Math Chemistry Problems, Chemistry, Math Problems

1.Option B because solutes are substances in solution that are dissolved by solvents. The second part adds anhydrous copper sulfate powder, and the solvent mass increases, so the concentration increases. Therefore, AD is wrong. If the temperature rises in the first serving, the solubility will change, so C is wrong.

2.Let Fa be X, then Bf is (8-X) According to the Pythagorean theorem, AF= then BF= trapezoidal AEBF Trapezoidal FCDE, so DE=, through E as a perpendicular line to cross BC at the point G, Fg=, according to the Pythagorean theorem, EF= can be known

3。Crossing point A is used as a perpendicular line to cross BC at point E, and point D is used as a perpendicular line to cross BC to point F. Connect the AEB to the CDE'Place.

Because DCF=36° DCE'=54° so e'cf=90° again because e'=∠f=90°e'd cf so quadrilateral e'DFC is a square.

Because m,n are the midpoints of ad,bc respectively, bc=10, ad=6, so dm=3, cn=5, so cf=2, so mn=df=cf=2

100 grams of saturated copper sulfate solution is divided into two parts, one part is heated to 30, and the other part is added to 1 gram of anhydrous copper sulfate powder, and the temperature is still maintained at 20, then in both cases, the color of the solution is not changed. Do you still need an explanation? The quality of the solution is different, the quality of the solvent is different.

The quality of the solute is different, the solubility is different, the concentration is different, is there still the same? Please, the reason is telling)

In 2 rectangular ABCDs, AB=6, BC=8, the rectangle is folded so that the point C coincides with the point A, then the length of the crease EF is.

3。In trapezoidal ABCD, the angle C=36°, the angle B=54°, M, N are the midpoints of AD and BC, respectively, if BC=10 and AD=6, then the length of Mn is.

3.The head of the AD glass cutter is inlaid with diamond, not graphite, otherwise the glass cannot be cut at all, and the hydrochloric acid will also corrode the iron.

You know that there are about (500,000) stationery boxes of this size in the supermarket.

The area of a stationery box is square meters.

The area of the football field is 8000 square meters.

8000 pcs.

1 + root number 2).

1+2 root number 2+2

3+2 root number 2

3+2 root number 2

9+12 root number 2+8

17+12 root number 2

The root number 2 12 root number 2 is 16 in the integer part

17 + 12 root number 2 integer part 17 + 16 = 33

AD was chosen, and the iron was corroded by hydrochloric acid, and the graphite was changed to diamond.

The third one has to use the binomial theorem.

Sodium metal is, the mass increased after combustion is, is the oxygen atom, this is very clear, sodium whether it is sodium oxide or sodium peroxide, the total amount should be, there is one oxygen atom in sodium oxide, there are two oxygen atoms in sodium peroxide, and the oxygen atom is divided, that is, sodium oxide and sodium peroxide, I don't know if you can understand it?

Sodium is all converted into sodium hydroxide, the total mass is 8g, sodium peroxide releases oxygen during the reaction, that is, so the total mass of the solution is, the total mass of the solute is 8g, so the mass fraction is 8 25 * 100% = 32%.

Solution: (1) If there is Na2O2Xg in the combustion product, then there is Na2O(7-X)G, then 46x 78+46(7-x) 62= The solution gives x= 7-x=, so the mass ratio = 31: 39 is 1; 12) Let the generation of oxygen yg generate naoh zg

156 solution y= 23 40= solution z=8g, so solution mass fraction = 8 (

A: --

1) For the main group elements, the outermost 2 electrons in the first period are considered stable structures, and the outermost 8 in the other periods are counted. Electron gain and loss occur during the formation of ionic compounds as well as in redox reactions. The two elements mentioned above are the main group elements, and they have a tendency to reach a stable structure, the outermost layer is greater than 4 is easy to obtain, and less than four is easy to lose, so as to achieve a stable structure of 8 electrons, which is exactly 4 stable, such as carbon, which is also the reason why metals have no negative valence.

Question 2) React with sulfuric acid first, because among all the reactions learned in middle school, the acid-base neutralization reaction is fast enough, and it must be the first reaction when you encounter it in the future.

3) Iron powder is grayish-black, and iron sheet is silvery-white.

4) Magnesium carbonate is a microsoluble substance, which is generally regarded as a precipitate in solution.

5 questions. Because there can be no water vapor in the copper mesh and oxygen heating, otherwise it will be **, after the concentrated sulfuric acid is removed, sodium bicarbonate should be used to react with acidic hydrogen sulfide to release carbon dioxide gas, and the unremoved hydrogen sulfide should be removed with concentrated sulfuric acid before the concentrated sulfuric acid, so the correct order should be

Question 6) Because the original reactor must contain air, the first thing that comes out is the air, and if it is received directly, the collected gas will be impure.

7) I really can't figure out the former, and I hope to forgive me. The latter can be used to remove carbon dioxide because sodium hydroxide is very easy to react with carbon dioxide, and the properties of hydrogen are stable and difficult to reflect.

8) There should be a gas valve on the right end of the conduit and it is not opened to indicate that the air tightness is good, otherwise the liquid level should sink, and the above phenomenon can only indicate that the device is blocked by something.

Shhh——— it's not easy, but it's done.

1) When there is an electron shell, the outermost shell is 2 to reach a stable structure, and there are two or more electron layers, and the outermost shell is 8 electrons to reach a stable structure.

When the number of electrons in the outermost shell is less than 4, it is easy to lose electrons;

When the number of electrons in the outermost shell is greater than 4, it is easy to get electrons.

1 Generally, it is easy to lose electrons when the number of electrons in the outermost shell is less than 4 The outermost shell of the gallium atom has 3 electrons less than 4.

So it's easy to lose, and generally more than 4 electrons are easy to get electrons, and the outermost atom of nitrogen has 5 electrons >4.

So you get a stable structure where 3 becomes 8 electrons.

2 Acid-base neutralization reaction will occur first Sulfuric acid and barium hydroxide will occur first.

3 White. 4 Yes.

6 At the beginning of the collection, the air in the tube has not been exhausted, so it is possible to collect the air, then it is impure, when the bubbles are released evenly, it means that the drug has begun to react, and what is released is oxygen, and it is best to collect at this time.

7 (2) Yes Because HCl in 1 is soluble in water, it is not possible to measure its volume.

In 2, CO2 is soluble in water, H2 is insoluble in water, and when it enters from A, it will cause CO2 to go out to achieve the purpose of washing.

8 This is because the water will definitely flow down under the action of pressure. Think about it, if the air tightness is good, then the pressure in the separating funnel will definitely decrease as the water drops! Then under the action of atmospheric pressure, the water will not fall!

When the pressure generated by the outside atmosphere - the pressure generated by the inside atmosphere = the gravity of the water, the water starts to rest! ）

I don't understand hi me.

1.The structure of the outermost 8 electrons is called the stable structure. Generally speaking, the outermost shell greater than 4 electrons is called a non-metal, and electrons are easily obtained in the reaction; The outermost shell is less than 4 electrons called metals, and it is prone to loss of electrons in the reaction.

2.It reacts with sulfuric acid first. Acid-base neutralization is considered first.

3.Silvery-white, iron powder is black. 4.Be.

6.Because the gas is the original air in the duct, if it is collected immediately, the collected gas will be impure.

7.（2）。(1) HCI is very soluble in water, and the volume cannot be measured by the drainage method.

8.No, ... The right gas collector cylinder did not say that it was sealed, why did the water not stay? Plug it.

Choose B2H2(G)+O2(G)=2H2O(L), H=36G

x 18g y x=，y=

co(g)+1/2o2(g)=co2(g),△h=z (710- z=

Before combustion, the volume of CO in the mixed source gas is divided into several acres of cleft=

18g of liquid water shows that hydrogen is 1mol per mu

Xun Pi slag 2 choose b

b. Carbon monoxide and carbon dioxide are both oxides of carbon and are not elemental and do not conform to this.

Ice is solid water, dry ice is solid carbon dioxide, and it's not elemental.

Oxygen and liquid oxygen are the same substance, but the state of defibrillation is different.

Chemically, different elements composed of the same element are called allotropes and ACD are not in line with each other.

b diamond and graphite are both composed of carbon elements.

b a, c, are not elemental. Both are two substances.

d is the same elemental substance, that is, the physical state is different.

Choose B1, carbon monoxide and carbon dioxide are both oxides and not elemental substances.

2. Diamond and graphite are both elemental substances composed of carbon, and this year-old sock is the original word in the textbook.

3. Ice Qiaoqi refers to water, the chemical formula is H2O, and dry ice is CO2, which can be seen from the chemical formula is not allotropic filial piety.

4. Oxygen and liquid oxygen are the same element, but the state is different, one is gaseous and the other is liquid.

Let ethylene be x mol and hydrocarbon cahb be y mol. (where CAHB A and B are the number of atoms of carbon and hydrogen).

After that, write the chemical equation, trim, and derive.

1、x+y=2

x+ay=4

x+1/2by=

After that, multiply 1 by 2 and subtract it from 2 to get a=2, and then take a=2 with 2 and subtract it with 3 to get 1 2by-2y=, because a=2, b can only be 2 or 4 or and 4 into 1 2by-2y=, and the value of b can only be 6, that is, b=6, and then bring b=6 into 1 2by-2y=, we can know y=. From this we know x=.

That is to say, mol of ethylene and mol of ethane are mixed.

Hydrocarbon A is ethane and the volume ratio is ethylene:ethane = 3:2.

The average molecular formula of the mixed gas is, ethylene is C2H4, the number of carbon atoms is 2, and the number of hydrogen atoms greater than 4 is only C2H6, let the volume fraction of C2H4 be X, the volume fraction of C2H6 is Y, and the column formula: X Y=1, 4X+6Y=, and the equation can be solved.

C2H6 (from 4CO2 can be obtained as C2, from greater than 4, the hydrocarbon H can be obtained from greater than 4, that is, 6), the ratio is 9:1 (the column equation 2x+6(2-x)= can obtain x=

The sulfate is all converted into barium sulfate precipitate, which can show that the amount of hydroxide ions added is 6 times that of Al ions, and Zaozhi is equivalent to Al3+ +6OH- =ALO-

When the amount of hydroxide ion Piyanmine is 4 times that of Al ion combustion, it can be completely converted to ALO-

In the answer given, C should be a price.

c The sulfate is all converted into barium sulfur precipitate, which can indicate that the amount of hydroxide ionic oxide ionic acid is 4 times that of Al ion Al3+ +4Oh- =Alo-

d Hehe, according to my years of experience in reviewing "blind" questions, I must choose more!!