Chemistry in junior high school is urgent and the topic is very long

1) Let the mass of iron in the sample be x

Mass of sulfuric acid = 20 * grams.

h2so4+fe=feso4+h2↑

x98 solution x= mass of Fe in the sample is.

Fe%= The amount of impurities is approximate.

In junior high school, you should have learned that the content of impurities (mostly carbon) in steel is about that, so it is judged to be pig iron.

2) After the reaction, the solute is FeSo4, and the mass of FeSo4 is Yg, and the mass of H2 is Zg

h2so4+fe=feso4+h2↑

y z98/ y= 98/ ∴z=

The mass of the solution is.

feso4%=

3) The reason why the waste liquid is not wasted is that the solute is only FeSo4, and pure FeSo44 can be prepared) must be filtered once first, because the sample contains insoluble impurities; But I don't think it works by atmospheric evaporation, because it will oxidize ferrous ions to iron ions, and the good way is to use the method of vacuum evaporation, and the solute FeSo4 can be obtained

1. Solution: The mass of pure H2SO4 is: 20g*

Let the Fe mass be X

fe+h2so4==feso4+h2↑

x56/x=98/

x = so the content of c is (

The pig iron content is 2%.

So it's pig iron products.

2. Let the mass of FeSO4 be Y, and the mass of H2 be ZFe+H2SO4==FeSO4+H2

y z98/

Y = Z = According to the law of conservation of mass, the mass of the resulting solution is equal to the mass of Fe participating in the reaction plus the mass of dilute H2SO4 minus the mass of H2, i.e.

So the mass fraction of the solute in FeSo4 solution is.

3. This approach is feasible.

It can improve the utilization rate of resources and reduce the pollution to the environment at the same time.

4. After filtration, pour the obtained solution into the evaporation dish to evaporate.

The added solution contains pure sulfuric acid: 20*, according to the chemical equation: Fe + H2SO4 = FeSO4 + H2, the iron consumed is: 56*, the mass fraction of iron is, and the sample contains 2% carbon, so it is pig iron.

The mass of the solution containing FeSo4 is 152*, and the mass of the solution is:

22g, mass fraction:. 4%

Thirdly, this statement is correct. Because the solute ferrous sulfate in solution is an important industrial raw material and pharmaceutical raw material.

The fourth question, decompression evaporation, the solid is the solute that is to be the first.

1.The implication is that you calculate the percentage of carbon.

H2SO4: grams.

fe+~~h2so4===feso4+h2↑x=

c%=(So it's steel.) 2.Solution volume = 20 ml = liters.

Keep it to yourself after the decimal point.

Next, let's look at y= from the previous question

w%=3.Agree, recycle resources and reduce pollution.

4.It looks like evaporation, but I don't know the specifics.

Georgxx, you can't count the amount of matter at all, because the solute of sulfuric acid is SO3, and you consume sulfuric acid.

When calculating the first question, you can't ignore it too much after the decimal point, because the carbon content is not high, so the error is large.

1.Write the chemical equation first:

fe+ h2so4 = feso4+h2;

m 20* x y ；

m is the mass of the iron, x is the iron sulfate, and y is the hydrogen;

Because "dilute sulfuric acid is added dropwise until no more bubbles are produced", the reaction is exactly complete.

So m=56*20*;

Whereas; , so it's steel;

The solute is Feso4=154*20*;

The total mass of the solution should be minus the overflowing hydrogen = 2*;

Therefore, the solute mass fraction of the solution obtained by the reaction is:;

3.Yes, because the reaction solution is a pure solute liquid at this time;

1) Filter out impurities;

2) heating and evaporation to obtain the crystallization of Feso4;

n（h2so4）=n（fe）=

m（fe）=

m(c)=c%=carbon content of pig iron is greater than; The carbon content of steel is less.

So for pig iron.

feso4%=

3.Yes, the solution can be made to contain alum.

4.The solution is filtered first, and then the solution is evaporated under reduced pressure.

Solution: Let the mass of the iron that occurs the reaction be x, the mass of the iron sulfate produced by the reaction is y, and the mass of the hydrogen gas produced is z

20g*fe+h2so4=feso4+h2↑

x y zx= y= z=

The mass fraction of carbon in ferroalloys.

Because pig iron has a carbon content of 2%.

Therefore, this ferroalloy is pig iron.

The quality of the solution.

The mass fraction of the solute in solution.

3.Consent The solution can be made into alum, and ferrous sulfate is an important industrial and pharmaceutical raw material.

4.The solute in the solution obtained by evaporating the solvent**.

1) Pig iron. 20* grams) – sulfuric acid weight.

fe+ h2so4=feso4+h2

Weight (g) original (min) weight 56 98 152 2

Carbon content in iron products.

3) Agree. It is made of green alum and used as a water purification agent and gas purification agent.

4) Filtration, evaporation, and concentration.

1) It should be pig iron, because only pig iron can be reflected;

Doing it with the conservation method is actually quite simple.

There are 3 carbon monoxide with a relative molecular weight of 28*3=84 and 2 carbon dioxide with a relative molecular weight of 44*2=88

A total of 172, where the relative molecular mass of carbon is 5*12=60

So the mass ratio of the carbon element is 60 172=

n(co)=3/28

n(co2)=2/44

Then the mass ratio of the carbon element is n(co) n(co2)n represents the number of moles.

Let the CO mass be 3m and the CO2 be 2m.

The mass ratio of the carbon element is 3m*12 28:2m*12 44=33:14

Because m(c) = n(c) * m(c) then c in m(co): c in m(co) = c in n(c) in co): n (c in co2).

n(co):n(co2) = c in n(co): n(c in co2) = 3 28:2 44 = 33 14

3*(12 28) is better than 2*(12 44).

In parentheses is the relative molecular pre-molecular quality of calcium gluconate

When selecting A through concentrated sulfuric acid, it means that there is no NH3, when clarifying lime water, it means that there is no CO2, there is HCL, and then, in oxygen, anhydrous copper sulfate can not be made blue, indicating that there is no CH4 and H2, and it is a mixed gas, so it can only be A.

The total volume of the selected D gas is basically unchanged, and there may be NH3, CO2 and HCl without turbidity, and CO2 cannot be ruled out, because no turbidity does not mean that there is no such reaction, because of the accumulation of turbidity requirements.

The decrease in the total volume of the gas indicates that there is an acidic gas that reacts with it and burns in O2, and the anhydrous copper sulfate cannot turn blue indicates that there is no water formation, indicating that the gas definitely does not contain H, and it is definitely not hydrogen and methane

"When passing through excess clarified lime water, no turbidity is seen, but the total volume of gas decreases" indicates that this gas may not contain CO2, and it should have a certain solubility in water, such as NH3 and HCl, because lime water is excessive, so the possibility of coexistence of HCl and CO2 is excluded; "Ignition in O2, combustion products can not make anhydrous CuSO4 powder blue" means that the flammable gas will not produce water, so it should be CO, no CH4, H2; then select A

A When the mixed gas passes through concentrated H2SO4, the total volume of the gas is basically unchanged, indicating that there is no NH3, because the concentrated sulfuric acid reacts with NH3.

When passing through the excess clarified lime water, no turbidity is seen, but the overall volume of the gas is reduced** There must be HCl, because the lime water is excessive, so there is no CO2

When ignited in O2, the combustion product can not make the anhydrous Cuso4 powder turn blue, indicating that the combustion product has no water, then the absence of H2, CH4 can be ruled out

Only CO can burn

So there is HCL, CO in the gas

Hope it works for you.

The first sentence of Choice A is not very useful.

The second sentence does not see turbidity, indicating that there is no CO2, the D option excludes the reduction of the total volume of gas, indicating that there is an acidic gas and its reaction, indicating that there is HCL The third sentence, after the gas comes out, there are CH4, NH3, H2, CO alternative combustion in O2, it cannot be anhydrous copper sulfate turning blue, indicating that there is no water formation, indicating that the gas is definitely not organic matter, definitely not hydrogen, there is because NH3 does not react with O2 or the reaction is not obvious, so in the end only HCl and CO are left

"When the mixed gas passes through concentrated H2SO4, the total volume of the gas is basically unchanged" means that there is no alkaline gas, that is, there is no ammonia.

When passing through the excess clarified lime water, no turbidity is observed, but the total volume of the gas decreases", indicating that there is no carbon dioxide and at the same time HCl

Ignition in O2, combustion products cannot make anhydrous Cuso4 powder turn blue", indicating that the gas does not contain hydrogen.

In summary, it does not contain CH4, NH3, H2 and CO2. Contains HCl, then there is only one gas, CO, you can determine that the mixture of gas is HCL and CO, choose A

aBecause there is no turbidity when passing through excess clarified lime water, the total volume of gas is reduced, so there is no carbon dioxide, but there is hydrochloric acid (hydrochloric acid and calcium hydroxide to produce calcium chloride).

Ignition in O2, combustion products can not make anhydrous Cuso4 powder blue means that no water is generated, so there is no methane, hydrogen, ammonia.

So choose A

When the mixture passes through concentrated H2SO4, the total volume of gas is basically unchanged - there is no NH3;

When passing through excess clarified lime water, no turbidity is observed, but the total volume of gas decreases - there is HCl;

After the remaining gas is exported, it is ignited in O2, and the combustion products cannot make the anhydrous CuSO4 powder turn blue - there is CO, but there is no H2 and CH4;

The composition of the original gas mixture is HCL and CO.

In fact, there is something wrong with this question, and these experiments cannot prove whether there is CO2 or not.

The design of this question is problematic:

Clause. 1. The mass fraction after mixing should be between the two, that is, less than 46% and more than 20%, so it is impossible to reach 50%.

It's like two cups of unsweetened sugar water can't be sweeter when mixed together. It can only be sweeter than the unsweet, and lighter than the sweet.

2. The solubility of salt generally does not exceed 40 grams, which can be found in the 37-page book, so the mass fraction of salt solution cannot exceed 30%, and the data given in the question is wrong.

It's impossible.

1. The mass fraction after mixing should be between the two, that is, less than 46% and more than 20%.

2. The mass fraction of salt solution cannot exceed 30%.

Agree that the mass fraction after mixing should be in between, i.e. less than 46% and more than 20%.

The amount of oxygen produced by MNO22KCLO3===2KCl+3O2 is n=, the consumption of KCLO3 is, the cleaning mass is circular and quietly produces KCL, and the mass is orange positive residue.

Then the mass of mno2 is .

The mass of the original mixture is 5+

Let the amount of potassium chlorate stool inflavus be x, and the amount of kcl is y2kclo3 = 2kcl + 3 o2

x y2 x=3 jujube skin y

x=,y=The original Zen mixture is:

The decrease in the mass of the whole reaction is due to the release of oxygen, given the amount of oxygen in the problem, and the mass of oxygen plus the remaining mass can be calculated and the result is the result, for example.

The amount of oxygen in the substance is.

The amount of matter multiplied by the molar mass is his mass.

Plus the rest of the quality and that's it.

The density given in the question is the easiest way to confuse you, and the easiest way is the best.

In the future, the analogous finger slippery question can be solved in this way.

The mass of the whole reaction decreases because Qing Hui releases oxygen, and given the amount of oxygen in the question, calculate the mass of oxygen plus the remaining mass, and that's the result, according to the law of conservation of mass.

O2: The mass of the original mixture is.

The amount of mno22kclo3===2kcl+3o2mno2 is .

The quality of this raw mixture is rotten due to the quarrel.