Measuring the Differences in Carbon Dioxide Production

In this investigation, you will understand how carbon dioxide alters the color of bromthymol blue and use a titration technique to measure the amount of carbon dioxide added to bromthymol blue. Using this technique you will also be able to compare the amount of carbon dioxide produced by a person at different levels of physical activity.

The Titration Technique:

Procedure: Use a straw to exhale air into a flask containing a solution of bromthymol blue. When the solution changes colors, practice changing it back again by adding drops of sodium hydroxide. The more drops of sodium hydroxide needed, the greater the amount of carbon dioxide in the flask. Practice this procedure until you are comfortable with adding the sodium hydroxide. (Important, you need to swirl the flask after adding the drops to see if the color changes, sometimes the change is delayed)

The Experiment:

How does a the amount of carbon dioxide a person exhales change as a result of physical activity?

As a group develop a hypothesis and design an experiment to test your hypothesis. You may use one or all of your group members as guinnea pigs. Very little information is included here as far as how you should conduct your experiment. You are expected to design your own experiment, taking into account controls and variables. Enough data should be taken to form conclusions. (You may want to use averages)

You will each turn in a lab report that should follow the lab report template.

 

Grading Rubric

 

Excellent (3) Satisfactory (2) Borderline (1) Unsatisfactory (0)
Format
Title Page Contains title, name, date, teacher, and period, and graphic Missing one except title or name Missing two, except title or name title or name missing
Clarity Logically sequenced - question, hypothesis, design, data, and conclusions; grammatically correct, all figures tables and graphs labeled, typed Sections labeled but not clearly separated, some grammatical errors, some missing labels Sections not labeled, no separation in sections, frequent grammar errors, section missing, not typed More than one section missing, no labels or separation of sections, grammar poor
Reproducability
Hypothesis Clear explanation of purpose, testable, hypothesis clearly states and expected outcome and a prediction Purpose of experiment not clear, expected outcomes not given Purpose of experiment not clear, hypothesis not written as a testable statement Hypothesis is not given or is not testabable
Design Clear step-by-step description of experimental procedures. Lists equipment and how describes chemicals used and how tests were performed Description is missing minor details, but detailed enough that it could be repeated. Description missing major details, such that it would be difficult for another scientist to repeat your experiment Description missing major details, impossible for another scientist to repeat experiment
Data
Organization Tables easy to read and clearly compare data gathered for the control and for the variable in the experiment, tables titled and labeled Tables somewhat disorganized, control and variable data present Table is very disorganized, labels missing, obviously missing data fields Control and variable not compared, tables not present or impossible to interpret
Trials Multiple trials of tests performed to check validity and included in tables, calculations shown (averages) Multiple trials performed but some data fields or calculations are missing Multiple trials performed, many fields missing, no calculations Multiple trials were not performed
Conclusion
Framework Restates hypothesis, supports or refutes it and explains the role of the test in making the decision Restates hypotheis and supports or refutes it Supports or refutes hypothesis without restating it Does not address the hypothesis
Evidence Uses data powerfully as evidence to support statements Uses some data to support statements Refers to the data in the tables as support Does not use data to support arguments
Logic Conclusion is logically forced from the data Conclusion is logical but not thoroughly defined The conclusion is logical but poorly defined The conclusion (based on the data) is incorrect
Error Identifies sources of error and explains effect on results Identifies sources of error Suggests possible sources of error but identifies no sources Does not address the possibility of error
Total: ___________ out of 30 possible