Beijing teachers recruit high school chemistry "ion reaction" teaching plan?

Knowledge and skills

Can write the ionization equation of acid, alkali and salt, and can re-understand acid, alkali and salt from the perspective of ionization.

Process and method

By writing the ionization equation of acid and alkali salts, students' ability of analysis, induction and summary is improved.

Emotional attitudes and values

Students feel the wonderful pleasure of exploring the mystery of matter and the chemical world in their study.

Second, the difficulties in teaching

focus

Writing of ionization equation

difficulty

Understanding acid, alkali and salt from the perspective of ionization

Third, the teaching process

Link 1: Introducing a new lesson

When I was in middle school, I did an experiment: two metal pieces connected to a small light bulb and a power supply were inserted into different solutions, and it was found that some solutions could make the small light bulb glow, while others could not. What solutions can make small light bulbs glow?

The students replied that sodium chloride solution, caustic soda solution, hydrochloric acid solution ... can make small light bulbs glow.

Ask why sodium chloride solution can conduct electricity. Let's learn "Ionization of acid, alkali and salt in aqueous solution".

Link 2: New Curriculum Teaching

1. Taking NaCl solution as an example, why does the solution conduct electricity?

Question: What particles are NaCl crystals made of?

Students answer Cl- and Na+.

Question: What happens when NaCl crystals are added to water? How to express this process?

Students answer that when NaCl is added to water, under the action of water molecules, Cl- and Na+ leave the surface of NaCl crystal and enter the water, forming hydrated sodium ions and hydrated chloride ions, which can move freely. Sodium chloride has been ionized. This process can be expressed by ionization equation as follows: NaCl=Cl-+Na+

The teacher explains the picture above and the students' answers. The schematic diagram can be presented on the big screen, and students can also read textbooks. )

2. Ionization of acids, bases and salts

According to the ionization equation of NaCl, the ionization equations of HCl, HNO3 and H2SO4 in aqueous solution are written, and how to summarize the essence of acid from the perspective of ionization is considered.

Students answer the ionization equations of HCl, HNO3 and H2SO4 in aqueous solution:

HCl = h++ Cl-HNO 3 = h++ NO3-h2so 4 = 2H ++ SO42-

HCl, HNO3 and H2SO4 can ionize H+. Therefore, from the point of view of ionization, acids are known: compounds in which all cations produced during ionization are H+ are called acids.

Ask questions, try to write the ionization equations of NaOH, Ca(OH)2, Ba(OH)2 and KOH, and think about how to summarize the essence of alkali from the perspective of ionization.

Students answer the ionization equations of NaOH, Ca(OH)2, Ba(OH)2 and KOH:

NaOH=Na++OH- Ca(OH)2=Ca2++2OH-

Ba(OH)2=Ba2++2OH- KOH=K++OH-

NaOH, Ca(OH)2, Ba(OH)2 and KOH can ionize OH-. Therefore, from the point of view of ionization, alkali is known: the compound in which all anions generated during ionization are OH- is called alkali.

Group activities list common salts and think about how to define salt from the perspective of ionization.

Student answers

Answer 1: According to the ionization equations of CuSO4, NaNO3 and MgCl2, compounds that can ionize metal cations and acidic anions are called salts. (Wrong answer, the purpose of this setting is to guide students to realize that ammonium ions are treated as metal cations. )

The group answered ②: (NH4) 2SO4 and NH4Cl are also salts, but the ionized cations are not metal cations.

Answer 3: The cations that can be ionized by salt are metal cations and ammonium ions, and the ionized anions are all acid ions.

……

The teacher concluded that salt is a compound that can ionize metal cations or ammonium ions and acid anions.

Link 3: Integration and Promotion

This paper puts forward the problem of judging whether Na2SO4, Na2CO3 and NaHCO3 are salts from the angle of ionization, and how to write their ionization equations.

Analysis: Ionization equations of Na2SO4, Na2CO3 and NaHCO3;

na2so 4 = 2Na ++ SO42-na2co 3 = 2Na ++ CO32-nah co 3 = Na ++ HCO 32-

The teacher needs to explain that NaHCO3 is an acidic salt, which is ionized into metal cations and acid ions when ionized.

Step 4: Summarize the homework.

Ask the students to answer what they have gained in this class, what they have learned and how they feel about learning.

Homework: how to write the ionization equation of NaHSO4? Is there any regularity in writing the ionization equation of acid salt?

Fourth, blackboard design.

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