Can anyone give me a few examples of the equation according to valence.

Is it redox trimming?

Cu+Hno3=Cu(NO3)2+NO2+NO+H20 can be ...... for nitric acid

It's also good to change the spawns yourself (no2, no, nh4no3, n2, n2o) and h2o2 to bleach kmno4.

kmno4+h2o2+h2so4=k2so4+mnso4+h2o+o2

None of the above are balanced

Reactions that can be leveled according to changes in valency are almost always redox reactions.

Here's how to trim a redox reaction:

1.The simplest: It can be conserved according to atoms, that is, the total number of atoms before and after the reaction is equal, and the corresponding number of atoms is equal.

2.The most effective: according to the conservation of electrons (which can be understood as the rise and fall of valence), because the essence of redox reaction is the gain and loss of electrons, and the gain of electrons must lead to the loss of electrons, and the conservation of electrons is used to make sure that it is right.

It's useless to say too much, let me give you an example.

cu+ hno3=

cu(no3)2+

no2↑+h2o

When encountering such a problem, we first observe who lowers the price of reactants and who increases the price.

cu(0)--cu2+,,hno3(+5)--no2(+4)

Therefore, Cu is the loss of electrons, Hno3 is the gain of electrons, according to the conservation of electrons, the coefficient of No2 should be 2 times that of Cu, write 2 first. cu+

hno3=cu(no3)2+

2no2↑+

H2O, at this time, the coefficients of Cu and No2 are determined).

However, it should be noted that Hno3 not only provides N of No2, but also No3-, so according to the conservation of atoms, the coefficient of Hno3 is 2+2==4, and the coefficient of H2O is 2

The final trim is. cu+

hno3=cu(no3)2+

no2↑+h2ofes2+(

hno3=(

fe(no3)3+(

so2+(no+(

h2o about this equation.

Let's start by marking their valence changes:

Fe from +2 to +3 (loss of 1e-) and S from -1 to +4 (loss of 5e-) both of these are reducing agents.

N from +5 to +2 (to get 3E-), it is also worth noting that Hno3 provides the N atom of No3- in addition to the N atom of No, this part of Hno3 is not used as an oxidizing agent, but only as an acid, and in the case of nitric acid with double action, the coefficient of the reactant is generally inverted by the coefficient of the product.

Now we are starting to make use of the conservation of electrons, trimming.

Fe from +2 to +3 (loss of 1e-) and S from -1 to +4 (loss of 5e-), so 1mol of reducing agent loses a total of 1+2 5=11mole-

n from +5 to +2 (to get 3e-), 1mol oxidant to get 3mole-, take the least common multiple, is 33

Therefore, first FES2 is matched with 3, NO is matched with 11, and then according to the conservation of atoms, FE(NO3)3 is matched with 3, and SO2 is matched with 6, so the coefficient of HNO3 is 3 3+11=20, and HO2 is 10

So the final answer is.

3fes2+20hno3=3fe(no3)3+6so2+11no+10h2o

Finally, check it with atomic conservation to determine the answer.

Hopefully, mine can help you!

The valency increases and loses electrons, which is a reducing agent, and is oxidized (up and down to lose oxygen).

According to the rise and fall of valence, the gain and loss of electrons is obtained, and then the balance equation is based on the electron balance of reducing agent and oxidant.

Not according to valence, but by least common multiple in mathematics.

For example, reaction: AL + NAOH + H2O = NAALO2 + H2

Let's look at o conservation first: no matching, it's already conserved.

Look at the conservation of h again: three in front and two in the back, then 3 2 before h2

Let's look at the conservation of al: no matching, it is now conserved.

Then the equation now is: AL + NAOH + H2O = NAALO2 + 3 2 H2

Find its least common multiple, which is the same as 2 on the left and right sides

Then becomes: 2Al + 2Naoh + 2H2O = 2Naalo2 + 3 H2

Check it again, it's all conserved, and the trim is over.

There is more trimming, more experience, and a lot of complex reactions, so you need to observe the method, take your time and don't worry.

The basic steps of the valence lifting method are: "one standard, two grades, three fixed, four flat, and five checks".

"One mark" refers to the marking of the valencies of the elements in the reaction where the oxidation and reduction reactions occur, indicating the total number of increases or decreases in each substance.

"Second" means that the total number of valence rises and falls is equal, that is, the number of two coprime (non-coprime should be divided) is cross-multiplied.

"Three determinations" refers to the coefficient before determining the chemical formula of oxidation products and reduction products by tracking method.

"Four flats" refers to the coefficient before the chemical formula of each other substance is balanced by observation.

"Five checks" means that in the reaction in which the aerobic elements participate, the total number of oxygen atoms on the left and right sides of the reaction formula can be checked whether they are equal (the ion reaction should also check whether the number of charges is equal), if it is equal, the equation has been balanced, and finally the equation "- - changed to "=".

This is more commonly used.

It is. Look at the rise and fall of the valence, how much it rises will decrease.

In fact, the gains and losses on both sides of the electrons should be conserved.

If you gain a few electrons, you will lose a few.

There is no such example!

Look at the rise and fall of the valence of the reputation, for example.

CU from 0 to +2 prices.

Lose 2 Celebrity.

n from +5 to +4.

To obtain 1 electric bond shield, the gain and loss of electrons should be conserved, so n*2, cu*1 (ascending n and cu) and then visually inspected.

Cu 4Hno3 (dilute) = Cu (No3)2 2NO2 2H2O

2 cu(no3)2 = 2 cuo + 4 no2 + o2n valence decreases by +5 to +4, decreasing by 1 valence.

o valence increases, -2 to 0, increases by 2 valence, but because it is O2, 2 O, a total of 4 valence, the coefficient is 4 no2 + o2

By nitrogen atoms, so 2 cu(no3)2, conserved by cu atoms, so 2 cu

Trim complete.

+5-2 -2 +4

cu(no3)2=o2+no2+cuo

The change in valency is marked first.

Then draw a double bridge line to mark the gain and loss of electrons.

5 to +4, +e

2 to 0, -2e*2

Let the gain and loss electrons be equal: +e*4

Put the corresponding no2 in front of 4, cu (no3) 2 in front of 2, and finally because there are two coppers on the left, there should also be two coppers on the right, and 2 in front of cuo.

2cu(no3)2=o2+4no2+2cuo

The balancing of chemical equations mainly has the following principles: 1. The atoms at both ends of the equation are conserved, that is, the total number of each atom corresponds to the same 2. Conservation of electrons: the total number of valencies reduced by all elements from left to right should be equal to the total number of increased valences, for example, the total valency of hydrogen increased in 2H2+O2=2H2O is 1*4=4, and the total valency of oxygen decreased is 2*2=4 Special:

There is no change in the valency of the elements at both ends of some reactions, such as Ca(OH)2+CO2=CaCO3 +H2O3, conservation of charge: the algebraic sum of positive and negative charges at the left and right ends should be equal in the ion equation of high school.

The valence of the redox element rises and falls, and then the electron gain is conserved Cu + Hno3 = Cu (No3) 2 + H2O + 2 NoCu 0 valence - Cu + 2 valence, and 2 electrons are lost.

n+5 valence – n+2 valence, giving 3 electrons.

Redox reaction electron gain and loss are conserved.

Take the least common multiple of the electron gain or loss.

3cu0 valence - 3cu + 2 valence, loss of 6 electrons.

2n+5 valence – 2n+2 valence, giving 6 electrons.

In this way, it is determined that 3Cu + 2Hno3 undergoes redox reaction, 3Cu + 8Hno3 = 3Cu (NO3) 2 + 4H2O + 2 NO, and 6Hno3 to generate salt 3 Cu (NO3) 2

First, the principle of balancing:

The number of atoms of each element before and after the reaction is equal, i.e., the mass is conserved.

The total number of electrons gained by the oxidant is equal to the total number of electrons lost by the reducing agent, i.e., the electrons are conserved.

The total value of the decrease in the valency of the oxidant is equal to the total value of the increase in the valency of the reducing agent.

Second, the trim step:

Standard valence: Write the chemical formula of the reactants and products, and mark the valency of the valence element.

Column Changes: List the rise and fall of the valency of the elements before and after the reaction.

Find the Total: Equalize the total number of increases and decreases in valence.

Matching coefficient: use the method of observation to balance the stoichiometric number of other substances, and after balancing, change the single line to an equal sign.

Check conservation: Check whether the two sides of the equation are "conservation of mass" and "conservation of charge".