Acid–Base Poker: A Card Game Introducing the ... - ACS Publications

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Acid−Base Poker: A Card Game Introducing the Concepts of Acid and Base at the College Level Xuemei Zhang* Neuroscience Research Institute and Department of Cellular Molecular and Developmental Biology, University of California at Santa Barbara, Santa Barbara, California 93106, United States S Supporting Information *

ABSTRACT: A card game has been developed to illustrate acids and bases to first-year general chemistry students. The game offers an enjoyable method to practice categorizing acids and bases. In this game, which is adapted from Texas Hold’em, a player uses his/ her knowledge of the properties of acids and bases to try to make the highest possible rank with five cards. The game can be used as a method to engage students at an early stage of chemical education, providing a different perspective from the textbook and a broad view of the acid−base properties of chemical compounds. This game sparked interaction and communication during a classroom trial, and suggests that card games can be an effective and entertaining way to help college students learn some aspects of general chemistry. KEYWORDS: First-Year Undergraduate/General, Second-Year Undergraduate, Interdisciplinary/Multidisciplinary, Acids/Bases, Humor/Puzzles/Games

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INTRODUCTION

way of teaching through enhancing problem-solving skills in lectures and discussion sessions has been quite successful.

In the early stage of chemical education, making sure that students are engaging in the topic is crucial to sustain the learning effort. Some students lose confidence because, as they reflected, “college classes are really hard and much more in depth compared to high school classes”.1 A more enthralling approach is apparently needed in college-level teaching to facilitate the learning of abstract material and sustain students’ interest. In recent years educational games have been adopted by many educators at the college level to tackle the difficulties they encounter in the classroom. Various chemistry games rooted deeply in specific areas of chemistry have been previously presented in this journal.2−7 Retrosynthetic Rummy3 displays the scope of total synthesis and the various types of reactions in a clear and fun way. Memorizing the members of the groups on the periodic table would otherwise prove to be a substantial effort without introducing ChemPoker.2 Most importantly, these games were met with more engagement, more enjoyment, and a better learning experience than the routine teaching process.8 Here, a card game resembling Texas Hold’em poker has been developed in an effort to teach students the concept of acids and bases at the college level. The topics chosen here are typically taught in the second semester of second-year general chemistry.9 What is not covered in this game, although also important in this part of the course, is the calculation of chemical equilibrium, ion concentrations after hydrolysis, and pH values of aqueous solutions; in these matters, the traditional © XXXX American Chemical Society and Division of Chemical Education, Inc.

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DESIGN OF THE DECK The deck for Acid−Base Poker is based on the design of a standard 54-card deck used for any typical card game. In place of the standard sequence from ace to king, molecules and ions are ordered according to their acid or base strength as indicated by the negative logarithms of their acid or base dissociation constants, i.e., by their pKa or pKb values. The standard suits, diamonds, hearts, spades, and clubs, represent the different acid−base categories: weak acids, strong acids, strong bases, and weak bases, respectively (Figure 1). Thus, acids are red, and bases are black. Each suit comprises six molecule cards and six ion cards. Additionally, the deck also contains four common material cards, lemon, gastric juice, 4% NaOH, and milk of magnesia, to which the player assigns a suit. On the common material card, the suit is not given and will be decided according to the player’s knowledge of the material. An ion card shows one of the ions formed from the dissociation of a molecule card substance (or HCO3−). For example, the acetate ion (clubs), a weak base, is the conjugate base of acetic acid (diamonds), a weak acid. Two subsuits, the empty heart and empty, upsidedown spade, were introduced to represent the neutral ion Received: August 4, 2016 Revised: February 27, 2017

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DOI: 10.1021/acs.jchemed.6b00590 J. Chem. Educ. XXXX, XXX, XXX−XXX

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products from the ionization of strong bases and acids, respectively.

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THE CARDS The cards are 3.0 in. × 2.25 in. and can be made by the class instructor. The cards’ templates may be printed in color on cardstock and cut out. Instructions and materials are provided in the Supporting Information. Each card except the jokers and the common materials contains a formula/symbol, a suit, a structural formula (if appropriate), and a name. The suit is to help students to align the acid−base category. Red represents acids, with hearts for strong acids and diamonds for weak acids. Black represents bases, with spades for strong bases and clubs for weak bases. For a more difficult game, a version without the suit printed on the card is also provided. In Table 1 and on the card summary (Supporting Information, page 2), the pKa10 and pKb11 values of weak acids and bases are presented in parentheses in red and black colors, respectively. All strong acids and bases here are

Figure 1. Suits for Acid−Base Poker, showing one example from each suit.

Table 1. Ranking of Hands in Acid−Base Poker

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DOI: 10.1021/acs.jchemed.6b00590 J. Chem. Educ. XXXX, XXX, XXX−XXX

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Goal of the Game

assumed to completely ionize; therefore, no pKa and pKb values are given. Poker games use face value to compare two sets of cards that are of the same ranking; here, pKa and pKb are used for this purpose. The more the weak acid or weak base undergoes hydrolysis, the smaller the value of pKa or pKb, and the higher its card ranks. Strong acids/bases are treated as being of equal strength to each other, but ranking higher than the weak acids/ bases.

Players can just keep track of the rounds they won in the simple play; they can collect tokens or small items, such as pennies used for betting, in the advanced play. At the end of the game, the winner of the game may get a special reward from the teacher.

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RANKING The best hands will be made by using cards in hand and the five cards in the middle to make the best possible five-card poker hand. Poker hands ranking from 2 pairs of conjugate acid−base pairs (the highest) to 4 alike (all acids or all bases or all pHneutral ions; the lowest) are shown in Table 1.

Arguable Cards

A few of the polyprotic acids and their deprotonation products are included in the cards: H2CO3, H2SO4, H2SO3, and H3PO4. The polyprotic aspect is fully acknowledged in the case of H2CO3: Four cards are present in the game that reflect the two steps of hydrolysis of H2CO3−H2CO3 (diamonds), two cards of HCO3− (one clubs, one diamonds), and CO32− (clubs). H2SO4 (hearts) is completely ionized to SO42− (empty hearts). Only the first step in the dissociation of H2SO3 and H3PO4 (both diamonds) is taken into account, resulting in the conjugate bases HSO3− and H2PO4− (both clubs). However, a player may use these cards to suit his/her advantage: For example, the HSO3− and H2PO4− ion cards may be used as red diamonds (housing weak acids), as the pKa of each is 7.2 and 7.21.

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THE EVALUATION Acid−Base Poker has been played in the discussion sessions of a general chemistry class consisting of mainly second-year and third-year students with chemistry, biochemistry, biology, and kinesiology backgrounds. The course focuses on the kinetics and equilibrium of chemical reactions; acids, bases, and buffers are essential parts of the course. There were 68 students registered for the class, and these students were split into two discussion sessions. Acid−Base Poker was played for 50 min in the discussion sessions, during which the students were organized in groups of 3−4. All of the students in the trial were engaged, and made an effort to win the game. The game was quite challenging as it requires the understanding of the core concepts of acids and bases and also the chemical structures of them and their relation to their acidity and basicity. The combinations of cards may become very interesting and totally unexpected, igniting exciting discussions among the students and creative ideas in order to win. For example, in one case, a group of students attained a conjugate acid−base pair of CH3CH2NH2 and CH3CH2NH3+, and they had also two other bases, H2PO4− and NH3, in the cards available for their hand. However, since CH3CH2NH2 was being used in the conjugate acid−base pair, it could not be used for a set of three bases. After some discussion, they found out that they could take H2PO4− as an acid (loses one proton to give HPO42−); therefore, they could form a set of three acids because they had two other acids in their hand. In another case, a student had two cards, nitrate (empty, upside-down spades) and ethylamine (clubs, pKb 3.35), in his hand; his opponent had another two cards, iodide (empty, upside-down spades) and pyridine (clubs, pKb 8.77). Shared by both of them were five cards: hydrogen carbonate (clubs, pKb 7.65), benzylaminium (diamonds, pKa 9.34), formic acid (diamonds, pKa 3.75), and sodium hydroxide and potassium hydroxide (both spades). The student thought they would tie at level 1, i.e., 4 alike (all bases). Only after a reminder from a thoughtful classmate did he realize he could actually achieve level 4, the pH-neutral salts. Since the arithmetic difference between the pKa of the cation and the pKb of anion is smaller than 2.00 (see Table 1, level 4), the resulting salts, benzylaminium hydrogen carbonate and ethylaminium formate, are both considered pH-neutral. His opponent was not so lucky: Pyridine (pKb 8.77) is a much weaker base than ethylamine (pKb 3.35), and it will not give a pH-neutral salt pairing with formic acid (pKa 3.75).

Joker

To increase the chances of making a hand, a joker can be used as a substitute for a missing card of the claimed rank, except for making a conjugate acid−base pair. However, hands made with one or both jokers are lower in rank than the corresponding “natural” hand.

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GAMEPLAY The rules of the poker game are based on those of Texas Hold’em.

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OBJECT OF THE PLAY The object of the game is to get the highest possible ranking of five cards using the ones from a player’s own hand and the shared cards.

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THE RULES OF PLAYING One deck should be used for four to six players. Depending on the setting, a simple way or an advanced way can be chosen by the players. Simple Play

The dealer shuffles the deck, deals 2 cards to each player, and places five cards face-up in the center as the shared cards. The player who has the highest hand combination wins the round. Advanced Play

Betting is involved and follows Texas Hold’em poker rules.12 Briefly, the dealer deals 2 cards to each player. This is then followed by a round of betting in which a player can check, bet, or fold. When all the betting has finished, three shared cards are dealt face-up in the middle of the table. After a second round of betting, a fourth shared card is dealt. This is then followed by a third round of betting after which a final shared card is placed face-up in the middle. After a final round of betting, the remaining players show their hands. C

DOI: 10.1021/acs.jchemed.6b00590 J. Chem. Educ. XXXX, XXX, XXX−XXX

Journal of Chemical Education

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As demonstrated above, the game is very versatile and makes the learning of concepts and structures of acids and bases really fun for students, especially for those not majoring in chemistry. Usually after the game, students were comfortable talking about not understanding some aspect of playing the game (which required certain chemical knowledge); this discussion made it easier for the teacher to identify the learning barrier and guide them over it. Through one open discussion, the lecturer realized that some students needed help to appreciate and distinguish the macroscopic and submicroscopic ways of thinking commonly used in chemistry. For example, “substance” is a macroscopic concept, and “molecule” is a submicroscopic one.13,14 In this game, a substance is classified according to its phenomenological properties, strong acid, weak acid, strong base, weak base, or neutral, which are at the macroscopic level of consideration; however, at the submicroscopic level, the acid−base properties of molecules and ions can be interpreted on the basis of the Lowry−Brønsted model. For instance, in the Lowry−Brønsted model, an ion such as NH4+ will participate as the conjugate acid of the base NH3 because NH3 can accept a proton. Nevertheless, according to the Arrhenius model, NaOH is a base because it has increased the concentration of OH− ions in an aqueous solution of that substance. As a result, the concepts of strong/weak acid−base and the differences between different approaches, especially the Arrhenius and Lowry−Brönsted models, become clearer to the students after the lecturer’s thoughtful emphasis subsequent to an exciting poker game. As a versatile learning tool, this game can also be used in different settings. When this game was given to a group of 7year-olds, they used it as a matching game finding the ionized pairs. This game could plant a very early seed in learning chemistry with a brief explanation of the game, such as the basic concepts of acids and bases, ionization, formulas, chemical structures. These concepts are not as common to encounter as other physics/chemistry concepts, such as temperature, speed, and force, for this young age group.

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CONCLUSION

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ASSOCIATED CONTENT

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Xuemei Zhang: 0000-0003-3238-2376 Notes

The author declares no competing financial interest.

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ACKNOWLEDGMENTS The author would like to thank Albert Miao in Dos Pueblos High School, Santa Barbara, for inspiring the authors, testing the game, and proofreading the paper; Maosheng Miao in the Department of Chemistry and Biochemistry, California State University, Northridge; and the students in his general chemistry class for the evaluation of the game. The author also wants to thank the reviewers for their insights, discussions, and suggestions which improved this paper to its current state.

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REFERENCES

(1) Appleby, D. C. How do college freshmen view the academic differences between high school and college? Psychology Teacher Network 2014, 24 (2), 1−3−5. (2) Kavak, N. ChemPoker. J. Chem. Educ. 2012, 89 (4), 522−523. (3) Carney, J. M. Retrosynthetic Rummy: A Synthetic Organic Chemistry Card Game. J. Chem. Educ. 2015, 92 (2), 328−331. (4) Kurushkin, M.; Mikhaylenko, M. Chemical Alias: An Engaging Way To Examine Nomenclature. J. Chem. Educ. 2015, 92 (10), 1678− 1680. (5) Franco-Mariscal, A. J.; Oliva-Martínez, J. M.; Almoraima Gil, M. L. Students’ Perceptions about the Use of Educational Games as a Tool for Teaching the Periodic Table of Elements at the High School Level. J. Chem. Educ. 2015, 92 (2), 278−285. (6) Franco Mariscal, A. J.; Oliva Martínez, J. M.; Bernal Márquez, S. An Educational Card Game for Learning Families of Chemical Elements. J. Chem. Educ. 2012, 89 (8), 1044−1046. (7) Russell, J. V. Using Games To Teach Chemistry: An Annotated Bibliography. J. Chem. Educ. 1999, 76 (4), 481−484. (8) Faust, J. L.; Paulson, D. R. Active learning in the college classroom. Journal on Excellence in College Teaching 1998, 9 (2), 3−24. (9) Contents refer to Chapter 15, “Acids and Bases”, in the following textbook: Tro, N. Chemistry: A Molecular Approach, 3rd ed.; Pearson Education Ltd.: NJ, 2013. Concepts introduced in Chapter 15 include the following: the nature and definition of acids and bases (sections 15.2 and 15.3), acid strength and acid ionization constants (section 15.4), base solutions (section 15.7), the acid−base properties of ions and salts (section 15.8), polyprotic acids (section 15.9), and acid strengths and molecular structures (section 15.10). (10) The pKa values are given according to the pKa table in CRC Handbook of Chemistry and Physics, 84th ed.; Lide, D. R.; CRC Press LLC: Boca Raton, 2003. (11) The pKb values are given on the basis of the rule that the sum of the pKa and pKb of a conjugate acid−base pair consisting of a weak acid and a weak base must always be equal to 14.00 at 25 °C. (12) How to Play Texas HoldEm PokerHands and Rules. https:// www.partypoker.com/how-to-play/texas-holdem.html (accessed Jan 2017). (13) Treagust, D.; Chittleborough, G.; Mamiala, T. The role of submicroscopic and symbolic respresentations in chemical explanations. Inter. J. Sci. Educ. 2003, 25 (11), 1353−1368. (14) Furió-Más, C.; Calatayud, M. L.; Guisasola, J.; Furió-Gómez, C. How are the Concepts and Theories of Acid-Base Reactions Presented? Chemistry in Textbooks and as Presented by Teachers. Inter. J. Sci. Educ. 2005, 27 (11), 1337−1358.

The designed game provides a complementary teaching method besides the instructor-led lectures. It helps the students to associate the basic concepts of acids/bases with exemplar compounds in an entertaining environment. After getting to know the basic rules of poker, students can actually gain the habit of critical thinking in connection with acids and bases; a practice of critical thinking helps to plant seeds for further interest in more advanced chemistry. The game can be used as a refreshing tool for third-year organic and biochemistry classes, where pKa and pKb values may be important in the choice of reagents for an organic reaction as well as for understanding the functioning of amino acid side chains.

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.6b00590. Text explanation of the ranking, the fronts and back of the cards, and a one-page sheet of all the cards in the deck (PDF) (DOCX) D

DOI: 10.1021/acs.jchemed.6b00590 J. Chem. Educ. XXXX, XXX, XXX−XXX