What is electrolysis?

a long time, people could not get a lot of pure substances in the free form.Such as for example:

• metals;
• alkali;
• chlorine;
• hydrogen;
• hydrogen peroxide;
• organic chlorine and others.

They received either a high content of impurities, from which it was impossible to get rid of, or not synthesized at all.But the connection is very important for use in industry and everyday life.But with the discovery of a process such as electrolysis, the huge scale of the problem has been solved.Today it is used not only for synthesis but also for many other processes.

What is electrolysis?As it happens, some of the phases formed, what is the main advantage of this method, try to understand the course of the article.

What is electrolysis?

To answer this question, we should first seek to understand the terminology and some basic physical and chemical concepts.

1. DC - a directed flow of electrons emitted by any source of electricity.
2. Electrolyte - substance solution which is able to conduct electricity.
3. electrodes - records of certain materials, interconnected to the electricity passed through itself (anode and cathode).
4. redox reaction - a process in which there is a change in the degree of oxidation of the participants.That is, some ions are oxidized and increase the value of the degree of oxidation, while others are reduced, lowering it.

understand all these terms, it is possible to answer the question that is electrolysis.This redox process comprising passing a direct current through the electrolyte solution and is terminated by the release of different products at the electrodes.

simple installation, which can be called the electrolyzer includes a few components:

• two glasses with the electrolyte;
• current source;
• two electrodes are connected to each other.

The industry uses a much more complex automated design provides high mass products - electrolysis baths.

The electrolysis process is rather complicated, subject to a number of theoretical laws and flows through the established order and rules.To correctly predict the outcome, you must clearly understand all laws and passing options.

Theoretical Foundations of

The most important fundamental canons that hold the electrolysis - the laws of Michael Faraday - the famous physicist known for his work in the field of electric current and all its accompanying processes.

total of two rules, each of which describes the essence of the processes in the electrolysis.

first law

first Faraday's law, the formula is written as m = kI * Δt, is as follows.

mass of substance discharged at the electrode is directly proportional to the electricity, which passed through the electrolyte.

The formula shows that the m - is the mass of the matter, I - current, Δt - time during which it was passed.There is also a value k, which is called the electrochemical equivalent compound.This value depends on the nature of the compound itself.Numerically, k is the bulk substance, which is released by passing the electrode through the electrolyte of one unit of electrical charge.

second rule electrolysis

second Faraday's law, the formula of which - m = M * I * Δt / n * F, is as follows.An electrochemical equivalent of the compound (k) is directly proportional to its molar mass and inversely proportional to the valency of the substance.

This formula is the result of the withdrawal of all United.It captures the essence of the second law of electrolysis.M - molar mass of the compound, I - current strength, missed the entire process, Δt - the entire electrolysis, F - Faraday constant, n - electrons that participate in the process.Their number is equal to the charge of the ion, participate in the process.

Faraday's law helps to understand what is electrolysis, and to calculate the possible yield by weight, the desired result is to predict and influence the course of the process.They constitute the theoretical basis of the transformations.

concept of the anode and the types

very important to have the electrolysis electrodes.The whole process is dependent on the material from which they are made, their specific nature and properties.Therefore, we consider in more detail each of them.

Anode - plus or positive electrode.That is one that joins the "+" pole of the power supply.Accordingly, to it from the electrolyte solution will move negative ions or anions.They will oxidize here getting a higher degree of oxidation.

Therefore, we can draw a little diagram that will help remember anodic processes: an anode "plus" - anions - oxidation.Thus there are two basic types of electrodes, depending on which will turn a particular product.

1. insoluble or inert anode.Such type includes an electrode which serves only to transfer electrons and oxidation processes, however it is not consumed and not dissolved.Such anodes are made from graphite, iridium, platinum, carbon and so on.Using these electrodes, the metals can be produced in pure gases (oxygen, hydrogen, chlorine and so on).
2. soluble anodes.When oxidative processes he dissolves and affect the outcome of the electrolysis.The basic materials of construction for this type of electrode: nickel, copper, cadmium, lead, tin, zinc and others.The use of such anodes necessary for the electrolytic process metals, electroforming, protective coating against corrosion and so on.

The essence of all processes taking place at the positive electrode is reduced to ensure that the category of the most electronegative of the potential value of the ions.Ivot why do anions hydrogen acids and hydroxide ions, and then the water, if it is a solution.The oxygen-containing anions in an aqueous electrolyte solution generally do not discharge at the anode, as the water makes it faster, releasing oxygen.

cathode and its characteristics

cathode - is a negatively charged electrode (due to the accumulation of electrons on it by passing an electric current).This is why it moves to the positively charged ions - cations which undergo reduction, i.e. lower oxidation state.

There also is pertinent to remember scheme: a cathode "minus" - cation - recovery.As a material for the cathode can serve:

• stainless steel;
• copper;
• carbon;
• brass;
• iron;
• aluminum and sundry.

It is at this electrode is restored to a clean metal compounds, which is one of the main ways to get them in the industry.It is also possible the transfer of electrons from the anode to the cathode, and if the first - soluble, its ions are reduced on the negative electrode.Here is a restoration of cations to hydrogen gas H2.Therefore, a cathode - is one of the most important parts in the general scheme of the process of electrolysis substances.

electrolysis of molten

terms of chemistry reporting process has its equation.With it, you can represent the whole scheme on paper and predict the outcome.The most important thing you should pay attention to - the presence or absence of the aquatic environment and the type of the anode (soluble or not).

If necessary to obtain the following products: alkali and alkaline earth metals, alkalis, aluminum, beryllium, gases from oxygen-containing anions, then there can be a question about the electrolysis of the electrolyte solution.Just melt because otherwise required connections fail.That is why the industry frequently synthesize these substances, using their dry anhydrous salts and hydroxides.

the whole equation of melt electrolysis is quite simple and standard.For example, if we consider it to be written and potassium iodide, the form will be as follows:

KI = K + + I-

cathode (K) "-": 1e + K + = R0

anode (A) "+":2I- - 2e = I20

Outcome of: KI = K + I2.

Similarly electrolysis is recorded any metal regardless of its electrode potential.

electrolysis of aqueous solutions

the case of electrolyte solutions, the outcome of the process will be quite different.After all, water is becoming an active participant.It is also capable of dissociating into ions and discharged from the electrodes.Therefore, in such cases important electrode potential of the ions.The negative values ​​below it, the more likely the more rapid oxidation or reduction.

electrolysis of aqueous solutions is subject to several rules, which should be remembered.

1. anode processes: discharge only anions hydrogen acids (except hydrofluoric).If an oxygen ion or fluoride ion, then water will be oxidized to release oxygen.
2. Cathodic processes are metals in the electrochemical voltage range (up to and including aluminum) on the cathode can not be restored due to the high chemical activity.This makes the water to release hydrogen.Metals from aluminum to hydrogen restored simultaneously with water to simple substances.Those that are after hydrogen in the electrochemical series (low activity), are easily reduced to the simple substances.

If you follow these rules, we can portray any electrolysis and calculate yield.In the case of a soluble anode circuit varies and becomes much more complicated.

Electrolysis salts

These processes are used to produce pure metals and gases, as this is technologically simple and economically advantageous.In addition, the products come with a high degree of purity, which is important.

example, copper electrolysis makes it possible to quickly obtain it in a pure form from a solution of any salt.The most commonly used copper sulfate or copper sulfate (II) - CuSO4.

How melt or from a solution of the salt can be extracted pure metal, which is so necessary in virtually all sectors of electrical engineering and metal engineering.

value and application process

Electrolysis - a very important process.On the basis of such necessary based technical operations as:

1. metal refining.
2. electroextraction.
3. Electroplating.
4. Electrosynthesis.
5. anticorrosive coating and others.