Marina Stojanovska, Bojan Šoptrajanov, Vladimir M. Petruševski


The easy oxidation of the substances containing aldehyde groups using a mild oxidizing agents, such as solutions containing copper(II) or silver(I) ions, can provide a mean to detect the presence of carbohydrates known as reducing sugars. However, using such tests, it is not possible to distinguish between aldoses and ketoses because the alkaline conditions in the reaction system lead to tautomerization of the α-hidroxyketone and immediate oxidation of the product so that both glucose and fructose will react with the oxidizing agents (the Tollens’ and Fehling’s reagents). In fact, the reaction of fructose is even faster than that of glucose. A misinterpretation or simple neglect of these experimental facts is present in some textbooks in the Republic of Macedonia and this influences the chemistry teaching by creating misconceptions among students and teachers.


misconceptions; monosaccharides; Tollens’ and Fehling’s reagents; reducing sugars; chemistry teaching

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Cambridge Dictionaires Onlilne, 2012, retrieved from http://dictionary.cambridge.org/dictionary/british/misconception (26 July 2013).

H. D. Barke, A. Hazari, S. Yitbarek, Students’ misconceptions and how to overcome them, in: Misconceptions in Chemistry. Addressing Per-ceptions in Chemical Education, Springer-Verlag, Berlin, 2009, pp. 21–36.

C. Horton (with other members of the Modeling Instruction in High School Chemistry Action Research Teams at Arizona State University), Student Alternative Conceptions in Chemistry, 2007, retrievedfrom http://www.scribd.com/doc/52664732/student-alternative-conceptions-in-chemistry (26 July 2013).

V. Kind, Beyond Appearances: Students’ Mis-conceptions about Basic Chemical Ideas (2nd edition), Durham University, Durham, 2004.

K. S. Taber, Chemical Misconceptions – Prevention, Diagnosis and Cure; Part 1 – Theoretical Back-ground, Royal Society of Chemistry, London, 2002.

K. S. Taber, Chemical Misconceptions – Prevention, Diagnosis and Cure; Part 2 – Classroom resources, Royal Society of Chemistry, London, 2002.

M. Stojanovska, The Occurrence of Erroneous Notions in Textbooks and Chemistry Teaching in Macedonia and Possibility for Their Elimination, Ph.D. thesis, SS. Cyril and Methodius University, Skopje, 2013.

S. Aleksovska, K. Stojanovski, Chemistry for the 3rd year of Reformed Gymnasium Education, Prosvetno delo, Skopje, 2003, p. 155 (in Macedonian).

S. Aleksovska, K. Stojanovski, Chemistry for the 4th year of Reformed Gymnasium Education, Prosvetno delo, Skopje, 2005, p. 42 (in Macedonian).

S. Aleksovska, Chemistry for the 8th grade of Eighth-year Secondary Education, Ministry of Education and Science of Republic of Macedonia, Skopje, 2010, p. 113 (in Macedonian).

P. S. Bailey, C. A. Bailey, Carbohydrates, in: Organic Chemistry: A Brief Survey of Conceptsand Applications (6th edition), Prentice Hall, New Jersey, USA, 2000, pp. 313–329.

W. Reusch, Virtual Text of Organic Chemistry, 1999, retrieved from http://www2.chemistry. msu.edu/faculty/reusch/VirtTxtJml/intro1.htm#contnt (26 July 2013).

R. J. Ouellette, Organic Chemistry: A Brief Intro-duction, Prentice Hall, Englewood Cliffs, NJ, 1994, pp. 384–386.

P. Keusch, Fehling’s test for reducing sugars, retrieved from http://www.demochem.de/D-Fehling-e.htm (27 December 2012).

B. Šoptrajanov, B. Podolešov, K. Stojanovski, I. Spirevska, L. Šoptrajanova, Chemistry for the 4th year of Gymnasium Education, Prosvetno delo, Skopje, 1993, p. 117 (in Macedonian).

M. Sikirica, K. Holenda, Carbohydrates, in: Chemistry through Investigation, 8, 2000, retrieved from http://eskola.chem.pmf.hr/udzbenik/u45/15%20ugljikohidrati.pdf (in Croatian, 26 July 2013).

M. Monković, V. Ivanovski, V. M. Petruševski, Demonstrations as a tool for ironing-out mis-conceptions: 3. A note on the reaction Pb2+(aq) + 2I–(aq) = PbI2(s): Exceptions from a priori expectations, Aust. J. Ed. Chem., 68 (2007), pp. 17–19.

M. Stojanovska, V. Petruševski, Comment on "Spectator ions ARE important! A kinetic of the copper–aluminium displacement reaction", J. Chem. Educ., 88 (2011), p. 16.

M. Stojanovska, V. M. Petruševski, B. Šoptrajanov, The concept of sublimation – iodine as an example, Educ. quím., 23 (2012), pp. 171–3a F.

M. I. Stojanovska, V. M. Petruševski, B. T. Šoptrajanov, On the existence of hydrogen salts of

monoprotic acids, J. Chem. Educ., 89 (2012), pp. 1168–1170.

V. Petruševski, M. Stojanovska, B. Šoptrajanov, Are all types of sublimation equivalent?, Chem. Educator, 17 (2012), pp. 98–99.

M. I. Stojanovska, B. T. Šoptrajanov, V. M. Petruševski, Addressing misconceptions about the particulate nature of matter among secondary-school and high-school students in the Republic of Macedonia, Creative Educ., 3 (2012), pp. 619–631.

M. I. Stojanovska, V. M. Petruševski, B. T. Šoptrajanov, Addressing students’ misconceptions concerning chemical reactions and symbolic representations, Chemistry: Bulg. J. Sci. Educ., 21 (2012), pp. 829–852.

K. Stojanoski, O. Trenčevska, Laboratory Tutorial for Biochemistry I Course, Ss. Cyril and Methodius University, Skopje, 2009, pp. 73–75.

K. Smith-Gratto, Toward Combining Programmed Instruction and Constructivism for Tutorial Design, Cameron University, Lawton, OK, 2012.

B. Mitrevski, O. Zajkov, Physics Lab, Critical thinking and gender differences, 9th Conference of the Society of Physicists of Republic of Mace-donia, Ohrid, Republic of Macedonia, 2012.

N. Krstevska, O. Zajkov, To click or not to click, that is the question, 9th Conference of the Society of Physicists of Republic of Macedonia, Ohrid, Republic of Macedonia, 2012.

DOI: http://dx.doi.org/10.20903/csnmbs.masa.2013.34.1-2.40


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