A chemistry problem, a chemistry problem, a quick solution

Alkaline Therefore, c(oh-)>c(h+) a is wrong.

Soluble in water alkaline, it is its weak acid S2 - step by step hydrolysis and the production of OH- makes the solution alkaline, these OH- all come from water, and only for the aqueous solution, there is C (OH-) = C (H+) and H+ in the solution in the form of Hs- H2S H+, so option B:

C(OH-)=2C(H2S)+C(Hs-)+C(H+) Note] 2C(H2S) is multiplied by 2 and the above charge conservation is different, here because the amount of hydrogen ions in the solution = the amount of hydroxide species, so for H2S, there must be 2molH+ in 1mol, so it should be multiplied by 2.

c.The conservation of charge c(s2-) should be multiplied by 2 because s2- with 2 units of negative charge c is wrong.

d.The charge is conserved with C(H+)+C(Na+)=C(OH-)+C(Hs-)+2C(S2-).

Option b c(oh-) = c(h+) + c(hs-) + 2c(h2s).

Bringing b into the equation of conservation of charge gives c(na+) = 2c(h2s) + 2c(hs-) + 2c(s2-) d error.

1.Conservation of charge:

C(Na+)+C(H+)=C(OH-)+2C(S2-)+C(HS-) comparison.

C is incorrect.

2.Conservation of materials.

C(Na+)=2C(S2-)+2C(Hs-)+2C(H2S).

dError can be known.

3.Bring the formula of conservation of material into the formula of conservation of charge.

Eliminate C(Na+) to obtain C(OH-)=C(H+)+C(Hs-)+2C(H2S).

It is known that b is correct.

I come when the remaining gas is no.

4no +3o2+2h2o=4hno3

16 x solution x is equal to 12ml In the second case, when the remaining gas is O2, 4NO + 3O2 + 2H2O = 4HNO3

20 x x = 15 ml of solution at this time to fill the tube, and then 1 5 x 20 = 4 ml of oxygen can also be used.

Therefore, the introduced oxygen is 15 + 4 = 19 ml

When the liquid level in the test tube is stable at 4 5, it means that there is 4 ml of gas in it, which can be either NO or O2

1. If it is 4 ml of NO, the reaction will drop 16 ml of NO4 + 3O2 + 2H2O = 4HNO3

16 x = 12 ml.

Namely: 12 ml of oxygen is required.

2. If 4 ml is O2, then the oxygen will react completely with 20 ml of NO first, and then the excess 4 ml of 4 NO + 3O2 + 2H2O = 4HNO3

20 y y = 15 ml.

That is: oxygen needs 15 + 4 = 19 ml.

Analysis: 20 ml of 4 to 5 for 16 ml.

The reaction is: 4O 3O2 2H2O 4Hno3 Discussion: (1) O2 is introduced so that 4mlNo is left at the end. According to the equation, O2 is required to be 16 4 3 12ml

2) O2 is introduced to exhaust the NO reaction, and at this time, the gas is 0. Then pass 4mlo2 again. then a total of O2 is 20 4 3 4 19ml

That is, O2 is 12ml or 19ml

Two cases: 1, 4NO +3O2 +2H2O = 4HNO3 in case of oxygen excess

20 x x = 15 then the gas in the test tube is all oxygen, and its volume is 5, so oxygen is introduced 15 + 4 = 19

2. Oxygen is less than 4NO +3O2 +2H2O = 4HNO3

y gets y=12

NO reacts with oxygen to form NO2 NO2 dissolves in water to form HNO3 and NO, and the total reaction formula is 4NO+3O2+2H2O=4HNO3

When the liquid level is stable at 4 5, 16 ml of oxygen is consumed, and the intake oxygen is 4 16=3 x x=12, and the incoming oxygen is 12 ml

Solution: The reduced mass is the mass of the carbon dioxide and water vapor that escapes

2naHCO==(heating) ==na2CO3+H2O+CO2 168 18 +44xx=

Mass fraction of sodium carbonate in the mixture: (

The metal is iron.

The chemical equation is: 4Fe(NO3)2== 2Fe2O3 + 8NO2 O2

Solution: No2 and O2 are combined, and their masses are the quantities of substances with calculated No2 and O2 respectively.

According to the equality of the number of electrons gained and lost in redox, it can be inferred that the metal is a variable metal. The chemical equation for the reaction can be written as follows: (let the metal be m, its valency is +n in nitrate, and its valency is +m in metal oxides).

2am(no3)n== am2om + 8no2 + o2

According to the equations of conservation of mass, conservation of charge:

The solution of the equation is discussed: a=2, m=3, n=2, m=56

So: the metal is iron.

The chemical equation is: 4Fe(NO3)2== 2Fe2O3 + 8NO2 O2

There may be two reactions to participation:

The reaction is NaOH + NaHCO3 = Na2CO3 + H2O

At 300, H2O is separated in gaseous form, according to the reaction relationship, the mass is reduced by 18g, NaHCO3 is reduced by 84g, according to the topic condition, the mass is reduced, so the mass of NaHCO3 is, so the mass of NaOH is 10g, N(NaOH)=, the amount of substance greater than NaHCO3. So the mass fraction of NAOH is 10 * 100%=

Then the reaction contains the decomposition of NaHCO3, and there is CO2 in the released gas, so there is no consonance in the gas, so only N(NaOH) N(NaHCO3) is comprehensible, so the mass fraction of NaOH is.

2na2o2＋2h2o====4naoh＋o2↑

2al+6h2o=2al(oh)3+3h2↑

That is, sodium peroxide reacts with water, aluminum, and sodium hydroxide solutions to form gram gas.

The final generation is sodium chloride and aluminum chloride.

Hydrochloric acid contains moles of chloride ions.

With sodium peroxide x mol, with aluminum y mol, there is.

32×2x+3y=

There is no solution, the estimation is entered incorrectly, and the hydrochloric acid volume is 200ml, which is calculated accordingly.

Solution: x = moles), y = moles).

So there are grams of sodium peroxide and grams of aluminum.

4.Let Fe be x grams in the solid.

fe ~ h2

xx = 7 grams.

Let the fe generated by the reaction be Y grams.

fe2o3+3h2==2fe+3h2o

yy = grams, so the original fe in the mixture is grams.

Raw iron oxide in grams.

NO2 02 is, CU(NO3)2

4 In the case of just complete reaction with naHCO3).

2al+2naoh+2h2o=2naaloh+3h2 I can't do it without a pen.

1. The number of molecules of the following two gases must be equal is (a) aThe molecular weight of N2 and C2H4 --- with equal mass and unequal density is 28, so equal mass, i.e., equal mol, i.e., equal number of molecules.

b.The same volume of CO and C2H4 --- not necessarily, it is the same mol at the same temperature and pressure, and with the same volume

c.Isothermal and equal volume O2 and N2 --- not necessarily, but also isobaric.

d.Isobaric equal volumes of N2 and CO2 --- not necessarily, but also at temperature.

MLA2 gas reacts exactly with 50ml of gas B2 completely, and the volume of gas produced is 100ml (under the condition of same temperature and pressure), try to infer the chemical formula of the gas product (A2B or BA2), and the basis for the inference is (Avogadro's law, the ratio of the volume of the gas is the ratio of the amount of the substance).

i.e. 2:1:2

2a2 + b2 = 2c

Mass is conserved, c is A2B or Ba2

1.Answer: When it comes to the number of molecules of matter, they are all astronomical.

It is not necessary to directly count the number of molecules and then compare them. To compare the number of molecules of matter, we must find a bridge of comparison, which is the "quantity of matter", because the amount of matter is proportional to the number of molecules.

a。The masses are equal to Mrs. N2 and C2H4, and since the molar masses of both are numerically equal, the amount of their matter is equal and their number of molecules must be equal. Since their densities are not equal, the information we can get is that they are certainly not equal in volume.

b。According to the gas equation of state: PV NRT. Only the volume, not the pressure and temperature, cannot know the amount of its substance. So b can't judge.

c。According to the Kraberon equation: PV NRT, when isothermal isochorc, only isobaric conditions can push out the amount of equal substance. C doesn't tell us about the pressure, so C can't tell.

d。Similarly, according to the equation of state of the gas: PV=NRT, isobaric equal volume, only when it is isothermal, can the amount of equal matter be pushed, so d cannot be judged.

2.The questions are incomplete and cannot be answered for you.

The molecular weight of ethylene is 28 and the molecular weight of ethylene is also 28Same mass, same relative molecular mass, so same amount of matter. It's the same molecular weight.

Gas? a2b。The volume ratio is equal to the quantity ratio of the substance. Because of the complete reaction, the composition ratio is a:b=2:1

1.Choose the terms a, b a because the molar masses of N2 and C2H4 are equal, so when the masses are the same, the amount of their matter is equal and the number of molecules is equal. Item B is of course correct, the volume is equal, and the amount of matter is equal. The C term must be isobaric and the D term must be isothermal.

2.The gas volume ratio is the ratio of the amount of gaseous substances, so a2:b2:c=2:1:2, and the product is a2b.