Junior high school chemistry questions

This problem does not require a calculation process and is done using the elimination method.

Option A: Carbon and oxygen can react incompletely to form CO, and it is impossible to form CO2 X with all the remaining carbon

Option B: It's possible.

Option C: Co will also react with oxygen to form CO2, which is also impossible XOption D: The reaction is not complete and is not possible. x

You see if your question is wrong, it should be:

Which of the following inferences about the mass of the substance produced by the reaction of 12 g of carbon and 24 g of oxygen into a closed container is "probably" correct?

co2,3g c

co,22g co2

co,8g o2

co2,16g o2,9g c

When 12 g of carbon and 24 g of oxygen are passed into a closed container, the mass of the substance formed after the reaction cannot be correct.

c + o2 = co2

12 24 y

Because 12 12 is less than 32 24

So 32 24=12 x=44 y

Get x=9g, y=33g

Again, c is not completely burned.

So the remaining c = 12-9 = 3g

So first a 3g c 33g CO2

If all the CO is generated, the ratio of C to O2 is 3 to 4.

If all CO2 is generated, the ratio must be 3 to 8.

Now it's 1 to 2 and it's somewhere in between.

So if there is an excess of carbon to produce 28 GC, it is better to have (24-16) grams.

If there is an excess of oxygen.

The above reflects the equation, and it is up to you to give birth.

Hypothesis: The oxygen reaction requires exactly x carbon.

c + o2 = co2

12 32 x=9g

x 24g has C.. remaining after the O2 reaction

Bringing the option into the equation, the mass of carbon can be calculated.

In fact, it is very simple, you only need to calculate the carbon content of 14g CO, 22g CO2 to know that it is incorrect, the law of conservation of mass.

In this problem, it takes 32Go to form CO2 when 12GC is completely reacted to generate CO2, and only 16Go is needed to completely generate CO, but there are only 24g in the container, so what is left in the container should be a mixture of CO and CO2. According to the reaction equation, calculate how many g O and C are needed to generate 14 gCo and 22 gCo2, and the result is exactly the amount given in the question.

The title is wrong, because it should be correct that B is because oxygen reacts with carbon at high temperatures to form carbon monoxide, and then reacts with carbon monoxide to form carbon dioxide, and B is exactly the same.

That's not right! What are the reaction conditions? Generally speaking, carbon is a very stable substance, and it does not react with oxygen at room temperature.

C, theoretically every answer is true, but C does not satisfy the fact of reflection, since C and O2 are to reflect, then their conditions will also meet C and Co, so C and Co cannot coexist.

A 2C+O2=2Co Two C's and one O2 reflect that A is incorrect.

According to the law of conservation of mass, the mass of element C in option b is less than 12g. So B is definitely wrong.

Fe2O3+3H2SO4====Fe2(SO4)+3H2O mixture is soluble in sulfuric acid.

Cuo+H2SO4====CuSO4+H2O mixture is soluble in sulfuric acid.

6NaOH+Fe2(SO4)3====2Fe(OH)3 precipitate+3Na2SO4 dropwise sodium hydroxide was added to generate a precipitate.

2NaOH+CuSO4====Cu(OH)2 precipitate+Na2SO4 dropwise added sodium hydroxide to generate a precipitate.

80 32 The mass of sodium hydroxide is: 150g*16%=24g

24g x=

Eventually, the sodium in the sodium hydroxide is converted into the sodium in the sodium sulfate. Two sodium hydroxide molecules correspond to one sulfur atom in one sodium sulfate molecule.

The mass fraction of elemental sulfur is: (

Because the sulfur element in sulfuric acid is finally converted into the sulfur element in Na2SO4, and Na2SO4 is obtained from NaOH, according to the title NaOH is 24g by the conservation of one step element can produce the mass of sulfur element, the specific steps are as follows:

2NaOH Na2SO4 S 2 NaOH is required because Na2SO4 has 2 Na elements

Relative molecular weight 80 142 32

Actual mass 24g

So s%=

Start by writing the chemical reaction formula (omitted).

Because the sodium hydroxide added dropwise first neutralizes the excess sulfuric acid, it reacts with iron ions (3-valent) and copper ions (2-valent) to form a precipitate, which is iron hydroxide and copper hydroxide.

According to the conservation of charge, it can be calculated that n (sulfuric acid) = 1 2 * n (sodium hydroxide) = n (s): m (sodium hydroxide) = 150 * 16% = 24gn (sodium hydroxide) =

n(sulfuric acid)=n(s)=

so m(s)=

w(s)=

Since a part of copper will be generated when iron and copper sulfate solution react, more copper is obtained in scheme A, so the answer is: A;

When I first did it, the answer was A, and the landlord's answer was wrong.

Choose the first set of solutions and support the first answer.

Because dilute sulfuric acid reacts with iron and not with copper.

The copper sulphate solution will be combined with copper.