Chemistry 8 Lesson 32: Oxidation – reduction reaction
1. Theoretical Summary
1.1. Reduction and oxidation
Reduction is the removal of oxygen from a compound. (Reducing agent is an electron donor, oxidizing agent is an electron acceptor)
Oxidation is the action of oxygen on a substance.
1.2. Reducing agent and oxidizing agent
A reducing agent is a substance that takes up oxygen from another substance.
An oxidizing agent is a substance that gives oxygen to another substance.
1.3. Oxidation-reduction reaction
Oxidation-reduction reaction is a chemical reaction where oxidation and reduction occur simultaneously.
– In the chemical equation: CuO + H2 → Cu + H2O
– Can represent the reduction and oxidation of CuO + H . reaction2 as follows:
⇒ Reduction and oxidation are two opposite processes, but occur simultaneously in the same chemical equation.
? Is the following reaction an oxidation-reduction reaction? Why ?
2 family2 + O2 → 2 family2O
Based on the signs of oxygen giving and taking up between substances to distinguish oxidation reactions from other types of reactions.
2. Illustrated exercise
2.1. Form 1: How to determine the type of chemical reaction
Lesson 1: Which of the following is an oxidation-reduction reaction?
A. Fe2 O3 + 6HNO3 → 2Fe(NO .)3 ) 3 + 3 HOURS2 O
B. FAMILY2 SO4 + Na2 O → Na2 SO4 + 2 HOUSES2 O
C. Fe2 O3 + 3CO → 2Fe + 3CO2
D. 2AgNO3 + BaCl2 → Three(NO3 ) 2 + 2AgCl
Repeat: A redox reaction is a reaction in which the oxidation number is changed.
Considering the change in oxidation numbers of substances in the above reactions, we can see that only answer C has a change in the oxidation number of Fe.3+ down Fe0; OLD+2 up+4
Lesson 2: Which of the following reactions is both a chemical reaction and an oxidation-reduction reaction?
A. CaO + H2 O → Ca(OH) 2
B. 2NO2 → WOMEN2 O4
C. 2NO2 + 4Zn → WOMEN2 + 4ZnO
D. 4Fe(OH) 2 + O2 + 2 HOUSES2 O → 4Fe(OH) 3
Nx: Answers A and B have no oxidation number change, so they are not a redox reaction. The remaining answers C and D.
A chemical reaction is a reaction where many substances join to form a new substance. Therefore, type of answer C.
2.2. Form 2: How to determine the reducing agent, the oxidizing agent in a chemical reaction
Lesson 1: For the reaction: Ca + Cl2 → CaCl2 .
The following conclusions correct?
A. Each Ca atom accepts 2e.
B. Each Cl atom accepts 2e.
C. Each Cl . molecule2 yield 2e.
D. Each Ca atom gives up 2e.
Shift → Ca2++2e
Cl2 + 2.1e → 2Cl–
Lesson 2: In the reaction: CaCO3 → CaO + CO2 , element carbon
A. Only oxidized.
B. Only eliminated.
C. Both oxidized and reduced.
D. Neither oxidized nor reduced.
OLD+4 → OLD+4
Lesson 3: In the reaction: Cu + 2H2SO4 (thick, hot) → CuSO4 + SO2 + 2 HOUSES2 O, sulfuric acid
A. is an oxidizing agent.
B. is both an oxidizing agent and an environmental agent.
C. is a reducing agent.
D. is both a reducing agent and an environment-forming agent.
S+6 → WILL+4 ⇒ H2SO4 Acts as an oxidizing agent
SO on the other hand42- acts as a medium for the production of CuSO . salts4
3.1. Essay exercises
Question 1: Completely burn 4.8g of coal powder in air. What is the volume of gas obtained after the reaction?
Verse 2: It is necessary to prepare 33.6 g of iron by using Fe . reduction shrinkage gas3O4.
a. Write chemical equations.
b. Calculate the mass of Fe3O4 need to use.
c. Calculate the volume of CO gas (dktc) used.
Question 3: Lead the HY airflow2 excess passes through 16 g of a mixture of two oxides CuO and Fe2O3 heated. After the reaction was cooled, reweighed and the mass of the mixture decreased by 25%. Calculate the mass percent of each oxide in the first mixture.
Question 4: Carbon oxide gas is used to reduce copper(II) oxide.
a. If a gram of copper(II) oxide is reduced, how many grams of copper will be obtained?
b. Given a = 150 g, calculate the result numerically.
3.2. Multiple choice exercises
Question 1: Choose the correct answer
A. The removal of oxygen from a compound is called oxidation
B. The reaction of oxygen with a substance is called reduction
C. A reducing agent is a substance that takes up oxygen of another substance
D. An oxidizing agent is a substance that takes up oxygen of another substance
Verse 2: For the following reaction, determine the reducing agent
Fe2O3 + 3 HOURS2 −to→ 2Fe + 3H2O
Question 3: Which oxide is reduced by hydrogen:
Question 4: For reaction:
3Fe + 2O2 −to→ Fe3O4
Which substance is the reducing agent?
D.Both A & B
Question 5: Which of the following is not an oxidation-reduction reaction?
A. 4Na + O2 −to→ 2Na2O
B. Cl2 + 2KBr → 2KCl + Br2
C. SMALL3 + HCl → SMALL4Cl
D. 2NaOH + Cl2 → NaCl + NaClO + H2O
After the lesson to know:
- Distinguish between reducing agent, oxidizing agent, reducing agent, and oxidizing agent in specific redox reactions
- Distinguish redox reactions from other types of reactions.