Chemistry questions about mass fractions, urgent

1) Answer: The mass fraction of solution A = the mass of a in solution A divided by the total mass of the solution, that is, the mass fraction of solution A = 9 51 + 9 = 9 60 = 15%.

In the same way, the mass fraction of solution b =

It is enough to prove that the answer about the mass fraction of A is wrong, otherwise the result of B cannot be correct, so the mass fraction of solution A is 15%)

2) A: Assuming that 30% of the sulfuric acid mass and 10% of the sulfuric acid mass are mg, the total mass of sulfuric acid after mixing is 2mg, where the mass of sulfuric acid (solute) = m * 30% = field * 10% = , so the mass fraction of the mixed solute is.

(51+9)*100%=15% The mass fraction of a is 15%30*15%+ B The solute mass fraction in the solution is.

2) Assuming a mixture of 30% sulfuric acid x and 10% sulfuric acid x. x*30%+x*10%) 2x=20% The mass fraction of the solute after mixing is 20%.

When diluting concentrated sulfuric acid, pour the sulfuric acid slowly into water and stir constantly.

To purify the river water, it depends on what impurities there are in the river water, such as BA ions, then first use hydrochloric acid to precipitate BA, filter it with filter paper, and finally use a burette to neutralize the river water to normal pH.

1,w%a=9/[51+9]x00%=15%w%b=[

Assuming that the mass of the solution is m, then [

Your answer is questionable. ~~

When diluting sulfuric acid, acid is added to the water. And stir constantly. Glass rods, beakers are required. Otherwise, high temperatures will be generated, and the purpose of stirring with glass rods is to prevent water splashing.

When purifying the water of the river.

First natural precipitation, then activated carbon, then filtration, and finally distillation.

I'll think about the equipment you need! .

What was said upstairs was actually correct. But you don't have to think about it that much, junior high school is like this

What is added to the solution is sulfuric acid solution, and what is precipitated is Baso4 precipitation. According to the equation BACL2 + H2SO4 BASO4 +2HCl

The mass of the solution obtained after 233 filtration is equal to the mass of the original barium chloride solution, so the mass of the added sulfuric acid solution = the mass of BaSO4 precipitate = 233, the mass of H2SO4 solute is 98, and the mass fraction of sulfuric acid is 98 233*100% =

nh4hco3

Let the total mass of the fertilizer be m, the mass of ammonium bicarbonate is n, and the nitrogen content in ammonium bicarbonate is 14 79 = then there is, m*12%=n*

The mass fraction was n m=12

Let ammonium bicarbonate fertilizer have 100 grams, and the mass of nitrogen is 12 grams, m (ammonium bicarbonate) m (nitrogen element) = 79 14, and the mass of ammonium bicarbonate =

Fe+H2SO4---FeSO4+H2Zn+H2SO4---ZNSO4+H2 Because zinc and iron react with sulfuric acid at 1:2, the amount of substances that obtain the mixture is molar due to the generation of gram hydrogen.

Therefore, assuming that it is all iron, the mass can be obtained as grams, and then according to the difference method, the amount of the substance to obtain zinc is moles, so the mass of iron is m=

So p=

Let the mixture contain x grams of iron, which reacts with dilute hydrochloric acid to form hydrogen ymol, and contains grams of zinc, which reacts with dilute hydrochloric acid to form hydrogen.

fe+2hcl=fecl2+h2

x---y56:1=x:y

x=56yzn+2hcl=zncl2+h2

Solve the system of equations.

x=,y=The mass fraction of iron is.

The ratio of the quantities of the two metals is 1 to 1, so that there is 56 (56+65).

So, what is the pre-filtration mixture at point A? solution and precipitate it. What is the quality of the mixture before filtration?

g, because it is the prepared solution and the added solution, and there is no gas generated. So how much is the precipitation? g。

So, the mass of the solution is the total mass minus the mass of the precipitate, that is. The Na2SO4 produced by the reaction of copper sulfate and sodium hydroxide is still in the solution, and of course it is counted in the mass of the solution.

Analysis: According to the information provided by the question stem, it can be seen that the mass of the precipitate is equal to the mass of the added sulfuric acid solution, and then the mass of the sulfuric acid is calculated according to the chemical equation of the reaction, and then the mass destruction fraction of the solute in the sulfuric acid solution can be calculated according to the formula of the mass fraction of the soluble sullen matter Answer: Solution:

Method 1: The mass of barium sulfate precipitate is equal to the mass of the sulfuric acid solution added, let the mass of barium sulfate precipitate be x, and the mass of pure sulfuric acid participating in the reaction is y

Answer: The mass fraction of the solute in the added sulfuric acid solution is:

bacl2+h2so4=baso4↓+2hcl

What enters the solution is H2SO4, and what goes out is to precipitate the number of jujube Baso4. Rock demolition.

The mass of the solution obtained after filtration is equal to the mass of the original barium chloride solution, so the mass of the added sulfuric acid solution = the mass of Baso4 precipitate = 233, the mass of the pure first H2SO4 solute is 98, and the mass fraction of sulfuric acid is 98 233 * 100% =

Dissolution. The mass of the reacted sodium carbonate is x

na2co3+2hcl==2nacl+h2o+co2106 73 117 44

x 73 x10% y z106 x=73 73x10% x=117 y=73 73x10% y=44 z=73 73x10% z=mass fraction of solute=solute solvent, solute is NaCl, should be the total amount before and after the reaction, before the reaction: after the reaction: So the total amount:

The mass of the solution after the reaction should be the mass of all the substances entering the reaction system minus the mass of the substances that run out, which should be.

So the mass fraction of solute =

It is not said that the hydrophilic salt is sodium chloride, which is not easy to seek.

(1) According to the law of conservation of mass, the mass of oxygen produced by the reaction is (2) The mass fraction of the solute in the solution in the hydrogen peroxide is calculated.

2h2o2==2h2o+o2↑，68g 32g

xg solves: x=

So, the quality score =

Think about it and tell me what you don't understand.

The number of atoms multiplied by the atomic mass divided by the total atomic mass of the compound (which is the atomic weight of the substance).

It's too much trouble......Give more bounty points.

You can find the mass fraction of an element by using the chemical formula of the substance in which it is located.