Have you ever thought about why some solutions conduct electricity, while others - not?For example, everyone knows that it is better not to take a bath at the same time putting the hair dryer.After all the water - a good conductor of electric current, and if the hair dryer falls into water, the short-circuit can not be avoided.In fact, water - not such a good conductor of current.There are solutions that conduct electricity much better.Such substances are called electrolytes.These include acids, bases and water-soluble salts.
Electrolytes - who are they?
question arises: why solutions of some substances pass electricity, and the other - no?The whole point of charged particles - cations and anions.When dissolved in water, electrolytes dissociate into ions, which under the action of the electric current moves in a predetermined direction.Positively charged cations move to the negative pole - the cathode and negatively charged anions move to the positive pole - the anode.The process of disintegration of matter into ions in the molten or dissolved in water, has a proud name - electrolytic dissociation.
This term coined by Swedish scientist S.Arrenius when studying the properties of the solution is passed electricity.For this, he closes the circuit through a solution of a substance and allowing the lamp lights at the same or not.If the bulb lights up - it means the solution conducts electricity, from which it can be concluded that the substance is an electrolyte.If the lamp remains extinct - that the solution does not conduct electricity, so this substance - non-electrolyte.By neeletrolitam include sugar solutions, an alcohol, glucose.But rastory salt, sulfuric acid and sodium hydroxide having a great electric current thus flows in them electrolytic dissociation.
How is dissociation?
later developed the theory of electrolytic dissociation, and Russian scientists have completed the IAHeels and VAKistyakovsky applying its justification chemical theory of solutions DIMendeleev.
These researchers found that the electrolytic dissociation of acids, alkalis and salts occurs in consequence of the hydration of the electrolyte, ie its interaction with water molecules.Jonah, cations and anions resulting from this process will be hydrated, that is associated with the water molecules that surround them dense ring.Their properties are significantly different from the non-hydrated ions.
Thus, in a solution of strontium nitrate Sr (NO3) 2, as well as in solutions of cesium hydroxide CsOH, electrolytic dissociation occurs.Examples of this process can be expressed by the following reaction:
Sr (NO3) 2 = Sr2 + + 2NO3 -,
ieby dissociation of one molecule of strontium nitrate formed one cation strontium nitrate and 2-anion;
CsOH = Cs + + OH-,
ieupon dissociation of one molecule, cesium hydroxide, cesium formed one cation and one anion is hydroxide.
electrolytic dissociation of acids is similar.For yodovodorodnoy acid, this process can be expressed by the following equation:
HJ = H + + CJ-,
ieby dissociation of one molecule yodovodorodnoy acid forms a hydrogen cation and one anion of iodine.
dissociation mechanism.
electrolytic dissociation of substances electrolytes occurs in several stages.For substances with ionic bonds, such as NaCl, NaOH, this process comprises three successive processes:
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first water molecule having two opposite poles (positive and negative) and is a dipole, oriented at the ion crystal.The positive pole, they are attached to the negative ion crystal and conversely, a negative pole - to the positive ions in the crystal;
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then there is hydration of ions of the crystal dipoles of water,
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and only then hydrated ions like in different directions and are beginning to move in a solution or melt chaotic as long as they will not work the electric field.
For substances with polar covalent bond, such as HCl and other acids, the dissociation process is similar, except that the initial transition occurs in a covalent bond through the action of an ionic water dipoles.These are the main points of the theory of the dissociation of matter.
