Mathematical notation of Faraday's unified law for electrolysis. Faraday's laws in chemistry and physics - a brief explanation in simple words

Laws of electrolysis (Faraday's laws)

Because the passage electric current through electrochemical systems is associated with chemical transformations, there must be a certain relationship between the amount of electricity flowing and the amount of reacted substances. It was discovered by Faraday and was expressed in the first quantitative laws of electrochemistry, later called Faraday's laws.

Faraday's first law . The amounts of substances converted during electrolysis are proportional to the amount of electricity that has passed through the electrolyte:

Dm = k e q = k e It ,

Dm is the amount of the reacted substance; k e - some coefficient of proportionality; q is the amount of electricity equal to the product of the current strength I and the time t. If q = It = 1, thenDm = k er, that is, the coefficient k e is the amount of substance that reacted as a result of the flow of a unit amount of electricity. Coefficient k uhcalled electrochemical equivalent .

Faraday's second law reflects the relationship that exists between the amount of the reacted substance and its nature: with a constant amount of passed mass electricity various substances, experiencing transformation at the electrodes (isolation from solution, change in valence), proportional to the chemical equivalents of these substances:

Dm i/A i= const .

It is possible to combine both Faraday's laws in the form of one general law: for excretion or transformation with current 1 g-eq any substance (1/zmole of a substance) always needs the same amount of electricity, called Faraday number (or faraday ):

Dm =It=It .

Accurately measured value of the Faraday number

F = 96484,52 ± 0.038 C/g-eq.

Such is the charge carried by one gram-equivalent of ions of any kind. Multiplying this number byz (the number of elementary charges of the ion), we get the amount of electricity that carries 1 g-ion . Dividing the Faraday number by the Avogadro number, we get the charge of one univalent ion, equal to the charge of the electron:

e = 96484,52 / (6,022035 × 10 23) = 1,6021913 × 10–19 C.

The laws discovered by Faraday in 1833 are strictly observed for conductors of the second kind. Observed deviations from Faraday's laws are apparent. They are often associated with the presence of unaccounted parallel electrochemical reactions. Deviations from Faraday's law industrial plants associated with current leakage, loss of substance when spraying the solution, etc. In technical settings, the ratio of the amount of product obtained by electrolysis to the amount calculated on the basis of Faraday's law is less than unity and is called current output :

B T = = .

With careful laboratory measurements for unambiguous electrochemical reactions current efficiency equal to one(within the experimental error). Faraday's law is strictly observed, so it is the basis of the most accurate method of measuring the amount of electricity that has passed through the circuit, by the amount of substance released at the electrode. For these measurements, use coulometers . Electrochemical systems are used as coulometers, in which there are no parallel electrochemical and side chemical reactions. According to the methods for determining the amount of formed substances coulometers are divided into electrogravimetric, gas and titration. Examples of electrogravimetric coulometers are silver and copper coulometers. The action of Richardson's silver coulometer, which is an electrolyzer

(–) Agï AgNO3× aqï Ag (+) ,

is based on weighing the mass of silver deposited on the cathode during electrolysis. When passing 96500 C (1 faraday) of electricity, 1 g-eq of silver (107 g) will be released at the cathode. When passingn F of electricity, an experimentally determined mass is released at the cathode (Dm to). The number of passed faradays of electricity is determined from the ratio

n = Dm /107 .

The principle of operation of a copper coulometer is similar.

In gas coulometers, the products of electrolysis are gases, and the amounts of substances released on the electrodes are determined by measuring their volumes. An example of a device of this type is a gas coulometer based on the reaction of electrolysis of water. During electrolysis, hydrogen is released at the cathode:

2H 2 O+2 e- \u003d 2OH - + H 2,

and oxygen at the anode:

H 2 O \u003d 2H + +½ O 2 +2 e – Vis the total volume of released gas, m3.

In titration coulometers, the amount of a substance formed during electrolysis is determined titrimetrically. This type of coulometer includes the Kistyakovsky titration coulometer, which is an electrochemical system

(–) Ptï KNO3, HNO3ï Ag (+) .

During electrolysis, the silver anode dissolves, forming silver ions, which are titrated. The number of faradays of electricity is determined by the formula

n = mVc ,

where m is the mass of the solution, g; V is the volume of titrant used for titration of 1 g of anode liquid; c – titrant concentration, g-eq/cm3.

Fundamentals > Tasks and Answers

Electrolysis. Faraday's laws

1 Find the electrochemical equivalent of sodium. Molar mass of sodium m \u003d 0.023 kg / mol, its valency z \u003d 1. Faraday constant

Solution:

2 Zinc anode mass m \u003d 5 g is placed in an electrolytic bath through which a current passes I \u003d 2 A. After what time t will the anode be completely used up for coating metal products? Electrochemical equivalent of zinc

Solution:

3 Find the Faraday constant if, when passing through the electrolytic bath of charge q = 7348 C at the cathode a mass of gold was released m \u003d 5 g. Chemical equivalent of gold A \u003d 0.066 kg / mol.

Solution:
According to Faraday's combined law

from here

4 Find elementary electric charge e, if the mass of the substance, numerically equal to the chemical equivalent, contains N o = N A /z atoms or molecules.

Solution:
Ions in an electrolyte solution carry a number of elementary charges equal to the valency z. When a mass of a substance is released that is numerically equal to its chemical equivalent, a charge passes through the solution that is numerically equal to the Faraday constant, i.e.

Therefore, the elementary charge

5 Molar mass of silver m 1 \u003d 0.108 kg / mol, its valence z 1 = 1 and electrochemical equivalent. Find the electrochemical equivalent of gold k2 if molar mass gold m2 \u003d 0.197 kg / mol, its valence z2 = 3.

Solution:
According to Faraday's second law, we have

hence the electrochemical equivalent of gold

6 Find the masses of substances released over time t \u003d 10 h on the cathodes of three electrolytic baths connected in series to the network direct current. The anodes in the baths - copper, nickel and silver - are lowered respectively into CuS solutions O 4, NiS0 4 and AgN0 3 . Electrolysis Current Density j =40 A/m2, cathode area in each bath S = 500 cm Electrochemical equivalents of copper, nickel and silver

Solution:
The current in the baths I=jS. According to Faraday's first law, the masses of substances released during electrolysis

7 When nickel-plating products over time t = 2 h deposited nickel layer thickness l =0.03 mm.
Find the current density during electrolysis. Electrochemical equivalent of nickel, its density

Solution:

8 An ammeter in series with the electrolytic cell indicates the current io \u003d 1.5A. What correction should be made to the ammeter reading, if during the time t \u003d 10 min a mass of copper was deposited on the cathode m = 0.316 g? Electrochemical equivalent of copper.

Solution:
According to Faraday's first law m = kI t , where I is the current in the circuit; from here I = m/kt \u003d 1.6 A, i.e. Ammeter reading needs to be corrected.

9 Wanting to check the correctness of the voltmeter readings, it was connected in parallel with a resistor with a known resistance R=30 Ohm. In series, an electrolytic bath was included in the common circuit, in which silver is electrolyzed. During t \u003d 5 min in this bath, a mass of silver stood out m = 55.6 mg. Voltmeter showed voltage Vo \u003d 6 V. Find the difference between the voltmeter reading and exact value voltage drop across the resistor. Electrochemical equivalent of silver.

Solution:
According to Faraday's first law m = kl t , where I is the current in the circuit. The exact value of the voltage drop across the resistance V=IR = mR/k t \u003d 4.91 V. The difference between the voltmeter reading and the exact value of the voltage drop

10 For silvering spoons through a silver salt solution over time t \u003d 5 h current is passed I \u003d 1.8 A. The cathode is n \u003d 12 spoons, each of which has a surface area S =50 cm2. How thick is the layer of silver deposited on the spoons? Molar mass of silver m \u003d 0.108 kg / mol, its valence z \u003d 1 and density .

Solution:
Layer thickness

11 Two electrolytic baths are connected in series. The first bath contains a solution of ferric chloride (FeCl 2 ), in the second - a solution of ferric chloride (FeCl 3 ). Find the masses of released iron on the cathodes and chlorine on the anodes in each bath as the charge passes through the bath. Molar masses of iron and chlorine.

Solution:
In the first bath, iron is bivalent (z1=2), in the second bath it is trivalent (z2 = 3). Therefore, when passing through solutions of identical charges, different masses of iron are released on the cathodes: in the first bath

in the second bath

Since the valence of chlorine atoms is z = 1, then a mass of chlorine is released at the anode of each bath

12 During the electrolysis of a solution of sulfuric acid (CuS O 4 ) power consumption N=37 W. Find the resistance of the electrolyte, if in time t = 50 min mass of hydrogen is released m = 0.3 g. Molar mass of hydrogen m \u003d 0.001 kg / mol, its valency z \u003d 1 .

Solution:

13 In the electrolytic method of producing nickel, W is consumed per unit mass m = 10 kWh h/kg of electricity. Electrochemical equivalent of nickel. At what voltage is electrolysis performed?

Solution:

14 Find the mass of liberated copper if W = 5 kW was spent to obtain it by the electrolytic method H h electricity. Electrolysis is carried out at a voltage V =10 V, efficiency installations h =75%. Electrochemical equivalent of copper.

Solution:
efficiency installations

where q is the charge passing through the bath. Mass of released copper m=kq; from here

15 What charge passes through a solution of sulfuric acid (CuS O 4 ) in time t \u003d 10 s, if the current during this time increases uniformly from I 1 =0 to I 2 = 4A? What mass of copper is released at the cathode in this case? Electrochemical equivalent of copper.

Solution:
Average current

The charge flowing through the solution

Finding the charge graphically is shown in fig. 369. On the graph of current versus time, the shaded area is numerically equal to the charge. The mass of copper deposited at the cathode,

16 When refining copper by electrolysis, a voltage V=10 V is applied to electrolytic baths connected in series, having a total resistance R = 0.5 Ohm. Find the mass of pure copper released on the cathodes of the bath during the time t =10h emf polarization e = 6 V. Electrochemical equivalent of copper.

Solution:

17 During the electrolysis of water through an electrolytic bath for a time t = 25 min current I \u003d 20 A. What is the temperature t released oxygen, if it is in a volume V = 1 l under pressure p = 0.2 MPa? Molar mass of water m \u003d 0.018 kg / mol. Electrochemical equivalent of oxygen.

Solution:

where R \u003d 8.31 J / (mol K) is the gas constant.

18 In the electrolytic method of producing aluminum, W is consumed per unit mass 1 m = 50 kWh h/kg of electricity. Electrolysis is carried out at voltage V1 = 1 6.2 V. What will be the power consumption W 2m per unit mass at voltage V2 = 8, 1 V?
Solution:

redox process, forcibly flowing under the influence of an electric current is called electrolysis.

Electrolysis is carried out in an electrolytic cell filled with electrolyte, in which electrodes connected to an external current source are immersed.

Electrode connected to the negative pole external source current is called cathode. At the cathode, the processes of reduction of electrolyte particles take place. An electrode connected to the positive pole of a current source is called anode. Oxidation processes of electrolyte particles or electrode material take place at the anode.

Anode processes depend on the nature of the electrolyte and the anode material. In this regard, electrolysis is distinguished with an inert and soluble anode.

An anode is called inert, the material of which is not oxidized during electrolysis. Inert electrodes include, for example, graphite (carbon) and platinum.

An anode is called soluble, the material of which can be oxidized during electrolysis. Most metal electrodes are soluble.

Solutions or melts can be used as the electrolyte. In an electrolyte solution or melt, ions are in chaotic motion. Under the action of an electric current, ions acquire a directed motion: cations move towards the cathode, and anions - towards the anode and, accordingly, they can be discharged at the electrodes.

With electrolysis melts with inert electrodes only metal cations can be reduced at the cathode, and anions can be oxidized at the anode.

During the electrolysis of water solutions on the cathode, in addition to metal cations, water molecules can be reduced, and in acidic solutions, hydrogen ions H +. Thus, the following competing reactions are possible at the cathode:

(-) K: Me n + + ne→ Me

2H2O+2 ē → H 2 + 2OH -

2H + + 2 ē → H 2

The cathode reacts first with highest value electrode potential.

During the electrolysis of water solutions with soluble anode, in addition to the oxidation of anions, oxidation reactions of the electrode itself, water molecules and in alkaline solutions of hydroxide ions (OH -) are possible:

(+) A: Me - n ē→ Me n +

anion oxidation E 0

2H2O-4 ē O2+4H+

4OH - - 4 ē \u003d O 2 + 2H 2 O

At the anode, the first reaction is with the smallest value electrode potential.

For electrode reactions, equilibrium potentials are given in the absence of electric current.

Electrolysis is a non-equilibrium process, therefore the potentials of electrode reactions under current differ from their equilibrium values. The displacement of the electrode potential from its equilibrium value under the influence of an external current is called electrode polarization. The amount of polarization is called overvoltage. The magnitude of the overvoltage is influenced by many factors: the nature of the electrode material, current density, temperature, pH environments, etc.

The overvoltages of cathodic precipitation of metals are relatively small.

With a high overvoltage, as a rule, the process of formation of gases, such as hydrogen and oxygen, proceeds. The minimum hydrogen overvoltage at the cathode in acidic solutions is observed for Pt (h=0.1 V), and the maximum for lead, zinc, cadmium and mercury. The overvoltage changes when acidic solutions are replaced with alkaline ones. For example, on platinum in an alkaline environment, the hydrogen overvoltage is h = 0.31 V (see Appendix).

Anode oxygen evolution is also associated with overvoltage. The minimum overvoltage of oxygen evolution is observed on Pt electrodes (h=0.7 V), and the maximum is observed on zinc, mercury and lead (see Appendix).

From the foregoing, it follows that during the electrolysis of aqueous solutions:

1) metal ions are reduced at the cathode, the electrode potentials of which are greater than the water reduction potential (-0.82V). Metal ions having more negative electrode potentials than -0.82V are not reduced. These include alkali and alkaline earth metals and aluminium.

2) on an inert anode, taking into account the overvoltage of oxygen, the oxidation of those anions occurs, the potential of which is less than the potential of water oxidation (+1.23V). Such anions include, for example, I - , Br - , Cl - , NO 2 - , OH - . Anions CO 3 2-, PO 4 3-, NO 3 -, F - - are not oxidized.

3) during electrolysis with a soluble anode, electrodes from those metals are dissolved in neutral and acidic media, the electrode potential of which is less than + 1.23V, and in alkaline - less than + 0.413V.

The total products of the processes at the cathode and anode are electrically neutral substances.

To carry out the electrolysis process, voltage must be applied to the electrodes. Electrolysis voltage U el-za is the potential difference necessary for the reactions to occur at the cathode and anode. Theoretical electrolysis voltage ( U el-za, theor) without taking into account overvoltage, ohmic voltage drop in the conductors of the first kind and in the electrolyte

U el-za, theor = E but - E k, (7)

where E but, E k - potentials of anodic and cathodic reactions.

The relationship between the amount of a substance released during electrolysis and the amount of current passing through the electrolyte is expressed by two Faraday's laws.

I Faraday's law. The amount of substance formed on the electrode during electrolysis is directly proportional to the amount of electricity that has passed through the electrolyte solution (melt):

where k is the electrochemical equivalent, g/C or g/A h; Q is the amount of electricity, Coulomb, Q=It; t-time, s; I- current, A; F\u003d 96500 C / mol (A s / mol) \u003d 26.8 A h / mol - Faraday's constant; E is the equivalent mass of a substance, g / mol.

In electrochemical reactions, the equivalent mass of a substance is determined by:

n is the number of electrons involved in the electrode reaction of the formation of this substance.

II Faraday's law. When the same amount of electricity passes through different electrolytes, the masses of substances released on the electrodes are proportional to their equivalent masses:

where m 1 and m 2 – masses of substances 1 and 2, E 1 and E 2, g/mol – equivalent masses of substances 1 and 2.

In practice, often due to the occurrence of competing redox processes, less substance is formed on the electrodes than corresponds to the electricity that has passed through the solution.

To characterize the loss of electricity during electrolysis, the concept of "Current Output" is introduced. current output In t is the ratio expressed as a percentage of the amount of the actually obtained electrolysis product m fact. to the theoretically calculated m theory:

Example 10. What processes will take place during the electrolysis of an aqueous solution of sodium sulfate with a carbon anode? What substances will be released on the electrodes if the carbon electrode is replaced with a copper one?

Solution: In a solution of sodium sulfate, sodium ions Na + , SO 4 2- and water molecules can participate in electrode processes. Carbon electrodes are inert electrodes.

The following recovery processes are possible on the cathode:

(-) K: Na + + ē → Na

2H2O+2 ē → H 2 + 2OH -

At the cathode, the reaction with the highest value of the electrode potential proceeds first. Therefore, the reduction of water molecules will occur at the cathode, accompanied by the release of hydrogen and the formation of hydroxide ions OH - in the near-cathode space. The sodium ions Na + present at the cathode together with the OH ions - will form an alkali solution NaOH.

(+)A: 2 SO 4 2- - 2 ē → S 2 O 8 2-

2 H 2 O - 4 ē → 4H + + O 2 .

At the anode, the reaction with the lowest value of the electrode potential proceeds first. Therefore, the oxidation of water molecules with the release of oxygen will proceed at the anode, and H + ions accumulate in the anode space. The SO 4 2- ions present at the anode with H + ions will form a solution of sulfuric acid H 2 SO 4 .

The overall reaction of electrolysis is expressed by the equation:

2 Na 2 SO 4 + 6H 2 O \u003d 2H 2 + 4 NaOH + O 2 + 2H 2 SO 4.

cathode products anode products

When replacing a carbon (inert) anode with a copper one, another oxidation reaction becomes possible on the anode - the dissolution of copper:

Cu-2 ē → Cu2+

This process is characterized by a lower potential value than other possible anodic processes. Therefore, during the electrolysis of Na 2 SO 4 with a copper anode, copper will be oxidized at the anode, and copper sulfate CuSO 4 will accumulate in the anode space. The total reaction of electrolysis is expressed by the equation:

Na 2 SO 4 + 2H 2 O + Cu \u003d H 2 + 2 NaOH + CuSO 4.

cathode products anode product

Example 11. Make an equation for the processes occurring during the electrolysis of an aqueous solution of nickel chloride NiCl 2 with an inert anode.

Solution: Nickel ions Ni 2+ , Cl - and water molecules can participate in electrode processes in nickel chloride solution. A graphite electrode can be used as an inert anode.

The following reactions are possible at the cathode:

(-) K: Ni 2+ + 2 ē → Ni

2H2O+2 ē → H 2 + 2OH -

The potential of the first reaction is higher; therefore, nickel ions are reduced at the cathode.

The following reactions are possible at the anode:

(+) A: 2 Cl - - 2 ē →Cl2

2H2O-4 ē O2+4H+ .

According to the standard electrode potentials at the anode

oxygen must be released. In fact, due to the high oxygen overvoltage at the electrode, chlorine is released. The magnitude of the overvoltage depends on the material from which the electrode is made. For graphite, the oxygen overvoltage is 1.17 V at a current density of 1 A / cm 2, which increases the potential for water oxidation to 2.4 V.

Therefore, the electrolysis of a nickel chloride solution proceeds with the formation of nickel and chlorine:

Ni 2+ + 2Cl - \u003d Ni + Cl 2.

at the cathode at the anode

Example 12. Calculate the mass of the substance and the volume of gas released on inert electrodes during the electrolysis of an aqueous solution of silver nitrate AgNO 3 if the electrolysis time is 25 minutes and the current strength is 3 A.

Solution. During the electrolysis of an aqueous solution of AgNO 3 in the case of an insoluble anode (for example, graphite), the following processes occur on the electrodes:

(-) K: Ag + + ē → Ag ,

2H2O+2 ē → H 2 + 2OH -.

The potential of the first reaction is higher, therefore, the reduction of silver ions occurs at the cathode.

(+) A: 2H 2 O - 4 ē O2+4H+ ,

anion NO 3 - not oxidized.

g or liters l.

Tasks

5. Write down the electrolysis reactions on inert electrodes and calculate the mass of the substance obtained at the cathode and the volume of gas released at the anode during the electrolysis of electrolyte solutions, if the electrolysis time is 20 minutes, the current strength I\u003d 2A if the current output is V t \u003d 100%. What substances will be released on the electrodes when replacing an inert anode with a metal anode specified in the task?

№№	Electrolyte	metal electrode
	CuSO4	Cu
	MgCl 2	Ni
	Zn(NO 3) 2	Zn
	snf 2	sn
	CdSO4	CD
	FeCl2	Fe
	AgNO3	Ag
	HCl	co
	CoSO4	co
	NiCl2	Ni

End of table

To describe processes in physics and chemistry, there are a number of laws and relationships obtained experimentally and by calculation. Not a single study can be carried out without a preliminary assessment of the processes according to theoretical relationships. Faraday's laws are applied both in physics and in chemistry, and in this article we will try to briefly and clearly talk about all the famous discoveries of this great scientist.

Discovery history

Faraday's law in electrodynamics was discovered by two scientists: Michael Faraday and Joseph Henry, but Faraday published the results of his work earlier - in 1831.

In his demonstration experiments in August 1831, he used an iron torus, on the opposite ends of which a wire was wound (one wire per side). At the ends of one first wire, he supplied power from a galvanic battery, and connected a galvanometer to the conclusions of the second. The design was similar to a modern transformer. Periodically turning the voltage on and off on the first wire, he observed bursts on the galvanometer.

A galvanometer is a highly sensitive instrument for measuring small currents.

Thus the influence was shown magnetic field, formed as a result of current flow in the first wire, on the state of the second conductor. This impact was transmitted from the first to the second through the core - a metal torus. As a result of the research, the influence of a permanent magnet that moves in the coil on its winding was also discovered.

Then Faraday explained the phenomenon electromagnetic induction in terms of lines of force. Another was an installation for generating direct current: a copper disk rotated near a magnet, and a wire sliding along it was a current collector. This invention is called the Faraday disk.

The scientists of that period did not accept Faraday's ideas, but Maxwell took the research to form the basis of his magnetic theory. In 1836, Michael Faraday established relationships for electrochemical processes, which they called Faraday's Laws of Electrolysis. The first describes the ratio of the mass of the substance released on the electrode and the current flowing, and the second describes the ratio of the mass of the substance in the solution and the mass of the substance released on the electrode, for a certain amount of electricity.

Electrodynamics

The first works are applied in physics, specifically in the description of the operation of electrical machines and apparatus (transformers, motors, etc.). Faraday's law says:

For a circuit, the induced emf is directly proportional to the magnitude of the speed magnetic flux, which moves through this contour with a minus sign.

It can be said in simple words: the faster the magnetic flux moves through the circuit, the more EMF is generated at its terminals.

The formula looks like this:

Here dФ is the magnetic flux, and dt is the unit of time. It is known that the first derivative with respect to time is the speed. That is, the speed of movement of the magnetic flux in this particular case. By the way, it can move, like a source of a magnetic field (a coil with current - an electromagnet, or permanent magnet) and the contour.

Here, the flow can be expressed by the following formula:

B is the magnetic field and dS is the surface area.

If we consider a coil with densely wound turns, while the number of turns is N, then Faraday's law looks like this:

The magnetic flux in the formula for one turn is measured in Webers. The current flowing in the circuit is called inductive.

Electromagnetic induction is the phenomenon of current flow in a closed circuit under the influence of an external magnetic field.

In the formulas above, you may have noticed the modulus signs, without them it has a slightly different form, such as it was said in the first formulation, with a minus sign.

The minus sign explains Lenz's rule. The current that occurs in the circuit creates a magnetic field, it is directed in the opposite direction. This is a consequence of the law of conservation of energy.

Direction induction current can be determined by the rule right hand or, we considered it on our website in detail.

As already mentioned, due to the phenomenon of electromagnetic induction, electrical machines, transformers, generators and motors work. The illustration shows the current flow in the armature winding under the influence of the stator magnetic field. In the case of a generator, when its rotor rotates by external forces, an EMF arises in the rotor windings, the current generates a magnetic field directed oppositely (the same minus sign in the formula). The greater the current drawn by the generator load, the greater this magnetic field, and the more difficult it is to rotate.

And vice versa - when current flows in the rotor, a field arises that interacts with the stator field and the rotor begins to rotate. When the shaft is loaded, the current in the stator and in the rotor increases, and it is necessary to ensure the switching of the windings, but this is another topic related to the design of electrical machines.

At the heart of the operation of the transformer, the source of the moving magnetic flux is an alternating magnetic field that occurs as a result of the flow of alternating current in the primary winding.

If you want to study the issue in more detail, we recommend watching a video that easily and clearly explains Faraday's Law for electromagnetic induction:

Electrolysis

In addition to research on EMF and electromagnetic induction, the scientist made great discoveries in other disciplines, including chemistry.

When current flows through the electrolyte, ions (positive and negative) begin to rush to the electrodes. Negatives move towards the anode, positives towards the cathode. At the same time, a certain mass of a substance is released on one of the electrodes, which is contained in the electrolyte.

Faraday conducted experiments, passing different currents through the electrolyte and measuring the mass of the substance deposited on the electrodes, deduced patterns.

m is the mass of the substance, q is the charge, and k depends on the composition of the electrolyte.

And the charge can be expressed in terms of current over a period of time:

I=q/t, then q = i*t

Now you can determine the mass of the substance that will be released, knowing the current and the time that it flowed. This is called Faraday's First Law of Electrolysis.

Second law:

Weight chemical element, which will settle on the electrode, is directly proportional to the equivalent mass of the element (the molar mass divided by a number that depends on chemical reaction in which the substance is involved).

In view of the foregoing, these laws are combined into the formula:

m is the mass of the substance released in grams, n is the number of electrons transferred in the electrode process, F=986485 C/mol is the Faraday number, t is the time in seconds, M is the molar mass of the substance g/mol.

In reality, due to different reasons, the mass of the released substance is less than the calculated one (when calculating taking into account the flowing current). The ratio of the theoretical and real masses is called the current output:

B t \u003d 100% * m calc / m theor

Faraday's laws have made a significant contribution to the development modern science, thanks to his work we have electric motors and generators of electricity (as well as the work of his followers). The work of EMF and the phenomena of electromagnetic induction gave us most of the modern electrical equipment, including loudspeakers and microphones, without which listening to recordings and voice communication is impossible. Electrolysis processes are used in the galvanic method of coating materials, which has both decorative and practical value.

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