"Chemical Reactions and Energy Changes" Chemical Reactions and Energy PPT (Lesson 2 Chemical Reactions and Electric Energy)

"Chemical Reactions and Energy Changes" Chemical Reactions and Energy PPT (Lesson 2 Chemical Reactions and Electric Energy)

Part 1: Essential knowledge and foundation of literacy

1. Conversion of chemical energy into electrical energy

1. Indirect conversion of chemical energy into electrical energy

(2) The key - combustion (oxidation-reduction reaction).

【Situation·Thinking】

Thermal power generation is the main power generation method in my country. To put it simply, it uses fuel to generate heat, heats water, and forms high-temperature and high-pressure superheated steam. Then the steam enters the steam turbine along the pipe and continuously expands to do work. It impacts the turbine rotor to rotate at high speed, drives the generator rotor (electromagnetic field) to rotate, and the stator coil cuts the magnetic induction lines. Emit electrical energy.

(1) How many forms of energy conversion exist in thermal power generation?

Tips: Chemical energy is converted into thermal energy, thermal energy is converted into mechanical energy, and mechanical energy is converted into electrical energy.

(2) Try to analyze what are the disadvantages of thermal power generation?

Tips: ① The fossil fuels used are non-renewable resources; ② The combustion of fossil fuels will produce a large amount of harmful gases (such as SO2, CO, etc.) and dust, polluting the environment; ③ Energy has been converted multiple times, and the energy utilization rate is low.

2. Chemical energy is directly converted into electrical energy - primary battery

(1) Experimental research:

(2) Principle analysis:

(3) Primary battery:

①Definition: The device of _______________ is called a primary battery.

②Working principle: (Take copper-zinc-dilute sulfuric acid primary battery as an example)

【Smart Judgment】

(1) The mixing of hydrochloric acid and sodium hydroxide solution releases heat, so the galvanic cell reaction can be designed. ()

Tip:×. The reaction between hydrochloric acid and sodium hydroxide is not a redox reaction.

(2) In the copper-zinc-dilute sulfuric acid primary battery, current can also be generated by replacing the copper with graphite rods. ()

Tips:√. The positive electrode material in the primary battery does not participate in the reaction and only plays a conductive role. The graphite rod can conduct electricity.

2. Chemical batteries - an important component of new and renewable energy

1. Primary battery - zinc-manganese dry battery

2. Secondary battery

【Micro thinking】

In daily life, are the batteries of electric vehicles and mobile phones classified as primary batteries or secondary batteries?

Tip: The batteries of electric vehicles and mobile phones can be recharged and used repeatedly, and they are all secondary batteries.

3. Developing fuel cells

Chemical Reaction and Energy Change PPT, Part 2 Content: Key Competencies·Quality Formation

Knowledge point 1: The composition conditions of the primary battery and the method of judging the positive and negative electrodes

[Key points to clarify doubts]

1. The composition conditions of the primary battery - "two poles, one liquid, one line and one reaction"

2. Working principle of primary battery

(1) Two reactions: positive electrode - reduction reaction; negative electrode - oxidation reaction.

(2)Three directions:

①Current direction: positive pole→negative pole;

②Electron flow direction (in the wire): negative electrode → positive electrode;

③Movement direction of anions and cations (in electrolyte solution):

Cation: negative electrode → positive electrode;

Anion: positive electrode → negative electrode.

3. How to judge the positive and negative poles of the original battery

[Error-prone reminder] (1) The two electrode materials that make up the primary battery are not necessarily metals. The positive electrode material can be a conductive non-metal, such as graphite. Bipolar materials may or may not participate in the reaction.

(2) Two metal electrodes with different activities are connected with wires and inserted into the electrolyte solution together to not necessarily form a primary battery. There must be a spontaneous redox reaction.

(3) When judging the positive and negative electrodes of the primary battery, it is necessary to consider not only the activity of the metal, but also the properties of the electrolyte solution. For example, in a primary battery composed of Mg-Al-HCl solution, the negative electrode is Mg; but in a primary battery composed of Mg-Al-NaOH solution, the negative electrode is Al and the positive electrode is Mg.

【Think·Discussion】

(1) How do the anions and cations move inside the primary battery? What is the reason for the movement?

Tip: Anions should move to the negative electrode, and cations should move to the positive electrode. This is because the negative electrode loses electrons, generating a large number of cations that accumulate near the negative electrode, resulting in a large amount of positive charge near the electrode, so the anions in the solution move to the negative electrode; the positive electrode gains electrons, and the cations near the electrode become electrically neutral because of the electrons. The substance makes the vicinity of the pole negatively charged, so the cations in the solution move to the positive pole.

(2) Can two metal electrodes with different reactivity be connected by wires and passed into the electrolyte solution to form a primary battery?

Tip: Not necessarily. In addition to ① two metals with different activities ② electrolyte solution ③ forming a closed circuit, a primary battery must also have a spontaneous redox reaction, as shown in the figure. Since neither Cu nor Ag can react with dilute sulfuric acid, it cannot form a primary battery. Primary battery.

【Case Demonstration】

[Typical example] (2019 Zibo Grade 1 Test) As shown in the figure, the pointer of the ammeter deflects, and at the same time the mass of the A pole decreases, bubbles are generated on the B pole, C is the electrolyte solution, the following statement is wrong ()

A.B pole is the positive pole of the primary battery

B.A, B, and C are Zn, Cu and dilute hydrochloric acid respectively.

The cations in C.C move towards the A pole

D. Oxidation reaction occurs at pole A

Knowledge point 2: Application of primary battery principle

[Key points to clarify doubts]

1. Speed ​​up the rate of chemical reactions

A spontaneous redox reaction, designed as a primary battery to speed up the reaction rate.

2. Compare the reactivity of metals:

When two metals are used as the two poles of a primary battery, the metal used as the negative electrode is generally more active than the metal used as the positive electrode.

3. Used for metal protection

Connect the protected metal to a more reactive metal.

4. Design primary battery

(1) Basis: Given a redox reaction, first analyze and find out the oxidant and reducing agent. Generally, the reducing agent is the negative electrode material (or is oxidized on the negative electrode), and the oxidizing agent is the cation in the electrolyte solution (or is reduced on the positive electrode). ).

(2) Steps: Take Fe+CuSO4====FeSO4+Cu as an example.

【Think·Discussion】

(1) In a primary battery, is the metallicity of the negative electrode material necessarily greater than that of the positive electrode material?

Tip: Generally, the metallicity of the negative electrode material in primary batteries is greater than that of positive electrode materials. There are also exceptions in special circumstances. For example, in Al-Mg-NaOH primary batteries, Al loses electrons more easily than Mg in a strong alkaline solution. Al is used as the negative electrode, and Mg Make positive pole.

(2) How to design a primary battery using Cu+2AgNO3====Cu(NO3)2+2Ag?

Tip: This redox reaction can be split into the following two half-reactions:

Oxidation reaction (negative electrode reaction): Cu-2e-====Cu2+.

Reduction reaction (positive electrode reaction): 2Ag++2e-====2Ag.

Therefore, Cu is used as the negative electrode, materials with poorer activity than Cu are used as the positive electrode, such as Ag, C, etc., and AgNO3 solution is used as the electrolyte solution. As shown in the picture:

【Case Demonstration】

[Typical Example 1] (2019·Yueyang High School Grade 1 Test) Soak four pieces of metal A, B, C, and D in dilute H2SO4, and connect them in pairs with wires to form various primary batteries. If A and B are connected, A is the negative pole; when C and D are connected, bubbles escape from D; when A and C are connected, A pole is relieved; when B and D are connected, B is the positive pole. Then the order of activity of the four metals from large to small is ()

A.A>C>D>B B.A>C>B>D

C.B>D>C>A D.A>B>C>D

[Problem-solving guide] Please pay attention to two points when answering this question:

(1) In the primary battery, the activity of the negative electrode metal is greater than that of the positive electrode metal;

(2) Be proficient in the basis for judging the positive and negative electrodes of primary batteries.

[Analysis] Choose A. When A and B are connected, A is the negative electrode, which means that A is more active than B; C and D are connected, and there are bubbles escaping from D, then C is the negative electrode of the power supply, and C is more active than D; A and C are connected When the A electrode is lightened, A participates in the electrode reaction and is consumed, so it should be an active metal; B and D are connected, and B is the positive electrode, then D is an active metal and serves as the negative electrode of the power supply. Therefore, A>C>D>B.

Keywords: PPT courseware for high school chemistry compulsory course 2 from the People's Education Press is free to download, chemical reaction and energy change PPT download, chemical reaction and energy PPT download, chemical reaction and electrical energy PPT download, .PPT format;

For more information about the "Chemical Reactions and Energy Chemical Reactions and Energy Changes Chemical Reactions and Electric Energy" PPT courseware, please click the Chemical Reactions and Energy ppt Chemical Reactions and Energy Changes ppt Chemical Reactions and Electric Energy ppt tag.

"The Rate and Limits of Chemical Reactions" Chemical Reactions and Energy PPT (Lesson 1: The Rate of Chemical Reactions):

"The Rate and Limits of Chemical Reactions" Chemical Reactions and Energy PPT (Lesson 1: The Rate of Chemical Reactions) Part One Content: Foundation of Essential Knowledge Literacy 1. The meaning and expression method of chemical reaction rate: [Micro Thinking] (1) In Reaction C(s)+CO2(g) 2CO(g)..

"Chemical Reactions and Energy Changes" Chemical Reactions and Energy PPT (Lesson 1 Chemical Reactions and Thermal Energy):

"Chemical Reactions and Energy Changes" Chemical Reactions and Energy PPT (Lesson 1 Chemical Reactions and Thermal Energy) Part One Content: Foundation of Essential Knowledge Literacy 1. Chemical Reactions and Energy 1. Experimental Exploration: 2. Exothermic Reactions and Endothermic Reactions (1)Meaning: ①Exothermic reaction:___..