In the Classroom
Thinking Outside the Classroom: Integrating Field Trips into a First-Year Undergraduate Chemistry Curriculum Kaya Forest* Department of Chemistry, Okanagan College, Penticton, British Columbia, Canada, V2A 8E1; *
[email protected] Sierra Rayne Water Treatment Technology Program, Thompson Rivers University, Kamloops, British Columbia, Canada, V2C 5N3
One of the most commonly cited reasons for recent marked enrollment declines in post-secondary chemistry programs is the lack of connection between chemical concepts taught in lectures and their real-world applications (1–3). As a result, students are unable to relate the chemistry they are studying with their personal experiences (4–8). Whether this is the sole reason, or even a major contributing factor, for fewer students continuing their chemistry education, today’s students learn in a manner quite different from previous generations. They tend to be highly visual learners and, seemingly more than students of even just a few years ago, to be interested in learning concepts that can be shown to have direct importance to their personal lives or career goals. While this is by no means universal, there is ample evidence that this characterization typifies the average student (2, 9, 10). Much of this work points to the need to connect what students learn in class with what they see and experience in their daily lives. Studies on implementing field trips in elementary- and secondary-education (4, 11–17) have shown these activities can have lasting cognitive and sociocultural effects on students. Much of this research has focused on how pre-visit orientation and post-visit follow-up generally improves the learning potential of the activity. There is also evidence that many practicing scientists were, at least in part, encouraged to enter science careers through positive experiences in similar activities as young students (16, 18). The first-year university chemistry curriculum provides the foundations for understanding processes that are encountered in society every day. From the polymers in clothing to the thermodynamics of driving a car to class, from the chemistry of soap to the science behind climate change, first-year chemistry concepts provide a unique perspective on daily routines. Ensuring that these applications of chemistry are described within the traditional curriculum provides an opportunity to help students see beyond their everyday experiences and into the world around them through a chemist’s eyes. Educators have spent significant time in recent decades trying to address the perceived shortfall of existing post-secondary curricula by incorporating a variety of strategies into science lectures and laboratories through projects or assignments (2, 7, 19–21) and laboratories using real samples (5, 22). While there is a substantial body of work detailing the use of field trips in pre-university education (2, 12–14), a less robust literature exists that provides examples of field trips that integrate concepts learned in a university chemistry curriculum ( 22–27, including several historical short essays on the topic). Of the more recent literature, Hartman describes a series of upper-level industrial chemical plant tours integrated into an industrial chemistry course to motivate a deeper understanding of the chemical industry (23). In a very recent article, Peterman articulates a series 1290
of field trip ideas for nonscience majors wherein he connects lecture material presented in the course text (8) directly with relevant local sites (24). The connection of a first-year chemistry curriculum for science majors to the broader societal impacts of chemistry on the world and on students’ lives is even more critical if we are to reverse the trend of diminishing student numbers in university chemistry programs by motivating students to pursue the discipline. Despite widespread acknowledgment of the value of field trips, it is our experience that the actual implementation and use of field trips within a chemistry curriculum is largely overlooked by most post-secondary chemistry departments, this despite their more widespread use in other departments (biology, earth science, geography) within the same institution. Several successfully implemented field trip ideas at a small college are presented here to illustrate practical ways of linking what students are learning in their chemistry lecture to real-world applications. Activity Examples Water (or Wastewater) Treatment Plant The first semester in most two-semester first-year university curricula proceeds from stoichiometry through aqueous reactions and gas laws. By mid-semester, these topics have been covered in sufficient detail to provide students with a basic understanding. At this point, a field trip to the local water (or wastewater) treatment plant (WTP) is a highly effective way of cementing these concepts. Numerous processes and procedures common to most treatment plants employ applications of firstsemester topics. Many WTPs employ coagulation and flocculation (28) through the addition of alum, Al2(SO4)3, or iron(III) chloride, FeCl3, Al2(SO4)3·18H2O(s)
− + 2Al3 (aq) + 3SO42 (aq) + 18H2O(l)
FeCl3(s)
− + Fe3 (aq) + 3Cl (aq)
to water at elevated pH levels created by adding lime, Ca(OH)2: − + Ca(OH)2(s) Ca2 (aq) + 2OH (aq) The aluminum or iron ions react with hydroxide to form large solid, gelatinous particulates (floc) that settle and physically remove undesirable materials in the water (e.g., bacteria, small particles, some organic and inorganic contaminants). The reactions involved in forming floc are based on acid–base and solubility concepts: − + Al3 (aq) + 3OH (aq) Al(OH)3(s)
− + Fe3 (aq) + 3OH (aq)
Fe(OH)3(s)
Journal of Chemical Education • Vol. 86 No. 11 November 2009 • www.JCE.DivCHED.org • © Division of Chemical Education
In the Classroom
The concept of “dosing”, in which WTP operators determine the quantity of FeCl3, for example, to add based on incoming water flows and a standard equation, is an example of the stoichiometry of a series of reactions reduced to a simple “plug in and go” equation. If values are recorded during the tour, the students can reproduce the equation through simplification of the stoichiometry used in the process reaction. For example, during the field trip, the students recorded flow data from the WTP (21.3 × 106 L/day) and the concentration of iron(III) chloride required to achieve the desired coagulation (15 mg/L) in the process. The WTP operator knew he had to add 0.22 kg of iron(III) chloride every minute so students were able to return to the classroom and calculate this dosing rate using first-principles stoichiometry. Disinfection of treated water is often accomplished in the WTP by addition of chlorine gas to destroy pathogenic microorganisms and to maintain a disinfection residual in the water as it travels through the distribution system. The hypochlorous acid produced (HOCl) is a strong oxidizer that destroys bacteria by disrupting the cell membrane through oxidation–reduction reactions (28). Cl2(g) + H2O(l)
− HOCl(aq) + Cl (aq) + H+(aq)
The concept of unintended and often undesirable side reactions from any chemical reaction can be illustrated using WTP chemistry. Chlorine gas also has the ability to react with organic impurities in the water to give harmful products such as chloroform and chloroacetic acid: 3Cl2(g) + 2CH4(aq)
2CHCl3(aq) + 3H2(g)
Cl2(aq) + CH3COOH(aq)
CH2ClCOOH(aq) + HCl(aq)
Many other chemical processes that occur in treatment plants can be connected to chemistry topics. The addition of sulfur dioxide to remove excess chlorine before release of overflow water into the environment can be used as an example of a redox reaction. Charcoal filter beds are used to remove residual solids as an example of bulk-scale filtration similar to use of activated charcoal in organic synthesis purification.
Most treatment plants have in-house analytical capabilities where students can view the instrumentation (Figure 1) used to measure pH, turbidity (a type of spectrophotometric technique to measure suspended solids), and nitrate, phosphate, and chlorine residue using colorimetric analyses. Students have an opportunity to use many of these or similar instruments in the laboratory throughout the semester and this provides them with a context for the use of instrumentation in an industrial setting. Water Quality Sampling Our department has portable field equipment used primarily to deliver service courses for an environmental monitoring program, but we also use this equipment to run a field trip-based laboratory experiment for our first-year chemistry classes. This laboratory experiment is generally performed shortly after the WTP field trip to further illustrate the analytes responsible for characterizing water quality. The experiment involves collecting several liters of water from the local river both upstream and downstream of the wastewater treatment plant (WWTP) outfall. Students use portable probes on site to measure conductivity, pH, and temperature, demonstrating the capacity to “take the lab into the field”. Spectrophotometers and reagent packets are used to analyze these samples colorimetrically for alkalinity, hardness, ammonia, nitrate, phosphate, copper, iron, and free chlorine residue. The upstream and downstream results are compared to determine the effects of WWTP effluent on water quality in the local river and lake system, which allows students to understand the cause of the algal growth visible downstream of the outfall to the WWTP discharge. Winery (or Brewery) By the later part of the second semester in most two-semester first-year university curricula, students will have been introduced to kinetics, acid–base chemistry, redox reactions, and organic chemistry. At this point, a field trip to a winery (or brewery) is an effective way of illustrating these topics (Figure 1). In addition to the opportunity to view an industrial process, if the winemaker or brewmaster is willing to take students through the entire process, applied aspects of kinetics, acid–base chemistry, redox reactions, organic chemistry, and laboratory analysis can readily be discussed.
Figure 1. Photographs from first-year chemistry field trips: (left) to a water treatment plant and (right) to a local winery.
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In winemaking, the initial grape crushing and subsequent fermentation steps can be used to illustrate solubility and extraction as the grapes are crushed and juice or entire berries are placed in large tanks. Kinetics, including rate of reaction and catalysis, can be described in the fermentation step where winemakers will hold the fermenting tanks at a precise temperature to ensure optimum flavor extraction, encourage vigorous yet controlled fermentation, and minimize side reactions. Description of the wine aging process, both in stainless-steel holding tanks and in oak barrels, allows for an in-depth discussion of organic functional group conversions (i.e., aldol condensations, dehydration and hydrolysis, de-aminations) and redox chemistry (e.g., phenol–quinone equilibria). The process of cold stabilization to remove residual tartaric acid present in a wine just prior to bottling is discussed as an example of the effect of temperature on solubility. The tour also includes a walk through the analytical lab of the winery. Experiments that occur in the lab of a winery, for example, include refractometry or density measurements to determine sugar and alcohol content, acid–base titrations (titratable acidity), and chromatography. As an on-campus follow-up to the winery tour (Textbox 1), students titrate a wine sample to determine the concentration of acid (assumed to be tartartic acid) as part of their more traditional acid–base titration experiment (acetic, phosphoric, and hydrochloric acids with sodium hydroxide) during the semester. Agricultural Research Station Our community has an agricultural research station (Agriculture and Agri-Food Canada) that houses analytical instrumentation with active research programs on plant, food, and beverage chemistry. By the end of the first semester, students have been introduced to methods of analysis such as mass spectrometry, gas–liquid chromatography, and UV–vis and IR spectroscopy in the context of isotopes, structural conformation, and bonding. The field trip to the agricultural research station is a unique chance for students to view such specialized instrumentation (as well as other advanced tools such as scanning and transmission electron microscopes), in addition to reinforcing
Procedure
1. Pipet 5 mL of white wine into a 125 mL Erlenmeyer flask. Add 25 mL deionized (DI) water and monitor the titration by ~0.1 M NaOH using a pH meter.
2. Pipet 5 mL of white wine into a 125 mL Erlenmeyer flask. Add 25 mL DI water and three drops of an appropriate indicator. Titrate with the ~0.1 M NaOH to the end point.
3. Graph your pH meter measured titration and identify the equivalence and half equivalence points of your wine sample. Assuming the acid present in the wine sample is tartaric acid, determine the approximate Ka for tartartic acid.
4. Determine the concentration of acid in the wine sample using both the graphical method and the titration data. Compare your results.
Textbox 1. Post winery tour on-campus follow-up wine laboratory experiment.
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the physical and chemical principles underlying the analytical method. The opportunity to see advanced instrumentation in use in a research capacity at such an early stage in their education can also serve to inspire students to continue on in chemistry as they see how chemistry is at the heart of scientific exploration in many different disciplines. Climate Change Showing students films such as An Inconvenient Truth and 11th Hour is an effective method of connecting first-year chemistry concepts with popular media. While many students may have already seen these films, the opportunity exists to extract some of the fundamental scientific principles behind climate change and connect it with concepts learned in the curriculum. A discussion of the film, its claims, and the underlying science in particular can be used to explore critical thinking skills. The greenhouse effect, for example, can be used to illustrate electromagnetic radiation and molecular vibration frequencies. As a way of introducing economics and the concept of a carbon footprint, students can calculate the thermodynamics and amount of carbon dioxide released in the use of various existing and proposed fuels. The “great ocean conveyor”, and in particular the resulting Gulf Stream, is a fundamental application of density owing to temperature and salinity. Pre- and Post-Field Trip Activities To ensure students obtain the most from their experience, they were prepared for the field trips through foreshadowing during lectures when relevant material was being covered, where attention was drawn to concepts or examples that they would see during the field trips. For several of the sites attended regularly (water treatment plant, winery), students were provided with a several-page handout that outlined the activity with particular emphasis on the chemical processes they would encounter, some of the basic chemical reactions involved, and the instrumentation that would be presented. Transportation, timing, and safety protocols were discussed several classes in advance of the trip and again just prior to the day of the trip. While these activities do not result in any form of formal evaluation, post-trip follow-up was performed via traditional assignment or exam questions that directly related to the activities undertaken (Textbox 2). Logistical and Pedagogical Evaluation In evaluating locations suitable for field trips, several factors must be considered. Safety at the site is paramount and requires students be briefed beforehand of any potential hazards. Consideration should be given to a second chaperone, particularly at sites that pose any substantial hazard. To ensure students obtain the greatest benefit from the activity, groups should generally be limited to 20 students, which often restricts this activity either to small classes or to laboratory sections at larger institutions. Coordination of field trips at larger institutions presents additional challenges that could be overcome with careful organization (activities staggered over several sites or over several weeks). The sites should be chosen that enable the group to be transported to and from the site (preferably in institutional or faculty vehicles for insurance purposes) and complete the tour within a 1.5 or 2 hour lecture or 3 hour laboratory time.
Journal of Chemical Education • Vol. 86 No. 11 November 2009 • www.JCE.DivCHED.org • © Division of Chemical Education
In the Classroom
Climate Change and Le Châtelier’s Principle
lactic fermentation of red wine is the conversion of malic
1. In addition to contributing to the greenhouse effect, an in-
acid, C3H5O 3COOH (Ka = 3.98 × 10–4), to lactic acid,
creasing carbon dioxide concentration in the atmosphere is
C2H5OCOOH (Ka = 1.40 × 10–4). Assuming all of the malic
predicted to result in widespread death of coral reefs through
acid is converted to lactic acid, what change in pH will result
acidification of the oceans.
if a 250 L barrel of wine that contains 0.175 M malic acid
H2O(l) + CO2(g)
pH of ocean drops by 0.27 units. Given that coral reefs are composed of millions of individual polyps with calcium car-
Wine Redox Titrations
content of wine. A wine chemist has a previously prepared
to describe why these animals are susceptible to increased
dichromate solution whose concentration label has gone
carbon dioxide levels.
missing. She can standardize the dichromate solution using
H2CO3(aq) CaCO3(s) + H+(aq)
+
an acid (H+).
−
H (aq) + HCO3 (aq)
+ 8H (aq) + Cr2O72−(aq) + 3SO32−(aq)
− Ca2+(aq) + HCO3 (aq)
Climate Change and Stoichiometry 2. The largest contributor to your greenhouse gas emission load is probably your vehicle and its combustion of gasoline. If you
2Cr3+(aq) + 3SO42−(aq) + 4H2O(l)
(a) Identify the species being oxidized and the species being reduced. (b) Determine the concentration of the dichromate solution if a 25.00 mL sample requires 29.63 mL of a 0.1745 M solution
assume gasoline is composed solely of octane (C8H18) that
of HCl to reach the stoichiometric (equivalence) point.
has a density of 0.703 g/mL, determine how many tonnes of CO2 you emit during a trip to Vancouver (426 km) if your car gets 7.8 L/100 km (note: 1 tonne = 1000 kg).
Water Treatment Disinfection and Gas Laws
Wine Acid–Base Chemistry
5. Potassium dichromate is often used to determine the alcohol
bonate (CaCO3) shells, use the equilibrium equations given
undergoes complete fermentation to lactic acid?
H2CO3(aq)
With a doubling of CO2 concentration, for example, the
4. One of the key reactions that occurs during the malo–
3. A chemist at a local winery needs to decide whether she has to cold stabilize a barrel of her wine before she bottles it. Bitartrate, −OOC(C2H4O2)COO−, will precipitate out of wine as large white crystals of potassium bitartrate if the bitartrate concentration is greater than 6.0 × 10–4 M. What initial concentration of potassium tartrate [HOOC(C2H4O2)COOK, Ka = 1.5 × 10–5] in the wine will lead to this unwanted precipitation reaction? Determine whether she has to cold stabilize the wine.
6. One of the most effective chemicals to disinfect drinking water before release into municipal distribution systems is chlorine gas. Most municipalities using Cl2 obtain their supplies in highly pressurized gas cylinders. Using both the ideal gas law and van der Waals equations, determine whether a new model of tank (400 L) containing 50 kg chlorine at 25 °C that is being shipped to you will rupture (if P > 40 atm) and leak the deadly gas into your warehouse [aCl2 = 6.260 (L2 atm)/ mol2; bCl2 = 0.0530 L/mol]. Explain the difference in pressures obtained using the two equations in terms of the intermolecular forces found in chlorine gas.
Textbox 2. Sample post-activity assignment or exam questions.
Many local industries and municipal infrastructure plants are eager to provide educational tours and are often willing to script their tours to the level and expertise of the students. For example, the local water treatment plant operator will describe the treatment process and will include the basic chemistry present (name of chemical used, general reaction classification), and the local winemaker will describe the functional group transformations that occur during fermentation and aging. Students are encouraged to ask questions and often are able to grasp the underlying chemical principles at a considerable depth. In addition to the simple act of getting outside of the classroom to see chemistry in action, many of these field trips make students aware that an understanding of chemistry is foundational to careers and occupations they had likely never thought would require such knowledge. On numerous occasions, students have expressed astonishment at the depth of chemical knowledge required by these nonchemistry and sometimes even nonsciencemajor workers. At least one field trip was incorporated into each semester of a two-semester first-year course over the last four years. While
some of the timing is at the discretion of the field trip-site personnel, the activities were undertaken in the fall semester before the middle of October—this allowed sufficient time for students to acquire the requisite basic knowledge (solution stoichiometry, reaction classifications) and occurred generally before the weather became too cold. The winter semester followed similar requirements—by the middle of March students were familiar with kinetics, equilibrium, and organic and acid–base chemistry, and the weather was sufficiently warm to allow for comfortable outdoor excursions. A second activity was scheduled if sufficient time remained in the course, generally in the winter semester. Depending on scheduling of course lecture and laboratory times, field trips have been organized to occur during both time slots. These field trips have been run solely as optional activities, in part to maintain flexibility in the scheduling of the activity but also because our institution has multiple centers and chemistry sections at other campuses do not engage in similar activities (as such, it cannot be an official, evaluated component of the course). Despite being optional, there has been essentially full attendance by students at each of these activities suggesting that
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students are eager to engage in such excursions. Quantitative research on the beneficial effect of these activities on students’ perception of chemistry, appreciation of the application of chemistry to the real world, and motivation to continue in the discipline would be difficult to conduct. However, course evaluations performed by students toward the end of every semester include, without exception, numerous references to the field trips (Textbox 3) suggesting, at least qualitatively, the lasting impact of these activities on students perception of the course.
made me much more interested in the subject to the point that I want to pursue a career in chemistry.
• Field trips have been great and very relevant.
• Relates the course material to interesting everyday activi-
• The trip to the water treatment plant was incredible. Not
ties. only did I learn that a lot of chemistry goes on to produce good drinking water, but it was a great break from lecture.
Conclusion We found the implementation of field trips into the firstyear undergraduate chemistry curriculum to be an excellent means of reinforcing on-campus lecture and laboratory concepts in stoichiometry, acid–base reactions and titrations, kinetics, and redox, organic, and analytical chemistry. With some forethought and planning, these activities were positioned within the curriculum to serve as a case-study around which several topics within a semester could be themed and to assist students to make connections among what they view as unrelated concepts. The use of foreshadowing helped to pique students’ interest in the real-world application of curriculum material, and the field trip itself was a valuable educational tool both as a way of reinforcing learned material and as a means of allowing students to engage and explore the topics beyond theory and calculation. The use of post-activity follow-up in the form of assignment or examination questions or laboratory exercises allowed the activity to reappear in a more traditional evaluation setting. In addition to being an opportunity to expose students to chemical principles in real-life applications, these field trip activities have also resulted in stimulating student interest in continuing their chemistry studies at the second-year level. Acknowledgments The authors would like to thank a number of people for their participation in these activities: Gerry Neilsen at Agriculture and Agri-Food Canada; Dena Gregoire at Jackson Triggs– Okanagan Estate; Kelly Symonds at Hillside Estate Winery; and the staff at the City of Penticton Water Treatment Plant. Literature Cited 1. de Vos, W.; van Berkel, B.; Verdonk, A. H. J. Chem. Educ. 1994, 71, 743–746. 2. Habraken, C. L.; Buijs, W.; Borkent, H.; Ligeon, W.; Wender, H.; Meijer, M. J. Sci. Educ. Technol. 2001, 10, 249–256. 3. Johnstone, A. H. J. Chem. Educ. 1997, 74, 262–268. 4. Donahue, T. P.; Lewis, L. B.; Price, L. F.; Schmidt, D. C. J. Sci. Educ. Technol. 1998, 7, 15–23. 5. Loyo-Rosales, J. E.; Torrents, A.; Rosales-Rivera, G. C.; Rice, C. P. J. Chem. Educ. 2006, 83, 248–249. 6. Phelps, A. J.; Lee, C. J. Chem. Educ. 2003, 80, 829–832. 7. Stout, R. J. Chem. Educ. 2000, 77, 1301–1302. 8. Chemistry in Context, 3rd ed.; Stanitski, C., Ed.; McGraw-Hill: New York, 1999. 9. Habraken, C. L. J. Sci. Educ. Technol. 2004, 13, 89–94. 10. Runge, A.; Spiegel, A.; Pytlik, L. M.; Dunbar, S.; Fuller, R.; Sowell, G.; Brooks, D. J. Sci. Educ. Technol. 1999, 8, 33–44.
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• Between the lectures and the great field trips, you have
• Makes chemistry more interesting ... and helps make me
• Referencing “real-life” chemistry in classes and taking us on
• I really liked the field trip to the water treatment plant – I
understand chemistry finally. field trips helps me learn more than just theory. have applied to the water quality program for next year. Thanks for the inspiration!
• Field trips have made chemistry almost freakishly exciting! When you include how chemistry can be used in the “real world”, it gives us a greater appreciation for what is being taught.
• The trips relate course material to the real world. Field trips are awesome!
Textbox 3. Examples of student feedback on course evaluations.
11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28.
Eshach, H. J. Sci. Educ. Technol. 2006, 16, 171–190. Kisiel, J. Sci. Educ. 2006, 90, 434–452. Knapp, D.; Barrie, E. J. Sci. Educ. Technol. 2001, 10, 351–357. Lucas, K. B. Sci. Educ. 2000, 84, 524–544. Martin, W.; Falk, J. H.; Balling, J. D. Sci. Educ. 1981, 65, 301– 308. Rudmann, C. School Sci. and Math. 1994, 94, 138–141. Orion, N. School Sci. and Math. 1993, 93, 325–331. Naizer, G. L. School Sci. and Math. 1993, 93, 321–324. Lee, D. R.; McClurg, F. A.; Nixon, G. A. J. Chem. Educ. 1986, 63, 1065–1066. Parrill, A. L. J. Chem. Educ. 2000, 77, 1303–1305. Walczak, M. M. J. Chem. Educ. 2007, 84, 961–966. Lunsford, S. K.; Speelman, N.; Yeary, A.; Slattery, W. J. Chem. Educ. 2007, 84, 1027–1030. Hartman, J. S. J. Chem. Educ. 2005, 82, 234–239. Peterman, K. E. J. Chem. Educ. 2008, 85, 645–649. Breedlove, C. H. J. Chem. Educ. 1985, 62, 778–779. Siggia, S. J. Chem. Educ. 1968, 45, 680. Stokes, J. C.; Lockhart, W. L.; Barnes, L. M. J. Chem. Educ. 1976, 53, 370. Environmental Engineer’s Handbook, 2nd ed.; Lui, D., Ed.; CRC Press: Boca Raton, 1999.
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2009/Nov/abs1290.html Abstract and keywords Full text (PDF) Links to cited JCE articles
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