What do you think are the difficulties and hot spots in the teaching of the principle of galvanic ba

I think the difficulty in teaching the principle of galvanic cells is to understand the essence of the conversion of chemical energy to electrical energy from the perspective of electron transfer.

The hot topic is to understand the concept, principle and composition of galvanic batteries. It can correctly judge the positive and negative electrodes of the battery, as well as the writing and electron flow direction of the two-pole reaction.

Chemistry discipline literacy is the accumulation of chemical knowledge, the understanding of basic principles, the quality of scientific thinking, the methods and habits of chemical learning, the synthesis of experimental and practical ability, and its basic literacy refers to the knowledge vision, rational analysis, emotional attitude, scientific spirit and other contents As an important part of the basic theory of high school chemistry, galvanic cell teaching is difficult for students to understand, master and apply due to the abstraction of its theory and the comprehensiveness of its application Therefore, for the teaching of chemistry in high school, teachers can combine the characteristics of chemistry discipline, start from the basic subject literacy, deal with the teaching materials boldly and reasonably, and design some problems that are difficult and appropriate from multiple angles and help students form "the heart is clear but not obtained", which can effectively stimulate students' thinking activities and improve the quality of teaching

[Mode Improvements].

The classroom activity mode has been changed to:

Create a situation **Activity Analyze the problem **Deepen Acquire new knowledge.

In the sound of a greeting card, the students were immediately filled with curiosity, how does a greeting card work? Then I pushed the boat down the river and told the students about the theme of **. Teachers provide the following materials at each table:

The electrodes are iron, copper, zinc, graphite; The solutions include dilute sulfuric acid, sodium hydroxide solution, copper sulfate solution, and absolute ethanol; There are also plastic ropes, wires, galvanometers. Students select materials from them to design galvanic batteries. Students work in groups to develop an experimental plan, and then use the experiment**.

Teachers are involved in the process and effectively guide and inspire. After the students completed the experiment, each group reported the experimental research and communicated with each other to understand the principle and composition conditions of galvanic batteries. Finally, the teacher designs a problem scenario for students to analyze the actual problem.

After class, a small family experiment was arranged - the galvanic cell experiment of fruits.

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The galvanic cell is a redox reaction that can be carried out spontaneously, and the oxidation reaction and reduction reaction occur on the negative and positive electrodes of the galvanic cell respectively, so as to generate an electric current in the external circuit. Judgment of the electrode of the galvanic battery: Negative electrode:

one pole of electron outflow; the pole where the oxidation reaction takes place; A pole of a more lively metal. Positive electrode: the pole where electrons flow in; the pole where the reduction reaction takes place; A pole of a relatively inactive metal or other conductor.

In galvanic cells, the outer circuit conducts electricity with electrons, and in the electrolyte solution, it conducts with ions.

Chemical energy is converted into electrical energy... The directional movement of electrons and the directional movement of ions produced by chemical reactions produce electric currents, discharges.

The negative electrode of the galvanic cell undergoes an oxidation reaction, loses electrons, and the electrons are transferred to the positive electrode through the wire, and a reduction reaction occurs, and electrons are obtained.

It seems that this is the case, but my own understanding, the teacher has not yet explained.

The more reactive metal undergoes an oxidation reaction, and electrons flow from the reactive metal (negative electrode) to the inactive metal (positive electrode).

Easy to learn the principle of galvanic batteries High School Chemistry Compulsory 2 It's really easy to learn chemistry.

1) When A and B are not connected, the device does not constitute a galvanic battery, and the zinc and hydrogen ions are replaced, and the ion reaction equation is: Zn+2H+

zn2+h2, so the answer is: zn+2h+

zn2+h2

A and B are connected with wires, the device constitutes a galvanic cell, copper is used as the positive electrode, and the electrons obtained by hydrogen ions on the positive electrode undergo a reduction reaction, and the electrode reaction formula is 2H+2E-H2

When discharging, the hydrogen ions in the electrolyte solution move to the positive copper electrode, so the answer is: positive; 2h+2e-h2

Oxidation; cu；

Reduced mass of zinc flakes =

65g/mol

So the answer is:;

2) The reaction is not a redox reaction, and it is an endothermic reaction, so it cannot be designed as a galvanic cell, so the answer is: no; This reaction is non-redox and the reaction is endothermic

The galvanic cell reaction is an exothermic reaction, which is generally a redox reaction, but what is different from the general redox reaction is that the electron transfer is not completed by the effective collision between the oxidant and the reducing agent, but the oxidation reaction occurs when the reducing agent loses electrons on the negative electrode, and the electrons are transported to the positive electrode through the external circuit, and the electrons obtained by the oxidant on the positive electrode undergo a reduction reaction, so as to complete the transfer of electrons between the reducing agent and the oxidant.

The directional movement of ions in the solution between the two poles and the directional movement of electrons in the external wire constitute a closed loop, so that the two electrodes react continuously, an orderly electron transfer process occurs, and an electric current is generated, so as to realize the conversion of chemical energy to electrical energy.

Non-redox reactions can also be designed as galvanic cells. From the perspective of energy conversion, galvanic batteries are devices that convert chemical energy into electrical energy; From the perspective of chemical reaction, the principle of galvanic cells is that the electrons lost by the reducing agent in the redox reaction are transferred to the oxidant through an external wire, so that the redox reaction is carried out on two electrodes.

Primary cell (English: primary cell), also known as primary cell, is a type of chemical battery that converts chemical energy into electrical energy to provide electricity. A battery can only be discharged once, and when all the chemicals inside have a chemical effect, it can no longer provide electrical energy, nor can it store the electricity provided externally, so it cannot be used again after a complete discharge, because its electrochemical reaction is irreversible.

This is different from a battery that can be recharged multiple times (storing power from an external source) and then discharging.

Hehe, the upstairs was exposed. I also wondered about the landlord when I was in high school. Here's the answer.

In fact, the landlord's question is very correct. It is true that in solution, anion and cation will directly undergo ionic reaction, but very rarely.

The conductivity of water is definitely not as good as metal. Is that right?

Also, in the anode section, the metal must lose electrons faster than the solute of the cathode, and since the metal has lost electrons here, it must be in a hurry to get electrons at the other end. This rate is beyond our imagination.

So at the cathode, the metal will desperately snatch electrons from the solute. Why? Because if a substance loses its own constituent electrons, or the nucleus, then the substance will be annihilated. Nature does not allow such a situation to occur autonomously.

So since there is such a good conductive medium as metal, why do electrons have to compete with water? When electrons want to react with cations through water, metals have already taken the electrons away.

That's the answer, you're pretty satisfied.

New addition: Maybe the landlord is not very clear about the principle of the galvanic battery. When two metal rods are inserted into an ionic solution, one of the metal rods will take away its own metal electrons due to the presence of cations in the solution (i.e., the positive ions in the solution (the positive electrode) lead the electrons in the metal (negative electrode)).

At this point, strictly speaking, the metal rod that has been robbed of electrons is already positively charged. Because of the loss of metal electrons, the positive and negative charges of the conductor rod are uneven, and the positive ones are much more than the negative ones, so they are positively charged.

After that, you will use the two ends of these two conductor rods as the two stages of the power supply (because it is a galvanic battery, since it is a battery, you have to use it) and connect it to the electrical appliance (that is, the conductor).

At this time, the conductor rod metal rod that has lost its electrons, with electrical appliances, the conductor rod that has not lost electrons, has been connected, and we can see them as an object. As mentioned above, the rod of a conductor that has lost its electrons is positively charged. Now that these three objects are connected, then they must have carried positive charges of the same nature.

The problem will be solved in the future, since it will be positively charged, then the conductor rod that has not lost electrons will of course attract negative ions in the solution after being inserted into the ionic solution. That is, an electric current is formed.

As for the landlord's question about why the positive ions in the solution do not react directly with the negative ions in the solution in the water, I have already said that there will be a reaction, but it is rare, and the reason is also in the last reply. Huh

Easy to learn the principle of galvanic batteries High School Chemistry Compulsory 2 It's really easy to learn chemistry.

The redox reaction is carried out in two separate vessels so that the transferred electrons pass through the external wires, thus obtaining an electric current.

Redox reactions.

Zinc is a reactive metal, volatile electrons, so it is the negative electrode of the galvanic battery, when the lost electrons of zinc flow to the copper electrode through the external circuit, it will make the electrons of hydrogen ions in the solution to generate hydrogen, the whole process, copper does not participate in the reaction, what occurs on zinc is the oxidation reaction, and the copper is the reduction reaction.

Easy to learn the principle of galvanic batteries High School Chemistry Compulsory 2 It's really easy to learn chemistry.

The essence of the redox reaction is the transfer of electrons, the galvanic cell is made by using the principle of electron transfer, and the electrolyte solution is used to separate the electron gain and electron loss reactions to produce the positive and negative electrodes of the galvanic battery. The direction of the current is from the positive electrode to the negative electrode, and the direction of the electrons is from the negative electrode to the positive electrode... Therefore, the negative electrode is the loss of electrons, and the positive electrode is the gain of electrons, which is the reaction principle of the galvanic battery.

Redox reaction (transfer of electrons or gain or loss).

(1) The device cannot form a closed loop, so it cannot form a galvanic battery, the zinc is chemically decayed, and the ion reaction is Zn+2H+=H2 +Zn2+, so the answer is: Zn+2H+=H2 +Zn2+;

The device is a galvanic battery, zinc volatile electrons are used as the negative electrode, Cu is used as the positive electrode, hydrogen ions are discharged on the positive electrode, the electrode reaction is 2H++2E-=H2, the zinc loses electrons and oxidizes the reaction, and the hydrogen ions in the electrolyte solution move to the positive Cu electrode, so the answer is: positive; 2h++2e-=h2↑；Oxidation; cu；

According to the equation of the relationship between zinc and transfer electrons, the mass of zinc consumed =

2 65g mol=, so the answer is:;

2) The galvanic cell reaction must be a spontaneous exothermic redox reaction, which is an endothermic reaction and not a redox reaction, so it cannot be designed as a galvanic cell, so the answer is: no

Copper does not react, but it is used as an electrode, even if the copper is replaced with a carbon rod. The positive electrode does not necessarily react.