Middle School Chemistry? Reward! Chemistry in the third year of junior high school for a detailed ex

It seems that some of them are out of class, and they belong to high school chemistry.

Hello, this one can be estimated approximately.

The O content is 4 times that of H, so the H content is, so that the C, O, and H contents add up to 92%, and the remaining N accounts for 8%.

Assuming 1 n, 14 8% = 175, it does not match.

Assuming 2 n, 28 8% = 350, exactly match.

Assuming 3 n, 42 8% = 525, it can only be 2 n, and the relative molecular weight is 350

Then use 69% by 350 to calculate c is, the closest is 20 c(240) times 350 to get o is, the closest is 4 o(64) times 350 to get h is, the closest is 16 h (16) plus 2 n of 28, so the calculated relative molecular mass is 348 and then take it back for testing, c is 240 348 =

o is 64 348=

H is 16 is a quarter of O64, both in line.

The total number of atoms is 20 + 4 + 16 + 2 = 42

The breakthrough is in n, because c accounts for 4 times and the O content is 4 times that of H, we can know that N accounts for 8%, and because the relative molecular mass is between 300 and 400, that is, the formula of N is between 24-32, and because the relative atomic mass of N is 14, we can know that there are 2 n atoms in the molecule, and then find the accurate relative molecular mass of 28 8% = 350, and then find the number of atoms of C h O.

Actually, I'm just here to confuse experience.

Is a% a mass score?

Then there is: the amount of NaOH substance is m*a% 40 ; The amount of H2SO4 substance is n*a% 98

Both are strong electrolytes, the reaction is complete, and the litmus is still purple after mixing, indicating that the two are just completely reacting, and the acid-base is just neutralized.

n(naoh)=2n(h2so4) →m*a%/40 = 2*n*a%/98

m = 80 98 n, i.e. m

C, complete reaction, 98m=80n, while litmus purple, acid excess, n>m

Solution: According to the meaning of the question, it can be seen that the substance is dissolved in 10 grams of water to become a saturated solution, and the solubility of the substance is x when t is set

100：x=10g：

Solution x=36g

The solubility of this substance is 36 grams at the time of answer.

The answer should be C.

Grease emits the most calories per gram of oxidation, so the least amount of grease is needed when the same amount of heat is generated;

The least amount of glucose is released per gram of oxidation, so the maximum amount of glucose is needed when the same amount of heat is generated.

You are right, don't be the answer to dance.

The same calorie 1kj is consumed separately, 1 18, 1, 1 can be compared with the size.

It should have something to do with their relative molecular mass.