How is the number of electrons transferred obtained?

Under the standard condition, chlorine gas reacts fully with a sufficient amount of magnesium powder, then the amount of chlorine gas is 1mol, and reacts with 1mol of magnesium to form 1mol of MgCl2, then the transfer of electrons is that the magnesium atom transfers 2 outer electrons to the chlorine atom respectively, and the number of transferred electrons is 2mol

It is derived from the rise and fall of the valence.

If there are transfer electrons, there must be a change in the valency of the same element, which must be a redox reaction. The change in the valency of a 1mol element is the number of electrons transferred by 1mol of the element. Let's take a few examples.

This reaction is a displacement reaction in a redox reaction. In the reaction, the valency rises from 0 to +2 per 1mol of ZN, and 2mol of electrons is lost to +1 valence hydrogen in 2mol of HCl, which is reduced to hydrogen, that is, the electrons are transferred to 2mol.

This reaction is a typical chemical reaction and is also a redox reaction. In the reaction, the valency of h increases from 0 to +1, while o decreases from 0 to -2. So in the equation, every 2molH2 loses 4mol of electrons and transfers to O2, that is, the number of electrons transferred is 4mol.

This reaction is a redox reaction between the same element. For every 1 mol of Fe, the loss of 2 mol of electrons becomes +2 valence, and the loss of 1 mol of electrons for 2 mol of Fe3+ makes its valency also become +2 valence. Therefore, the electron transfer is 2mol

dilute) = 3cu(NO3)2+2NO+4H2O

This reaction is a typical redox reaction. Cu is fully involved in redox, while Hno3 is only partially involved in redox. It can be seen that nitric acid first oxidizes Cu to Cuo, and then metathesis with Hno3.

The reaction is more complicated from the perspective of nitric acid, and there is only one reducing agent Cu, so the number of electrons lost by Cu must be the number of transfer electrons, that is, 3molCu is increased by 2 valence and loses 2mol electrons, that is, 6mol.

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The method for calculating the number of electron transfers is as follows:

Calculate the number of electron transfers in each equation, calculate the number of reactive substances according to the equation, calculate the molar amount, how many molecules are in 1 mole is the quantity value, 1 mole = 1 Avogadro constant (about a particle, according to the chemical equation, the number of electron transfers can be calculated.

The problem of electronic transfer (gain and loss) is analyzed, and "three attentions" should be achieved

First, it is necessary to pay attention to whether the disproportionation reaction occurs, for example, when the disproportionation reaction between Cl and H O and NaOH occurs, 1 mol Cl transfers 1 mol of electrons.

Second, it is necessary to pay attention to variable ridge dry valence elements, such as 1molfe reacts with sufficient hydrochloric acid to transfer 2mol electrons, and reacts with sufficient nitric acid to transfer 3mol electrons.

Third, we should pay attention to the problem of excess, such as a small amount of Cl and a sufficient amount of Cl in Febr solution, and the number of electrons transferred is not the same.

Number of transfer electrons = number of electrons given by oxidizing agent = number of electrons lost by reducing agent.

So, just count the number of electrons gained by the oxidant or the number of electrons lost by the reducing agent.

For example, the following reaction:

The number of electrons transferred is 2e-

Observe how many moles of electrons are transferred for each mole of the redox reaction, and then multiply this value by how many moles the chemical reaction takes place.

Single-line bridge method. The arrow points from the oxidized element in the reducing agent to the reduced element in the oxidant, and the direction of the arrow is the direction of electron transfer. The total number of transferred electrons is indicated on the bridge.

Two-line bridge method.

The arrows point to the reduction product by the oxidant, and the reducing agent points to the oxidation product, respectively. The arrows refer to the same element at both ends; The arrows do not indicate the direction of electron transfer, only the change before and after electron transfer. Indicate the number of electrons gained and lost on the bridge; The total number of electrons gained and lost is equal.

Example: Copper and oxygen reflect to form copper oxide, copper is bivalent, the number of the previous is 2, and the number of electrons transferred is 2*2e=4e.

The movement of electrons between two atoms or other chemical substances like molecules, etc. Electron transfer is a redox reaction that changes the oxidation state of two reactants.

The change in valency is multiplied by the foot code of the changing element and then multiplied by the number of measurements in front of the chemical formula.

For example, 2H2O2 = (MNO2 catalyst) = 2H2O+O2 Calculate the number of electrons transferred, you can calculate the transfer of elements with increased valency, and you can also calculate the transfer of elements with reduced valency.

In this reaction, part of the oxygen element -1 becomes -2, and part -1 becomes 0, and the number of electrons transferred is.

Varying valency = 1

Foot code = 2 The number of meters in front of the chemical formula = 2

Number of electrons transferred = 2 2 1 = 4

The increase and decrease are divided into half, so the final number of electrons transferred is 4

Observe the valence element by transferring the number of electrons, calculated or lost, do not calculate the readdition of the two. The simplest calculation techniques are: according to the amount of the rise and fall of the valence of the substance and the number of hetics on the equation; Calculate one mole of reaction to transfer electrons, multiply the amount of silver by the amount of reactive species.

The method for calculating the number of electron transfers is as follows:

1. In chemistry: calculate the number of electrons transferred in each equation, calculate the number of reactive substances according to the equation, calculate the molar amount, how many molecules are in 1 mole and have a quantitative value, 1 mole = 1 Avogadro's constant (about a particle, the number of electron transfers can be calculated according to the chemical equation Bipai;

2. Physics: The number of electrons can be calculated according to the ampere of the current, 1 ampere = coulomb second; 1 coulomb is about the amount of electricity equivalent to an electron.

The number of electrons transferred is observed to observe the valence element, calculated or lost, and the addition of the two is calculated. The simplest calculation techniques are: according to the amount of the rise and fall of the valence of the substance and the number of hetics on the equation; One mole of reaction electrons is calculated and multiplied by the amount of reactive species.

The method for calculating the number of electron transfers is as follows:

1. In chemistry: calculate the number of electron transfers in each equation, calculate the number of reactive substances according to the equation, calculate the molar amount, how many molecules are in 1 mole is the value, 1 mole = 1 Avogadro number shed constant (about a particle, the number of electron transfers can be calculated according to the chemical equation;

2. Physics: The number of electrons can be calculated according to the ampere of the current, 1 ampere = coulomb second; 1 coulomb is about the amount of electricity equivalent to an electron.

Problem 1: How to calculate the number of transferred electrons First mark the valency of the element with valency change, and then calculate the value of the increased valency and the value of the decreased valency, if there is more than one element that rises or falls, calculate the sum of the increased or decreased values, and the value of the increased valency (or decreased valency) is the number of transferred electrons.

Question 2: What is the number of transferred electrons and how to calculate it This is easy to calculate in the whole reaction, only the valency of cuprous sulfide Cu2S elemental oxygen has changed, from the change before the reaction to the post-reaction, the valency of copper in copper sulfide is from +1 liter to +2 valence, each copper atom loses 1 electron, the valency of sulfur in copper sulfide changes from -2 valence to +6 valence, each sulfur atom loses 8 electrons, and each oxygen atom in the elemental oxygen changes from 0 valence to -2 valence to gain 2 electrons. And the number of oxygen (referring to the number of atoms) is respectively, that is, copper loses 4 electrons, sulfur loses 16 electrons, and oxygen loses 20 electrons, so the number of electrons transferred should be 20.

Question 3: How do you see the number of electrons transferred? 10 points Find the atom with a change in valency.

The valence of the compound has risen and fallen. The Cl atom in Kclo3 drops and the Cl atom in Kclo3 rises by 6. So the number of electrons transferred is 6e-.

If you don't understand, ask your teachers and classmates, be sure to understand, don't be embarrassed.

Question 4: How to calculate the number of electrons transferred The change in valency is multiplied by the number of atoms, such as: 4HCl+MNO2===MnCl2+2H2O+Cl2The valency of chlorine is from -1 to 0 liters 1, and the number of atoms whose valency changes is 2 The number of lost electrons:

Number of electrons transferred = number of electrons lost by reducing agent = number of electrons gained by oxidant.

2al+6hcl===2alcl3+3h2

For example, in this reaction, the number of electrons transferred = the number of electrons lost in aluminum = h + the number of electrons gained.

Aluminum electron loss number: One aluminum atom loses three electrons to become aluminum ion, two aluminum atoms lose six electrons to become two aluminum ions, aluminum electron loss number = 6

H+ Electron Number: Two hydrogen ions get 2 electrons to become one hydrogen molecule, six hydrogen ions get 6 electrons to become 3 hydrogen molecules, H+ gets electron number = 6

The atom, the basic unit of matter, is made up of electrons, neutrons, and protons. Neutrons are not charged, protons are positively charged, and atoms are not electrically charged to the outside. Relative to the nucleus of neutrons and protons, the mass of electrons is extremely small.

The mass of a proton is about 1840 times that of an electron.

When electrons are free from their nuclei and move freely in other atoms, the net flow phenomenon is called an electric current.

The ability of various atoms to bind electrons is different, so they become positive ions due to the loss of electrons, and become negative ions when they gain electrons.