"What are we doing to help kids achieve?"

     My students and I tend to have good experiences with a hydrate inquiry lab that I have "tweaked" (see the previous blog). Essentially, my students have some practice with hydrates in the lab and then they are provided an unknown hydrate. They must separate off the water by heating and calculate the mass of the anhydrous salt and container before they come up and put it on the scale. As an added twist, they must also ask me a question about what information they need from me to calculate the mole to mole ratio of the salt to water. It has worked well in the past but then in some of my other classes we hit third quarter.....

     It was after winter break, before spring spring break and everyone was tired. There had been no snow days. Juniors were stressed over taking the ACT and other mandated tests. It was the last week of the quarter. The atmosphere was that it would be hard to get any major labs done. I really wanted to fit in this lab. Some of my classes had really struggled with moles and were nailing percent composition and the idea of hydrates. I really did not want to give this lab up but I felt like it was a bit much at the time. Here was my "Plan B".

     First, I demonstrated how to apply the concept of percent composition to hydrates. We solved for the percent of water in copper (II) sulfate pentahydrate. We then used that information to predict the mass of an amount of the anhydrous salt of copper (II) sulfate. We did the calculation and demonstration as a class. Students were then given three homework problems that involved finding the percent of water in three different hydrates. The next day, the first part of the lab was a quick check to see if they did the homework and showed their work. Each student then came up and were assigned one of the three hydrates on their homework. The task was to heat the hydrate enough to drive off the water and predict the final mass on the scale. Students were to calculate the mass of the anhydrous salt and the container as it was cooling. They then had to show me their work before they found the final mass. I had to see their work first and I was the only one to have access to the scale. The closer they got to the correct predicted value on the scale, the higher their grade.

     This "plan B" worked well and there were several features I liked about it as a teacher. It emphasized the importance of doing homework. If students did not do their homework and actually apply it, they would not predict the correct mass. Each student received a different salt or different amounts or both. This meant that they could help each other but it made direct copying difficult. Another nice feature is that because it is a microscale lab, every student had to participate and do their own experiment. Students also got immediate feedback. They knew as soon as they put the dried salt and container on the scale if they successfully did the calculations. In some cases, students knew right away that their predicted mass was incorrect. I let those students try it again for some credit. Most students did well. Overall, this lab activity was managable, easy to grade, provided immediate feedback and got the chemicals in the hands of as many students as possible.  

   Do you have a "plan B" that worked better than expected?  Would love to hear from you....

The American Chemical Society will celebrate Earth Day on April 22, 2017. This year's theme is Chemistry Feeds Our World. I have gathered some resources related to food and cooking from ChemEd X in honor of the theme. I have also included links to other resources. 

Two high school chemistry teachers have recently shared information and resources from food chemistry elective courses they have developed. First, Tracy Schloemer published a blog titled Developing a Cooking Chemistry Elective and followed it up a month later with Cooking Chemistry: Additional Resources. Later, Erica Posthuma-Adams published an article, Developing a High School Chemistry Elective, that outlines how she pulled together resources to design her elective course.

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Fig. 1 - Food press from Developing a Cooking Chemistry Elective

In 2013, Tom Kuntzleman published JCE Classroom Activity #92: Testing for Iodide in Table Salt. The activity was originally published in the Journal of Chemical Education. Tom created a video of the activity procedure that includes a twist of his own. More recently, Tom has been experimenting with McCormick's new natural food dyes. He has written two blog posts Chemical Investigations of McCormick's Color From Nature Food Colors. Part 1: Sky Blue and Investigations of Chemicals in Natural Food Coloring. Part 2: Berry that include videos of some of his experiments. 

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Fig. 2 - McCormick's Color From Nature Food Colors

In 2012, I posted an activity that many of you might be familar with, Green Eggs Solubility Activity. I have assigned this as a take-home activity, but I have also used it in class. 

Hal Harris is an avid reader and has written many book reviews for ChemEd X. One that stands out as a good fit for this year's Earth Day theme is What Einstein Told His Cook: Kitchen Science Explained.

The American Chemical Society offers a wealth of resources on this year's theme as well as themes from previous years on it's page titled: Chemists Celebrate Earth Day (CCED) 2017.

You can also find lots of related activities by searching the ACS ChemClub resources. 

Of course, a search of food related terms on the Journal of Chemical Educationsite will yield a plethora of articles. Erica Jacobsen had compiled a list of food related JCE articles for National Chemistry Week in 2000 that offers lots of ideas.

If you are celebrating Earth Day 2017, I hope you will share your plans with our ChemEd X community.

With the start of the third trimester, it was time to reintroduce to my new students how to properly write chemical formulas with those polyatomic ions that they had become familiar with fourteen weeks ago during the first trimester. Since it been such a long gap of time since some of my student's last chemistry lesson, I needed my students to review and to practice once again writing chemical formulas correctly before we started calculating molar masses. In the past, I had used the app Chem App Lite with the iPad to allow the students to practice balancing charges and writing their chemical formulas correctly. However, as it often goes with technology, ....I found that Chem App Lite was no longer available on the iTunes store. So I decided to search for another app that would allow my students the same type of practice. In my app store search, I found Chemical Formula Challenge by Zhang Bozheng. The app is very similar with some added bonuses.

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Fig 1. Screenshot of iTune Store description 

According to the app store description, Chemical Formula Challenge is "An educational game to improve your ability to form chemical formulas from chemical names. You can either play it yourself or challenge a friend". The app features different levels of play such as easy, normal, and hard regarding the difficulty of the ions. As an example, beryllium chloride is considered "easy" while lead II nitride is considered "hard". The app then gives the user several ions to choose from and the user must then select the correct number of ions needed to balance the formula correctly. The game also allows for the ion charge to be shown or to be removed during play and does allow its background music to be turned off. Next, the different game modes include no mistakes (one mistake and game over), a timed practice with every mistake forfeiting 1 second, and freeplay that will keep track of the total number of formulas formed.  

What became an added bonus was two player mode. In two player mode, users would position the device between them so that each user is looking at the screen from either the top or from the bottom. The screen is then split so that it is right side up for each user. Once the game starts, the same chemical formula is projected for each user and the user must then select the correct combination of ions to correctly match the given chemical formula name. As the user inputs the correct formula it moves onto the next. If a mistake is made then it is game over for that user and the other user is considered the winner. You can input the number of formulas that must be answered before it proclaims you the winner.  

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Fig 2. Screen shot of on player game

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Fig 3. Screen shot of two player game

Well, the app was an instant hit with the students as they simply used it in free play mode to practice their formula writing skills. The students quickly recalled the roman numerals and their meaning and starting recognizing the polyatomic ions and the rules associated with when to use parenthesis and when not too. Since we have been in the middle of March Madness and many of my students have been filling in their brackets, many have turned our chemistry excercise into a challenge among students that they themselves initiated with the finals taking place before Spring Break. I came in as a 1 seed! I hope your students enjoy it as much as mine have.

In this post I will explore the chemistry of the Sunflower dye found in McCormick’s Color from Nature food dyes. This is the last in a three-part series in which several experiments and demonstrations that can be done with Color from Nature food dyes are described. A box of McCormick’s Color from Nature food dyes contains three packets of dyes: Sky Blue, Berry, and Sunflower. These food dyes provide a great resource for a variety of simple, yet interesting chemistry experiments. In Part 1 of this series, investigations that can be done with the Sky Blue dye are described. In Part 2 of this series, the Berry dye is explored.

The Sunflower food color is intended to impart a yellow color to foods. The ingredients list for the Sunflower dye lists “turmeric oleoresin”, and this is probably the component responsible for the bright yellow color observed in the Sunflower food color.

Turmeric is known to contain curcumin (Figure 1), a bright yellow compound. Curcumin is an acid-base indicator.^1,2 At or below pH 8 curcumin is fairly non-polar so it does not dissolve well in water (Figure 1, upper structure). Around this pH curcumin also has a yellow color, and emits yellow-green fluorescence. Above pH 8 curcumin loses a proton and gains a negative charge, allowing the resulting ion to dissolve well in water due to ion-dipole attraction (Figure 1, middle structure). This change also causes a loss of fluorescence and a color change to orange-red.¹ At even higher pH, the phenolic protons are lost, ^1,2 which causes curcumin to be even more negatively charged (Figure 1, bottom structure). The loss of protons causes yet another color change.

curcumin

Figure 1: Chemical structure of curcumin at pH < 8 (top) around pH 8 (middle) and pH > 10 (bottom). Curcumin is the main colorant in turmeric powder.

Interestingly, curcumin binds to borates to form rosocyanine, a red colored complex (Figure 2).³ The rose-red color of this complex allows for a sensitive test for the presence of borates through addition of solutions of curcumin.

rosocyanin

Figure 2: Structure of rosocyanine

When experimenting with the Sunflower dye, I found it did not dissolve well in water, but it did dissolve well in acetone and alcohols. These observations are consistent with the presence of curcumin in the dye. When illuminated with a violet laser or UV light, a solution of the Sunflower dye in acetone or alcohol emitted yellow-green fluorescence, further indicating the presence of curcumin. Also, the Sunflower colorant acted as an acid-base indicator: yellow in acid and red in base. Finally, an alcoholic solution of the Sunflower colorant changed to rose-colored upon addition of borates. All of these observations all point to the dye containing curcumin. In the video below you can see several investigations that can be performed with the Sunflower colorant that make use of the curcumin found in this food coloring.

In contrast to the other Color from Nature dyes, the Sunflower dye contains not one but two components responsible for its color. “Annatto extracts” is also listed in the ingredients for the Sunflower dye. The main coloring component in annatto extract is bixin, which is converted to norbixin under alkali conditions⁴ (Figure 3). Norbixin fluoresces, giving off orange light.⁵

bixin and norbixin

Figure 3: Chemical structures of (top) bixin and (bottom) norbixin

After addition of base to a solution of the Sunflower dye (acetone as solvent), the resulting solution was observed to fluoresce orange upon illumination with UV/violet light. You can see this experiment at the end of the video posted above. This test suggests that the compound bixin is contained in the Sunflower dye. The orange fluorescence observed at high pH is consistent with the formation of norbixin, even though I am not completely convinced this is what is going on.

Similar to the Sky Blue and Berry dyes, it is easy to obtain the absorption (Figure 4) and emission (Figure 5) spectra of the Sunflower dye. The spectra obtained contain many similarities to previously reported absorption and emission spectra of curcumin,⁶ bixin,^4,5 and norbixin,⁴ suggesting a combination of these compounds is contained in the Sunflower dye. Several differences exist between the Sunflower dye spectra and those of the pure compounds. However, this is to be expected if the Sunflower dye contains a mixture of curcumin, bixin, and norbixin. I have not yet attempted to separate these compounds from the Sunflower dye for individual identification. Suggestions on how to do so (using simple methods!) would be greatly appreciated!

absorption spectrum of sunflower dye

Figure 4: Absorption spectrum of Sunflower food coloring dissolved in alcohol (dashed line) and with added NaOH (solid line).

Emission spectrum of sunflower dye

Figure 5: Emission spectrum of Sunflower food coloring dissolved in alcohol (dashed line) and with added NaOH (solid line). Excitation wavelength = 405 nm (violet laser pointer)

I hope you enjoyed this series on the chemistry of the various colorants found in McCormick’s Color from Nature food colors. Be sure to pick up a packet at your local grocery or retail store and do some experiments. If you learn something new about the chemistry of these dyes, be sure to share it with us in the comments. I look forward to hearing from you.

Happy experimenting!

1. Priyadarsini, K. I.Molecules 2014, 19, 20091-20112.

2. https://www.researchgate.net/profile/Indra_Bhatt/publication/235993633_Curcumin_-_Biological_and_medicinal_properties/links/56fa56c408ae7c1fda31a118.pdf

3. Lawrence, K.; Flower, S. E.; Kociok-Kohn, G.; Frost, C. G.; James, T. D. Anal. Methods, 2012, 4, 2215 – 2217.

4. Santos, L. F.;  Dias, V. M.;  Pilla V.; Andrade, A. A.; Alves, L. P.; Munin, Monteiro, V. S.; Zilio, S. C. Dyes and Pigments2014, 110, 72-79.

5. Alwis, D. D. D. H; Chandrika, U. G.; Jayaweera, P. M. Journal of Luminescence2015, 158 60–64.

6. Chignell, C. F.; Bilski, P.;  Reszka, K. J.; Krzysztof, F. J.; Motten, A. G.; Sik, R. H.; Dahl, T. A. Photochemistry and Photobiology 1994, 59, 295-302.

What are we doing to help kids achieve?

Third quarter is like a marathon. Fourth quarter is like a sprint. Third quarter had ten weeks of no breaks, no snow days, grey weather, the flu and, in the mind of a teenager, anything over spring break is better than sitting in chemistry class. Fourth quarter has state testing, the ACT, AP testing, fewer days and more interruptions.

The first week into fourth quarter it was time for an assessment over heat and phase changes. Half of the material we completed before spring break and half after….less than ideal. Students are about to face a week of state testing that consists of a couple of hours every morning doing high stakes testing. Also, before spring break many students had a type of end of year test in several classes (a weird new requirement in the state of confusion...I mean Ohio). Bottom line, we were not able to cover as much material as I would have liked. I knew I had to get a test in and students were already entering the phase of being over tested and stressed.

    Students came in and it was announced that they could have a “group” test.  Here were the rules.

1. You may take the test with a partner that the teacher assigns.
2. You both need to put your name on the test.
3. You need to agree on the answer before you write it down.
4. If one person does not agree, then he/she can write down a separate answer that is different from the partner. Each answer will be graded separately.
5. Either partner can decide to opt out and take a test on their own. But this decision must be made before the test.

Here is the interesting part: Grades were a bit better than usual but not spectacular. Few students chose to opt out or answer questions separately. So the question is….why do it?

The answer may be in the anecdotal evidence. The conversations between students were mini debates. “Are you sure this is correct?” “How do you know?” “What about this other data?” “Should we label that number?” “What about the energy of the particles during a phase change?” And on, and on, and on….They were having discussions between themselves that I would not have been able to elicit as a teacher.

So here is the question...is this a worthwhile idea? Do students have an unfair advantage during a “group” test? Or do students challenge and teach each other in ways that I could not teach them as the instructor? The questions they were asking each other sure did seem “scientific”. Do you think this is a valid form of assessment?

Currently, many discussions have been going on about academic integrity, posting homework keys and cheating. We can only provide opportunities for students to learn. Part of me believes that what they do with those opportunities is up to them. I also know that I cannot stick my head in the sand and be ignorant that cheating occurs. A group test did allow students to challenge one another in a healthy way. It also allowed me to ask slightly more difficult questions that I otherwise may not have included on the exam. If students work with each other on a graded assignment...is this an unfair advantage or does it create an enhanced learning environment? How often should this occur if ever? What do you think?

First, a word of caution...this pick is the result of a four year messy journey and a 17 page paper (that I helped author) about the struggles of trying to figure out how to teach. For those who do not have a lot of time, I will give you the one page executive summary. I found myself professionaly and personaly struggling with my teaching career. Each week I decided to put on paper, or in a blog, one concrete action that I could take that I was pretty sure would help at least one student. After almost three years and close to a hundred entries, the entries were separated into categories by multiple people. The result was pretty clear....my biggest struggles were with assessment. How do I really know what students know or what they have learned? Thanks to Dr. Ellen Yezierski at Miami Univesity Ohio and Dr. Jordan Harshman at University Nebraska Lincoln we were able to come up with an action plan that uses "Data Driven Inquiry". Essentially, do your best to find out what students do and do not know as a teacher. Tackle the topics they are not sure about with proven, vetted and researched teaching methods and check again. Sounds simple and seems like common sense but in reality it is difficult to do...but not impossible. And...in the end...the data shows it really does work. Interested? Check it out the article we collaborated on and published in the Journal of Teacher Action Research. I would love to read your comments. 

Highlighting the 2017 Awardee – Laura E. Slocum

The James Bryant Conant Award was established in 1965 and has had several sponsors. Most recently, Thermo Fisher Scientific sponsored the award from 2007 – 2016. The award is intended to recognize, encourage, and inspire outstanding teachers of high school chemistry. It is fitting that the Journal of Chemical Education and ChemEd X have established an endowment that will permanently fund the award. The award provides $5000 to the awardee along with travel to the award ceremony and a framed certificate. And, I think it is even more fitting that the 2017 Awardee, Laura Slocum, has a history with JCE as a precollege assistant editor from 2007 – 2011.

I had the opportunity to introduce Laura during the Chemistry Teacher Program at the ACS spring national meeting in San Francisco on April 2nd. This post contains some of the information I highlighted in that introduction. Laura received a framed certificate from the editor in chief of JCE, Dr. Norb Pienta. He also presented her with an early edition of a book written by James Bryant Conant himself. We had an opportunity to hear Laura speak as part of the program. She was also honored at a formal banquet on April 4th. The award citation included on the certificate Slocum received reads:

For inspiring students to learn the beauty of our molecular world and for contributions to chemistry education as a researcher, editor, and exemplary educator.

Although it is not necessary, many of the Conant awardees have previously been honored with a Regional Award. In 2006, the Division of Chemical Education endowed the Regional Award for Excellence in High School Teaching. Each of the ten Regions of the American Chemical Society solicits nominations for this award. Laura Slocum received the award in 2012 at the Central Regional Meeting. The winners receive $1000, an engraved plaque and travel expenses to the meeting where they are honored.

Patricia Mabrouk recently wrote a blog “Nominate Outstanding High School Chemistry Teachers”, for ChemEd X that offers advice for nominators and candidates that are completing the nomination materials for the Regional Award. Beyond the advice, the Mabrouk encourages members of the community to take action. If one follows the link to past Regional Award winners, they will find a sorry number of empty spaces meaning that no one had received the award. The annual deadline for Regional Award nominations is April 1. Of course, this advice would also apply to the Conant Award and other teaching awards. The annual deadline for the Conant Award is November 1^st.

Search “Conant Award” on the ACS.org website and you will see an outline of attributes that a potential candidate should demonstrate: Quality Teaching, Abilityto Challenge & Inspire Students, Participates in Extracurricular Activities and Cutting-Edge Pedagogy. How do we relay all of these attributes to the committee that will choose the award winner? In Pam’s blog, you will find a document that she wrote about compiling a CV - a curriculum vitae. Higher Ed folks are more familiar with keeping a CV than many of us at the precollege level. This goes beyond your education and employment history that is part of your resume and provides a broader view of the candidate.

Slocum has been involved in many local, state and national organizations including the American Chemical Society, the National Science Teacher’s Association, National Mole Day Foundation, the Indiana Alliance of Chemistry Teachers, Hoosier Association of Science Teachers, Inc., the American Modeling Teacher Association, the American Association of Chemistry Teachers and more. Just as this is not an all-inclusive list, it also does not do justice to the depth of her involvement in these organizations. Laura has done countless presentations, hosted symposiums, served as chair for ACS regional and national High School Days and Chaired the High School programming for more than one BCCE. She has received many awards for her dedicated work. Slocum was trained in Modeling Instruction in 2010 and now helps lead workshops introducing others to the pedagogy. She wrote a blog post for ChemEd X about using a timeline she created to post around her classroom as she follows the chronological order suggested by the supporting curriculum that many Modeling Instruction teachers use. When compiling a CV, you will record all of those types of details. It is definitely easier to keep a running list than to try to create one from memory later.

As I mentioned previously, Slocum has had a long history with JCE. Before she became a precollege assistant, she had published¹ and also reviewed articles. Reviewing articles is a scholarly activity that should be included in your CV. It can help prepare you to submit your own work for publication. To become a reviewer for JCE, you should read Information for Reviewers on the JCE website. You can apply to review for ChemEd X by using our contact form.

I think you will agree that based on even the barest outline of Laura’s work listed here, we have plenty of evidence that she does demonstrate the attributes listed above. Every Conant Awardee has a unique story. I hope that by sharing some of Laura Slocum’s story, you will be inspiredto not only nominate a colleague, but also add some chapters to your own story. Unfortunately, not every outstanding chemistry teacher will be honored with an award, but if we follow in the footsteps of those that have walked before us we can be proud of the effort.

1 - “Online Chemistry Modules: Interaction and Effective Faculty Facilitation”, Theresa Julia Zielinski, Marcy Hamby Towns, and Laura E. Slocum, Journal of Chemical Education200481 (7), 1058.

On April 22, 2017, people all over the world will be coming together to stand up for science. The March for Science is a part of a global movement by scientists, science-enthusiasts, and evidence-based policy makers to celebrate the integral role science plays in all our lives. The March will serve to further several goals, I encourage you to read about them.

As educators we can help! Everyday we are “humanizing” science. We teach the scientific process and show our students science is about expanding our knowledge and understanding of the world around us. Through our laboratory investigations we are illustrating that data and evidence, not personal beliefs or opinions, are necessary for constructing conclusions. The March for Science is taking place in Washington DC and in over 480 satellite locations. (Find one in your state.) If there isn’t an official march near you, you can opt to participate virtually.

I will be marching with my students on April 22. Will you join me?

As many chemistry teachers know, grading lab reports can be a very time-consuming task. For me, the lab report that has required the most time to grade is a stoichiometry lab that I have been doing the past couple years. Though we do at least four “formal” lab reports each year, what makes this one different is that it involves a lot more calculations and subsequent results than any of our other labs. Regardless of how well they organized their report or wrote their conclusions, their results need to be checked for accuracy. This takes time. Even after eventually being able to generally eyeball their work, it still takes more time than I would like. So, this year I finally decided to sit down and generate a tool for me to expedite this process—the stoichiometry calculator.

First, a brief background on the lab and the requirements students must meet. This will help to explain why the calculator is so useful.

Summary of Stoichiometry Lab

1.  I set out 7 different compounds

Sr(NO₃)₂, Pb(NO₃)₂, KOH, NaOH, Na₂CO₃, K₂CO₃, and CaCl₂

2.  Using their Solubility of Compounds at STP table, students choose which two compounds they would like to combine that will form a precipitate. Since each compound does not necessarily form a precipitate with every other compound, there are a total of 10 different reactions that can be performed. 

3.  Once decided, my only rule is that each group must start with 2 g of the metal compound of greater molar mass.

4.  Students must use their recent understanding of mass/mole conversions and BCA tables to calculate how much of the other reactant they will need to ensure no leftover reactants as well as their theoretical yield. 

5.  Solutions are then made and combined, precipitates are formed, filtered, and left overnight to dry.

6.  The following day, their actual yield is recorded and they are able to determine their percent yield. 

Calculation-Based Requirements in Lab Report

I have only included the requirements that the calculator generates here, but you can find the grading rubric for the lab in the "supporting information" below.

1. Initial mass of other reactant
2. Theoretical yield
3. Percent yield
4. Completed BCA table (moles of each species involved at different parts of the reaction)

Once lab reports have been typed, I now have approximately 160 reports, each with 1 of 10 potential reactions, to sift through. In honor of an awesome cartoon, it is at this point I say “go go gadget stoichiometry calculator!” I move the student’s report to one side of my computer screen, the calculator to the other side, and I’m ready. I read what is necessary and when I arrive at their calculations and results sections, all I need are 2 values:

1. Initial mass of metal compound of greater molar mass
2. Actual yield

From these 2 values, the spreadsheet will automatically calculate the required results mentioned above.

After using this for the first time this year, I managed to take what would normally be a 2-3-minute process of my own self-checking calculations and cut it down to a 10-15 second process. I find the 2 values I need, type them in, check their numbers with mine and….done. It may not sound like a big deal but even if I check a student’s calculations in 2 minutes like I used to, when you compare that to the 15 seconds it takes me to achieve the same result using the stoichiometry calculator, for 160 lab reports that is a difference of nearly 5 hours! 

To be clear, I would never claim this calculator is some product of pure genius and skill—far from it. It only required some of the most basic Excel skills, knowledge of molar masses, and an understanding of the molar ratios involved for each reaction. In other words, anyone can make one! However, if you would like to download this one and modify it however you want, then at least much of the work has already been done for you. There we go again….saving time!

I should also mention that the benefits of making a stoichiometry calculator go beyond its use for grading lab reports. It didn’t take too long before I realized that I could also use it to generate stoichiometry problems with ease. Between the frequency of quick assessments, retakes, practices, examples, and generating test questions, this was huge. I could put in some random mass value for a reactant in a known reaction and whip up the answer key in less than 5 seconds. 

Whether you decide to make your own or download this one, I strongly recommend it. After all, have you ever heard of a teacher complaining of having too much time on their hands? 

Resources To Inform Teaching and Learning

The April 2017 issue of the Journal of Chemical Education is now available online to subscribers. Topics featured in this issue include: green chemistry; environmental chemistry; using food chemistry to teach; 2016 Jame Bryant Award; development of important skills; chemical education research: assessment; advanced laboratories; from the archives: water quality.

Green and Environmental Chemistry

Green Chemistry: Cover Feature

A student uses a calorimeter constructed from paper cups to measure the heat capacity of metals. In the laboratory experiment, "Greening" a Familiar General Chemistry Experiment: Coffee Cup Calorimetry to Determine the Enthalpy of Neutralization of an Acid–Base Reaction and the Specific Heat Capacity of Metals, A. M. R. P. Bopegedera and K. Nishanthi R. Perera demonstrate that with slight modifications, paper-cup calorimetry is just as effective as styrofoam-cup calorimetry. Paper cups have an overall lower impact on the environment, providing an opportunity to discuss the principles of green chemistry within the first-year chemistry curriculum. Additional articles on green chemistry as well as environmental chemistry and water quality are available throughout this issue.

Green Chemistry

CO₂ Dry Cleaning: A Benign Solvent Demonstration Accessible to K–8 Audiences ~ Reuben Hudson, Henry M. Ackerman, Lindsay K. Gallo, Addison S. Gwinner, Anna Krauss, John D. Sears, Alexandra Bishop, Kristin N. Esdale, and Jeffrey L. Katz

Using Greener Gels To Explore Rheology (making "slime" using green chemistry) ~ Brendan Garrett, Avtar S. Matharu, and Glenn A. Hurst

Greener Oxidation of Benzhydrol: Evaluating Three Oxidation Procedures in the Organic Laboratory ~ Kelli S. Khuong

Synthesis of (3-Methoxycarbonyl)coumarin in an Ionic Liquid: An Advanced Undergraduate Project for Green Chemistry ~ Pedro Verdía, Francisco Santamarta, and Emilia Tojo

Bringing Catalysis with Gold Nanoparticles in Green Solvents to Graduate Level Students ~ Vikram Singh Raghuwanshi, Robert Wendt, Maeve O’Neill, Miguel Ochmann, Tirtha Som, Robert Fenger, Marie Mohrmann, Armin Hoell, and Klaus Rademann

Environmental Chemistry

Assessing Student Knowledge of Chemistry and Climate Science Concepts Associated with Climate Change: Resources To Inform Teaching and Learning ~ Ashley Versprille, Adam Zabih, Thomas A. Holme, Lallie McKenzie, Peter Mahaffy, Brian Martin, and Marcy Towns

Project-Based Learning in Undergraduate Environmental Chemistry Laboratory: Using EPA Methods To Guide Student Method Development for Pesticide Quantitation ~ Eric J. Davis, Steve Pauls, and Jonathan Dick

Learning Principal Component Analysis by Using Data from Air Quality Networks ~ Luis Vicente Pérez-Arribas, María Eugenia León-González, and Noelia Rosales-Conrado

Gaining Hands-On Experience with Solid-State Photovoltaics through Constructing a Novel n-Si/CuS Solar Cell ~ Zexun Jin, Yecheng Li, and Jimmy C. Yu

Using Food Chemistry To Teach

In a nod to this year’s ACS Chemists Celebrate Earth Day theme of “Chemistry Feeds the World”, Norbert Pienta explores some ideas about Teaching about Chemistry Related to Food in the April editorial. (For more resources related to food and cooking from ChemEd X in honor of this theme, see Deanna Cullen’s recent blog post.)

For additional content in the April issue on food, see:

Engaging Students in Real-World Chemistry through Synthesis and Confirmation of Azo Dyes via Thin Layer Chromatography To Determine the Dyes Present in Everyday Foods and Beverages ~ Kristi Tami, Anastasia Popova, and Gloria Proni

A Tasty Approach to Statistical Experimental Design in High School Chemistry: The Best Lemon Cake ~ Lucia Liguori

Comment on “Analysis of Citric Acid in Beverages: Use of an Indicator Displacement Assay” ~ Krzysiek Konski, Jessica Saw, and Angel A. J. Torriero

Commentary: 2016 ACS James Bryant Conant Award

The ACS James Bryant Conant Award recognizes high school teachers for using high-quality teaching methods, their ability to challenge and inspire students, their extracurricular work, and their willingness to work for continual improvement. (This award will be sponsored permanently by the Journal of Chemical Education and ChemEd X beginning in 2017.) In Teacher CEO, Deanna M. Cullen describes the 2016 awardee, Julia Winter of Michigan, and conducts a short video interview with her.

Development of Important Skills

The Chemistry Teaching Fellowship Program: Developing Curricula and Graduate Student Professionalism ~ Kris S. Kim, Darius G. Rackus, Scott A. Mabury, Barbora Morra, and Andrew P. Dicks

The Coffee Project Revisited: Teaching Research Skills to Forensic Chemists ~ Hilary J. Hamnett and Ann-Sophie Korb

Chemical Education Research: Assessment

What We Don’t Test: What an Analysis of Unreleased ACS Exam Items Reveals about Content Coverage in General Chemistry Assessments ~ Jessica J. Reed, Sachel M. Villafañe, Jeffrey R. Raker, Thomas A. Holme, and Kristen L. Murphy

High Structure Active Learning Pedagogy for the Teaching of Organic Chemistry: Assessing the Impact on Academic Outcomes ~ Michael T. Crimmins and Brooke Midkiff

Advanced Laboratories

Introducing Students to Inner Sphere Electron Transfer Concepts through Electrochemistry Studies in Diferrocene Mixed-Valence Systems ~ Karen Ventura, Mark B. Smith, Jacob R. Prat, Lourdes E. Echegoyen, and Dino Villagrán

Anisotropic Rotational Diffusion Studied by Nuclear Spin Relaxation and Molecular Dynamics Simulation: An Undergraduate Physical Chemistry Laboratory ~ Michael M. Fuson

Introducing Students to a Synthetic and Spectroscopic Study of the Free Radical Chlorine Dioxide ~ Sarah C. Sutton, Walter E. Cleland, and Nathan I. Hammer

Fabrication of an Economical Arduino-Based Uniaxial Tensile Tester ~ Julien H. Arrizabalaga, Aaron D. Simmons, and Matthias U. Nollert

From the Archives: Water Quality

Water quality is a critical environmental issue. This issue features two labs for students to explore how to filter water to make safe and clean drinking water:

Rapid Production of a Porous Cellulose Acetate Membrane for Water Filtration using Readily Available Chemicals ~ Adrian Kaiser, Wendelin J. Stark, and Robert N. Grass (open access article available through the ACS AuthorChoice program)

Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection To Gain Experience at the Nanochemistry–Microbiology Interface ~ Ping Y. Furlan, Adam J. Fisher, and Michael E. Melcer, Alexander Y. Furlan , John B. Warren

Enjoy access to a collection of articles, hands-on experiments, and demonstrations from past issues of Journal of Chemical Education on the topics of water properties and water in the environment as part of the Chemists Celebrate Earth Day 2014 “Wonders of Water”.

Informing Teaching and Learning

With 94 volumes of the Journal of Chemical Education to inform teaching and learning, you will always find useful resources—including the articles mentioned above, and many more, in the Journal of Chemical Education. Articles that are edited and published online ahead of print (ASAP—As Soon As Publishable) are also available.

Earth Day, on April 22, is nearly here. The American Chemical Society (ACS) annually joins in the day, focusing on chemistry aspects of the environment, through Chemists Celebrate Earth Day (CCED). As Journal of Chemical Education editor Norb Pienta mentions in his April 2017 editorial Teaching about Chemistry Related to Food (freely available), ACS’s selected theme for this year’s CCED is “Chemistry Helps Feed the World.” Past themes have included plants, soil, water, etc., but the topic of agriculture brings it all together, viewed through the lens of chemistry. Where to begin with the theme? Pienta mentions one misunderstood example, corn, and its potential for sharing with students. He also points out that the Journal is rich in resources related to food chemistry. The articles he mentions are mainly directed toward the chemistry of the foods themselves, rather than the agricultural steps it takes to get the foods. Deanna Cullen also had a recent post highlighting ChemEdX resources related to food and cooking.

One of the articles from the April issue also focuses on a final food product—lemon cake. A high school educator in Norway uses cake and the variables involved in its making (e.g., ingredient amounts, baking temperature, baking time) as an opportunity for experimental design. Her article title A Tasty Approach to Statistical Experimental Design in High School Chemistry: The Best Lemon Cake (available to subscribers) describes the evaluation goal—which combination produces the “best” lemon cake? The project involves many considerations, with students making decisions such as which qualities of the cakes to assess in their quest for the “best,” which of the many variables to adjust in the selected recipe, and how to organize a taste test panel.

I could see implementing these parts in a standard high school classroom. But, Liguori takes it even further, with the application of statistical experimental design, which she states that no literature has been reported in connection with the high school classroom. She uses the mathematics program Geogebra, with tools such as making three-dimensional response surface plots for the experiment. I readily admit this is well beyond my current knowledge. But, I see it as an professional development opportunity. It could take the shape of learning more through self-study. It might mean collaborating with a mathematics teacher either at the high school or college level. Or, one might just pull the non-mathematical pieces from the article and use it as a delicious example of experimental design for students. Any way you slice it, it is another reminder that chemistry does help feed our world.

Share and Celebrate

Interested in sharing CCED in your classroom or with other teachers in your area? ACS’s Celebrating Chemistry publication is geared toward readers in fourth through sixth grades, with free PDFs available online in English and Spanish. The ACS ChemClub page also offers an Agricultural Chemistry curated link collection with activities and articles from around the web.

More from the April 2017 Issue

Mary Saecker offers her round-up of all the content from this month’s issue of the Journal. Visit JCE 94.04 April 2017 Issue Highlights.

Have something to say about a current or past article from JCE? We want to hear! Start by submitting a contribution form, explaining you’d like to contribute to the Especially JCE column. Then, put your thoughts together in a blog post. Questions? Contact us using the ChemEd X contact form.

I have had a variety of students with a broad range of academic abilities in my class at once. This hook doesn’t feel particularly deep until I stop and reflect for a moment on what that looks like. On one hand, I have taught in a school that did not allow honors classes until junior year, and on the polar opposite, in a school with quasi-rigid tracking via honors and non-honors. I have had students with developmental disabilities, and students who have taught me brilliant, beautiful insights. Now, these groups aren’t necessarily mutually exclusive, but to challenge every student to the best of my ability, I have employed a variety of tools within the “differentiation by readiness” tools.

This figure below has inspired me as I plan and prioritize learning goals for my diverse set of students.

I have provided a few resources to illustrate how this has played out in my classroom:

• Macroscopic view- Unit Plan: A descriptive unit plan of my mole unit (loosely based upon part of the Toxins unit from Living by Chemistry Curriculum, as purchased from Key Curriculum Press). Here’s a link to a post on my scope and sequence if you would like context as to where this fits into the school year.
• Note: This took me a few years of trial and error to develop. This unit is still tough for my students. In the grand scheme of things, I have found that even if students STRUGGLED in this unit, by the time we got to stoichiometry two units later, ideas had cemented for many.
• Nanoscopic view- Selections of a Different Quiz Versions: Four versions of a quiz my students took during the mole unit (note: they are loosely based upon a quiz in the Toxins 1 Unit from the Living by Chemistry Curriculum, as purchased from Key Curriculum Press, but now is accessible via Macmillian Learning). Below is a brief description as to how I used these tools.

1. Modified: Given to students who, in lieu of extended time, were given shortened versions of assessments. The school’s policy: if a student has extended time, the workload quickly builds up in every class to use that extra time. This was determined to be a potential spiral of doom for the student- thus the modified assessments. I typically eliminate a multiple choice response (3 choices vs 4), increase scaffolding on short answer and/or reduce the number of short answer questions, as shown below. Additionally, there is added scaffolding in the short answer as compared to the General Chemistry version.

modified sample problems

2. Regular: Given to (most) general chemistry students. There is one more short-answer question compared to the modified version, and there are 4 multiple-choice answers from which to choose.

regular sample problem

3.  Honors B1: Given to some honors students, some general chemistry students - it depended upon where they were at in their learning progression. Some general chemistry students were more prepared for this challenge than honors. The multiple-choice is reduced by one question so that I can give more challenging/time consuming short-answer questions as shown below.

4. Honors B2: Given to some honors students, some general chemistry students (arguably fewer)- this has a TOUGH final short answer problem (source: “Placebos” task, Solving Real Problems in Chemistry, Pacific Crest). My top students had practiced with an analogous problem from the same college-level text prior.

Thanks for reading- please share your differentiation tips if you have found things that work for you and your students!

PS- Good luck to your AP students in the coming weeks.

In my years as a chemistry teacher, I did a water of hydration lab like the one described in Chad’s post about his hydrate lab experience. To assist in grading the lab results for this and other quantitative labs that we did, I created Excel spreadsheets where the students’ results could be entered. The spreadsheet then did all the required calculations and compared the students’ results to the theoretical value. This made grading the lab reports much quicker and more accurate, flagged incorrect student calculations, allowed a much more complete discussion of the lab results and permitted “what if” questions to be discussed.

In my class, the students did not see the spreadsheet results until after their lab reports were turned in. Once the reports were turned in, all students received a print-out of the class results. In the case of the water of hydration lab, the spreadsheet also calculated class average values and we discussed how results are more reliable when based on repeated determinations of experimental results rather than on just one. Because the classes were quite large, there was not time for the students to enter their own data into the spreadsheet, so they wrote the data on a form I prepared and I typed the data in myself. A sample spreadsheet for the experiment is attached. The names of the students have been blanked out. The spreadsheet template, of course, can be used year after year by blanking out the data.

If you are interested in additional experiment spreadsheets that I used, comment below.

Do you ever have that Go-To demonstration or website for an activity that you really value? You've been using it for a few years, tweaked it to make it better - only to send your students there one year and have the activity fall flat on its face because the website is no longer available?

That almost happened to me this year.

As described in a previous post here on ChemEd X-Change, I use Molecule Lab on iPads, coupled with an online simulation to introduce students to Maxwell-Boltzmann distributions. The pairing of the simulations really complemented each other, and students left with a good foundation for moving forward with energetics and kinetics discussions. In the previous post linked earlier, I take you through the process of the lesson and give some background on my discussion with students.

This week I intended to use the same process, having the students work through the two simulations as my typical introduction to Maxwell-Boltzmann. Luckily, I'm now in the habit of checking simulations I use the night before a lesson just to verify that they still work. When I found that Java simply wouldn't cooperate I started searching for replacements. I ended up stumbling upon the Wolfram Demonstrations Project (See note below about the simulations). This platform, created by the same group that put forth Mathematica and Wolfram Alpha, has a simulation "player" that uses Mathematica output for various simulations. Included in this collection is a similation that will create Maxwell-Boltzmann distribution curves for different conditions. The conditions that can be varied are temperature and molar mass of the gas. 

And while I did find this simulation quite clean and easy to use with the sliders provided so students could change conditions, I did miss the molecular motion provided by the previous simulation that no longer works for me due to Java issues. Another improvement would be adding a second gas (with its own set of sliders) to the same graph for an easier direct comparison between conditions. But linking the observations of the simulation with observations from MoleculeLab allowed students to generate a better understanding of the concept of Maxwell-Botlzmann Distribution Plots, and thus the simulation was useful.

I intend to explore the Wolfram collection more, and will share any simulations that I put into circulation within my class.

Do you have any Go-To simulations you rely on for your teaching sequence? I'd love to hear about them.

Note: In order to use these simulations, you need to download their CDF Player. Once the CDF Player is downloaded, you can download the actual simulations and save them to your hard drive. The simulations are pretty small - with many less than 100 KB. The CDF Player, however, takes up over a GB of space on your hard drive. But it's worth it! There are numerous simulations available.

Registration is now open for the inaugural Chemical Education Xchange Conference with a theme of Chemistry Instruction for the Next Generation. Recent chemical education research has informed the expectations of the Next Generation Science Standards and the revised AP chemistry curriculum along with changing expectations at the postsecondary level. The Journal of Chemical Education is sponsoring the virtual conference to support the chemistry education community by bringing together chemistry education researchers and chemistry educators at the secondary and postsecondary level to address the implications of increasing the use of student-centered strategies. The sessions are led by authors selected from among those who have published recent articles, activities and research in JCE on the topic of student-centered instruction in chemistry.

Using the ChemEd X Conference platform allows the authors to augment their published articles with additional information and resources beyond those offered in their original publication. The original JCE article, other online materials that the author chooses to share and ensuing conversation can be distributed to conference attendees using various digital technologies such as email, text messaging, Twitter and Facebook in addition to the ChemEd X Conference web site. The organizers hope to engage high school chemistry teachers, pre-service chemistry education students, professors working with pre-service students, chemical education researchers and anyone else with a stake in improving chemistry education in this conference.

The homepage of the Chemistry Education for the Next Generation conference offers a schedule of the sessions and provides specific details about the conference. Each consecutive session will last several days. Participants wishing to attend a specific session will have access to all of the materials the author(s) has provided and have ample time to construct thoughtful commentary. Invited authors and those posting comments should respond to questions in a timely fashion. The organizers anticipate that the conversation may serve to help bridge the gap between research and practice and help inform decisions as our community integrates student-centered strategies and improved chemistry education practice./p>

The conference is hosted by precollege associate editors of JCE: Greg Rushton of Stony Brook University in New York and Deanna Cullen of Whitehall High School in Michigan. Cullen is also the editor of ChemEd X. The conference website offers information pages with details about registering for the conference and also attending sessions. Only those who create an account at ChemEd X Conferences can participate in the conversation. All chemistry education researchers and educators are invited to register free of charge. JCE has made all of the articles open access for registered attendees.

The conference is scheduled to run May 8–27, 2017. The Conference opens on May 8th with an introduction from the organizers. The presentation for session #1 opens on this day as well and that session will be open for conversation May 10 - 12.

ChemEd X and the Journal of Chemical Education (JCE) are collaborating to offer a virtual conference like most have never seen before. It is not a webinar. You do not have to schedule specific hours to view a live presentation. I think of it as similar to a virtual book/journal club with the added benefit of having the author leading it. In this case, authors were selected from among those who have published recent articles, activities and research in JCE on the topic of student-centered instruction in chemistry. The theme of this inaugural conference is Chemistry Instruction for the Next Generation.

What is the conference about?

The whole chemical education community is in the midst of adjusting curricula, learning new strategies, looking for better assessments and reworking lessons as we move toward a more student-centered environment. The research supporting the move continues to grow. National and state mandates have pushed implementation. But sadly, there remains a gap between research and practice. I have been fortunate enough to have some excellent chemical education mentors that have not only devoted themselves to doing the research, but also to supporting those that can benefit from the research, the instructors. I hope that with this virtual conference, we can help to bring more instructors and researchers together so that we can develop a stronger community as we work toward improved practice.

Attendees will have free access to the JCE articles along with anything else the authors have decided they would like to share in relation to the original article. Because the specific content of the articles varies, we expect that the augmented materials will vary as well. Participants wishing to attend a specific session will have access to all of the materials the author(s) has provided and have ample time to construct thoughtful commentary. In turn, invited authors and those posting comments should respond to questions in a timely fashion.

Who Are The Presenters?

Topics include inquiry activities, professional development/collaboration, assessment, science practices, Modeling Instruction, research pertaining to using particulate models, etc. Even more exciting is the fact that the participating authors represent so many parts of our chemical education community. We have chemical education researchers, high school chemistry instructors, college chemistry instructors, pre-service teachers and graduate students involved.

Why Should You Attend?

As instructors, we want out students to engage, question, discuss and generally ponder the topics we cover so that they will develop deeper conceptual understanding. I have tried to model these skills and strategies for my students but just as they need to practice these skills, so do we. It is only by engaging in these types of activities and discussions that we will truly understand the depth of the topics put before us in this conference. This is why I think this unique platform can be powerful. Any learning/understanding that occurs here will happen because of engagement among all stake-holders in our community and thoughtful commentary. If we expect our students to take responsibility for their own learning, should we not push ourselves to do the same? I wonder how much we might learn just by putting our student hats on and practicing the skills and strategies that we expect our students to practice in our own classrooms. We may develop empathy which can be powerful in its own right. We might even have an "Ah-Ha" moment or two during the conference that will cause an even greater shift. 

I hope that you will register and commit to not only reading the materials offered, but also joining the conversation. My colleague, Greg Rushton, and I hope that this conference will help to bridge the gap between research and practice and that the conversation will continue beyond the end of this conference. We are hosting this event together. Read our introduction on the conference website. Only those who create an account at ChemEd X Conferences can participate in the conversation. Thanks to JCE, there is no charge. The conference is scheduled to run May 8 – 27, 2017. The Conference opens on May 8th with an introduction from the organizers. The presentation for session #1 opens on this day as well. The session is open for conversation May 10 - May 12. If you register, we will notify you when each session opens.

A few months ago I was searching the internet, looking for a better way to teach stoichiometry to my pre-AP chemistry students. While my methods of dimensional analysis “got the job done” for most students, I would still always lose students and many lacked true understanding of what was happening in the reaction. I wanted to try something new that would promote a better chemical understanding. In my search for this elusive stoichiometry method, I came across Dena Leggett’s ChemEd X blog post entitled “Doc Save Everyone”, as well as other posts about BCA tables from Lauren Stewart, Lowell Thomson, and Larry Dukerich. These posts highlighted the method of using a “Before, Change, After” (BCA) table to organize stoichiometry problems, turning stoichiometry problems into a chemical “Sudoku puzzle”.

I agree with other bloggers that teaching BCA tables takes commitment and time. However, when you see your students solve complex limiting reactant problems without breaking a sweat, it is worth it. I have been converted to BCA tables!  I want to share my experience teaching BCA tables to my pre-AP Chemistry students for the first time. I hope you can use my experience as a springboard for new lessons in your classroom.

From reading other’s blog posts about their BCA experiences, I learned the BCA method would not be the quickest or the easiest for students to grasp as it requires a deeper understanding of concepts. I decided that I needed a “carrot” to keep my students motivated in this process. I teamed up with an engineer at a local manufacturing business (through the AACT Science Coaches program) to help me develop a real-life problem for the students to solve with stoichiometry. We decided to have students solve a rusting problem at a manufacturing plant. Students needed to develop a process that would use a strong acid to remove unwanted rust from steel parts and use a strong base to neutralize the waste acid to meet EPA guidelines. This project gave me an acid-base titration context to work with for stoichiometry and limiting reactants. I believe this real-life context kept my students motivated to learn stoichiometry and use of theBCA table, even when the work got challenging.

The acid-base context helped me formulate questions that would assess student understanding of limiting and excess reactants in chemistry. Students only needed to know basic information about acids and bases (acids have a pH < 7, bases have a pH > 7, etc.) to apply it to limiting reactants. Through BCA and acid-base titration questions, I could figure out if students were just crunching the numbers or if they were correctly thinking about the chemistry of the reaction. This is where BCA got tough. I now had a group of students that did not understand the chemistry and I could not just rely on them memorizing the dimensional analysis process to get through like before. The “change” or “C” row was the most challenging feature of BCA tables for students to grasp. I showed my students how to use proportions to figure out the numbers or how to solve for “x” or 2x” to complete this row. With practice, most students mastered it, but I still had some students struggling.

To students, much of chemistry is “invisible” as molecules are too small to see. I realized that my struggling students were not “seeing” the molecules in their head and therefore had no clue what the numbers represented in the BCA table. A few days before the test, I decided to make concrete connections between lab observations, molecules, and the math. I guided my students through the “Visual BCA Chart” worksheet (available as supporting information below the post). From numbers of moles given, we drew in the acid and base molecules in the reactant beakers and then predicted the products and leftovers (excess) in the product beaker after mixing. We went back to the BCA chart to make connections between the drawings and the numbers in the chart. After we answered the questions, we performed the reaction in lab using 1 M strong acid, 1 M strong base, and phenolphthalein indicator solution. Since the concentrations were equal and 1M, I had students use 1 mL for each mole in the chart. Through the indicator change and pH paper tests, students confirmed their answers to the problems and made connections between lab observations, BCA math, and molecules reacting. This was powerful and I had many “aha” moments. Eventually, students were able to do the rest of the problems on their own and help explain ideas (like problem #3 with a 1:2 ratio) to their peers.

My hope is you can take this idea I generated from reading ChemEd X blogs, run with it, and make it better. BCA has transformed my stoichiometry unit into one focused on understanding and real-life applications. Once my students figured out the BCA chart, limiting and excess reactants problems were a breeze. By the end of the stoichiometry unit, I felt I had fewer students overwhelmed by the chemical concepts than in previous years. I feel that next year will be even better as I plan to start the unit off with a visual BCA chart worksheet like the one I shared. Connecting lab observations, particulate diagrams and the BCA math were key in helping my students understand the chemistry of limiting reactants.

NGSS standards addressed: (HS PS 1 - 7) Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.

ACKNOWLEDGEMENTS:​

Special thanks for Science Coach: Dan Mack, Paint Process Engineer, John Deere​

AACT Science Coaches: https://teachchemistry.org/about-us/science-coaches

ChemEd X Blog Posts

Doc Saves Everyone: Applying BCA Tables To Titration Calculations: https://www.chemedx.org/blog/doc-saves-everyone-%E2%80%93-applying-bca-tables-titration-calculations

Rethinking Stoichiometry: https://www.chemedx.org/blog/rethinking-stoichiometry

Conceptual Chemistry: https://www.chemedx.org/blog/conceptual-chemistry

One Teacher's Attempt at Using BCA Table for Stoichiometry: https://www.chemedx.org/blog/one-teachers-attempt-use-bca-tables-stoichiometry

What are we doing to help kids achieve?

     I don't know why I tend to get OCD over "rates" labs. Somehow...I just think they are cool. Students can change a wide variety of conditions and they see stuff "happen". Sometimes I think as a teacher I am clouded by my judgement of what I want or think is cool and forget what we do is about student learning.

     I did have a rates microscale lab that worked really well. (As a matter of fact...about this same time last year I wrote about it here.) It worked well on several levels and each year I try to get a few more "bugs" out of the process.  But sometimes, I have a hard time leaving "well enough" alone. I went to a regional ACS meeting this summer and some teachers were demonstrating "green" chemistry. I found a published rates lab using vitamin C, peroxide and iodine solution....all items I could purchase from the store. I thought it would be great to have students do a lab that would show the concepts with common household items bought at a store. In true science teacher fashion, I tried the lab before the students did. I substituted "betadiene" iodine solution instead of "iodine" tincture to save some money. It worked. And then there was lab day...

     Honestly...I am not sure what happen. It may have been some type of contamination or it could be I just majorly messed something up. It was a disaster. There was little to no correlation for some classes. I am still not 100% sure where the mistake happened. So, what do you do when you have a disaster lab day?

     First, I was honest with the students. I explained why I switched labs from last year and what I was hoping they were going to learn. They were great with the idea. We all talked about how sometimes science is hard and the experiment does not always go as planned. Second, I realized that sometimes things just do not go well. The good news is that no matter how bad the experiment or demonstration fails, the students are probably coming back the next day and every new day is an opportunity to learn from our previous mistakes and simply begin again.

     Have you had a bad lab day recently? Don't get down on yourself too much. We are all human. Try to use the experience as a learning opportunity for yourself and for your students. 

I found a version of this demonstration online a couple of years ago. I admit, when I first tried it with my class it was mostly for a crowd pleaser to demonstrate the activity series of metals, but I then became very intrigued by the processes occurring. The original source only referenced the “single replacement reaction” between Mg_(s) and AgNO_3(aq). Therefore, when I saw a grayish product (silver) I was not surprised. However, I was surprised by the white flash and the production of a white product, which were reminiscent of the classic combustion of magnesium demonstration. This led to some research and my conclusions that follow.

I should note that the quotation marks above (around single replacement reaction) are due to my utter loathing of the terms single displacement/replacement (instead of oxidation-reduction) and double displacement/replacement (instead of precipitation and acid-base) as they are usually presented. I omit both from my teaching, but that is the topic of another piece.

I start the class period by having my students write and balance the following:

Not sure what to do after the AP chemistry exam? Have you considered having your students make solar cells? If your AP kids can understand batteries, solar cells are a logical next step. I usually do independent projects after AP along with final presentations, but I stumbled upon this activity the other day and my mind exploded in excitement and thought I would share. In the future, I would definitely do this with my students!

Renewable energy is all over the news now, and rightly so: it is vital necessity for the growing energy needs of our society. There are a variety of solar cells both on the market and in research. A chart of record efficiencies as put together by the National Renewable Energy Lab in Golden, CO will give you the sense of the scope of work being performed all over the world.

The specific mechanism of operation varies greatly based upon material. For instance, in a silicon solar cell, p-type and n-type silicon are sandwiched together. In emerging photovoltaics (PV), there are multiple layers of material. All of this is to create a system that allows current to flow in one direction (create a diode).

In general, a dye-sensitized solar cell (DSSC) works analogously - electrons must flow in one direction to make a current. Light goes in and is absorbed by a dye. This creates an Coulombically-bound electron-hole pair (exciton) (a hole is simply the absence of an electron). The exciton diffuses and eventually splits. This leaves a hole (cation dye) behind and an electron that travels through titania (TiO₂). The architecture of the device allows for electrons to flow in one direction through the circuit while at the same time, hole (cation dye) regains an electron via a redox reaction with iodide. Once you have regenerated the neutral dye, this cycle can happen over and over again with electrons flowing through a circuit. A much better explanation (with pictures!) can be found here and here.

What dye will you use with your students? Raspberry juice. Yep, raspberries. The original source for fabrication and testing with undergrads/high school students is found in a 1998 J. Chem. Ed. article written by Grätzel himself, one of THE pioneers in DSSC (and other photovoltaics). Here is a 2013 J. Chem. Ed. (Subramanian et. al.) article to source needed TiO₂ from toothpaste. Subramanian et. al. were kind enough to put the fabrication in the supporting information, which is free to all. Here is yet another prep from the University of Wisconsin-Madison, and their great youtube video to help visualize the fabrication of devices and testing. However, the link they cite to purchase kits does not work, so if you have the means, you can purchase kits with all the supplies from Arbor Scientific (who recommends blackberries...why not test raspberries and blackberries to see which creates the highest voltage cell?).

As I said, my mind is exploding with project ideas for students to engage as creative scientists after the AP exam. Source of TiO₂ (toothpaste method vs. purchased vs. other TiO₂ source)? Raspberries vs. blackberries vs. just a dye you have lying around the lab, like crystal violet? Concentration (or number of drops) of iodine (used to supply electrons via redox reaction your students likely saw prepping for AP exam)? I would have all of my students fabricate and test the original raspberry cell and then have them choose a variable to test so every group gets something that works.

In short, please respond below if you have done this with your students and how it went.

• Materials, supplies, background information and information on preparing the paste can be found on the MRSEC Education Group website.
• A kit that contains the supplies (conductive glass, nanocrystalline TiO₂, binder clips, KI electrolyte, manual, etc.) to create five titanium dioxide raspberry solar cells can be ordered from the Institute for Chemical Education. The kit contains enough nanocrystalline titanium dioxide to be used many times.
• The preview graphic is adapted with permission from Demonstrating Electron Transfer and Nanotechnology: A Natural Dye-Sensitized Nanocrystalline Energy Converter, Greg P. Smestad and Michael Gratzel, Journal of Chemical Education, 199875 (6), 752. DOI: 10.1021/ed075p752. Copyright 1998 American Chemical Society. Figure 4. Assembled solar cell or detector showing offset glass plates, clips, and elec- trical contact points. The stained TiO₂ layer is in contact with the carbon-coated conductive layer. Light enters the sandwich through the TiO₂-coated glass plate, which is the anode of the electro- chemical device.

Sources are noted within the text above and here as well:

1. http://education.mrsec.wisc.edu/289.htm; https://www.youtube.com/watch?v=Jw3qCLOXmi0

2. Gratzel, et. al., 1998: http://pubs.acs.org/doi/pdf/10.1021/ed075p752

3. Subramanian, et. al. 2013: http://pubs.acs.org/doi/pdf/10.1021/ed3001232

4. A. Gleue's website, accessed 5/3/2017: http://teachers.usd497.org/agleue/Gratzel_solar_cell%20assets/How%20does...