Junior 2 Chemistry is better and more difficult Please answer in detail, thank you 11 19 11 5

Let the molecular weight of y be 1So.

x is, z is.

The total molecular weight of X2YZ3 is 4

Mass score 1 4, i.e. 25%.

It's a matter of proportion

The mass fraction of y in x2y is about 40%, then my (my+2mx)=40% gives my mx=4 3

In the same way, the mass fraction of y in yz2 is about 60%, then there is my (my+2mz)=60%, and my mz=3 1

Then by the least common multiple, there is my:mx:mz=12:9:4, so in x2yz3, the mass fraction of y is 12 (2*9+12+3*4).

Let the atomic weight of x be a, the atomic weight of y be b, and the atomic weight of z be c, then there is:

b (2a+b)= solution a=

b (2c+b)= solution c=

In compound X2yZ3, the mass fraction of y is:

w=b/(2a+b+3c)=b/(

According to the mass fraction of y in compounds x2y and yz2, assuming that the atomic weight of y is 40 (generally 100%), the atomic weight of x is 30 and the atomic weight of z is 25, then the mass fraction of y in x2yz3 is 23.

The relative atomic mass of b,s (23) divided by the mass fraction of sodium in this compound (i.e., s.

Molecular formula: C14H14N3NaO3S

Molecular Weight: CAS Number: 547-58-0

Density: g cm3

c14h14n3nao3s .

This is the methyl orange molecular formula.

There's at least one of each atom.

Divide their respective relative atomic masses by their mass fractions and take the maximum value to select c

The relative atomic mass of Na is 23, assuming that the molecule contains only one Na atom, the relative molecular mass of methyl orange is 23 divided by 7% to get 329, if the relative molecular mass of methyl orange is less than this value, the number of Na atoms is less than one, which is unrealistic, you can also try the other four elements, choose C

The mass of hydrogen released by the complete reaction of the steel sample is, then, the mass of hydrogen released by the complete reaction of the steel sample = , and the mass of hydrogen obtained in the third experiment is that the steel sample is not completely reacted, then the dilute sulfuric acid is completely reacted; So the answer is: ;

(1) When the amount of H2 produced is, there is (H2SO4 participates in the reaction, so when produced, the sulfuric acid is not excessive.

Sulfuric acid reacts with iron 1:1 so the number of moles of iron is.

then the mass of iron is 56

So the percentage of iron is.

2) When the mass is the sulfuric acid reaction is finished.

Because the mass lasts and the amount of H2 produced is.

So the number of moles of iron is (

So the iron mass of the reaction is.

And because the percentage of iron is about.

So the iron content in the steel sample is about greater than.

So iron doesn't react and plays sulfuric acid after the reaction.

The sulfuric acid reaction is complete, because the amount of hydrogen in the three experiments has been increasing, and if the reaction is completed, there is no possible .

This is a question about conservation of elements.

Since it is a reaction in pure oxygen, then the oxygen element is known to be present in the reactants.

And because the products are aerobic and carbon and hydrogen, the two elements carbon and hydrogen are only provided by this substance.

That is, the elements that must be present are carbon and hydrogen.

When the oxygen element in pure oxygen can provide oxygen in the product, then the substance does not need oxygen.

When pure oxygen provides some of the oxygen, the rest has to be provided by the substance, and then the substance needs to be aerobic.

Hence oxygen is an indeterminate element.

Oxygen can be obtained from oxygen, but it can also contain oxygen itself.

But since they are burned in pure oxygen, c and h must be obtained from themselves.

For example, CH4 (methane) is burned in pure oxygen to produce CO2 and H2O. Oxygen is obtained from the air.

C2H5OH (ethanol) is burned in pure oxygen to form CO2 and H2O, which are not only obtained from the air, but also contain oxygen in the ethanol itself.

Therefore, the substances that produce CO2 and H2O must contain C, H, and possibly O

Must contain elements C, H, and may contain element O.

You have chemistry in your second year of junior high school?!

There is definitely a CH element.

There may be an o element.

The questions on which you do your homework are all relatively basic, and the difficulty is not as difficult as the exam questions.

If you want to learn chemistry well in the third year of junior high school, you can try to take notes and memorize all the content of the notes. It's a stupid idea, but it's definitely useful. Look at your notes and look at the test papers you have done.

Or you can buy a set of test papers for yourself. If you only rely on listening to class and homework, I'm afraid it won't be enough. If you don't memorize something, such as the periodic table, metal elements, noble gases, and the commonly used chemical reaction equations of iron, aluminum, copper, and salts, it is difficult to learn well.

I've graduated from college and started working now, but I can still remember a little bit of chemistry in the third year of junior high school, which can only mean that I memorized it too many times at that time. At that time, it seems that Yuzhu Chemistry has not scored below 95 points, and it is all memorized, and practice makes perfect, and it will definitely not become hungry and rotten for rote memorization.

b.A mixture of the two.

Elemental sodium oxide reacts with water and the solution is also alkaline.

There is no obvious phenomenon of calcium chloride.

4Na + CO2 = 2Na2O + C white solid dissolved in water, dilute hydrochloric acid is added, and the gas generated can mix the clarified lime water.