Some questions about redox reactions

What you're talking about is a redox reaction. As long as the valency of any element in the reactant rises and falls. It can be two liters and one down; It can also be two drops and one liter; It can also be an element that rises and falls, i.e., disproportionation and centering. Here is the definition of redox reaction:

Oxidation-reduction reaction (also known as redox reaction) is a chemical reaction in which the valency of an element rises and falls accordingly before and after the reaction. A chemical reaction in which there is a change in the valency of an element during the reaction is called a redox reaction. This reaction can be understood as consisting of two halves, namely oxidation and reduction.

All such reactions observe conservation of charge. In redox reactions, oxidation and reduction must be carried out in equal quantities at the same time. The two can be likened to the relationship between yin and yang that is interdependent, transformed, ebb and flow, and oppositional to each other.

Redox reactions are also present in organic chemistry.

Redox reaction substance: the transfer of electrons takes place. (i.e., in ionic compounds, it is the gain and loss of electrons, and in covalent compounds, it is the deviation and bias of electrons).

Supplement: 1. The one with an increased valence must be a reducing agent, and another reactant is partly used as an oxidant and partly as a reducing agent. This question is a bit biased, and I can't think of such a reaction for a while.

Let's give you a similar example, it is also part of a part, 3Cu + 8Hno3 = 3Cu (NO3) 2 + 2 No + 4H2O, this reaction copper price rises, as a reducing agent, 2 N in nitric acid is reduced in price, 6 N is unchanged, that is, 2 nitric acid is oxidizing, and the remaining 6 are acidic.

It's all possible.

A in 1 should be a reducing agent, the element with an increased valence in B is a reducing agent, and the reduced element is an oxidizing agent.

Just judge according to the principle.

The essence of redox reaction is the gain and loss of electrons, that is, the rise and fall of valence, 1, possibly.

2. Possibly. 3. Not necessarily, there are also displacement reactions, etc.

Pure hand fighting, give points buddy

Albert Einstein also had a chemistry problem.

(1) Potassium chlorate is catalyzed by manganese dioxide to generate potassium chloride and oxygen, and the chemical equation of the reaction is: 2kclo3mno

KCL+3O2, the valency of Cl element in the reaction decreases from +5 valence to -1 valence, and the valency of O element increases from -2 valence to 0valence, and it can be seen from the change of valency that the direction and number of electron transfer can be expressed as <>, so the answer is: <>

2) Reaction 2kmNO4

16HCl (concentrated) 2KCl + 8H2

o+5cl2

Mn gets electrons, Cl loses electrons, the reaction is transferred 10E-, the "two-line bridge method" means that the direction and number of electron transfer of the reaction is <>, when there is 5mol chlorine gas generated under the standard condition, the electron transfer number of the reaction is 10Na, when there is chlorine gas generation under the standard condition, the electron transfer number of the reaction is Na

So the answer is: <>na

3) Reaction Na2

In S+I2=2Nai+S, the oxidant is iodine element, and the oxidation product is S, so oxidation I2

S, reaction O2

4hi═2i2

In 2H2O, the oxidant is oxygen, and the oxidation product is I2, so oxidizing O2

i2, so the oxidation order is: O2

i2 s so the answer is: o2

i2 s or s i2 o2

4）nahso4

It is an acid salt of a dibasic strong acid, which can be understood as fully ionized When the solution is neutral after the reaction, its reaction formula is: 2NaHSO4

ba（oh）2

baso4+na2so4

2H2O, then the ionic reaction equation is: 2H++SO4

ba2++2oh-

BaSO4+2H2O, at this time the solute in the solution is only Na2

SO4, add BA(OH)2

The ionic reaction equation is: BA2++SO4

baso4, so the answer is: 2h++so4

ba2++2oh-

baso4+2h2o；so4

ba2+=baso4

5) Sodium bicarbonate is weakly alkaline, and reacts with hydrochloric acid to form sodium chloride, carbon dioxide and water, and the reaction ion equation is HCO3

H+=H2O+CO2, so it can be ** hyperacidity, so the answer is: HCO3

h+=h2o+co2

I think your chemical formula should be written incorrectly, it should be 6HCl (concentrated) + KCLO3=KCl+3Cl2 +3H2O

Non-crossing regularity:

When the redox reaction occurs between different valence states of the same element, ** should be reduced, and the low price should be increased, and they mostly become the same valence state, and it is impossible to cross the phenomenon. This law is often used to determine the relationship between quantities, indicating the direction and number of electron transfers, for example, 6HCl (concentrated) + KCLO3 = KCl + 3Cl2 + 3H2O

To put it simply, in an inorganic reaction, there is a chemical reaction in which the valency of the elements rises and falls, that is, the electron transfer (gain, loss or shift) is a redox reaction. In organic reactions, the action of introducing oxygen or removing hydrogen from organic matter is called oxidation reaction, and the action of introducing hydrogen or losing oxygen is called reduction reaction.

In the reactants:

The loss of electrons (or electron pair deviation) is a reducing agent with an increased valency.

When an electron (or electron pair bias) is obtained, it is an oxidizing agent, and its valency decreases.

In the product: The element being oxidized is called the oxidation product, and its valency is increased during the reaction.

The element being reduced is called the reduction product, and its valency decreases during the reaction.

Redox reaction, divergence reaction, centering reaction and other types.

A disproportionation reaction is a reaction in which the same element is converted from one valence state to two valence states. A ** state, a low-price state, that is to say, the same substance is both an oxidant and a reducing agent.

The centering reaction is when different valence states of the same element rise or fall to the same valence state. But beware of compliance.

There are exceptions to any problem.

In general, where there is a reaction with the participation of elemental matter, the valency of the elements contained in the element will change, so such a reaction is a redox reaction, but when the forest is large, there are all birds, such as the following reaction:

2O3 = 3O2, which is about the transformation of the two elements of oxygen under certain conditions, their decomposition and compounding, but there is no change in valency.

Then there is the dehydration of sugars, C6H12O6

6C+6H2O, this should belong to the decomposition reaction, right? What does the carbon black in this decomposition product belong to? Is it simple to calculate late? Can you find a catalyst to make the following reaction take place, of course, you have to give a liquid of Luda to the energy:

6c+6h2+3o2

c6h12o6

We don't think about the significance of the reaction, we think about whether the reaction can happen, and if we really find a mechanism that can happen, it would be very good.

Reactions in which elemental elements are involved or generated do not necessarily belong to the redox reaction.

For example, 3o2 = (discharge) = 2o3, and when lightning is discharged, it produces ozone with digging fingers.

There is no change in valence culture before and after the reaction, so it is not a redox reaction.

It should be said that the chemical reaction with the participation of elemental substances must belong to the redox reaction.

A decomposition reaction with elemental formation must be a redox reaction.

Not necessarily, the basis for judgment is whether there is a transfer of electrons, the rise and fall of valence, such as the conversion between white phosphorus and red phosphorus, and the transformation between graphite and diamond, all of which are elemental, rented but not redox Zheng Naying.

The first question is selected, because there is no change in the valence of any element before and after the reaction, which is the criterion for judging whether it is redox or not.

The second question is that water only acts as an oxidant (a), water only acts as a reducing agent (d), water acts as an oxidant and a reducing agent (c), and water is neither an oxidant nor a reducing agent (b). The method of judging this problem is that if the hydrogen ions become hydrogen atoms before and after the reaction, that is, the hydrogen ions are reduced (the valency of hydrogen is reduced), then water is an oxidant, and in the same way, if the oxygen atoms become oxygen atoms, that is, the oxygen ions are oxidized, then the water is the reducing agent.

Option A: 2Na2O2+2H2O=4NaOH+O2. In this reaction, Na2O2 is both an oxidant and a reducing agent, which is manifested in the fact that two -1 valence oxygen ions in the two Na2O2 lose one electron and become 0 valence oxygen atoms to form oxygen, and the other two -1 valence oxygen ions get two electrons to become -2 valence oxygen ions to participate in the formation of NaOH.

Therefore, 2H2O is only a trim that participates in the chemical reaction in the reaction, i.e., it is neither an oxidizing agent nor a reducing agent.

Option B: 4Fe(OH)2+O2+2H2O=4Fe(OH)3. Fe(OH)2 in this reaction is the reducing agent and O2 is the oxidizing agent.

Specifically, the +2 valence ferrous ions in the four Fe(Oh)2 lose one electron to become +3 valence iron ions to participate in the formation of Fe(Oh)3, and the two oxygen atoms of O2 get 4 electrons to become -2 valence oxygen ions to participate in the formation of Fe(Oh)3. Therefore, 2H2O is only a trim that participates in the chemical reaction in the reaction, i.e., it is neither an oxidizing agent nor a reducing agent.

Option C 2F2+2H2O = 4HF+O2. F2 in this reaction is the oxidizing agent and H2O is the reducing agent. Specifically, two fluorine atoms of 2 F2 get 4 electrons to become -1 valence fluoride ions to participate in the formation of 4HF, and -2 valence oxygen ions in 2 H2O lose 2 electrons to become 0 valence oxygen atoms to participate in the formation of O2.

Therefore, H2O is a reducing agent.

Option d 2al+2naoh+2h2o=2naalo2+3h2. H2O in this reaction is the oxidizing agent and Al is the reducing agent. Specifically, 6 +1 valence hydrogen ions in 2 H2O and 2 NaOH get 6 electrons to become hydrogen atoms to form hydrogen, and 2 Al aluminum atoms lose 6 electrons to become +3 valence aluminum ions to form Naalo2.

Therefore, H2O in this reaction is the reducing agent.

This topic examines that the valency of H and O elements in H2O does not change during the reaction process of H2O.

Br2 + SO2 + 2H2O = H2SO4 + 2HBR water only plays the role of a reaction medium, and its valence does not change before and after the reaction, and it is neither an oxidant nor a reducing agent.

A 2Na2O2 + 2H2O = 4NaOH + O2 The O in O2 is all from Na2O2, Na2O2 is both an oxidant and a reducing agent, and water is neither an oxidant nor a reducing agent.

The valence of B 4Fe(OH)2+O2+2H2O=4Fe(OH)3H2O has not changed, it is the same before and after, and water is neither oxidant nor reducing agent C 2F2+2H2O=4HF+O2

Before the reaction, O in H2O is -2 valence, and after the reaction, it becomes 0 valence, and water is the reducing agent D 2Al+2NaOH+2H2O=2Naalo2+3H2 Before the reaction, H in H2O is +1 valence, and after the reaction, it becomes 0 valence, and water is the oxidant.

It is judged by whether the valency of the elements in the water has changed.

If the elements in the water only have reduced valency, they are oxidants; If the elements in the water only have an increased valence, it is a reducing agent; There are both oxidants and reducing agents; There is no change in valence, neither oxidant nor reducing agent.

The answer is too round, fooling people? There is no problem with the answer, ordinary people just don't know it very clearly, I have a simple way, look at the equation in the question, hydrogen and oxygen in water do not gain or lose electrons, judging from the products, there is no elemental generation, so as long as the atoms in the water molecule have no valence state change, that is, there is no electron transfer, then this water is the same as in the question, but the answer is different, let's figure it out for yourself.

Kid, you know, if an atom gains electrons and then loses electrons (mn in this reaction), these electrons are not considered to be "transferring" electrons, is it understandable?

So, the mno2 in this is the catalyst, and all the lost electrons come back, isn't it, so the electron transfer does not take into account the electron gain or loss of Mn

The essence of this reaction is that the Cl price decreases and the O price increases, so 6mol O mol transfers 4mol electrons and 6mol O2 transfers 24mol 、、、

If you don't understand, you can 、、、 me

The rise and fall of valence can only be considered in terms of one substance:

Based on CL:

The first step is down to 10, the second step is not down, the third step is down to 2, a total of 12 is down on the basis of o:

The first step rises by 4, the second step rises by 4, and the third step rises by 4, for a total of 12 rises based on MN:

The first step rises by 6, the second step drops by 2, and the third step drops by 4, for a total of no rise or drop.

So in general, the lifting of 12 and the transfer of electrons are 12mol, resulting in the formation of 3mol O2.

Of course, in terms of the total reaction, it is easier to eliminate the intermediate products, and there is no error.