Redox Reactions
Curriculum Expectations:
This section will list a variety of resources which compliment these expectations. There are three lessons within this section called Lesson 4.1, Lesson 4.2 and Lesson 4.3. Please note all of these lessons address the above expectations and each of these lesson are at the heart of electro chemistry because they address essential concepts.
In addition there is a sample lesson plan.
- F2.1 use appropriate terminology related to electrochemistry, including, but not limited to
- F2.3 write balanced chemical equations for oxidation-reduction reactions, using various methods including oxidation numbers of atoms and the half-reaction method of balancing [AI, C]
- F3.1 explain redox reactions in terms of the loss and gain of electrons and the associated change in oxidation number
This section will list a variety of resources which compliment these expectations. There are three lessons within this section called Lesson 4.1, Lesson 4.2 and Lesson 4.3. Please note all of these lessons address the above expectations and each of these lesson are at the heart of electro chemistry because they address essential concepts.
In addition there is a sample lesson plan.
Lesson 4.1: Characterizing Oxidation and Reduction
LEARNING GOAL
CONTENT
Pedagogical reasoning:
- Students will learn that an atom or molecule is oxidized if it loses electrons and is reduced if it gains electrons. In other words when an atom or molecule is oxidized in a chemical reaction, another atom or molecule must be reduced.
- Students will learn to predict if a redox reaction will be spontaneous via oxidation-reduction tables
- Students should define the following key terms within their notes. Key terms : Ionic equation, net ionic equation, oxidation, oxidation reduction reaction, oxidizing agent, redox reaction, reducing agent, reduction, spectator ions.
CONTENT
Pedagogical reasoning:
- Please note that teaching this lesson with visuals is extremely helpful because the with visual presentation students can see the molecular inner working of a redox reaction. The following resources address the above mentioned learning goals.
Images of Oxidation Reduction Reactions
- When the match is struck the potassium chlorate decomposes to give potassium chloride and oxygen. The sulfur burns in the oxygen and finally ignites the woof of the match. Ask students to identify the oxidinzing and reducing agent. (modified from Mcgrawill)
- Image Reference
- Ask students to watch the following video to visually conceptualize the transfer of electrons.
Alternative to Youtube Video
This is an excellent animation which again illustrates the gain and loss of electrons in redox reactions.
Inquiry Investigation
Ask students to work the following interactive activity and to make sure they go through it slowly ask them to take notes.
This lab exercise allows students to test the relative strengths of redox reactions that occur in for metal atoms and ions.
CONSOLIDATION
HOMEWORK
Common Misconceptions:
1) Students may think that the substance that is oxidized is the oxidizing agent and similarly the substance reduced is the reducing agent.
This is an excellent animation which again illustrates the gain and loss of electrons in redox reactions.
Inquiry Investigation
Ask students to work the following interactive activity and to make sure they go through it slowly ask them to take notes.
This lab exercise allows students to test the relative strengths of redox reactions that occur in for metal atoms and ions.
CONSOLIDATION
- Students should discuss the activity with a partner and be able to explain it. If possible ask students to connect their learning with the can ripper lesson starter.
HOMEWORK
- Ask students to complete the post quiz as a form of assessment for learning. Make sure that they all receive a mark of 100% without the help of a partner to gauge at their true understanding of the material.
Common Misconceptions:
1) Students may think that the substance that is oxidized is the oxidizing agent and similarly the substance reduced is the reducing agent.
- To clear up this misconception tell students to remember that...
- The best way to avoid this confusion is to provide students with the following acronyms: OIL RIG (oxidation is losing and reduction is gaining of electrons) or LEO GER (losing electrons is oxidation and ganining electrons is reducing)
- In disproportionation reactions, a single element undergoes both oxidation and reduction These reactions involve elements that can have more than one oxidation number.
LESSON 4.2: Redox Reactions Involving Compounds
LEARNING GOAL
CONTENT
Balancing Half reactions, oxidizing agents, reducing agents.
Detailed notes + Worksheets with solutions:
Detailed notes:
Inquiry Investigation
- Students will learn that equations for redox reactions involving ionic compounds that can be separated into an oxidation half reaction and a reduction half-reaction.
- Students will familiarize themselves with rules that allow balancing of a chemical equation using half reactions.
- The STSE component of this chapter will address how the smelting and refining of ores involves oxidation and reduction.
- Key Terms: disproportionation reaction, half reaction, refining, smelting.
CONTENT
Balancing Half reactions, oxidizing agents, reducing agents.
Detailed notes + Worksheets with solutions:
Detailed notes:
Inquiry Investigation
- This lab exercise allows students to test the relative strengths of redox reactions that occur in for metal atoms and ions. A detailed list of learning goals along with solution to the lab questions can be found in the attachment below:
Inquiry Investigation lesson.pdf | |
File Size: | 684 kb |
File Type: |
CONSOLIDATION
HOMEWORK
Common Misconceptions: Redox Reactions Involving Compounds
- Ask students to once again use appropriate terminology to explain the chemistry behind the lab. This is an excellent exercise to get students talking about the chemistry behind each experiment rather than always writing about it.
HOMEWORK
- Students can either write a lab report on the inquiry investigation or they can simply answer the questions within the pakacge provided.
Common Misconceptions: Redox Reactions Involving Compounds
- Students may assume that ions must be included in order to have a balanced chemical equation.
- Balancing equations via half reactions only requires the removal of spectator ions.
LESSON 4.3: Redox Reactions involving molecular compounds
LEARNING GOAL
CONTENT
Assigning Oxidation numbers: Learners will be able to assign oxidation numbers to atoms in neutral compounds and polyatomic ions.
Common types of oxidation reduction reactions
Potential Lesson Plan
Balancing Redox reactions
An interesting activity
This activity is designed to help students get a grip on assigning oxidation states to elements in compounds. Materials that will be needed are posted below: trump cards, record sheets and rules sheet.
- Students will learn the rules to assign oxidation numbers to atoms in a molecule or a compound. They will balance chemical equations involving molecular compounds by assigning oxidation numbers to all atoms and the following the set of rules.
- Key Terms: Oxidation number
CONTENT
Assigning Oxidation numbers: Learners will be able to assign oxidation numbers to atoms in neutral compounds and polyatomic ions.
Common types of oxidation reduction reactions
Potential Lesson Plan
Balancing Redox reactions
- http://oise-is-chemistry-2011-2012.wikispaces.com/CCUA+Group+6
An interesting activity
This activity is designed to help students get a grip on assigning oxidation states to elements in compounds. Materials that will be needed are posted below: trump cards, record sheets and rules sheet.
Additional Resources
- Detailed notes for teaching this expectation can be found at: http://colgurchemistry.com/Chem12/chem12.htm
- Activity 9.1 Using Lewis Structures to Assign Oxidation Numbers, p. 607
Common Misconceptions Redox Reactions involving molecular compounds
A common misunderstanding for students is that the oxidation numbers represent an ionic charge in a polyatomic ion or a covalent molecule. This is not the case. Instead Oxidation numbers are imaginary numbers that were invented for purpose of keeping track of electrons. When chemist assign oxidation number they assume that electrons in a bond spend all their time around a more electronegative element. Additional confusion may arise from the notation that oxidation number is the same as the common charge for some elements (i.e. Cl‑) To help address this area of confusion the teacher should have strict rules which tell students where to place the charge.
Students may think that oxidation numbers can only be whole numbers (integers).
Closing Ideas for Oxidation Reduction Reactions
This is an excellent resource to show to students in case they want to review the lesson taught in class.
A common misunderstanding for students is that the oxidation numbers represent an ionic charge in a polyatomic ion or a covalent molecule. This is not the case. Instead Oxidation numbers are imaginary numbers that were invented for purpose of keeping track of electrons. When chemist assign oxidation number they assume that electrons in a bond spend all their time around a more electronegative element. Additional confusion may arise from the notation that oxidation number is the same as the common charge for some elements (i.e. Cl‑) To help address this area of confusion the teacher should have strict rules which tell students where to place the charge.
- The ionic charge must always be written following the number (Ca2+)
- The oxidation numbers are always written with the charge in front of the number (Ca+2)
Students may think that oxidation numbers can only be whole numbers (integers).
- Oxidation numbers do not always have to be whole number and this can be illustrated via the formation of magnetite (Fe3O4), which is combination of iron (II) and iron (III).
- This is not true. Let students know that if a molecule is oxidized (i.e. CH4), the reducing agent will be CH4.
Closing Ideas for Oxidation Reduction Reactions
This is an excellent resource to show to students in case they want to review the lesson taught in class.
References