Electrochemical Cells
Curriculum Expectations:
This section will list a variety of resources which compliment these expectations. There are three lessons within this section called Lesson 6.1, Lesson 6.2 and Lesson 6.3. 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.
- F2.4 build a galvanic cell and measure its cell potential [PR, AI]
- F2.5 analyse the processes in galvanic cells, and draw labelled diagrams of these cells to show the oxidation or reduction reaction that occurs in each of the half-cells, the direction of electron flow, the electrode polarity (anode and cathode), the cell potential, and the direction of ion movement [AI, C]
- F2.6 predict the spontaneity of redox reactions, based on overall cell potential as determined using a table of standard reduction potentials for redox half-reactions [AI]
- F3.3 describe galvanic cells in terms of oxidation and reduction half-cells whose voltages can be used to determine overall cell potential
- F3.2 identify the components of a galvanic cell, and explain how each component functions in a redox reaction
- F3.4 explain how the hydrogen half-cell is used as a standard reference to determine the voltages of another half-cell
This section will list a variety of resources which compliment these expectations. There are three lessons within this section called Lesson 6.1, Lesson 6.2 and Lesson 6.3. 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 6.1: Galvanic Cells
LEARNING GOAL
- Students will learn that Galvanic cells can convert chemical potential energy into electrical energy which can then be used to power other devices.
- Key Terms: anode, cathode, cell notation, cell potential, electric current, electrical potential difference, electrochemistry, electrode, electrolyte, external circuit, galvanic cell, inert electrode, slat bridge, standard cell potential, standard reduction potential, and voltage.
Vine (7 Second Vid) Watermelon battery Vine
Does the watermelon battery really work Work?
Perhaps it does work?
Given the above videos the teacher can allow the students to either think about potential solution to whether or not the watermelon battery works. If possible the teacher can allow students to build the battery in class. As an exemplar the teacher can provide the lemon battery. The method to making the lemon battery is described below.
Building Lemon Battery
Safety First
Materials:
Safety First
Materials:
- lemon
- strip of copper (electrode # 1)
- strip of zinc (electrode # 2)
- Voltmeter + two cables
- A thermometer or clock with an LCD display
- Roll Lemon
- Insert copper and zinc metals into lemon.
- Measure voltage.
Image reference: http://carvercenterct.org/wordpress/wp-content/uploads/2013/10/STEM-logo.jpgž
Science
Engineering
Science
- The concepts of galvanic cells. The anode, cathode, electrode, oxidation, reduction and etc.
- Redox reactions, reduction potentials, Nernst Equation,
- Large Voltaic cells from 1840 to 19th century using zinc electrode and a sulfuric acid were widely used in the printing press.
Engineering
- The building of the lemon battery.
- Calculating volts, amperes, electrical cell potential (Ecell = Ecathode – Eanode) and other relevant calculations of voltage and current.
- Chapter 10 Launch Lab What Determines Voltage?, p. 633
- Potato Clock Activity 10.1 Make a Potato Clock, p. 637
- Ask students to recall the famous potato clock which is usually made a younger age level. If the students have not seen a potato clock the teacher can show a demonstration http://www.xump.com/InstructorGuides/13037-Instructor-Guide.pdf OR they can watch the following video:
CONTENT
For a detailed discussion of galvanic cells section 10.1 Galvanic Cells, pp. 634-48 in Mcgrawhill is an excellent resource
This may be nice video to watch to understand galvanic or voltaic cells.
For a detailed discussion of galvanic cells section 10.1 Galvanic Cells, pp. 634-48 in Mcgrawhill is an excellent resource
This may be nice video to watch to understand galvanic or voltaic cells.
http://www.kentchemistry.com/links/Redox/GalvanicTutorial.htm
This person does an amazing job at teaching Voltaic c ells/Galvanic cells. I would recommend that the teacher provides these videos to the students as a resource. So If they have time to watch them then they can do so on their own time. This excellent for students that need more time to understand.
This person does an amazing job at teaching Voltaic c ells/Galvanic cells. I would recommend that the teacher provides these videos to the students as a resource. So If they have time to watch them then they can do so on their own time. This excellent for students that need more time to understand.
In addition to the above video I have provided a sample Lesson plan which the teacher can use at their own discretion.
Sample lesson plans
Students can watch the following video within which there is a excellent summary of the information that makes up a galavanic cell.
Common Misconceptions: Galvanic/ Voltaic Cells
Students may not be unclear about the difference between voltage and electric current.
Sample lesson plans
- http://www.arborsci.com/Data_Sheets/P6-2100/highschool_chemistry.pdf
- http://mypages.iit.edu/~smile/index.html
- Idea 1: Inquiry Investigation 10-A Measuring Cell Potentials of Galvanic Cells, pp. 670-1
- Galvanic cells lab
- Idea 2: http://thesolararmy.org/jfromj/04_Chemistry_Lesson_Plan.pdf
- Idea 3: http://www.uccs.edu/Documents/chemistry/nsf/106%20Expt9V-GalvanicCell.pdf
- Idea 4: See powerpoint for the in class lesson
Students can watch the following video within which there is a excellent summary of the information that makes up a galavanic cell.
Common Misconceptions: Galvanic/ Voltaic Cells
Students may not be unclear about the difference between voltage and electric current.
- This is an excellent video: http://www.youtube.com/watch?v=1xPjES-sHwg
- http://www.colorado.edu/physics/phys2020/phys2020_fa12/images/Ohm%27s_Law.jpg
- Please that this misconception of anode on the left only applies short hand notation when representing galvanic cells. Show students a diagram of a voltaic cell, the anode can appear on left or the right. Remind them that in a laboratory setting the anode can be on any side so do not assume that the left side is the anode.
- Free electrons do not flow through the electrolyte in a cell. The flow of electric current in a cell involves the flow of anions and cations and a redox reaction (reduction at the cathode and oxidation at the anode). Please tell students that the diagrams that they see are showing the flow of ions through the electrolyte not the electrons.
- The energy comes from the chemical change in the zinc. The energy comes from the chemical change in the zinc when it dissolves into the acid. The zinc is oxidized inside the lemon, exchanging some of its electrons with the acid in order to reach a lower energy state, and the energy released provides the power
Lesson 6.2: Application of Galvanic Cells
Curriculum Expectation:
- F3.5 explain some applications of electrochemistry in common industrial processes (e.g., in refining metals such as aluminum and zinc; in the production of hydrogen)
- F3.6 explain the corrosion of metals in terms of an electrochemical process, and describe some common corrosion-inhibiting techniques (e.g., painting, galvanizing, cathodic protection)
- Student will understand that all batteries are essentially galvanic cells or a set of galvanic cells connected in series.
- Key terms: alkaline battery, battery, button battery, catheodic protection, corrosion, dry cell, fuel cell, galvanizing, primary battery, sacrificial anode, secondary battery.
Investigating Corrosion
Students investigate and summarize factors affecting corrosion and corrosion prevention by visiting the following learning stations. In totol there are 7 learning stations. One student in a group of 8 will only visit one station and that student will report back to their group and present their findings via their preferred learning style.
- Station A: Steel Wool (moist) Corrosion
- Station B: Corrosion of Pure Iron / Galvanized Iron Nails
- Station C: Aluminum Foil Corrosion
- Station D: Iron Nail Corrosion
- Station E: Corrosion Prevention: Copper Plating of an Iron Nail
- Station F: Steel wool + vinegar corrosion
- Station G: Steel Wool + bleach Corrosion
Students choose any one of the following sites to go to and reflect on corrosion & its impact on society & environment
Corrosion Doctor’s Website:
Electrochemical Corrosion Protection:
Corrosion in History:
Historical Theories on Corrosion:
McGrawhill
- Section 10.2 Applications of Galvanic Cells, pp. 649-59
- Activity 10.2 Modelling Corrosion Prevention, p. 658
Common Misconceptions : Application of Galvanic Cells
Students may think that half cells do not need to be electrically neutral, but that one half cell can be positive with cations and the other half cells can be negative with anions.
- Explain that ions migrate in the internal circuirt whereas electrons flow in the external ciruti which matinas electrically netural half cell comparments.
Lesson 6.3: Driving Spontaneous Reactions
Curriculum Expectation:
Inquiry lesson
OISE Lesson Plan
Common misconceptions Driving Non spontaneous reactions
Students may think cell potential can used to deduce the spontaneity of a reaction.
- F3.5 explain some applications of electrochemistry in common industrial processes (e.g., in refining metals such as aluminum and zinc; in the production of hydrogen)
- Students will understand that the flow of current in a galvanic cell can be reversed by applying an external source of electrical energy.
- Key Terms: Chlor-alkali process, Electrolysis, Electrolytic cell
Inquiry lesson
- Excellent Teacher Resrouce: http://www.electrosynthesis.com/pdfs/Guide.pdf
OISE Lesson Plan
- http://oise-is-chemistry-2011-2012.wikispaces.com/CCUA+Group+6
Common misconceptions Driving Non spontaneous reactions
Students may think cell potential can used to deduce the spontaneity of a reaction.
- Spontaneity reaction does not always have to take place because a high amount of activation energy may be required or a more favourable reaction may occur.
Consolidation to the Unit
Consolidation to the Electrochemistry Unit
- Ask students to think back to the guiding questions and answer them.
References