Ask the second year of science There is a question about chemical reactions

Combustion in oxygen produces CO2 and H2O

From here it can be known that there must be c and h. in this substance

Oxygen consumed =

And the mass of o in the product =

So it turns out that the substance still has element O.

So there are three types of c, h, and o.

Do you know chemical equation trimming? C2H6O + 3O2 = 2CO2 + 3H2O, from the product point of view, there must be carbon and hydrogen, because there is no reactant, and there is in the product, and the existence of oxygen can be seen from the equation. If you don't understand this, you can look at the mass after reflection minus the amount before reflection, oxygen is, divided by carbon dioxide 44 is equal to 1, divided by water 18 is equal to, divided by oxygen 32 is equal to, so the above equation is obtained.

I don't know what your current level of knowledge is, can you understand what I said, don't understand it and ask again.

+O2=CO2+H2O can be known to contain c and h, m(c)=

m(h)=, and "must contain o2

Iron content of soy sauce 25mg 100ml

He absorbs milligrams of iron from soy sauce in a day.

fe---feso4

14 x solution yields x = 38g

If Xiao Ming's mother needs to supplement a total of grams of iron, she needs to take 38 grams of ferrous sulfate.

152 y gets y=80g

The iron content in 152 grams of ferrous sulfate is equivalent to the amount of iron oxide in 80 grams.

Mass fraction of iron in ferrous sulfate = amount of ferrous sulfate taken.

It is an acidic oxide, so strong bases can be, generally use NaOH, the chemical equation is 2NaOH + 2CO2 = Na2CO3 + H2O, Ca(OH)2 does not work because Ca(OH)2 is slightly soluble in water.

2.The greater the purity of the oxygen, the more fully it reacts with the carbon in the pig iron, and the greater the purity of the steel being refined.

3.Add the mass of the reactants, and then subtract the mass of the remainder to obtain the mass of the generated gas, A is, B is, C is the data of the classmate is wrong, it should be, it is still calculated in this way, but B participates in the reaction of the two reactants are the least, so the sample of B is completely reacted; The mass fraction equation is 2Fe + H2SO4 = FeSo4 + H2, and the mass of hydrogen is substituted (, to find the mass of Fe, and then divide by 9g of the sample mass to calculate the mass fraction of iron in the sample; Knowing the mass of Fe, you can find the mass of FeSO4 (solute), and the mass of the solvent is the mass of the reactant minus the mass of hydrogen.

Ca(OH)2 solution.

The concentration of Ca(OH)2+CO2=CaCO3+H2O is large, and the reaction is more thorough.

Comrade, there is a problem with the data.

By clarifying lime water, the oxygen content of Ca(OH)2+CO2=CaCO3+H2O pure oxygen is much higher than that of air, so that the contact area between the metal and oxygen is large and the reaction is sufficient, thereby increasing the efficiency.

The third question is too troublesome to calculate, so you can use a calculator to calculate it yourself.

Add the mass of the reactants, and then subtract the mass of the remainder to obtain the mass of the generated gas, A is, B is, C is the data of the classmate is wrong, it should be, it is still calculated in this way, but B participates in the reaction of the two reactants are the least, so the sample of B is completely reacted; The mass fraction equation is 2Fe + H2SO4 = FeSo4 + H2, and the mass of hydrogen is substituted (, to find the mass of Fe, and then divide by 9g of the sample mass to calculate the mass fraction of iron in the sample; Knowing the mass of Fe, you can find the mass of FeSO4 (solute), and the mass of the solvent is the mass of the reactant minus the mass of hydrogen.

n% = 35% in ammonium nitrate

Now the nitrogen content is gentle, so the nitrogen content of impurities must be greater than n%= in Qiaoyin A

n% in b = n% in c =

So choose C

The answer is c. The remainder is a mixture, indicating that at least one of the substances A and B has not reacted completely. If both A and B happen to be completely reactive, then according to the conservation of mass, the mass that produces C should be the sum of the masses of A and B, and now there is no complete reaction, then the mass of C must be less than the sum of the masses of A and B, and the sum of the masses of the mass of C generated and the mass of Unreacted A or (and) B is equal to the sum of the important ones when A and B are not reacting.

If it is not a mixture, then only C can choose answer A, and if it is a mixture, only C can be selected, and the mass is conserved.

If the reaction is complete, then only the substance C is obtained, because the remainder is a mixture, then there is a surplus in A and B, according to the conservation of mass, if A reacts completely with B, then there is C=A+B, because there is a surplus in One of A and B, so the answer is C

Because C is a compound, and what remains after the reaction is a mixture, it means that there is something else besides C. The mixture is A+B grams, so C is less than A+B. I haven't read a book in a long time, so that's how it should be.

Conservation of mass, if the product is not a mixture, choose A; Now it is a mixture, which means that the reaction is not finished, and all the substances are A+B grams, so the mass of C is naturally not as much as A+B

Because the residue is a mixture, either A or B must have an incomplete reaction in order to form a mixture with C, so the mass of C must be less than (A+B)G

Because the residue is a mixture, it is known that A and B are not fully reacted and there is a surplus, so the mass of the product C is less than (A+B)G

For example, CaCO3+2HCl=CaCl2+H2O+CO2 limestone is dissolved in hydrochloric acid to produce gas, and calcium chloride solution is gased.

They all told you that the biogenesis mixture is C+X

So a+b=c+x