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KMID : 1059520100540040479
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Journal of the Korean Chemical Society
2010 Volume.54 No. 4 p.479 ~ p.486
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Analysis of High School Science Textual Descriptions of Scientifically Debatable Compounds According to the Experimental Results by MBL: A Case Study of Carbonic Acid in Water and Aqueous Solution of Carbon Dioxide
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Jeoung Jee-Young
Min Kyeong-Jin
Chae Hee-Kwon
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Abstract
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The purposes of this study are to investigate the description of scientifically debatable carbonic acid in the Korean high school textbooks, characterize the physical properties of ’carbonic acid solutions’ by using an MBL set-up and compare the properties with textual ones. Four different aqueous solutions of carbon dioxide have been prepared and analyzed: naturally aerated aqueous solution, dry ice-dissolving solution, CO₂ -bubbling solution and commercial carbonic acid water. Experimental findings showed that pH and conductivity of these 4 solutions ranged from 3.85 to 5.66 and from 0.21 ㎲/cm to 272.1 ㎲/cm, respectively. Out of these solutions, the dissociation constant(Ka₁) of the bubbling solution at room temperature could be calculated to 5.7×10^-7 which value is comparable to the textual 4.3×10^-7 within experimental errors, which means that textual compound is not pure carbonic acid but the equilibrated mixture of carbonic acid and the aqueous solution of carbon dioxide. On the other hand, textual analysis showed that most of high school textbooks used carbonic acid as an example of weak acid and buffer solution of the blood but none of them distinguished the carbonic acid from the aqueous solution of carbon dioxide. Only one textbook, however, tiered two species in the chemical equation.
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KEYWORD
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Carbonic acid, Aqueous solution of carbon dioxide, Science textbook
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