Achievement Task

Students should form teams of three students that represent research consultants hired by a photochemical company to develop a procedure to recover silver from its waste discharge stream. This company is concerned about government fines if the concentration of silver in their discharge stream is too high. They would also like to recover the silver to sell to other companies that could use it in some of the new technologies.

Your team is responsible for producing a final report and making a presentation for the company. The report should include:

1. a description of the technologies and industries that use silver

2. a detailed description of the best method for removing silver from the waste stream

Use a variety of resources to research the current uses of silver. Provide an in depth description of the technology involved.

Summarize your results in an appropriate format.

Based on the estimates provided by a silver recovery plant in the States, the company should be able to recover 4,000 kg of silver per year. Your consultant group must work together to determine the best method of removing that silver from the silver nitrate in the discharge stream and provide a detailed cost estimate to the company.

This estimate should include:

1. the mass of silver nitrate needed to recover 4,000 kg of silver
2. the reaction, in the form of a balanced chemical equation, to be used to obtain silver from silver nitrate
3. the cost of materials needed to obtain elemental silver (found in chemical supply catalogues)
4. two or more sets of data and calculations that support the recommended method and materials purchased. Calculations should include the stoichiometry used to determine the mass and cost of reactants.
5. a consideration of any safety concerns associated with the reaction

Keep the following points in mind while doing this task:

1. You will need to use an activity series to identify the metals that will displace silver from silver nitrate. You will then choose and defend your choice of metal based on cost, availability and safety of reactions
2. If possible, you should actually perform the reaction in order to determine your percentage yield. This should be considered in your choice of metal and overall cost as well.
3. To achieve the lowest cost, consider the container size and compare vendors. You should also choose the purest form of the metal since lower grades contain impurities that will lower your percent yield.

Note: This activity is based on the article "A Silver Opportunity" by Debra Desser found in the April, 1996 issue of Science Teacher.

Write a report that describes your recovery procedure. This report should include all data in a table format, calculations, total costs, and a conclusion summarizing why this is the best method to use and what conditions are needed to obtain the best percent yield.

In a table format, describe the advantages and disadvantages of recovering silver using this procedure.

Prepare a presentation for the company. You will be competing with the other teams in the class for this contract. The other teams are allowed to pose questions to the presenters and challenge their estimates. Your presentation should include:

1. a visual display to support your reasoning that includes accurate calculations
2. a creative component that distinguishes your presentation from others

You will also provide the company with:

1. the summary of your research into the current uses of silver
2. the written report describing your recovery procedure and the advantages and disadvantages
3. all references used listed in APA style