Module 4

Module 4—Batteries and Balance

Module Summary

 

In this module you investigated technological applications of the scientific principles associated with reduction–oxidation reactions.

 

You considered the following module question:

• How are principles of oxidation and reduction applied to electrochemical cells?

You used your understanding of electron transfer reactions and skills and techniques to predict, explain, and interpret chemical changes in order to investigate electric (e.g., voltaic) and electrolytic cells.

 

As you found with the chemical systems you investigated in Module 3, the chemical behaviour of both electric and electrolytic cells can be explained using half-reactions, net ionic equations, and cell potentials. You paid careful attention to the products and reactants in the equations you wrote. This allowed you to make observations that confirmed your predictions for both types of electrochemical cells.

 

You also learned to apply your knowledge of stoichiometry to reduction-oxidation reactions occurring in these cells. You extended your understanding of reaction chemical entities by using information about amperage and time to calculate moles of electrons participating in a chemical process. In the case of an electrolytic cell, you regarded electrons as the limiting reagent in the cell’s operation.

 

Concept Map or Graphic Organizer

 

As you worked through Module 4, you may have added information to a concept map or graphic organizer based on the module and lesson questions listed in the Module 4 Concept Organizer. Now is a good time to review the relationships in your concept map or graphic organizer and to try to answer the module and lesson questions.

 

A sample Module 4 concept map shows one set of possible links between the questions. Remember that this is one possible description only—there are many other correct possibilities. However, if your completed concept map or graphic organizer differs significantly from the sample, you may wish to contact your teacher or to compare your map or organizer with those of other students in your class. This will ensure that your interpretations of lesson materials and your descriptions are accurate.

 

Module Assessment

 

When you were in elementary school, you might have constructed an electrochemical cell using a potato or a lemon. You have come a long way in understanding electrochemical cells. In this Assessment you will demonstrate your understanding of the scientific principles and technical knowledge involved in the design and operation of electrochemical cells.

 

With an electrochemical cell made from a potato or a lemon in mind, investigate ONE of the following research questions:

• Do all cells of this kind produce the same voltage?
• Do all cells of this kind operate for the same length of time?
• Can different voltages be recorded from cells constructed using the same fruit or vegetable?
• Is it possible to make these kinds of cells using a wide range of fruits and vegetables?

Read through the parts of conducting an experiment described in the table provided. Formally document your work in two of these steps, and submit your documentation to your teacher for assessment. Document your work in the format that best allows you to provide accurate, detailed, and complete descriptions of your work; e.g., video, audio, text, or a combination of formats.

 

Part	Criteria
Planning an Experiment	State the problem to be investigated. List manipulated, responding, and controlled variables for the proposed experiment. Describe an experiment to test the problem developed. Describe how variables will be manipulated or controlled. Provide instructions about what observations and data must be collected, including experimental controls. List conclusions that cannot be made from the proposed experiment (identify design limitations and possible conclusions).
Performing an Experiment	Provide evidence of the student’s own experiment. Write the procedure describing the experiment that was carried out, and describe how the data were collected. Include raw data and other observations for all trials and controls. Include organized (processed) data from the experiment.
Analysis of Experimental Work/Design	Thoroughly describe the processes used to analyze the data. State a conclusion that can be supported by the data analyzed. List conclusions that cannot be made from the proposed experiment (identify design limitations). Identify a new question or problem that arises from this experiment.

Chemistry 30 Learn EveryWare © 2009 Alberta Education