A Student-Led Lab: The Carbonate Project

text: A Student-Led Lab: The Carbonate Project over 3 samples glass bottles of unknown white powder

Can high school students truly drive their own lab experience? I’d say after enough time and exposure, they can. This is what led me to develop a version of the Carbonate Project to have students perform after the AP Exam. This experience requires students to do some research, execute previously performed lab techniques, and identify an unknown substance. 

A number of years ago I stumbled across Emily Dudek’s 1991 Journal of Chemical Education article, A Carbonate Project - Introducing Students to the Chemistry Lab. In this article, she discusses a four-step lab procedure that allowed her students to identify an unknown alkali metal carbonate. As I read through the four processes she identifies (a chemical reaction with mass loss, a gravimetric analysis, a collection of gas over water and a titration), I realized that all of these procedures were processes that my students had experienced between chemistry and AP Chemistry. I began to explore if my students could do this project, without any explicit instructions from me. 

Concepts: 
laboratory design
Procedure time: 
> 90 minutes
Time required: 

After introducing the assignment I provide the rest of the class period for research and planning and then two more class periods for experimentation. Students who need time beyond these three periods are encouraged to meet with me after school or at another time which works in their schedule.  

 

Procedure: 

I present my students with the following proposal. 

Student-Led Project

Your goal over the next few class periods will be to identify an alkali metal carbonate. To do it you will need to perform (at minimum) two experiments, using techniques we have worked on in class, in order to get enough information to verify the identity of your substance.  

You should work in a group of 2  for this task.

As your common task for the second semester, your research group will submit two forms of documentation. First is a research and planning document. Second is an abstract discussing your experiment along with all data collected. These will be submitted for review via google classroom.  

Research Proposal

Your research proposal should include the following: 

  • Names of group members.
  • Some properties that could be used to identify alkali metal carbonates. 
  • Reactions that alkali metal carbonates undergo that you could perform in a lab setting.  
  • Two lab techniques that you think that you could use to get enough information to identify an alkali metal carbonate.  
  • A minimum of 5 sources for your research.  

 

Like Ms. Dudek’s project, I keep my carbonates to Li, Na, and K, but omit that information for the students. Each pair of students will receive an unknown sample labeled with a number. They need to submit a detailed proposal to me explaining the two lab techniques they plan on using, a detailed procedure and materials list for each. I also require citations of 5 resources. Once the plans are approved, they may begin executing the procedures in the lab. I require two experiments to ensure that their identification is verifiable. I encourage having a third procedure available in case one of the original two provides inconclusive data. I also offer guidance with regard to available materials, minimizing waste, and student safety. 

See the Supporting Information to access the document I provide students outlining the expectations for their Abstract and Project Reflection. (Readers must log into their account to access. Not a member? Register for free!)

The students genuinely enjoy the experience. As typical high achievers they relish being “right” and knowing the answer. It is valuable for them that sometimes the experiment doesn’t work as expected. Some students get beautiful data on their first go around. Others have a hard time initially and need to complete further trials or need to change an experiment entirely. Often students want to “leave out” their inconclusive trials, which leads to many vibrant discussions on how there is no bad data, just data we haven’t understood yet.  

When students have enough evidence to identify the carbonate, I have them write an abstract including their identification, explaining the process used, and including the evidence collected.  Students turn this in collectively. The more valuable analysis, is the reflection students are asked to write individually.  They address frustrations, successes and things they would do differently. The questions guide students to think deeply about the experience, and many have indicated that the open-ended nature of the project makes it the most authentic science experience they have the opportunity to complete while in high school. 

This modified version of the Carbonate project is a way to make the open-ended nature of scientific research accessible to the high school student, sparking interest and developing skills. 

Preparation: 

To get ready for the lab I create jars of unknown samples, labeling them A, B and C. Each jar contains about 2-3 grams of the individual sample and is typically enough for students to complete two to three experiments. I pass out unknowns to groups of students as their plans are approved. I make sure that balances, eudiometer tubes, bunsen burners, funnels, filter paper, beakers and deionized water are available. I also try to have a decent quantity of 3M HCl and solid Calcium Chloride at the ready, as they are something students often request. I keep all of these materials easily accessible for me, but not displayed for the students. I want their research to influence their planning more than visible equipment.

Attribution: 

Dudek, E. A Carbonate Project Introducing Students to the Chemistry Lab. J. Chem. Education, 1991, 68 (11) 948-950.

25 Self-Reflection Questions to Get Students Thinking About Their Learning https://blog.futurefocusedlearning.net/25-self-reflection-questions (accessed 1-27-2023)

Safety

General Safety

For Laboratory Work: Please refer to the ACS Guidelines for Chemical Laboratory Safety in Secondary Schools (2016).  

For Demonstrations: Please refer to the ACS Division of Chemical Education Safety Guidelines for Chemical Demonstrations.

Other Safety resources

RAMP: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies

 

NGSS

Analyzing data in 9–12 builds on K–8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data.

Summary:

Analyzing data in 9–12 builds on K–8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data. Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

Assessment Boundary:
Clarification:

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

Summary:

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of a design.

Assessment Boundary:
Clarification:

Scientific questions arise in a variety of ways. They can be driven by curiosity about the world (e.g., Why is the sky blue?). They can be inspired by a model’s or theory’s predictions or by attempts to extend or refine a model or theory (e.g., How does the particle model of matter explain the incompressibility of liquids?). Or they can result from the need to provide better solutions to a problem. For example, the question of why it is impossible to siphon water above a height of 32 feet led Evangelista Torricelli (17th-century inventor of the barometer) to his discoveries about the atmosphere and the identification of a vacuum.

Questions are also important in engineering. Engineers must be able to ask probing questions in order to define an engineering problem. For example, they may ask: What is the need or desire that underlies the problem? What are the criteria (specifications) for a successful solution? What are the constraints? Other questions arise when generating possible solutions: Will this solution meet the design criteria? Can two or more ideas be combined to produce a better solution?

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.

Summary:

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.
Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments.

Assessment Boundary:
Clarification:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models.

Summary:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

Assessment Boundary:
Clarification:
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Comments 1

Chris Cunningham | Fri, 05/19/2023 - 14:39

This looks fantastic!  I am planning on trying this out with some of my AP sections.  Do you have any other suggestions for someone trying this for the first time?  Also wondering besides the four labs mentioned above if there were any others that your students often tried out?  I am just trying to make sure I have the necessary materials.

Thanks!