, Ca(OH)2). In a strong electrolyte, the substance dissolved in it is mostly in the form of ions (anions and cations); there are practically no molecules that are undissociated.
Weak electrolytes are substances that only partially dissociate into ions. Weak electrolytes, along with ions in solution, contain undissociated molecules. Weak electrolytes do not give a strong concentration of ions in solution.
The weak ones are:
- organic acids (almost all) (C2H5COOH, CH3COOH, etc.);
- some of the inorganic acids (H2S, H2CO3, etc.);
- almost all salts, slightly soluble in water, ammonium hydroxide, as well as all bases (Ca3 (PO4) 2; Cu (OH) 2; Al (OH) 3; NH4OH);
- water.
They practically do not conduct electric current, or conduct, but poorly.
note
Although pure water conducts electricity very poorly, it still has a measurable electrical conductivity, due to the fact that water dissociates slightly into hydroxide ions and hydrogen ions.
Most electrolytes are corrosive substances, so when working with them, be extremely careful and follow safety regulations.
An electrolyte is a substance that in the solid state is a dielectric, that is, does not conduct electric current, however, in a dissolved or molten form it becomes a conductor. Why is there such a drastic change in properties? The fact is that electrolyte molecules in solutions or melts dissociate into positively charged and negatively charged ions, due to which these substances in such a state of aggregation are able to conduct electric current. Most salts, acids, bases have electrolytic properties.
Instruction
What substances are strong? Such substances, in solutions or melts of which almost 100% of the molecules are exposed, and regardless of the concentration of the solution. The list includes the vast majority of soluble alkalis, salts and some acids, such as hydrochloric, bromine, iodine, nitric, etc.
How do medium-strength electrolytes differ from them? The fact that they dissociate to a much lesser extent (from 3% to 30% of molecules decay into ions). The classical representatives of such electrolytes are sulfuric and phosphoric acids.
Electrolytes are solutions containing a high concentration of ions that provide the passage of electric current. As a rule, these are aqueous solutions of salts, acids and alkalis.
In humans and animals, electrolytes play important role: for example, blood electrolytes with iron ions transport oxygen to tissues; electrolytes with potassium and sodium ions regulate the water-salt balance of the body, the work of the intestines and the heart.
Properties
Pure water, anhydrous salts, acids, alkalis do not conduct current. In solutions, substances break down into ions and conduct current. That is why electrolytes are called second-order conductors (unlike metals). Electrolytes can also be melts and some crystals, in particular zirconium dioxide and silver iodide.
The main property of electrolytes is the ability to electrolytic dissociation, that is, to the disintegration of molecules when interacting with water molecules (or other solvents) into charged ions.
According to the type of ions formed in the solution, alkaline electrolyte is distinguished (electrical conductivity is due to metal ions and OH-), saline and acidic (with H+ ions and acid base residues).
To quantitatively characterize the ability of the electrolyte to dissociate, the parameter "degree of dissociation" is introduced. This value reflects the percentage of molecules that have undergone decay. It depends on:
the substance itself;
solvent;
substance concentration;
temperature.
Electrolytes are divided into strong and weak. The better the reagent dissolves (decomposes into ions), the stronger the electrolyte, the better it conducts current. Strong electrolytes include alkalis, strong acids, and soluble salts.
For electrolytes used in batteries, such a parameter as density is very important. The operating conditions of the battery, its capacity and service life depend on it. Density is determined using hydrometers.
Electrolyte Handling Precautions
The most popular electrolytes are a solution of concentrated sulfuric acid and alkali - most often potassium, sodium, lithium hydroxides. All of them cause chemical burns of the skin and mucous membranes, very dangerous eye burns. That is why all work with such electrolytes must be carried out in a separate, well-ventilated room, using protective equipment: clothing, masks, goggles, rubber gloves.
Near the room where work with electrolytes is carried out, a first-aid kit with a set of neutralizing agents and a tap with water should be stored.
Acid burns are neutralized with a solution of soda (1 tsp per 1 tbsp of water).
Alkali burns are neutralized with a solution of boric acid (1 tsp per 1 tbsp of water).
For eyewash, neutralizing solutions should be twice as weak.
Damaged areas of the skin are first washed with a neutralizer, and then with soap and water.
If the electrolyte is spilled, it is collected with sawdust, then washed with a neutralizer and wiped dry.
When working with electrolyte, all safety requirements. For example, acid is poured into water (and not vice versa!) not manually, but with the help of devices. Pieces of solid alkali are lowered into water not with hands, but with tongs or spoons. It is impossible to work in the same room with batteries on different types of electrolytes, and it is also forbidden to store them together.
Some jobs require "boiling" the electrolyte. This releases hydrogen, a flammable and explosive gas. In such premises, explosion-proof electrical wiring and electrical appliances must be used, smoking and any work with open fire is prohibited.
Store electrolytes in plastic containers. Glass, ceramic, porcelain dishes and tools are suitable for work.
In the next article, we will tell you more about the types and applications of the electrolyte.
Electrolytes are substances whose solutions or melts conduct electricity. Electrolytes include acids, bases and salts. Substances that do not conduct electric current in a dissolved or molten state are called non-electrolytes. These include many organic matter, for example, sugar, etc. The ability of electrolyte solutions to conduct electric current is explained by the fact that electrolyte molecules, when dissolved, decompose into electrically positively and negatively charged particles - ions. The value of the charge of an ion is numerically equal to the valency of the atom or group of atoms that form the ion. Ions differ from atoms and molecules not only by the presence of electric charges, but also other properties, for example, ions have neither smell, nor color, nor other properties of chlorine molecules. Positively charged ions are called cations, negatively charged anions. Cations form hydrogen H + , metals: K + , Na + , Ca 2+ , Fe 3+ and some groups of atoms, for example, the ammonium group NH + 4; anions form atoms and groups of atoms that are acid residues, for example Cl - , NO - 3 , SO 2- 4 , CO 2- 3 .
The breakdown of electrolyte molecules into ions is called electrolytic dissociation, or ionization, and is a reversible process, that is, an equilibrium state can occur in a solution in which how many electrolyte molecules decompose into ions, so many of them are re-formed from ions. The dissociation of electrolytes into ions can be represented general equation: , where KmAn is an undissociated molecule, K z+ 1 is a cation carrying z 1 positive charges, A z- 2 is an anion having z 2 negative charges, m and n are the number of cations and anions formed during the dissociation of one electrolyte molecule. For example, .
The number of positive and negative ions in a solution can be different, but the total charge of the cations is always equal to the total charge of the anions, so the solution as a whole is electrically neutral.
Strong electrolytes almost completely dissociate into ions at any concentration in solution. These include strong acids (see), strong bases and almost all salts (see). Weak electrolytes, which include weak acids and bases and some salts, such as mercuric chloride HgCl 2 , dissociate only partially; the degree of their dissociation, i.e., the proportion of molecules decomposed into ions, increases with decreasing solution concentration.
A measure of the ability of electrolytes to decompose into ions in solutions can be the electrolytic dissociation constant (ionization constant), equal to
where square brackets show the concentrations of the corresponding particles in the solution.
When a constant electric current is passed through the electrolyte solution, the cations move to the negatively charged electrode - the cathode, the anions move to the positive electrode - the anode, where they give up their charges, turning into electrically neutral atoms or molecules (cations receive electrons from the cathode, and anions donate electrons at the anode) . Since the process of attaching electrons to a substance is reduction, and the process of donating electrons by a substance is oxidation, when an electric current is passed through an electrolyte solution, cations are reduced at the cathode, and anions are oxidized at the anode. This redox process is called electrolysis.
Electrolytes are indispensable integral part liquids and dense tissues of organisms. In physiological and biochemical processes, such inorganic ions as H +, Na +, K +, Ca 2+, Mg 2+, OH -, Cl -, HCO - 3, H 2 PO - 4, SO 2- 4 (see Mineral exchange). Ions H + and OH - in the human body are in very low concentrations, but their role in life processes is enormous (see Acid-base balance). The concentration of Na + and Cl - ions significantly exceeds that of all other inorganic ions combined. See also Buffer solutions, Ion exchangers.
Electrolytes are substances whose solutions or melts conduct electric current. Typical electrolytes are salts, acids and bases.
According to the Arrhenius theory of electrolytic dissociation, electrolyte molecules in solutions spontaneously decompose into positively and negatively charged particles - ions. Positively charged ions are called cations, negatively charged anions. The value of the charge of an ion is determined by the valency (see) of the atom or group of atoms that form this ion. Cations usually form metal atoms, for example, K+, Na+, Ca2+, Mg3+, Fe3+, and some groups of other atoms (for example, the ammonium group NH 4); anions, as a rule, are formed by atoms and groups of atoms that are acidic residues, for example Cl-, J-, Br-, S2-, NO 3 -, CO 3 , SO 4 , PO 4 . Each molecule is electrically neutral, so the number of elementary positive charges of cations is equal to the number of elementary negative charges of anions formed during the dissociation of the molecule. The presence of ions explains the ability of electrolyte solutions to conduct electric current. Therefore, electrolyte solutions are called ionic conductors, or conductors of the second kind.
The dissociation of electrolyte molecules into ions can be represented by the following general equation:
where is an undissociated molecule, is a cation with n1 positive charges, is an anion with n2 negative charges, p and q are the number of cations and anions that make up the electrolyte molecule. So, for example, the dissociation of sulfuric acid and ammonium hydroxide is expressed by the equations:
The number of ions contained in a solution is usually measured in gram ions per 1 liter of solution. Gram-ion - the mass of ions of a given type, expressed in grams and numerically equal to the formula weight of the ion. The formula weight is found by summing the atomic weights of the atoms that form a given ion. So, for example, the formula weight of SO 4 ions is equal to: 32.06+4-16.00=96.06.
Electrolytes are divided into low molecular weight, high molecular weight (polyelectrolytes) and colloidal. Examples of low molecular weight electrolytes, or simply electrolytes, are ordinary low molecular weight acids, bases and salts, which in turn are usually divided into weak and strong electrolytes. Weak electrolytes do not completely dissociate into ions, as a result of which a dynamic equilibrium is established in the solution between ions and undissociated electrolyte molecules (equation 1). Weak electrolytes include weak acids, weak bases, and some salts, such as mercuric chloride HgCl 2 . Quantitatively, the dissociation process can be characterized by the degree of electrolytic dissociation (ionization degree) α, the isotonic coefficient i and the electrolytic dissociation constant (ionization constant) K. The degree of electrolytic dissociation α is the fraction of electrolyte molecules that decomposes into ions in a given solution. The value of a, measured in fractions of a unit or in%, depends on the nature of the electrolyte and solvent: it decreases with increasing solution concentration and usually changes slightly (increases or decreases) with increasing temperature; it also decreases when a stronger electrolyte is introduced into the solution of a given electrolyte, forming the same nones (for example, the degree of electrolytic dissociation of acetic acid CH 3 COOH decreases when added to its solution of hydrochloric acid HCl or sodium acetate CH 3 COONa).
The isotonic coefficient, or van't Hoff coefficient, i is equal to the ratio of the sum of the number of ions and undissociated electrolyte molecules to the number of its molecules taken to prepare the solution. Experimentally, i is determined by measuring the osmotic pressure, lowering the freezing point of the solution (see Cryometry) and some other physical properties solutions. The values i and α are interconnected by the equation
where n is the number of ions formed during the dissociation of one molecule of a given electrolyte.
The electrolytic dissociation constant K is the equilibrium constant. If the electrolyte dissociates into ions according to equation (1), then
where, and - concentrations in solution of cations and anions (in g-ion/l) and undissociated molecules (in mol/l), respectively. Equation (3) is a mathematical expression of the law of mass action as applied to the process of electrolytic dissociation. The more K, the better the electrolyte decomposes into ions. For a given electrolyte, K depends on temperature (usually it increases with increasing temperature) and, unlike a, does not depend on the concentration of the solution.
If a weak electrolyte molecule can dissociate not into two, but into a greater number of ions, then the dissociation proceeds in stages (stepwise dissociation). For example, weak carbonic acid H 2 CO 3 in aqueous solutions dissociates in two steps:
In this case, the dissociation constant of the 1st stage significantly exceeds that of the 2nd stage.
Strong electrolytes, according to the Debye-Hückel theory, in solutions are completely dissociated into ions. Examples of these electrolytes are strong acids, strong bases, and almost all water-soluble salts. Due to the complete dissociation of strong electrolytes, their solutions contain a huge number of ions, the distances between which are such that electrostatic attraction forces appear between oppositely charged ions, due to which each ion is surrounded by ions of the opposite charge (ionic atmosphere). The presence of an ionic atmosphere reduces the chemical and physiological activity of ions, their mobility in an electric field, and other properties of ions. The electrostatic attraction between oppositely charged ions increases with an increase in the ionic strength of the solution, which is equal to half the sum of the products of the concentration C of each ion and the square of its valency Z:
So, for example, the ionic strength of a 0.01 molar solution of MgSO 4 is
Solutions of strong electrolytes, regardless of their nature, with the same ionic strength (however, not exceeding 0.1) have the same ionic activity. The ionic strength of human blood does not exceed 0.15. For a quantitative description of the properties of solutions of strong electrolytes, a quantity called activity a was introduced, which formally replaces the concentration in equations arising from the law of mass action, for example, in equation (1). Activity a, which has the dimension of concentration, is related to concentration by the equation
where f is the activity coefficient, showing what proportion of the actual concentration of these ions in the solution is their effective concentration or activity. As the concentration of the solution decreases, f increases and in very dilute solutions becomes equal to 1; in the latter case, a = C.
Low molecular weight electrolytes are an indispensable component of liquids and dense tissues of organisms. Of the ions of low molecular weight electrolytes, H+, Na+, Mg2+, Ca2+ cations and anions OH-, Cl-, HCO 3 , H 2 PO 4 , HPO 4 , SO 4 play an important role in physiological and biochemical processes (see Mineral metabolism). Ions H + and OH- in organisms, including the human body, are in very low concentrations, but their role in life processes is enormous (see Acid-base balance). The concentrations of Na+ and Cl- greatly exceed the concentration of all other ions combined.
For living organisms, the so-called antagonism of ions is highly characteristic - the ability of ions in solution to mutually reduce the action inherent in each of them. It has been established, for example, that Na + ions in the concentration in which they are found in the blood are poisonous for many isolated organs of animals. However, the toxicity of Na+ is suppressed when K+ and Ca2+ ions are added to the solution containing them in appropriate concentrations. Thus, K+ and Ca2+ ions are antagonists of Na+ ions. Solutions in which the harmful effect of any ions is eliminated by the action of antagonist ions are called equilibrated solutions. Antagonism of ions was discovered when they act on a variety of physiological and biochemical processes.
Polyelectrolytes are called high-molecular electrolytes; examples are proteins, nucleic acids and many other biopolymers (see Macromolecular compounds), as well as a number of synthetic polymers. As a result of the dissociation of macromolecules of polyelectrolytes, low molecular weight ions (counterions) are formed, as a rule, of a different nature and a multiply charged macromolecular ion. Some of the counterions are firmly bound to the macromolecular ion by electrostatic forces; the rest are in solution in a free state.
Soaps, tannins, and certain dyes are examples of colloidal electrolytes. Solutions of these substances are characterized by equilibrium:
micelles (colloidal particles) → molecules → ions.
When the solution is diluted, the equilibrium shifts from left to right.
See also Ampholytes.
Electrolytes include acids, bases and salts. Their molecules have ionic or covalent strongly polar bonds. Non-electrolytes include, for example, hydrogen, oxygen, sugar, ether, and many other organic substances. The molecules of these substances contain covalent low-polar and non-polar bonds.
Theory of electrolytic dissociation by S. Arrhenius
The theory of electrolytic dissociation, created by S. Arrhenius in 1887, makes it possible to explain the electrical conductivity of electrolyte solutions and melts. The fact is that the molecules of acids, salts and bases, when dissolved or melted, decompose into ions - positively and negatively charged. This process is called dissociation or ionization.
By themselves, ions in a solution or melt move randomly. In addition, in addition to dissociation, the opposite process takes place simultaneously - the combination of ions into molecules (, or molarization). From this we can conclude that the dissociation is reversible.
When an electric current is passed through an electrolyte solution or melt, positively charged ions begin to move towards a negatively charged electrode (cathode), and negatively charged ones begin to move towards a positively charged one (anode). Therefore, ions of the first type are called "cations", and the second type - "anions". The cations may be metal ions, hydrogen ion, ammonium ion, etc. Hydroxide ion, ions of acidic residues and others act as anions.
Degree of dissociation, strong and weak electrolytes
Various electrolytes in aqueous solutions may completely or incompletely decompose into ions. The former are called strong, the latter are called weak. The number showing which part of the dissolved molecules dissociated into ions is called the degree of dissociation α.
Strong electrolytes are strong acids, all salts and water-soluble bases are alkalis. Strong acids are perchloric, chloric, sulfuric, nitric, hydrochloric, hydrobromic, and a number of others. Alkalis include hydroxides of alkali and alkaline earth metals - lithium, sodium, potassium, rubidium, cesium, calcium, strontium and barium.