Fostering Innovation through an Active Learning Activity Inspired by

Aug 13, 2014 - Fostering Innovation through an Active Learning Activity Inspired by the Baghdad Battery. Xu Lu and Franklin Anariba*. Engineering Prod...
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Fostering Innovation through an Active Learning Activity Inspired by the Baghdad Battery Xu Lu and Franklin Anariba* Engineering Product Development, Singapore University of Technology and Design, Singapore 138682, Singapore S Supporting Information *

ABSTRACT: A hands-on activity based on general electrochemistry concepts with the aim at introducing design science elements is presented. The main goals of the activity are to reinforce electrochemical principles while fostering innovation in the students through the assembly and optimization of a voltaic device and subsequent evaluation by powering several light emitting diodes. The voltaic device consists of metal clips that function as electrodes prepared from Cu and Al metal sheets immersed in rice wine in a paint box, which works as the electrolyte. The active learning activity highlights the historical context of energy storage devices, and can be used as a tool for fostering “outside-the-box” thinking in the students, as well as encouraging team collaboration. This active learning activity is suitable for high school students with a background in chemistry, for undergraduate engineering and architecture students, and for general undergraduate students enrolled in an introductory general chemistry course, regardless of their interest in design science. KEYWORDS: First-Year Undergraduate/General, High School/Introductory Chemistry, Electrochemistry, Demonstrations, Hands-On Learning/Manipulatives, Electrolytic/Galvanic Cells/Potentials

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activity highlights the historical context of charge storage devices, which is used as an educational tool for fostering “outside-the-box” thinking in the students,16 as well as encouraging team collaboration. This classroom active learning activity was developed with incoming university students in mind, though it can be applied to first-year university students. The activity in its current form should be given 90 min, which includes time for a brief historical introduction and demonstration of the Baghdad battery (Part I; 30 min), instructions, assembly and optimization of the electrochemical device, and powering of the LEDs (Part II; 40 min) (more details in the Supporting Information), and a final discussion led by the instructor on how electrochemical principles can be used to illustrate design science concepts (Part III; 20 min).

e describe the development and implementation of an active learning activity which introduces design science elements (creativity and innovation through assembly and optimization) to students based on the application of principles of electrochemistry. Such a task can be accomplished through an active learning methodology involving electrochemistry topics. One such topic is the battery,1−4 particularly the Baghdad battery.5−8 A survey of the current literature did not find works addressing the Baghdad battery, either as an electrochemical device or as an educational instrument. However, several batteries of varying designs have been fabricated and proposed for hand-on classroom activities. These efforts include mini-galvanic cells as concentration cells used to determine equilibrium constants9 and to light LEDs,10 lemon cells11 to power a calculator, a piezo buzzer, a desktop clock, LEDs,12 and small motors.13 Other examples are an aluminum-air battery used to power a small motor or light,14 and a household battery used to power various toy cars.15 In general, these active learning activities were designed to teach principles of electrochemistry through the use of readily accessible and economic materials/objects to which students could relate, such as household materials. In this active learning activity, students are first presented with a historical context of charge storage devices through a demonstration using replicas of the Baghdad battery. Second, students use the Baghdad battery to observe the difference between an electromotive series and a Galvanic series. Finally, inspired by the Baghdad battery, students design and assemble an electrochemical device, herein referred to as the XuLu Cu− Al Array, with the goal of lighting up six LEDs. The voltaic device consists of Cu and Al electrodes immersed in rice wine, which functions as the electrolytic solution. The active learning © XXXX American Chemical Society and Division of Chemical Education, Inc.

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PART I: THE BAGHDAD BATTERY AS CLASSROOM/LECTURE DEMONSTRATION The Baghdad battery (Figure 1) and its historical context as elaborated in the Supporting Information section was introduced to students enrolled in the Integrated Learning Program (ILP) in chemistry. Replicas of the Baghdad battery were utilized in a classroom setting to (1) Demonstrate to students the simple dynamics involved in harnessing electrochemical energy by coupling the device to a multipurpose meter in DC mode to measure both voltage and current values. However, the instructor may replace the multipurpose meter with a data logger connected to a laptop attached to a projector to

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PART II: THE XuLu Cu−Al ARRAY AS AN ACTIVE LEARNING CLASSROOM ACTIVITY Inspired on the fabrication and evaluation experience of the Baghdad battery, an array of electrochemical cells comprised of a Cu metal as the cathode and Al metal as the anode was built, as shown in Figure 2 and construction details are presented in the Supporting Information section. Figure 1. (A) Assembled replica of a Baghdad battery; (B) Cu and Fe electrodes housed in a ceramic clay vessel.

(2)

(3)

As from

demonstrate voltage stability curves and current discharge characteristics of the electrochemical cell. Introduce students to the concept of a corrosion cell driven by environmental factors (e.g., pH, humidity, salinity) since from an electrochemical standpoint the Baghdad battery is a galvanic corrosion cell whereby the Fe corrosion process at the anode highly influences its power output. Highlight to students the difference between an electromotive series (standard reduction half potentials) and a Galvanic series.16 it can be observed from Table 1, the calculated values the electromotive series, which is a calculation from the

Figure 2. Construction of the XuLu Cu−Al Array: (A) fabrication of Cu−Al electrode pairs, and (B) assembly of a 24-cell array in series.

The electrical circuit of the electrochemical device was accomplished by the addition of the electrolytic solution to each of the cells in the array. The electrolyte of choice was a locally acquired rice wine, containing water, rice, 20% alcohol by volume, and 0.27 M NaCl. The intention was to replicate an ancient electrolytic solution while at the same time have easy and affordable access to materials for implementing the activity. As these were suboptimum working conditions, copper and aluminum in rice wine were used in the hands-on activity. When 13.0 mL of electrolyte per cell was used, the first cell in the array provided 0.604 V and a transient current of 23.69 mA, while one array (24 cells connected in series) exhibited voltage and current values of 13.1 V and 5.80 mA, respectively. The major galvanic electrochemical reactions at the electrodes can be described in the following way:

Table 1. Standard Reduction Half Reaction Potential (Electromotive Series) and Baghdad Battery Potential Values (Galvanic Series) Reaction

E°red/Va

ΔEcell/V (Electromotive series)b

EBaghdad Battery/V (Galvanic series)c

Cu2+ + 2e− Sn2+ + 2e− Fe3+ + 3e− Zn2+ + 2e− Al3+ + 3e−

+0.34 − 0.13 − 0.44 − 0.76 −1.66

+0.47 +0.78 +1.1 +2.0

+0.025 +0. 085 +0.57 +0.30

a

Voltage values are reference against the standard hydrogen electrode (SHE). bVoltage difference calculated when Cu acts as the cathode electrode. cVoltage difference measured when Cu acts as the cathode electrode in rice wine with [NaCl] = 1.0 M and 20% alcohol.

Anode Al(s) → Al3 +(aq) + 3e−

(1)

Cathode

standard reduction half reaction potentials (1 M, 1 atm, 298 K), indicate the trend of Sn < Fe < Zn < Al. However, the values measured through the Baghdad battery, which was not under standard reduction conditions, provide a slightly different trend: Sn < Fe < Al < Zn. That is, on the basis of the Galvanic series, Al and Zn swap places, most likely due to the formation of a surface oxide film that rendered the Al surface passive. At this point, the instructor should highlight that reduction potential values associated with the electromotive series, although very useful to indicate the relative activity of the metals in reference to one another, does not take into consideration environmentally influencing factors. On the other hand, the Galvanic series is based on evaluation of the corrosion process under actual real-life conditions, where more practical applications can be found, especially in engineering structures such as bridges (engineering students) and in designing spaces (architecture students). The comparison and discussion between the two series should be based on the trends of the reduction potentials, and not on the difference of the absolute values obtained.

2H+(aq) + 2e− → H 2(g)

(2)

with the overall reaction as 2Al(s) + 6H+(aq) → 2Al3 +(aq) + 3H 2(g)

(3)

The active learning activity based on the XuLu Cu−Al Array, which is named after the coauthor, was presented to students enrolled in the Integrated Learning Program (ILP) in chemistry. Students were divided into groups of 5 students; however, groups of 3 or 4 students should be also appropriate. Students were given 1 plastic paint box containing 24 wells, 23 Cu−Al electrode pairs as shown in Figure 2, 1 Cu and 1 Al electrodes with connecting Cu wires, 2 jump wires with alligator clips, 450 mL of rice wine, 350 mL of vinegar, 1 pair of tweezers, sandpaper, and 1 multipurpose meter. The task of the activity consisted in using the materials provided to design and assemble a voltaic device that ensures maximum power (P = voltage × current) capable of powering six 10 mm LEDs (4 green and 2 white) connected in series to a breadboard. The B

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expected configuration was in series arrangement of the cells. Details on the breadboard and LEDs arrangement can be found in the Supporting Information section. Students were instructed to utilize their recent acquired knowledge to achieve their task, and in order to enhance the experience of fostering creativity and teamwork within the group, communication between groups was initially discouraged. A single activity sheet was handed out and later collected for data collection purposes, a copy which can be found in the Supporting Information section. The measurements of several activity sheets collected are summarized in Table 2, and should be taken as guideline values for future in-class active learning activities. Table 2. Voltage and Current Values of Assembled Electrochemical Devices Obtained by Student Groups during the Active Learning Activity Group 2 1 4 3 6 7 5

Average Voltage/Va 11.7 10.9 9.1 8.0 7.9 6.7 4.4

Average Current/Aa,b 3.6 1.8 7.9 8.0 3.9 1.5 8.7

× × × × × × ×

−3

10 10−3 10−4 10−4 10−4 10−5 10−5

Figure 3. Initial arrangement of the Cu−Al electrode pairs in the corresponding paint box wells. Inset A shows the electrode pairs standing on their side, while inset B displays the electrode pair positioned along the short axis of the paint box wells. Eventually, all groups realized the device configuration shown in Figure 4.

LEDs ON 5 4c 4 3 3 2c 2

pairs in the direction perpendicular to the expected arrangement (see Figure 3B). As a result, students groups needed different time spans to realize the appropriate assembly. For instance, a few groups realized the appropriate arrangement in ∼5 min while other groups needed close to 20 min.

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a

Voltage values were collected within 15 s of closing the circuit, and taken from three measurements. bCurrent values were taken after voltages readings, and may not be representative of initial values as the current fluctuated greatly. Averages taken from three measurements. c Next LED was ON, but its intensity was remarkably low.

HAZARDS No electrical shock hazard exists when building and using the XuLu Cu−Al Array since even though its voltage can be above 10 V, its current output is in the low microamperes, and therefore, its power output is only in the millijoules range. Therefore, students can work through the electrochemical device optimization in a safe manner. Students should be encouraged to wear gloves at all times and to avoid unnecessary contact with the electrolytic and cleaning solutions.

As observed in Table 2, there was a wide range of variability in terms of voltage and currents values obtained by the various student groups. The highest recorded average voltage was 11.7 V (close to our value of 13.1 V) and the highest recorded current was 3.6 mA (62% our value of 5.80 mA), both obtained by group 2. Since the 10 mm LED devices have a forward voltage of 2.2 V, to light up all six LEDs a voltage difference of 13.2 was required from the electrochemical device. In other words, the designed task of lighting up all six LEDs was difficult, and was in line with our proposed level of difficulty. In general, instructors may change the level of difficulty by simply modifying the forward voltage of the LED devices, for instance, by reducing their size from 10 to 2 mm. Since there is a voltage dependence of the LEDs, a correlation between the average voltage harnessed and the number of LEDs lighted up by the students was observed. The forward current controls the light intensity of the LEDs, and in this active learning activity, the LEDs had a forward current of 20 mA. In that context, students were able to light up LEDs with varying degree of intensity. In particular, group 2 was able to light up the most, 5 LEDs. Once the students received materials and instructions, a variety of group dynamics were set in motion. Of particular interest is the fact that eventually all groups achieved the electrical arrangement described in the XuLu Cu−Al Array. The key aspect of this configuration is the placement of the Cu−Al electrode pairs into the paint box wells in series. Two examples of initial yet unsuccessful assembly of the Cu−Al electrode pairs in the paint box wells from two different student groups are shown in Figure 3. In one occasion, the students place the rolled Cu−Al electrode pair on the wells standing up (see Figure 3A), while in another occasion, the students unfolded the Cu and Al pieces and placed the Cu−Al electrode

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PART III: DISCUSSION

Design Science Element: Optimization Process

Upon completion of Part II of the activity, the instructor should allocate 15−20 min for discussing the significance of the exercise within the framework of design science. One key element associated with the many aspects of design science is the optimization process.17 Optimization appears in the innovation process as a design enabler because it is a tool found in the design process kit utilized toward product realization.18 Not surprisingly, students reported the process of device optimization as the main challenge of the exercise, and resorted to their knowledge of electrochemistry to provide creative answers: 1. Clean Cu−Al electrode pairs with vinegar. 2. Add vinegar to the electrolyte solution. 3. Vary the electrolyte volume. 4. Infuse ions to the solution by adding either table salt or orange juice. 5. Increase the immersed surface area of the electrodes in the electrolyte solution. 6. Sandpaper the electrodes. 7. Physical adjustment of the Cu−Al electrode pairs. All proposed creative solutions led to various degrees of improvements in the harnessing of higher voltage and current values. Points 1 and 6 addressed the removal of an oxide layer from both Cu and Al electrodes in order to change the nature C

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created a high level of interest, enthusiasm, and engagement in the students, in spite of the fact that it was not graded and its content was not to be assessed. Figure S8 in the Supporting Information section displays instances of various groups working collaboratively as a team with a high degree of enthusiasm and engagement.

of the surface redox reactions affecting the potential difference across the electrodes and generated electron flow. Points 2 and 4 intended to increase the hydronium ion (H3O+) concentration (lower pH) in the electrolytic solution as according to the Nerst equation, a lower pH signals a larger potential drop across the electrodes. Points 3 and 5 increased the effective electrode surface area, increasing overall current values since surface area is linearly related to current flow.19 Finally, point 7 referred to the ability to ensure an in series electrode configuration and optimized electrical contact. In other words, students took practical and effective steps to optimize the device based on their recalled knowledge of voltaic electrochemical cells. Figure 4A displays design assemblies of

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SUMMARY The active learning activity described here consists of the introduction of the Baghdad battery within its historical context, followed up by an active learning activity of the design and assembly of the XuLu Cu−Al Array to power several LEDs, and a final discussion on using electrochemical principles to illustrate design science elements (e.g., the optimization process) and team collaboration. It is important to note that all of the various devices, such as the Baghdad battery under various electrolytic solutions, and the XuLu Cu−Al Array powering four colored 5 mm LEDs, can be used for classroom/ lecture demonstrations to visualize fundamental concepts in electrochemistry, especially in illuminating the simplicity of harnessing electrochemical energy. A limitation of the active learning activity as presented here is that students may not be familiar with design science in general and may have difficulty associating the optimization process with a design process leading to innovation. Hence, current work is underway to expand this active learning activity into a longer workshop session tailored with an introduction to design science before implementing the activity. Taken together, this work seeks to incorporate elements of design science into the curriculum of general chemistry through an active learning methodology as well as take advantage of well-known electrochemical processes to illustrate optimization as a design enabler tool. Furthermore, this report is an example of a novel interdisciplinary effort at the interface of chemistry and design science, which grants both students and instructors a new perspective in terms of delivering chemical education.

Figure 4. LEDs (10 mm) lighted up by various assembled voltaic devices: (A) 5 LEDs (4 green + 1 white), and (B) 6 LEDs (4 green + 2 white) obtained by connecting two assembled voltaic devices in series.

the voltaic devices and their ability to power various LEDs. Due to the difficulty of the task, none of the student groups were able to light up all 6 LEDs; however, on their own initiative two student groups decided to connect their electrochemical devices in series to light up all 6 LEDs, as shown in Figure 4B.

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Emphasizing the Design Science Elements

Creativity entails the materialization of a goal-oriented novelty, and deals with the intentional creation of ideas or physical objects through the psychological process of creative thinking. Innovation implies the creation of a new product that serves some purpose, which is brought about through a design process. Hence, the design process involves the generation of novelty (creativity) and its adjustment toward some specific objective (innovation).17 In this active learning activity, the creative characteristic was displayed in the design and assembly of the electrochemical device based on Cu and Al electrodes and the rice wine as the electrolytic solution. The optimization process of the device, which consisted in undertaking a series of iterative processes designed to increase the ability to power up LEDs, embodied the innovative aspect. Furthermore, the active learning activity provided an environment conducive for creative thinking, which was further catalyzed by team collaboration. Students had to brainstorm collectively to figure out how to engineer the device, unleashing their creative thinking by proposing a wide range of solutions, a process that was not straightforward for all groups, since each group spent a specific time in this step. Once all of the parts of the device were identified and assembled, various solutions to optimize it (e.g., higher voltage and current values) were set in motion, bringing about a dynamic atmosphere favorable for innovation through the process of device optimization. As far as the motivational aspect is concerned, the active learning activity

ASSOCIATED CONTENT

S Supporting Information *

Information on Singapore University of Technology and Design, Integrated Learning Program (ILP), historical context of the Baghdad battery, fabrication and evaluation of the Baghdad battery replicas, preliminary characteristics of the Baghdad battery, fabrication of the XuLu Cu−Al array, final configuration of the XuLu Cu−Al Array, breadboard configuration, extended applications of the XuLu Cu−Al Array, teamwork and collaboration, and a modifiable student activity worksheet. This material is available via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS Support for this research was granted by the undergraduate research opportunities programme (UROP) from the Office of Education at Singapore University of Technology and Design. Ms. Michelle Lim from Singapore Polytechnic is kindly D

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acknowledged for fabricating the Baghdad battery replicas. The comments from the reviewers are kindly acknowledged.

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REFERENCES

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