Help solve a junior high school chemistry problem 5

Analysis: The mass relationship between the two substances participating in the reaction was calculated by using the ratio of the relative masses of C and D and the relationship between the number of molecules of C and D in the reaction. According to the mass relationship between C and D, the mass of C is calculated from the mass of D. Finally, using the law of conservation of mass, the mass of substance B participating in the reaction is obtained, and the mass ratio of b to d can be calculated

Answer: Analysis: If the ratio of C and D to the molecular mass is 9:22, then the mass ratio is (2 9):(4 22)=9:44, and the mass of C is X, 2A+5B=2C+4D

x944 = x = the mass of b participating in the reaction according to the law of mass conservancy, then the mass ratio of b to d is 8g::11

Therefore, C

The answer is that the mass ratio of b to d is 8:11

Let a be 2m, b be n, c be 18a, then d is 88a, and then compare to get the formula: 2m, solve m=13a, and then according to the law of conservation of quantity of matter: 26a+n=18a+88a, solve n=80a, so the mass ratio is 8:11

Let a be 2xmol, then b is 5xmol, c is 2xmol, d is 4xmol, the ratio of the relative molecular mass of c and d is 9 :22, then c 2x d 4x = 9:22

Therefore, the amount of d generated corresponds to the amount of c generated, so the two of b are.

The mass ratio of b to d is 10:11

A is incorrect, macroscopic is better than microscopic, the type, number, and mass of atoms have not changed, so the type and mass of the elements remain unchanged, and the sum of the mass of the reactants participating in the reaction is equal to the sum of the mass of the product.

b is correct, in chemical change the molecule is divided into atoms, the atoms are recombined into new molecules, the type of molecule must change, and the type of matter must change. But the type, number, and mass of atoms do not change, so the type and mass of the elements do not change, and the sum of the masses of the reactants participating in the reaction is equal to the sum of the masses of the products.

a.The law of conservation of mass is related to microscopic processes, because the atom is the smallest particle in chemical change, so the type, number, and mass of atoms do not change, so the sum of the masses of the reactants participating in the reaction is equal to the sum of the masses of the products.

b, correct, not wrong.

b That's right, the total mass of the reactants in the chemical change is equal to the total mass of the products, so the mass of the reaction does not change...

You can't change the type of substance.

The question requires that the wrong B is correct.

1, (the products are MGO2 and MG3N2, the total mass is less than 40 g).

2,O2 is a white solid.

1.More than 40g because the generated magnesium oxide binds oxygen, and the oxygen has mass.

2.Magnesium is easier to combine with oxygen in the air because the product is more stable.

2 Oxygen is basically white magnesium oxide, not yellow-green.

1 < 2 oxygen MGO is more stable than Mg3N2.

The reaction formula can be written as: mg+n2+o2 - mgo+mg3n2 can be regarded as the last generation of mg4n2o (it will not actually be generated, for the convenience of calculating the assumptions) known mg24g then divide the base by 4 to get 24 + 14 * 1 2 + 16 * 1 4 = 35<40

11g CO2 contains element C, mass = 11, 44 * 12 = 3g, 9g H2O, mass = 9, 18 * 2 = 1g, because 3+1=4g<8g

It shows that in addition to C and H, there are o oxygen elements in organic matter, and the mass of oxygen = 8-4 = 4g.

Number of atoms c:h:o = (3 12):(1 1):(4 16) = 1:4:1

So x=1, y=4, z=1

The mass fraction of carbon in CO2 is 12 44, and 11 gCO2 contains 11 * 12 44 = 3 g of carbon

In the same way, the mass of hydrogen is calculated as 9*2 18=1g

Because it is completely burned.

According to the law of conservation of mass, the reactant contains 3g of carbon and 1g of hydrogen, and only the original organic matter has carbon and hydrogen in the reactant.

So 8g of organic matter has 4g of carbon + hydrogen, and the remaining 4g is oxygen.

So the mass ratio of carbon, hydrogen, and oxygen is 3:1:4 because the relative molecular mass is 32, which is 12:4:16

Therefore, the ratio of the number of moles of carbon, hydrogen, and oxygen, that is, the number of atoms, is 1:4:1, so CH4O, X=1, Y=4, O=1

In 11g of CO2, C accounts for 11 44 * 12 = 3 g, H accounts for 9 g of H2O, and H accounts for 9 18 * 1 * 2 = 1 g

In total, it accounts for 4g of the organic matter, and it is 8g, and there is 4g of o at will, according to the molar ratio of c, h, o 3 12:1 1:4 16=1:4:1 so x=1 h=4 y=1

Therefore, the chemical formula of the organic substance is CH4O, and according to the gas chemical formula, the amount is 32, so its final chemical formula is CH4O, which can be burned in oxygen, and the final judgment is methanol CH3OH

CO reduces iron oxide to form CO2, and together with CO2 in the original gas mixture, it reacts with Ca(OH)2 to form white precipitated CaCO3

From this point of view, the C in the white precipitate CaCO3 is all ** in the C in the mixed gas, and the mass of C in the mixed gas is calculated to be 30 *4g=, then the mass of the white precipitate is X

Note: 12 100 is the mass fraction of carbon in a calcium carbonate molecule) to obtain x = 10 g

So the final white precipitate mass is 10g

I hope my answer is helpful to you. o(∩_o~~

This reaction does not look at the CO reduction to generate CO2, which is finally converted into CaCO3 precipitation.

It turns out that the content of C is 10g, i.e., and finally CaCO3 is 10g

Both the C in the mixture and the C in CO2 are eventually converted into CO2, so the mass of the total C is 4 30%=

The final CO2 is 10g of white precipitated CaCO3.

You can easily list the calculation steps in between, and that's how this is how you can play the slow problem.