As for some of the questions in the third year of junior high chemistry, who will

1) False, aluminum's strong corrosion resistance is due to the fact that aluminium will form a dense alumina protective film on the surface of the air to prevent further corrosion. Aluminum is chemically reactive than iron.

2) Yes, but more importantly, copper.

3) Prevent pollution.

5) Gold is chemically stable and has a high melting point.

6) For example, the thermite reaction or charcoal reduction of iron oxide is not carried out in solution; There are elemental elements participating and forming in the displacement reaction, so there must be an element in the valence that changes from "+" or "-" to 0 valence.

7) Metal activity, also known as metal reduction, see .

1) Why is the sentence "due to the strong corrosion resistance of aluminum, so the chemical properties of aluminum are not as lively as iron" wrong, please explain!

Corrosion resistance is relative and depends on the chemical properties of the substance and the corrosive acid used.

2) Is aluminum widely used to make wires?

No. 3) What is the main purpose of the old battery?

Environmental protection and waste utilization.

5) What is the chemical meaning of "real gold is not afraid of fire"?

Gold is chemically stable.

6) Why is the sentence "displacement reactions are all carried out in solution" wrong? ”

cuo + h2 == h2o +cu

Do not proceed in solution.

There must be a change in the valency of the elements during the displacement reaction", why is this sentence true?

A compound reacts with an elemental substance to form another compound with an element.

7) What is metal mobility? What is it also called? (Example: How to arrange the activity of magnesium, iron, zinc, and aluminum from large to small?) ）

The chemical activity of a metal, also known as metallicity.

From large to small: magnesium, aluminum, iron, zinc.

1 Aluminum will form Al2O3 to form a dense oxidation mold that resists corrosion.

2 Yes. Good conductivity and light weight.

3 Prevent heavy metal poisoning Batteries contain heavy metal elements so it is necessary to **.

5 ag has a high melting point. Therefore, it takes a very high temperature to dissolve, much higher than the average metal, so I am not afraid to practice.

6 The thermite reaction 2Al+Fe2O3=Al2O3+2Fe is not carried out in solution.

The displacement reaction is a reaction of one elemental substance to produce another elemental substance, so there must be a change in the valency of the element.

Potassium, Calcium, Sodium, Magnesium, Aluminum, Manganese, Zinc, Chromium, Iron, Nickel, Tin, Lead (Hydrogen), Copper, Mercury, Silver, Platinum.

k ca na mg al mn zn cr fe ni sn pb (h) cu hg ag pt au

The main component of patina is basic copper carbonate, which can be decomposed by heat to obtain cuo, if it is completely basic copper carbonate, it will be reduced after decomposition.

If the powder is completely cu, it will gain weight25

So the possibility is between a decrease of 40 5 and an increase of 25.

So ACD is all possible.

The answer should be (14*10%+1) (14+1).

According to the definition of the weight percentage concentration of the solution, if the solute is added to the solution, of course, the mass of the solute must be added to the numerator and denominator.

Mass fraction of sodium chloride = solute solvent.

After mixing, the amount of solvent is the sum of the two, and the weight of 1g of sodium chloride must be added. . .

The concentration of the solution = the mass of the solute (the mass of the solute + the mass of the solvent) x 100%.

c Among the four substances, K2CO3 has the largest molecular weight, so among the above substances of the same mass, the amount of K2CO3 is the smallest, so the CO2 gas is emitted the least.

c because both have (CO3)2-

The greater the relative mass of the front, the less gas is released.

Each substance releases one molecule of CO2 after a reaction, so the greater the amount of matter, the more CO2 is released.

Among the four substances, the formula of K2CO3 is the smallest, and the amount of substances is the largest, and the amount of gas emitted is the most under the same mass.

Look at the landlord's problem The amount of material involved doesn't seem to be in the third year of junior high school I was in high school The amount of material The landlord will not be excusable.

1) The amount of hydrogen can be calculated directly according to the formula.

n=m/m=

2) The amount of zinc can be calculated according to the amount of hydrogen due to the exact complete reaction nzn=nh2=

3) The mass fraction of the solute is calculated from (2) the mass of zinc is very good, mznso4=nznso4mznso4=

w=m m total =

The previous mol is the unit of the amount of the substance, m can be understood as the relative atomic mass or molecular mass, m is the mass of the substance itself, mznso4 is the mass of zinc sulfate, which represents the dividing line.

The landlord is a junior high school student.,I'm also a junior high school student.。。 I'll tell you the same way I did in junior high school, I don't know anything.

Let : the mass of zinc involved in the reaction is x, and the mass of ZnSO4 is y

zn + h2so4 === znso4 + h2↑

x y solves x=13 y=

Isn't the quality of generating h2 given to the title?。。 Or is zn 13g?

The mass of Zn in the sample x=13g The mass fraction of Zn 13g 20g=65% (Do you ask this?) ）

Solute mass. I don't understand the title. That's what it means anyway. Hope it helps.

n(h2)=

zn---h2---znso4

1mol 1mol

x = mass score = number seems to be very large).

According to the law of conservation of mass, it can be seen that the mass of A participating in the reaction = 4+7-10=1 gram, and the mass of B participating in the reaction is 10 grams, so the mass ratio of reactant A to B is 1:10

Law of conservation of mass: reaction a mass m=4+7-10=1

ma/mb=1/10

Before and after the reaction, the quality is balanced.

The resulting product is 11 grams in total. Reactant B 10 g is completely reactive, so there is 1 g A involved in the reaction. So the mass ratio is 1:1