Why choose A for this chemistry question, and why A for this chemistry question?

Definition of electrolysis: The process by which an electric current passes through a substance causing a chemical change. Chemical change is the process by which a substance loses or gains electrons (oxidation or reduction).

The electrolysis process is carried out in an electrolytic cell. The electrolytic cell consists of two electrodes, one and two electrodes, submerged in a solution containing positive and negative ions, respectively. The current flows into the negative electrode (cathode), and the positively charged positive ions in the solution migrate to the cathode and combine with the electrons to become neutral elements or molecules; The negatively charged negative ions migrate to the other electrode (anode), donating electrons, becoming neutral elements or molecules.

Let's take a look at the question options:

B: The products of the cathode and anode should be hydrogen and chlorine.

c：..Metals: copper and oxygen.

d：..Hydrogen and chlorine.

If in doubt, please refer to Encyclopedia: Electrolysis.

The order of the affinity of the positive and negative ions to the electrons of all the above solutions:

The higher the affinity, the easier it is to get electrons.

Cu2+>H+>Na+>OH->Cl->SO42- and then take a look...

Dilute NaOH solution, Na+, H+, OH-, natural selection A.

B produces chlorine, C produces metallic copper, and D produces chlorine. This question mainly considers the elemental stability of anions and cations.

Because only a has both hydrogen and oxygen.

You should choose an A for this chemistry question. Since iron is more reactive than copper, the negative electrode of this battery is iron, and the positive electrode is copper, and the reaction that occurs on the two electrodes is: iron loses electrons at the negative end and becomes ferrous ions, and hydrogen ions at the positive end get electrons and become hydrogen.

Of the four options, only item A is correct.

Iron has a higher order of chemical activity than copper. In galvanic cells, iron is the one that loses two electrons and hence a correct. The iron piece is the electron, so it is the negative electrode, not the positive electrode, b error.

Galvanic cells are converting chemical energy into electrical energy, hence c error. Iron is losing electrons, therefore, electrons flow from the iron sheet to the copper sheet, d error.

Galvanic battery principle: Generally, the metal with strong mobility is the negative electrode, so the iron sheet is the negative electrode, and the copper sheet is the positive electrode. Electrons are exported from the negative electrode to the positive electrode, so the negative electrode iron loses two electrons to form ferrous ions, and on the positive electrode, the hydrogen ions in citric acid get electrons.

The electrons are from the negative electrode through the wire to the positive electrode. The current is output from the positive electrode to the negative electrode. This device is a power generation device, which is a device that converts the energy (chemical energy) stored in lemons and iron sheets into electrical energy.

To write this question, it is important to understand that this is a galvanic battery device, which converts chemical energy into electrical energy. If you don't understand this, but you can know. , this device has an electric current passing through, that is, it is converted into electrical energy, c wrong.

Furthermore, the iron plate is the negative electrode, the copper sheet is the positive electrode, the negative electrode loses electrons, and the positive electrode gains electrons. Electrons flow from the negative electrode to the positive electrode, and b and d are wrong. A is correct, iron is converted to 2 valence most of the time in galvanic cells or electrolytic cells, and only when it is ignited with chlorine.

This is a galvanic cell and the cell has electrodes. The metal in the galvanic battery is highly mobile as the negative electrode, because it is easier to lose electrons, and lemon juice is equivalent to an electrolyte. Negative loss of positive gain, iron does negative electron loss, a no problem.

The galvanic cell converts chemical energy into electrical energy, and iron loses electrons and flows to the positive electrode through the wire, BCD is wrong.

If it is a normal galvanic battery, it may be better to understand a little, you can think of the substance in the lemon to get electrons to the positive electrode.

Iron is more active than copper, as a negative electrode, oxidation reaction, rise and loss of oxygen, so the electrons from iron to copper, the reaction converts chemical energy into electrical energy, so that the Ford watch hands can be deflected.

In B, Fe is the negative electrode, C is from chemical energy to electrical energy, and D is from Fe to Cu

Iron is chemically reactive more than copper, so electrons flow from iron to copper (d-error). Electrons flow from the negative electrode to the positive electrode (B error). This device converts chemical energy into electrical energy (C error).

According to the law of conservation of mass, it can be seen that the mass after the reaction of a is 4+6+111+4-84-15=26g

So after the reaction, only the mass of C decreases, while the mass of A, B, and D increases, so C is the reactant, and A, B, D are the products, so the reaction is a decomposition reaction.

D is wrong in a:b:c:d=22:9:111:80, and the one in a is wrong.

If you look at the table, you can see that only substance C is decreasing.

And according to the law of conservation of mass, it can be seen that option A is to be measured as 12

So all the added products are.

c reduce. A change of many is a decomposition reflection.

Metallic ratio of iron.

Copper, silver should be high, in the presence of iron elements.

Copper or silver ions are displaced, and the +2 valence ion of iron is produced. The +3 valence ion in the presence of iron in the solution reacts with the elemental iron.

Produces iron +2 ions. Therefore, there are no copper ions, silver ions and 3-valent iron ions in the presence of iron elements.

Because. Ionic reduction.

The silver ion is greater than the copper ion and the iron ion is greater than the iron ion.

And because. Iron is in excess.

So the iron will be first and.

Silver-copper ion reflected.

Finally, it reacts with iron ions.

Will trivalent iron. Reduced to bivalent iron.

So at this time. There won't be.

Trivalent iron examples and copper ions. Silver ions.

Hope it helps!

A represents the element of iron, which is attached to elemental matter, iron atom B represents hydrogen atom, hydrogen element C represents -2 valence oxygen ion D, which represents elemental water.

So choose A

AFE can denote iron element, iron element, iron atom, BH denotes hydrogen element and hydrogen atom, not elemental matter.

CO2- only denotes oxygen ions.

DH2O denotes the compound water and also the molecular formula of water.

1 iron atom.

Iron elemental iron.

2 a hydrogen atom.

Hydrogen element 3 is an oxygen ion.

4 a water molecule.

The meaning of the representation is the most, choose A, there are three kinds.

A can represent the iron element, the iron atom, the element symbol iron b

Hydrogen element, element symbol.

c oxygen ions. d Water molecules, water.

Because it can represent one iron atom or it can represent the element of iron, it can also represent that the element of iron can only represent one hydrogen atom.

3.It can only represent oxygen ions.

4.A water molecule. Water is an element. I didn't have it, so I chose A

An element symbol that can have many subscripts and subscripts. The more subscripts there are, the more certain its meaning is. Bare is an elemental symbol, and naturally its connotation is the greatest!

AFE can denote iron atom, iron element,

Element symbols. b can only be indicated.

Hydrogen element, hydrogen atom.

c oxygen ions. d water molecules.

fe stands for iron atom, iron element, elemental iron; h denotes the element hydrogen. The symbol in option c only indicates peroxide ions; H2O stands for water molecule, water as a substance. Therefore, option A has 3 meanings, option B has 1 meaning, option C has 1 meaning, and option D has 2 meanings.

It can be seen that a is the correct answer.

AFE stands for iron atom, elemental iron, iron element;

h denotes hydrogen element, hydrogen atom.

It only indicates oxygen ions;

H2O stands for water molecule, water as a substance.

Of course, it's A, because the metal element can be directly represented by the Rong symbol, and the general multiple-choice questions are the answers, I hope you can understand what I said.

B iron is more reducible than copper, and when it reacts with the same oxidant ferric ions, the iron with strong reducibility reacts first, so if there is iron, there must be copper, and there is not necessarily iron if there is copper.

b Trivalent iron reacts first with iron and then with copper.

The answer is b. Iron and copper are added to the ferric chloride solution, and the iron ions react with the iron element first, and then react with the copper if the iron ions are left. According to the title, KSCN is added to the solution after the reaction, and the solution is not colored, indicating that there are no iron ions in the solution.

Answer B, there is no copper left, which means that copper is in solution in the form of copper ions, so the remaining solid cannot be iron (iron will displace with copper ions).

Well, I think your chemistry question is relatively simple, because you should belong to junior high school knowledge, and he just gave you a simple equation, which belongs to the equation of combustion, so you only need to consider some conditions to promote combustion.

The answer is c. There are equations that can be seen for one molecule of methane consumption and two molecules of oxygen. And after changing to petroleum liquefied gas.

Meaning that the all-in-one machine's petroleum liquefied gas consumes more oxygen volume than one volume of methane gas. In order for the gas to be fully combusted, more oxygen needs to be provided, so we can increase the oxygen supply or reduce the gas supply.

The words of who should be chosen for this question are in line with the meaning of the question.

Choosing D is a compound, not a mixture.

aThis substance is composed of five elements, and it cannot be said that this molecule is composed of five elements, the molecule is a microscopic particle, and the element is macroscopic.

The choice b aldicarb molecule is a microscopic formulation, an aldicarb molecule is composed of 7 carbon atoms, 14 hydrogen atoms, 2 nitrogen atoms, 2 oxygen atoms, 1 sulfur atom, A is false, B is correct, and C is wrong.

The ingredients in Shennong Dan are not only aldicarb, but also mixtures. d error.

1. Select D.

Because: a adds hydrochloric acid, if zinc will have bubbles, the solid will slowly disappear zn+2HCl=H2+zNCL2;

B calcium oxide: CaO+2HCl=H2O+CaCl2, calcium chloride is soluble in water, and the solid disappears;

C calcium carbonate: CaCO3 + 2HCl = H2O + CO2 + CaCl2, solids disappear;

d Barium sulfate: It does not react with hydrochloric acid, because it can only make weak acid from strong acid, and sulfuric acid is stronger than hydrochloric acid.

2. The molecular weight of sulfuric acid is 98, so the amount of 49 grams of dilute sulfuric acid with a mass fraction of 20% is 49*20% 98 = mol.

A: Mg+H2SO4=MGSo4+H2, the reaction ratio is 1:1

B: MGO + H2SO4 = MGSO4 + H2O, the reaction ratio is 1:1, and the reaction generates 1 part of water;

C: Mg(OH)2+H2SO4=MGSo4+2H2O, the reaction ratio is 1:1, and the reaction generates 2 parts of water;

d: MgCO3+H2SO4=MGSo4+H2O+CO2, the reaction ratio is 1:1, and the reaction generates 1 part of water;

Obviously, the answer is C, because this reaction produces the most water and dilutes the concentration of the solution.

3. Removing a small amount of copper oxide in charcoal powder obviously requires that charcoal powder cannot be reduced, and no new impurities can be introduced;

Various methods: add hydrochloric acid - CuO + 2HCl = CuCl2 + H2O, filter, wash and dry;

Add sulfuric acid - Cuo + H2SO4 = CuSO4 + H2O, filter, wash and dry;

Handmade, I hope you are satisfied!!

Because barium sulfate is insoluble in dilute hydrochloric acid.

Because the substances in each option react with sulfuric acid in a ratio of 1:1, and the solute in the solution is MgSO4, then the amount of solute is the same, just calculate which one will produce the most water, which is obviously C

3.Add excess dilute hydrochloric acid, and the reaction occurs: CuO+2HCl=CuCl2+H2O, and then filter.

The displacement reaction produces hydrogen bAlkaline substances, acidic substances and alkaline substances react cCO2 is generated, and strong acid is used to produce weak acid DInsoluble in strong acids.

The same amount of sulfuric acid reacts completely, so the solute mass is equal, and then the reaction equation is written, and C produces the most water, that is, the solvent mass is the largest, and the solute mass fraction is the smallest.

3.Add acid, then filter, dry.

2hcl+cuo＝cucl2+h2o

1 d Zinc is a metal and soluble in acids. Calcium oxide reacts with water to form calcium hydroxide, which is then neutralized with hydrochloric acid. Barium carbonate is soluble in acids while barium sulfate is insoluble.

2·c The four options with dilute sulfuric acid all produce magnesium sulfate, and A generates hydrogen and runs away. B generates another molecule of water, so the amount of solvent increases, but C produces two molecules of water, more than one molecule of water and one molecule of carbon dioxide, and the carbon dioxide runs away.

3·CuO+H2SO4====CuSO4+H2O carbon does not react with dilute sulfuric acid. Then filter it, and the filter residue is carbon.