Blue Bottle Experiment - ACS Publications - American Chemical Society

Apr 12, 2017 - Mahidol University International College, Mahidol University, ... School of Chemical Sciences, The University of Auckland, Auckland 114...
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Laboratory Experiment pubs.acs.org/jchemeduc

Blue Bottle Experiment: Learning Chemistry without Knowing the Chemicals Taweetham Limpanuparb,*,† Cherprang Areekul,† Punchalee Montriwat,‡ and Urawadee Rajchakit§ †

Mahidol University International College, Mahidol University, Nakhon Pathom 73170, Thailand Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg 41296, Sweden § School of Chemical Sciences, The University of Auckland, Auckland 1142, New Zealand ‡

S Supporting Information *

ABSTRACT: The blue bottle experiment is a popular chemical demonstration because of its simplicity and visual appeal. Most papers on the topic focus on a new formulation or a new presentation, but only a few discuss pedagogical application for a full lab session. This article describes the use of this experiment in the first session of undergraduate chemistry laboratory at the Mahidol University International College. Practical activities are designed to foster critical thinking and student-centered learning during a four-hour lab session. The main theme of our teaching is scientific method. Students are encouraged to work with a peer to propose hypotheses and test them. With a series of guidances and hints from the instructor and group discussion, students can propose the reaction mechanism for the experiment without knowing the identity of the chemicals in the reaction. Procedures described in this article may be used elsewhere with minimal modification. KEYWORDS: First-Year Undergraduate/General, General Public, Hands-On Learning/Manipulatives, Aqueous Solution Chemistry, Demonstrations



INTRODUCTION To the best of our knowledge, the very first publication of the blue bottle experiment was in this Journal in the 1960s.1,2 There are many reports1−31 on various modifications and pedagogical applications of the experiment, including our recent articles.28,29 A comprehensive review of the history of this reaction from the synthesis of methylene blue in 1876 can be found in ref 29. In brief, the blue bottle reaction is made of an acyloin and a redox dye in an alkaline solution, with an exception of the ascorbic acid system, where the reaction takes place under acidic conditions. If methylene blue is used as a redox dye, the solution is colorless when it is left to stand, and the solution turns blue temporarily when it is shaken. As shown in Figure 1, the cycle of bluing and turning colorless may be repeated many times. Since the solution is usually prepared in a plastic bottle, this gives rise to the name “blue bottle experiment”. It was believed that the main product of this reaction is gluconate,32 but a report by Anderson et al. in 2012 suggests various other products.23



the use of this reaction to teach chemical mechanism to various audiences from primary school to graduate students. Students are given the blue bottle solution, but they are not informed of the composition of the solution. In 1999, Engerer and Cook14 developed a worksheet that helps students propose hypotheses and suggest methods to test them. Through a series of tests and observations, most students are able to arrive at a reasonable reaction mechanism that is consistent with the experimental evidence. Having the worksheet as a guide for the past three years, we have developed experimental procedures and pedagogical presentation of the experiment to meet our student expectation and to bring in new discoveries in the scientific literature to the class. The teaching context is an undergraduate chemistry laboratory class for science students of various majors. The majority of them are dentistry, biomedicine, and food science students. This paper discusses our approach to use the experiment to teach chemistry to mostly nonchemistry students. The student worksheet and instructor notes in the Supporting Information are designed to help teachers adopt this experiment with minimal effort.

JUSTIFICATION

Despite numerous papers on different formulations and presentations, there are limited materials for the actual use of the blue bottle experiment in a laboratory class. Most of the literature discusses only the use of the blue bottle experiment for demonstration activities rather than hands-on lab experiments. Campbell2,4 and Engerer and Cook14 have pioneered © 2017 American Chemical Society and Division of Chemical Education, Inc.

Received: November 6, 2016 Revised: March 24, 2017 Published: April 12, 2017 730

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presented to students after they have verbally proposed hypotheses and methods to test hypotheses to prevent students from taking information from the late part of the worksheet to complete the first activity. Throughout the activities, students may use letters (A, B, C, ..., X, Y, Z) to stand for chemical compounds or species. Therefore, prior knowledge of the chemicals in the reaction mixture is not required during the experiment.



EXPERIMENTAL DETAILS

Mechanism of the Bluing Process

The solution turns blue because oxygen in the atmosphere oxidizes the redox dye. This first activity aims to demonstrate the role of atmospheric air in the reaction and dispel alternative suggestions. Students are first given the reaction mixture in a closed/sealed container (e.g., a tube, a bottle, or a plastic bag) for experimentation. They are asked to explain how the reaction mixture turns blue upon shaking. Students may have many different alternative hypotheses, for example, two layers of liquid mix during shaking, the blue color comes from the bottle cap, or the energy from shaking leads to the blue color.2 To provide conclusive proof, Campbell’s original demonstration was to use natural gas to remove oxygen in a bottle. We find that this is risky and propose three alternative procedures below: (A) As shown in Figure 2A, in addition to the first poly(ethylene terephthalate) (PETE) bottle, which is partially filled with the solution to allow air gap for reaction, the second bottle is completely filled with the solution so that no air is present. (B) Two compartments are made side by side in a thick plastic bag (e.g., a zip bag) by an impulse sealer. As shown in Figure 2B, the left compartment is about 50% filled with the solution and 50% atmospheric air by volume, whereas the right compartment is 100% filled with the solution. (C) A setup with a series of test tubes as shown in Figure 2C is more spectacular. Two holes are drilled in each cap for long and short glass tubes, and glue/plasticine is applied to the cap to prevent leakage. The reaction mixture turns blue when atmospheric air is pumped into the system by an aquarium air pump or a vacuum system. If a vacuum line is used, an empty tube should be added as a liquid trap. For experiments A and B, prior to sealing, a solid object (e.g., a glass marble) can be added to the bottle or the bag so that students see the effect of shaking. If an air bubble still remains in the bottle or the bag, it can be removed by a needle, and the needle hole can be sealed with transparent tape or a paraffin film. If an unreactive gas such as nitrogen or helium is available, it can be used to show a negative result as well. For experiments A and B, the bottle or the bag can be purged with unreactive gas rather than completely filled with the solution. The solution in the bottle or the bag will not change its color when shaken. For experiment C, the reaction mixtures in the test tubes do not change the color at the same time but rather change one after another. If an unreactive gas is used, the reaction mixtures will turn colorless one-by-one from the tube directly connected to the gas tank to the tube furthest away. Atmospheric air can be reintroduced into the system, and the reaction mixture in the test tube that directly receives the air will change to blue first. For the chemical traffic light experiment,5 where indigo carmine is used instead of methylene blue, the three colors yellow, red,

Figure 1. Blue bottle reaction. The colorless solution changes to a blue color after shaking, and the blue solution gradually turns back to colorless. The bluing/debluing cycles can be repeated many times. The total reaction is generally autoxidation of an acyloin to a diketone catalyzed by a redox dye. Additional catalysts may be presented in the green version of the reaction, where ascorbic acid is the reducing agent.



EXPERIMENTAL AND LEARNING OBJECTIVES There are various formulas to prepare the blue bottle reaction mixture: the classical version,2 the green chemistry version,18,19,28 and the rapid version.29 For convenience, here we use the classical version, in which a liter of solution is made of 20 g of NaOH, 20 g of glucose, and 10 mg of methylene blue. The reaction mixture eventually turns yellow or brown within about an hour, so it is advised that a small amount of reaction mixture be prepared before each use. By using stock solutions, we save the time to dissolve the solid chemicals and can freshly prepare reaction mixtures just before class or during class. We prepare stock solutions of 5 M NaOH, 1 M glucose, and 0.01% (w/v) methylene blue. The stock solutions can generally be stored for months, but the glucose stock solution may need refrigeration. Detailed procedures are described in the next section and in the instructor notes. It is possible to run the experiment with other variations of the blue bottle experiment, but they may be relatively more complicated or more expensive. Six activities are presented in the next section. The first three activities guide students to formulate their own reaction mechanism. Students are asked to explain the striking visual behavior of the experiment by proposing the mechanism of reaction during the bluing and debluing steps. Our procedures help them verify their proposed mechanisms. The fourth activity, a study of the dependence of the debluing time on the temperature, gives an introduction to chemical kinetics, and the fifth activity, chemical pattern formation, shows the link between chemistry and other disciplines. The last activity is a student-designed experiment/postlab exercise that may be made to align with student level and/or major such as food science33 or chemical engineering.31 The first three activities and the last activity should be run in sequence, but the fourth and fifth are independent. If time is limited, we recommend using the first two and then adding selected optional activities from the other four depending on the context of the class. The worksheet may be edited or given to students page by page as appropriate. Alternatively, it may be 731

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Figure 2. (A) The blue bottle solution changes from colorless to blue from top to bottom (left). When the bottle is completely filled with blue bottle solution, there is no color change when it is shaken (right). (B) A zip bag and impulse sealer can also be used instead of PETE bottes. (C) Four tubes show a replacement of atmospheric air by nitrogen and vice versa. The color change starts from the left to the right for both bluing and debluing since both gases are passed though the tubes from the left.

wrong. For example, in a popular video on YouTube,34 the instructor explains that the solution turns back to colorless because the gas returns to the atmosphere. We propose the two procedures as shown in Figure 3 to conclusively prove that the gas from the air is used up in the reaction and does not return to the atmosphere either as oxygen or carbon dioxide. (A) Upon continuous shaking, a soft PETE bottle containing the solution shrinks. As shown in Figure 3A, a dent is noticeable if the solution is left overnight. (B) A manometer is more sensitive and thus provides a quicker result. The apparatus in Figure 3B works best when the screw cap is fastened first and the rubber tube is connected to the manometer afterward. A small difference in the initial level of water may be noticeable because connecting the rubber tube to the glass tube decreases the volume and hence increases the pressure. The suggested order of connection is to minimize this initial difference. We find that it is best to run this activity with a magnetic stirrer as opposed to shaking by hand. Students reported contradicting results when a flask and rubber stopper were used because manual shaking causes the stopper to move and affects the manometer reading. Students learn at this stage that the air is consumed during the bluing stage of the reaction. In fact, the air is consumed at

and green may be observed at the same time at different tubes (see the last activity, the student-designed experiment). In principle, this apparatus may also be modified to demonstrate the concept of countercurrent exchange by varying the concentration of the solution so that there is a concentration gradient in the liquid phase in addition to the gas phase. However, this is beyond the scope of the present article. After completion of this first activity, students should see that a gas in the atmosphere plays a role in the bluing step and that the energy from mixing does not lead to the color change. The procedures above in combination with the fact that the solution when shaken gently starts to turn blue from the top lead to the following mechanism of the bluing step: L(aq) + A(g) → B(aq)

(1)

where L is the colorless (leuco) form of the compound, B is its blue form, and A stands for air. Gas Consumption Test

The oxidized dye reacts with the acyloin to form a diketone compound and the reduced form of the dye. This is the most difficult step for students because it involves three colorless compounds. Many students and instructors have this step 732

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Figure 3. (A) A dent in the PETE bottle can be observed after shaking for a period of time. (B) A manometer is used to show the reaction mechanism of the blue bottle experiment. The solution is stirred using magnetic stirrer in a jar connected to a manometer. The rate of water rise is ∼0.01 cm/s on one side of the manometer (the diameter of the manometer tube is ∼0.03 cm). After the stirrer is turned off and the blue solution turns colorless, the water continues to rise slowly.

all times, but the consumption occurs at a significantly higher rate during stirring. The air, however, does not return to the atmosphere after the solution turns back to colorless. It is now possible to write a mechanism of the debluing step: B(aq) + X(aq) → L(aq) + Y(aq)

(2)

where X is another colorless reactant and Y is a colorless product. L must be regenerated in this step because the bluing and debluing may be repeated. Duration and Intensity of Blue Color

It is possible to observe that the duration and intensity of the blue color is related to the manner of stirring. In contrast to Engerer and Cook’s suggestion to count the number of shakes and rate the intensity by the naked eye,14 the use of a vortex mixer and a phone camera35−37 in Figure 4 is less subjective and yields more consistent results. Students can observe that the duration and intensity of the blue color increase with shaking time and then eventually reach a maximum. However, the intensity reaches the maximum long before the duration. The difference suggests that when the solution is stirred, a gas from the air, A(g) is dissolved in the solution first:

A(g) → A(aq)

Figure 4. A student uses a vortex machine to stir the reaction mixture and a smart phone to measure the intensity of the blue color and to time the reaction.

(3)

The dissolved gas, A(aq), quickly reacts with L to form the blue compound B. After L has all been turned into B, more A(g) can 733

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still be dissolved into the solution until a saturation point is reached. After completion of the first three activities, students learn that the bluing step is relatively faster, as it appears to occur instantly, and that the debluing step appears to be the slowest step and the rate-determining step. The combination of the steps makes the total reaction A(g) + X(aq) → Y(aq)

(4)

Students find it thought-provoking to discuss that L/B is a catalyst system and that it is comparable to hemoglobin in mammals or hemocyanin in crustaceans, which help carry oxygen for cellular respiration. At this point or during the sixth activity, students may be shown various modifications of the blue bottle experiment, such as the chemical traffic light or the vanishing valentine experiment, to help them grasp the idea. The conclusion and comparison are useful for pedagogical purposes here, but the instructor should be aware of the limitations of this overly simplified model. In reality, the redox dye does not carry the oxygen, but the dye rather gets oxidized, unlike the red-blood cell, and there are more chemical species involved in the reactions.26 Effect of Temperature

Since the debluing step is easily observed in a convenient time frame, it is a suitable system to study the temperature dependence of the reaction rate. Inspired by the video,34 we keep four sets of two solutions:33 2.5 mL of 5 M NaOH + 2.5 mL of water in a test tube (solution A) and 2.5 mL of 0.01% (w/v) dye + 2.5 mL of 1 M glucose + 15 mL of water in a flask (solution B) at four different temperatures (5−35 °C). The two solutions are mixed at the same time by a pair of students. Figure 5 shows the debluing process in each of the four flasks. In contrast to the protocol in the video, where the reaction mixture is kept at the desirable temperature and later shaken, our method provides more consistent results and excludes possible complications such as the temperature dependence of the gas solubility or differences in the rate of the bluing step. As the experiments at the four temperatures are performed at the same time, students can clearly see different rates of reaction at different temperatures. The differences in temperature are only 10 K (18 °F), but the differences in the time are much more pronounced. Though these activities are semiquantitative, they can lead to further discussion regarding the Arrhenius equation and Boltzmann distribution. The discussion can also link to the need for thermoregulation in warm-blooded animals and food preservation by refrigeration.

Figure 5. The debluing times of the reaction at different temperatures differ significantly. Times after mixing (in mm:ss) are shown in the picture.

systems, mathematics, physics, and chemistry are all required. The activity can also be presented in the context of a STEAM (science, technology, engineering, and mathematics, together with art) activity. Student-Designed Experiment/Postlaboratory Exercise

If time permits, students should be encouraged to experiment with different procedures/formulations, subject to instructor approval and availability of the equipment/chemicals. The scope of this activity can be just 10 min in class or a miniproject where students thoroughly plan their experiments. It may also be presented as postlaboratory exercise questions without an actual experiment. Some possibilities are suggested below. (A) Variation of dyes and reducing agents or variation of the procedures are relatively easy and can be prepared in advance. Common variations of the dye include the chemical traffic light5 (see Figure 7), where indigo carmine dye is used, and the vanishing valentine experiment,6 where resazurin is used. As suggested by Staiger et al.,27 it is also possible to test food items to see whether they contain reducing agent(s) and/or dye(s) that lead to the blue bottle reaction. Our preliminary experiments suggest that other chemicals (e.g., acetoin, dihydroxyacetone, cysteine, and bovine serum albumin) and

Pattern Formation

As shown in Figure 6, patterns form spontaneously when the blue bottle reaction mixture is poured onto a Petri dish.10,12,16,25,28−30,38 Additional dye (2 mL of 0.01% w/v methylene blue) is usually added to the blue bottle reaction mixture (20−25 mL) to promote the pattern development and make it more easily visible.28,29 The patterns vary depending upon the type and proportion of reactants. The chemical basis of morphogenesis was first proposed by Turing in 1952 without any concrete examples.39 Real-life examples on macroscopic and microscopic scales were discovered later, and Turing’s reaction−diffusion model has now been accepted into textbooks.40,41 Students are encouraged to find similarity between patterns in the reaction and patterns in nature. Students can appreciate that all branches of science are well-connected. To understand the patterns in living 734

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Figure 6. Patterns develop after 20−25 mL of the blue bottle solution is poured onto a Petri dish and additional methylene blue (2 mL of 0.01% w/v methylene blue) is added to the solution. Patterns are visible after 30 s and begin to disappear after 180 s.

show the effect of vessel size and speed of agitation, similar to the large-scale demonstration by Piccione and co-workers.31



HAZARDS The blue bottle reaction mixture generally causes irritation. Leakage of various equipment is the main risk for experiments to fail as well as a serious physical hazard for instructors and students. Care should be taken to seal the system so that there is no leakage of gas or liquid during the operation. Screw caps are preferred to rubber stoppers because of this requirement. NaOH is corrosive, and methylene blue may stain. Other dyes and reducing agents may be used in place of methylene blue and sugar. Hazard information may be different for these alternative formulations. Refer to the Supporting Information of ref 29 for a summary of safety information for other chemicals. Splash goggles and rubber gloves should be worn when handling the chemicals. Glucose and other food items in this experiment should not be consumed.

Figure 7. The three colors yellow, red, and green of the chemical traffic light can be observed at the same time when equipment in the first activity is used.



food items (e.g., milk, egg white and yogurt) may be used in place of sugar/vitamin C, but using food items, reaction time to turn back to colorless is longer. As this is the first report of the use of non-acyloin compounds as reducing agents for the blue bottle experiment, it leaves open the discussion of food antioxidants. Further investigation should be conducted to understand the nature of these new families of reducing agents in the blue bottle reaction.42 (B) If the composition of reaction mixture is changed, students may observe changes in the debluing time. The addition of base and reducing agent reduces the time, while the addition of the dye has the opposite effect.21 (C) Generally, the temperature effect is observed for all reactions. However, the susceptibility to temperature depends on the activation energy. The debluing step may be studied by using a thermostated spectrophotometer as a mini-project for interested students.25 (D) The scale-up effect on the mass transfer between the gas and solution interface may be of interest to chemical engineering and industrial chemistry students. A small-scale setup using 50−2000 mL beakers and magnetic stirrers can

RESULTS AND DISCUSSION

Students completed the experiments as the first laboratory in class and submitted a worksheet at the end of laboratory period. One week afterward, graded worksheets were returned to students, and they were asked to fill out an evaluation form and informed consent document. The study was approved by the Institute for Population and Social Research’s Institutional Review Board (IPSR-IRB COA. No. 2016/12-150). Our questionnaire (see the Supporting Information) covers student background, plus/delta questions, and student’s learning and numerical rating43 of the activities. All students enrolled in ICCH224 Integrated Laboratory Techniques in Chemistry I signed informed consent to participate in our classroom study. The responses show that students are fascinated by the color change and pattern formation and that the activities are effective in helping students learn to make a basic scientific conclusion from experimental evidence. Tallies of the rating questions (A: Rate the contents of this experiment. B: Rate the concept of this experiment. C: Rate the suitability of the experiment for this concept. D: Rate the sufficiency of your knowledge for this 735

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ORCID

experiment.) collected from 23 students are shown in Figure 8. The results show that students are generally satisfied with our teaching of the blue bottle experiment.

Taweetham Limpanuparb: 0000-0002-8558-6199 Notes

The authors declare no competing financial interest.



ACKNOWLEDGMENTS This work would not have been possible without the help of students/technicians, Suphattra Hsu, Athikhun Suwannakhan, Rattha Noorat, Supaporn Phomsurin, Warangkana Yimkosol, Natthapatch Siriphatcharachaikul, and the ICCH224 class. The authors also appreciate helpful comments and suggestions from the associate editor and four anonymous reviewers. We were previously funded by the Mahidol University International College in a related project (Contract 005/2015).



Figure 8. Average student ratings of the six activities on a Likert scale (1 for most unsatisfied to 5 for most satisfied) on the content, concept, suitability, and sufficiency of student knowledge for the six activities.

(1) Dutton, F. B. Methylene blue-Reduction and oxidation. J. Chem. Educ. 1960, 37 (12), A799. (2) Campbell, J. A. KineticsEarly and often. J. Chem. Educ. 1963, 40 (11), 578−583. (3) Alyea, H. N.; Dutton, F. B. Tested Demonstrations in Chemistry; Division of Chemical Education, American Chemical Society: Easton, PA, 1965. (4) Campbell, J. A. Why Do Chemical Reactions Occur?; Prentice-Hall: Englewood Cliffs, NJ, 1965. (5) Chen, P. S. Oxidation and Reduction of Indigo Carmine Aided by Benzoin. J. Chem. Educ. 1970, 47 (4), A335. (6) Chen, P. S. Resazurin - Reduction and Oxidation. J. Chem. Educ. 1970, 47 (4), A335. (7) Chen, P. S. Entertaining and Educational Chemical Demonstrations; Chemical Elements Publishing Company: Camarillo, CA, 1974. (8) Shakhashiri, B. Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry; The University of Wisconsin Press: Madison, WI, 1985; Vol. 2, pp 142−146. (9) Cook, A. G.; Tolliver, R. M.; Williams, J. E. The Blue Bottle Experiment Revisited: How Blue? How Sweet? J. Chem. Educ. 1994, 71 (2), 160−161. (10) Adamcikova, L.; Sevcik, P. The Blue Bottle Experiment and Pattern Formation in This System. Z. Naturforsch., A: Phys. Sci. 1997, 52, 650−654. (11) Vandaveer, W. R., IV; Mosher, M. The blue bottle revisited. J. Chem. Educ. 1997, 74 (4), 402. (12) Adamcikova, L.; Sevcik, P. The Blue Bottle Experiment-Simple Demonstration of Self-Organization. J. Chem. Educ. 1998, 75 (12), 1580. (13) Hile, L. The Blue Bottle Revisited. J. Chem. Educ. 1998, 75 (9), 1067. (14) Engerer, S. C.; Cook, A. G. The blue bottle reaction as a general chemistry experiment on reaction mechanisms. J. Chem. Educ. 1999, 76 (11), 1519−1520. (15) Mowry, S.; Ogren, P. J. Kinetics of methylene blue reduction by ascorbic acid. J. Chem. Educ. 1999, 76 (7), 970−973. (16) Pons, A. J.; Sagues, F.; Bees, M. A.; Sorensen, P. G. Pattern formation in the Methylene-Blue-Glucose system. J. Phys. Chem. B 2000, 104 (10), 2251−2259. (17) Bees, M. A.; Pons, A. J.; Sorensen, P. G.; Sagues, F. Chemoconvection: A chemically driven hydrodynamic instability. J. Chem. Phys. 2001, 114 (4), 1932−1943. (18) Wellman, W. E.; Noble, M. E.; Healy, T. Greening the Blue Bottle. J. Chem. Educ. 2003, 80 (5), 537−540. (19) Noble, M. E. Out of the Blue. J. Chem. Educ. 2003, 80 (5), 536A−536B. (20) Baker, C. The “Blue Bottle” Reaction. Educ. Chem. 2006, 2006 (November), 155.

The blue bottle reaction is usually used as a short demonstration to draw student attention. In this paper, however, we have discussed the use of the reaction in a 4 h practical session for undergraduate students. Various concepts relating to scientific methods, reaction mechanism, chemical kinetics, and pattern formation can be demonstrated using the experiment. Chemical symbols for elements and compounds are usually required for most chemical laboratories. The activities presented here followed an approach proposed by Campbell where the identities of the chemicals are not revealed to students until the end of the experiment. This helps students foster their scientific thinking process through a series of hypothesis testing and improve their vigilance when dealing with chemicals. When the identities of the compounds are revealed at the end, the information may be discussed in the context of cellular respiration, combustion reactions, and redox reactions of organic compounds. This adds a myriad of possibilities for pedagogical discussion.



CONCLUSIONS This article presents a series of activities where chemical mechanism and scientific method are taught without presenting the complex chemical formulation. It promotes student interest in chemistry and can be particularly useful for a class of diverse academic background or for students interested in medicine/ biology. The activities require only basic equipment and chemicals and can easily be repeated elsewhere.



ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.6b00844. Student worksheet (PDF, DOCX) Survey form (PDF, DOCX) Instructor notes (PDF, DOCX)



REFERENCES

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. 736

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(21) Limpanuparb, T. The Colorful Chemical Experiment Kit; National Science and Technology Development Agency: Pathum Thani, Thailand, 2006. (22) Deese, W. C.; Ramsey, L.; Cox, C. The Blue Bottle Demonstration. Sci. Scope 2007, 31 (4), 66−68. (23) Anderson, L.; Wittkopp, S. M.; Painter, C. J.; Liegel, J. J.; Schreiner, R.; Bell, J. A.; Shakhashiri, B. Z. What Is Happening When the Blue Bottle Bleaches: An Investigation of the Methylene BlueCatalyzed Air Oxidation of Glucose. J. Chem. Educ. 2012, 89 (11), 1425−1431. (24) Fleming, D. Beyond the “Blue Bottle”. Educ. Chem. 2014, 2014 (May), 12−13. (25) Hsu, S. Beyond the Blue Bottle Experiment. B.Sc. (Chemistry) Dissertation, Mahidol University International College, Nakhon Pathom, Thailand, 2014. (26) Limpanuparb, T.; Hsu, S. The Colorful Chemical Bottle Experiment Kit: From School Laboratory to Public Demonstration. In Proceedings of the Pure and Applied Chemistry International Conference (PACCON 2015), Bangkok, Thailand, Jan 21−23, 2015; Chemical Society of Thailand: Bangkok, Thailand, 2015; pp 470−473. (27) Staiger, F. A.; Peterson, J. P.; Campbell, D. J. Variations on the “Blue-Bottle” Demonstration Using Food Items That Contain FD&C Blue #1. J. Chem. Educ. 2015, 92 (10), 1684−1686. (28) Rajchakit, U.; Limpanuparb, T. Greening the Traffic Light: Air Oxidation of Vitamin C Catalyzed by Indicators. J. Chem. Educ. 2016, 93 (8), 1486−1489. (29) Rajchakit, U.; Limpanuparb, T. Rapid Blue Bottle Experiment: Autoxidation of Benzoin Catalyzed by Redox Indicators. J. Chem. Educ. 2016, 93 (8), 1490−1494. (30) Rajchakit, U.; Limpanuparb, T. The Blue Bottle Experiment. Thai Sci. Technol. J. 2016, 24 (1), 1−11. (31) Piccione, P. M.; Rasheed, A. A.; Quarmby, A.; Dionisi, D. Direct Visualization of Scale-Up Effects on the Mass Transfer Coefficient through the “Blue Bottle” Reaction. J. Chem. Educ. 2017, DOI: 10.1021/acs.jchemed.6b00633. (32) Roesky, H. W. Spectacular Chemical Experiments; Wiley-VCH: Weinheim, Germany, 2007. (33) Jang, N. Y.; Won, K. New pressure-activated compartmented oxygen indicator for intelligent food packaging. Int. J. Food Sci. Technol. 2014, 49 (2), 650−654. (34) FlinnScientific. Reaction Kinetics in Blue. https://www.youtube. com/watch?v=InhTcvg1AlA (accessed March 11, 2017). (35) Kehoe, E.; Penn, R. L. Introducing Colorimetric Analysis with Camera Phones and Digital Cameras: An Activity for High School or General Chemistry. J. Chem. Educ. 2013, 90 (9), 1191−1195. (36) Kuntzleman, T. S.; Jacobson, E. C. Teaching Beer’s Law and Absorption Spectrophotometry with a Smart Phone: A Substantially Simplified Protocol. J. Chem. Educ. 2016, 93 (7), 1249−1252. (37) Moraes, E. P.; Confessor, M. R.; Gasparotto, L. H. S. Integrating Mobile Phones into Science Teaching To Help Students Develop a Procedure To Evaluate the Corrosion Rate of Iron in Simulated Seawater. J. Chem. Educ. 2015, 92 (10), 1696−1699. (38) Pons, A. J.; Sagues, F.; Bees, M. A.; Sorensen, P. G. Quantitative analysis of chemoconvection patterns in the methylene-blue-glucose system. J. Phys. Chem. B 2002, 106 (29), 7252−7259. (39) Turing, A. M. The chemical basis of morphogenesis. Philos. Trans. R. Soc., B 1952, 237 (641), 37−72. (40) Gaylord, R. J.; Nishidate, K. Modeling Nature: Cellular Automata Simulations with Mathematica; TELOS: New York, 1996. (41) Klipp, E.; Liebermeister, W.; Wierling, C.; Kowald, A.; Herwig, R. Systems Biology: A Textbook, 2nd ed.; Wiley-VCH: Weinheim, Germany, 2016. (42) Limpanuparb, T.; Roongruangsree, P.; Areekul, C. R. Soc. Open Sci. 2017, submitted. (43) van Schenk Brill, D.; van Gestel, B. Students’ Appreciation of an Online Lab ExperimentA Case Study. Presented at the SEFI 37th Annual Conference on Engineering Education, Rotterdam, The Netherlands, 2009.

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