A chemistry question in the first year of high school, thank you for the answer

b The basic principle of redox is that the rise and fall of the chemical valence must be equal, that is, the teacher often says that there must be a rise, and nitric acid is a reactant after reading the question, which is very important, if nitric acid is a reactant, then you see that the valence of n in other substances containing nitrate has decreased, so there must be an element that will rise, that is, fe, and fe2|so4|3 and fe|no3|3 iron elements are +3 valence, only feso4 as a reducing agent to meet the topic, that's it, everything changes, don't see how difficult it is, lay a good foundation, and then add some innovation in ideas, evolution, I believe you will learn chemistry well.

The most important thing in the redox reaction is to find out the elements whose valency changes, the price increase is the reducing agent, which is oxidized, and the price reduction is the oxidant, which is reduced, because nitric acid is the oxidant, and the valence element is only iron, and the increasing valence of the reducing agent is known to rise from positive bivalent to positive trivalent, so ferrous sulfate is the reducing agent.

Reducing agent + oxidizing agent – oxidation product + reducing product.

Generally speaking, the reducing product in the same reaction is weaker than the reducing agent, and the oxidation of the oxidation product is weaker than the oxidant, which is the so-called "strong reducing agent to weak reducing agent, strong oxidant to weak oxidant".

So the reducing agent is FeSo4

b Due to the strong oxidation of nitric acid, ferrous ions cannot coexist, and there can be no FeSo4 in the product, that is, the reducing agent is FeSo4

This problem needs to be clarified about the rise and fall of valency in redox reactions.

First of all, nitric acid is a strong oxidant [memory] valency can only be reduced, therefore, another reactant as a reducing agent, there must be an element in a lower valence state, only the valency of no and feso4 can be increased, and the unit of no is +2 valence, and the nitrogen in nitric acid is +5 valence, if the reaction is neutralized, there will be a +3 or +4 valence of nitrogen generation [understanding], and there is no such compound told in the question, therefore, it can only be feso4

The analysis above feso4 is in place.

Pay attention to the oxidation and reduction of common particles, pay attention to classification and induction, and summarize memory!

Did you make a mistake with fe2|?so4|?

You should know that the elements are conserved, and the valency rise and fall should be conserved.

It is not difficult to deduce the answer through several attempts.

m = 20 * 14% = m = 30 * 24% = mass fraction of the mixed solution: (

v=(20+30)/

Concentration of the substance of the mixed solution: n=(

c=3.Let dissolve xmol x*101 (x*101+1000)=20% x=

What did you ask? Wait for ...... in the issue

The answer A should be very easy, when the hydrochloric acid is excessive, that is, the CaCO3 can be fully reacted, and the equation can be seen at a glance, and the answer D refers to the addition of hydrochloric acid can fully react the KhCO3, but not the CaCO3 can be fully reacted, at this time X, but after adding CaCO3, there must be gas released, so X<5. Okay, now cacl2

cahco3

CO2 so the increase in the right bottle is, and the increase in the left bottle is. From this we get y= +

It feels like b and the molecular weights of the two substances are equal, so when x and y have infinite masses, x=y must be x=y, so it would be good to select b alone.

The mass of CO2 produced by the reaction of XGKHCO3 with hydrochloric acid = YGCACO3 - the mass of CO2 reacted with hydrochloric acid, that is, because the molecular weight of KHCO3 and CaCO3 is the same, X-X 100*44=Y-Y 100*44 so X=Y

For convenience, 1 liter of water is provided, which needs to absorb ammonia in the state of the marker x.

Then, the ammonia mass after the absorption of the source m 1000 and its body bridge signal product v m 915(l) (

Its molar concentration c=(x =

Joining the above equations, we can solve x =

Therefore, 1 volume of water should absorb about the volume of ammonia.

First of all, a concentrated sulfuric acid in the air will absorb water and become larger. And the amount of sulfuric acid itself does not change, so the concentration of the solution decreases.

b. Sodium hydroxide will react with CO2 in the air to form sodium carbonate CO2 2NaOH = Na2CO3 + H2O The amount of solute substances increases, so the concentration of the solution increases.

c Chlorine water will prevent hypochlorous acid from decomposing for a long time, and chlorine gas will also overflow, so the concentration d is basically unchanged.

A concentrated sulfuric acid has water absorption, then the amount of solvent increases, the concentration decreases B will absorb CO2 and deteriorate into Na2CO3, and the reaction process also generates water, then the solvent increases, the solute decreases, and the concentration must decrease.

In C, HClO decomposes when photographed, and Cl2+H2O=HCl+HCl, a reversible reaction, is due to the decrease of HCl, then the reaction equilibrium must shift to the right, and the amount of Cl2 decreases.

The only possible thing is D, it will not have a chemical reaction, the water will evaporate, the solvent will decrease, of course, this explanation can also be used to question the first three answers, but the amount of solutes in B and C is reduced, A is definitely less volatile than D, D is the most appropriate answer.

A will absorb water B absorb C02 C Green water will reduce volatile concentration D It's okay to choose B

2co+o2=2co2

The total volume of CO2 measured after the X X reaction is 11 2L, so the amount of the substance is.

Hence the quality is.

If the amount of the original CO substance is x, then the original mass of CO2 is 18-28x, and the newly generated CO2 is x*44=44x

Then there is equation 18-28x+44x=22 to get x= so the original mass containing CO2 is 18-28x=11g

The amount of CO2 substance 11 44 = , so the volume of CO2 in the original gas mixture (standard condition) is.

The amount of the original CO substance is: volume is , so the density of the original gas mixture in the standard condition is (

As can be seen from the question, the amount of carbon is moles.

That is, the total mass of the mixture is molar.

m 18 can be obtained by the cross method, and the volume ratio is 1 to 1

m Density Density is available.

According to the conservation of mass, 16ga and 22GB exactly produce c and, then c is, according to the first condition, 8ga and 11gb should exactly produce sum, and the amount of matter given by the question is, so m(c)=

16ga+22gb==

8ga and 15GB reaction, B excess, take A as a calculation. generated.

Divide by the mass of friction.