Exercises for the three conservation relationships in the hydrolysis of chemical salts. Thank you

5 25, C(NH4+) was measured in the solution of (NH4)2SO4, (NH4)2 CO3 and (NH4)2Fe(SO4)2 at a concentration of 1 mol L-1, and C (in mol L-1), respectively. The following judgment is correct ( d ).

a．a=b=c b．a>b>c c．a>c>b d．c>a>b

8 There are 25ml of Na2CO3 solution, CH3Coona solution and NaOH solution, and the concentration of the substance is correct

A The order of the size of the pH of the 3 solutions is

b If the three solutions are diluted by the same fold, the pH change is the largest

c If hydrochloric acid is added separately, the pH is the largest

d If the pH of the three solutions is 9, the order of the concentration of the substances is

9 Oxalic acid is a dibasic weak acid, and the solution of potassium hydrogen oxalate is acidic. In KhC2O4 solution, the following relationship is correct.

is (cd).

a．c(k+)+c(h+)=c(hc2o4—)+c(oh—)+c(c2o42-)

b．c(hc2o4-)+c(c2o42-)= mol•l-1

c．c(c2o42—)>c(h2c2o4)

d．c(k+)=c(h2c2o4)+c(hc2o4-)+c(c2o42—)

So in which cases is the hydrolysis of salt considered? 1.Hydrolysis should be considered when analyzing and judging the acidity and alkalinity of salt solutions. 2.Hydrolysis of salt is taken into account when determining the type and concentration of ions in a salt solution. Such as what ions are contained in the Na2S solution

1) Conservation of charge: The positive charge of all cation bands in the solution is equal to the negative charge of all anion bands.

C(Na+)+C(H+)=C(OH-)+2C(CO32-)+C(HCO3-), why is the carbonate preceded by 2; Is it (2)=(4) to add up the anion and ions of jujube without cultivating and dismantling?

In order for the values to be equal, the number of charges must be used as the coefficient of each ion. For example, in solid sodium carbonate, when the sodium ion is 2, the carbonate is 1, and in order to be equal to 1, it must be multiplied by 2

Among the three conservation formulas, 1. The coefficient of the concentration of each ion in the charge conservation formula is the number of charges; 2. The coefficient of the concentration of each ion in the material conservation formula is the number of material elements; 3. The coefficient of the concentration of the number of each ion in the proton conservation formula is the number of h+ that corresponds to the particle. It is also important not to get the coefficient wrong. 】

<> one. Conservation of electric charge.

The total negative charge of the anion in the electrolyte solution is equal to the total positive charge of the cation, and the application of the heavy silver guess of charge conservation is to list the equation according to the conservation of charge, compare or calculate the amount of distress of the ion of the substance or the amount of the concentration of the substance.

In an electrolyte solution, no matter how many ions are present, the solution is always electrically neutral, and the coefficient is determined by the number of charges carried.

For example: Na2CO3C (Na+)+C (H+)=C (OH-)+C (HCO3-)+2C (CO32-).

Two. Conservation of materials.

In the case of electrolyte solutions, conservation of materials means that the amount of matter of atoms (or ions) of an element before the electrolyte change (reaction or ionization) is equal to the sum of the quantities of all the atoms (or ions) containing that element in the solution after the electrolyte change. In essence, the conservation of materials belongs to the conservation of the number of atoms and the conservation of mass.

Conservation of other elements in the solution except hydrogen and oxygen.

Example: C (Na+) = C (HCO3-) + C (H2CO3) + C (CO32-).

Three. Conservation of protons.

Regardless of whether hydrogen ions are bound or lost in the solution, the total number of hydrogen atoms is always a fixed value, that is, the amount of hydrogen ions bound and the amount of hydrogen ions lost are equal in the front curve type.

Charge and material calculations, about the removal of strong ions.

For example, the ion concentration of water ionization conservation (this is called proton conservation): C (OH-) + C (CO32-) = C (H+) + C (H2CO3).

An example is given below: three conserved in a sodium carbonate solution.

Conservation of charge: that is, the "total positive charge" of the cation in the solution is equal to the "total number of negative charge" of the anion, note that the charge number here is not the ion number.

For example, the ratio of the number of charges carried by carbonate ions to carbonate ions in sodium carbonate solution is 1:2

The cations in the sodium carbonate solution are Na+ and H+, and the anions are CO32-, HCO3 and OH, so the column formula is as follows:

c(na+)+c(h+)=2c(co32－)+c(hco3－)+c(oh－)

Proton conservation: refers to the electrolyte itself does not ionize H+ and OH in the solution, the H+ and OH produced by water ionization are equal, and the ionized H+ may be combined with acid ions in addition to the existence of H+ in the form of H+, such as the combination of H+ and CO32 in sodium carbonate solution to form simple and buried H2CO3 or HCO3The column is as follows:

c(oh－)=c(h+)+c(hco3－)+2c(h2co3)

Conservation of materials: It refers to the fact that the different forms of existence of a traveling imitation element are derived from the initial particle, such as sodium carbonate solution, the Na element has only one form of existence, that is, Na+

There are three types of C elements: CO32-, HCO3, and H2CO3

In Na2CO3, the ratio of the number of Na+ to C atoms is 2:1The column is as follows:

c(na+)=2[c(co32－)+c(hco3－)+c(h2co3)]

The three major conservation of salt hydrolysis:

1. Conservation of charge:The total negative charge of the anion in the electrolyte solution is equal to the total number of positive charges of the cation, and an important application of charge conservation is to list the equation according to the conservation of charge, compare or calculate the amount of the substance of the ion or the quantity concentration of the substance.

2. Conservation of materials:In the case of electrolyte solutions, conservation of materials means that the amount of matter of atoms (or ions) of an element before the electrolyte change (reaction or ionization) is equal to the sum of the quantities of all the atoms (or ions) containing that element in the solution after the electrolyte change. In essence, the conservation of materials belongs to the conservation of the number of atoms and the conservation of mass.

3. Conservation of protons:Regardless of whether hydrogen ions are bound or lost in solution, the total number of hydrogen atoms is always a constant value, which means that the amount of hydrogen ions bound and the amount of hydrogen ions lost are equal.

1. The coefficient of the concentration of each ion in the charge conservation formula is the number of charges; 2. The coefficient of the concentration of each ion in the material conservation formula is the number of material elements; 3. The coefficient of the concentration of each ion in the proton conservation formula is the number of h+ that corresponds to the particle's gain or loss.

As a simple example, Na2CO3 solution.

Conservation of charge is the simplest So the amount of positively charged ions = so the amount of negatively charged ions.

The volume is the same, and the concentration is OK.

c(na+)+c(h+)=2c(co32-)+c(hco3-)+c(oh-)

Here, because every 1 CO32- has a 2 charge, the CO32- ion has a charge of x2

The conservation of materials is actually the conservation of elements.

The conservation of Na and C before and after Na2CO3 hydrolysis, and the amount of Na and C before and after hydrolysis remained unchanged.

Before hydrolysis, Na2CO3-2Na-1C, that is, NNA=2NC, and still NNA=2NC after hydrolysis

However, after CO32- hydrolysis, in addition to the original CO32- form, it is also partially hydrolyzed into HCO3 and H2CO3

For example, Na2CO3 ionizes 1000 CO32-

Of these, 20 were dehydrolyzed to HCO3-, (leaving 980 CO32- in their original state).

And 2 of the 20 HCO3- were dehydrolyzed to H2CO3. (18 keep HCO3-).

In this way, there are 980 CO32- and 18 HCO3- and 2 H2CO3 in the solution, but C is still 1000.

Pre-hydrolysis CNA=2cCO32-

After hydrolysis, CNA+=2 (CCO32-+CHC3-+CH2CO3) is the conservation of the material.

Proton conservation, that is, the ionization of water must be ch+=coh- conservation of protons, that is, the conservation of water ionization h+ and oh-.

The H+ fraction ionized from water in sodium carbonate solution is decombined with CO32- to form HCO3- and H2CO3

And the water and electricity ionized oh- did not bind anything.

ch+=coh-

Fractions H++CO32-——HCO3-, H2CO3

ch++chco3-+2ch2co3=coH- (2ch2co3 because 1 CO32- to bind 2H+).

The conservation of protons can also be determined by .Conservation of protons = conservation of charge - conservation of material.

The so-called "protons" are hydrogen ions, and when the transfer of protons [hydrogen ions] occurs between the components in the solution, the total number of protons obtained by the proton particles must be equal to the total number of protons lost by the proton particles, which is the so-called "conservation of protons".

Proton conservation essence: H+ ionized by water is equal to oh- ionized by water

Proton conservation formula: the concentration of H+ in solution minus the concentration of weak electrolyte resulting from the ionization of H+ from bound water multiplied by the number of bound H+ = the concentration of OH- in solution minus the concentration of weak electrolyte resulting from the ionization of OH- by binding water by the number of bound OH-.

Conservation of materials: The type and number of atoms do not change before and after the reaction.

Conservation of protons: It is based on the theory of acid-base protons, which refers to the number of acids lost in the process of reaction or ionization, which is equal to the number of protons obtained by the base.

Proton conservation means that the hydrogen ions and hydroxide ions ionized by water are 1:1 because water liberates hydroxide and forms an acid radical with one more hydrogen atom Truth be told, proton conservation is useless. All the conservation of protons is done by addition and subtraction of the conservation of charge and the conservation of materials.

You can completely ignore this kind of conservation and it is too frustrating.

The hydrogen ions ionized by water are equal to the hydroxide ions, but the ions of some salts can combine with certain ions ionized by water to reduce the concentration of the ion, and the reduction is equal to the concentration of particles formed after combining the ions, so that the remaining ions plus the particles generated are equal to the concentration of another ion ionized by water.

Sodium carbonate: conservation of electric charge.

n(na+)+n(h+)=2n(co32-)+n(hco-)+n(oh-)

In the above equation, the total charge of anion and cation should be equal, since the charge of 1mol of carbonate is 2mol of negative charge, the amount of charge carried by carbonate is twice the amount of its substance.

Conservation of materials. N(Na+) is twice the amount of carbonate ionic substances, and after ionization and hydrolysis, carbonate exists in three forms.

n(na+)=2[n(co32-)+n(hco3-)+n(h2co3)]

Conservation of protons. n(h+)=n(oh-) ionized by water

The hydrogen ions ionized from water in the aqueous solution of sodium carbonate exist in three forms of (H+, HCO3-, H2CO3), in which 2mol of hydrogen ions ionized by water are in 1mol of carbonic acid molecule.

Na2CO3 = 2Na + CO3 2- charge is conserved.

Conservation of materials. Conservation of protons.

c(h+)+c(na+)=c(co3-)+2c(co32-)+c(oh-)+c(hco3-)

When in doubt, please ask.