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Conception, threshold concepts and troublesome
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Published under licence by IOP Publishing Ltd International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
1






Conception, threshold concepts and troublesome knowledge in
chemical reactions topic
A M Ulfa
1*
, W Wiji
1
, and S Mulyani
1

1
Departemen Pendidikan Kimia, Sekolah Pasca Sarjana, Universitas Pendidikan
Indonesia, Jl. Dr. Setiabudi No. 229, Bandung 40154, Indonesia

*
Corresponding author’s

email: [email protected]
Abstract. This study aims to analyze the conception, threshold concept, and troublesome
knowledge in chemical reaction topic. This study uses qualitative methods, document analyses,
as well as interviews with chemistry teachers to obtain information about threshold concepts and
troublesome knowledge. From the results of the analysis of several journals obtained that there
were still many misconceptions encountered when students study chemical reactions. While the
results of the interview, threshol concept in chemical reaction consisted of mixtures, physical
and chemical properties, material changes, concepts of protons and electrons, electron
configurations, chemical bonds, intermolecular forces, attractive forces between charges,
compound nomenclatures, chemical formulas, and Lavoisier's laws. While troublesome
knowledge includes complexity of particles involved, complexity of interactions that may occur,
complexity of applying Lavoisier's Law, and language used.
1. Introduction
A chemical reaction is one concept that is the basis for further learning chemistry because almost all
chemical matter always involves chemical reactions. By understanding the concept of chemical
reactions students can understand the phenomena that occur around them, for example, photosynthesis,
the combustion process, iron solidification, even the digestive processes that occur in the human body.
At the beginning of the chemistry learning process, students are introduced to the concept of chemical
reactions, usually by the way students carry out their chemical reactions or through teacher
demonstrations. However, the reason why chemical reactions occur in general is not at all considered,
students are only introduced to the nature of chemical bonds and related ideas of chemical energy [1].
For students to understand chemical reactions, they must distinguish between concepts such as
elements, compounds, mixtures, atoms and molecules. Besides, they must also recognize changes in
material form and understand that atoms are rearranged to form new substances with different chemical
properties [2]. To understand the material in chemistry learning, students need to connect the three levels
of chemical representation. Students' ability to connect the three levels of chemical representation
reflects the mental models that students have [3]. Mental models are defined as simple representations
of ideas in a person's mind that are used to describe and explain a phenomenon [4]. Students use mental
models to reason, describe, explain, predict phenomena, test new ideas, and present data based on the
knowledge they have to communicate it to others or solve problems in learning chemistry [5,6]. When
students can connect the three levels of chemical representation to a concept, students have a complete
mental model.

International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
2






For students to have a complete mental model, the teacher needs to improve the learning strategy
continuously. The right learning strategy can be obtained by analyzing the advantages and disadvantages
of the learning strategies that have been done before. Based on the results of the analysis, the teacher
can find out what conception students have in learning material. While based on conceptual
characteristics, a teacher must analyze what is the threshold concept of the concept that students will
learn and what can potentially be trouble (troublesome knowledge) in learning the concept. So the
purpose of this study is to find out conceptions, threshold concepts, and troublesome knowledge in
chemical reactions from various studies that have been done before and from the teaching experience of
chemistry teachers.
2. Method
This study used qualitative methods including document analysis such as journal articles. Several
conception journals, threshold concepts and troublesome knowledge related to chemical reactions were
analyzed. In addition, this study also conducted interviews with four chemistry teachers to get more
information related to threshold concepts and troublesome knowledge. Chemistry teachers interviewed
were teachers who were or had taught chemical reaction in class. The teacher is given questions that
will reveal what are the threshold concepts and troublesome knowledge in chemical reaction. In addition,
the teacher is also asked to explain the reasons for the answers. The next step is to make a transcript of
interview result. For troublesome knowledge, from some of the teacher's answers are categorized into
six categories of troublesome knowledge, namely ritual knowledge, inert knowledge, conceptually
difficult knowledge, alien knowledge, tacit knowledge, and troublesome language.
3. Result and Discussion
3.1. Conception in chemical reactions
According to Duit [7], conception is a mental representation of outside world characteristics or
theoretical domains. Conception is a manifestation of one's interpretation of an object being observed
which often even appears before learning, so it is often termed pre-learning conception. The conception
that will be discussed in this article consists of conceptions that are following scientific concepts (the
appropriate concepts) and concepts that are not by scientific concepts (misconceptions) in chemical
reactions. Conception was identified from several research articles that had been done before. Research
conducted by Ahtee and Varjola [2] found that students provide answers that include at least one
component that shows a good understanding of chemical reactions, namely atomic reorganizations,
breaking and reformation of bonds, and changes in physical or chemical properties. Few students can
properly explain the meaning of chemical reactions. Meanwhile, according to Yarroch [8] half of the 14
students he interviewed could correctly explain the relationship of atoms in a molecule (using a circle
representing an atom). Research conducted by Chandrasegaran [9] found that students could correctly
mention the symbol of an atom. In addition students can also explain that the change in color occurs due
to the formation of new compounds. Most students can also write each substance on the reactants and
products in the same amount, this shows that students understand about Lavoisier's Law. Students can
also write net ionic equations correctly without involving the spectator ion in them.
Research on wrong concepts or misconceptions about chemical reactions has been carried out by
experts. Chandrasegaran et al. [9] show there are 14 misconceptions in chemical reaction because
students are still confused in macroscopic and submicroscopic representations. Students tend to guess
to predict substances at the macroscopic level to submicroscopic levels, and limited understanding in
the representation of symbolic levels. Then when writing the chemical equation Yarroch [8] examined
that of the 14 high school students he interviewed, only half were able to represent the arrangement of
atoms in the molecule correctly. Although students can write chemical equations and equate equations
correctly but do not understand the meaning of these particles. This shows that new students can
understand chemistry at the macroscopic and symbolic level, whereas for the submicroscopic level they
have not been able to analyze and interpret it. Baah and Ampiah [10] identifies the inability of students

International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
3






to balance combustion reaction equations involving hydrocarbons, the inability of students to predict
the correct product of the reaction due to difficulties in writing the correct formula of the product and
the inability of students to translate reactions in the form of statements in symbol equations.
Katmiati's research [11] revealed several misconceptions that occur in chemical reactions, namely
molecules and compounds formed from cations and molecules, polyatomic ions decompose into smaller
particles and mistakenly write down ion charges and chemical formulas of a compound. This is in line
with the research conducted by Hasanah [12]. She added several misconceptions that occur in chemical
reactions, including cations that bind to positively charged atoms and anions will bind to negatively
charged atoms, products of aqueous or solids (precipitation) are present as ions, and ionic compounds
in solids are present in the form of the molecule.
3.2. Threshold concept in chemical reactions
Threshold concepts can be considered a concept similar to gates, opening up new ways of thinking about
subjects that were previously inaccessible and potentially becoming difficulties for students [13,14].
Threshold concepts in chemical reactions were identified from interviews with four chemistry teachers
(can be seen in Table 1). Information obtained from interviews with chemistry teachers based on
teaching and learning experiences that the threshold concepts for chemical reactions are concept of
mixtures, physical and chemical properties, material changes, concepts of protons and electrons,
electron configurations, chemical bonds, forces between molecules, attractive forces between charges,
compound nomenclatures, chemical formulas, and Lavoisier's law.
Table 1. Threshold concepts in chemical reactions based on interviews with teachers

The first teacher said that the concept of mixtures, physical and chemical properties, and material
changes had been studied by students during junior high school. In the learning concept of mixtures, the
teacher will usually explain solvents, solutes, and various phases of compounds. So when the teacher
gives examples of compounds in chemical reactions such as NaCl(aq), students will understand that
water is a solvent and NaCl as a solute. The third teacher reveals when students understand changes in
physics and chemistry, students can find out what changes occur in a reacted compound. For example,
the occurrence of chemical changes can be seen from several observable changes such as color changes,
gas formation, the formation of precipitations and changes in temperature. So when shown a chemical
reaction that produces precipitations, students can imagine what a chemical reaction might be. Also, by
understanding the nomenclature of compounds and chemical formulas students can formulate chemical
formulas which will be written in the reaction equation.
The second teacher reveals that students must understand the concepts of protons and electrons to
determine the number of protons or electrons in the number of ions. Besides, students must also
understand electron configurations so students can determine the number of valence electrons in an
element. Because to react to an element or compound, students must know in advance the number of
electrons in the valence of these elements. Another concept that becomes the threshold concept in a
chemical reaction is chemical bonds. Students must understand chemical bonds to determine the
characteristics of compounds when dissolving or settling or forming gases. Also, to find out whether a
compound breaks down into ions or forms molecules and also understands the charge of each atom or
element in forming a bond. Students must understand that a compound is formed due to the presence of
Teacher Threshold Concept
Teacher 1 Concept of mixtures, physical and chemical properties, material
changes
Teacher 2 Concept of protons and electrons, electron configurations,
chemical bonds, forces between molecules, attractive forces
between charges
Teacher 3 Physical and chemical properties, compound nomenclatures,
chemical formulas
Teacher 4 Compound nomenclatures, Lavoisier's law

International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
4






chemical bonds, this bond is due to the attraction of the atoms in the molecule. If this force is disturbed
or given activity, a chemical reaction will occur.
In addition to some of the concepts above, the fourth teacher reveals that students must also
understand Lavoisier's Law before studying chemical reactions. Because when students equate the
reaction equation, students must know that the number of atoms contained in the compound before and
after the reaction or in the reactants and products must be the same as the sound of Law Lavoisier. The
results of research on the threshold concept can be used to develop curriculum and teaching materials
so that students do not experience obstacles and difficulties in learning [15,16,17].
3.3. Troublesome knowledge in chemical reactions
Meyer and Land [13] suggest that knowledge that is conceptually difficult or problematic for students
is called troublesome knowledge. Troublesome knowledge in students will be the main obstacle to
learning. Similar to the threshold concept, troublesome knowledge in this study were identified from
interviews with chemistry teachers (can be seen in Table 2). Four chemistry teachers revealed the
troublesome knowledge of chemical reactions consisting of the complexity of possible reactions, the
complexity of the particles involved, the complexity of applying Lavoisier's Law, and the language used.
Table 2. Troublesome knowledge in chemical reactions based on interviews
with teachers
Teacher Troublesome Knowledge
Teacher 1 The complexity of the reactions that occur, the language
used, the complexity of the particles involved
Teacher 2 The complexity of reactions that may occur
Teacher 3 the complexity of applying Lavoisier's Law, the language
used
Teacher 4 The language used
The first teacher revealed that when the teacher gives an example of a simple chemical reaction,
students can understand it. But when the teacher gives examples of more complex chemical reactions,
students experience difficulties. Besides, the complexity of the particles involved in chemical reactions
also causes students to experience troublesome knowledge. For example, when given training to balance
simple reaction equations such as Fe + HCl → FeCl2 + H2, students can complete it. However, when the
particles involved in the reaction are more complex, such as Cu + HNO3 → Cu (NO3)2 + NO + H2O,
students experience difficulties.
Furthermore, the second teacher said that when a chemical reaction involves large compounds, for
example, K2Cr2O7 is reacted with other reactions, students are confused to determine the results of the
reaction that occurs. However, the second teacher revealed that the language used does not have the
potential to be troublesome knowledge for students in studying chemical reactions. According to the
third teacher, troublesome knowledge in chemical reactions is the complexity of applying Lavoisier's
law. Students have difficulty in equalizing product and yield coefficients involved in chemical reactions.
In addition to the three things above, the fourth teacher revealed the language used could potentially
become troublesome knowledge for students when studying chemical reactions. The number of
compounds that are not yet known to students who use scientific language is a difficulty for students
when they have to change it into a chemical formula or from a chemical formula into the name of the
compound. The four things above can cause students to experience misconceptions when studying
chemical reactions. Therefore, research on troublesome knowledge can be useful for teachers to
determine strategies, media, and appropriate teaching materials. Inappropriate learning strategies can
cause discrepancies between what the teacher teaches and what students learn [18].
4. Conclusion
Concepts that are following scientific concepts (the appropriate concept) in chemical reactions are an
atomic reorganization, bond breaking and reformation, and changes in physical or chemical properties.

International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
5






While misconceptions consist of molecules and compounds formed from cations and molecules,
polyatomic ions decompose into smaller particles, mistaken in writing ion charges and chemical
formulas of a compound, cations will bind to positively charged atoms and anions will bind to charged
atoms negative, products aqueous or solids (precipitations) are present as ions, and ionic compounds in
solids are present in molecular form.
Meanwhile, threshold concepts for chemical reactions are a concept of mixtures, physical and
chemical properties, material changes, concepts of protons and electrons, electron configurations,
chemical bonds, inter-molecular forces, attractive forces between charges, compound nomenclature,
chemical formulas, and Lavoisier's laws. Whereas troublesome knowledge consists of the complexity
of possible reactions, the complexity of particles involved, the complexity of applying Lavoisier's Law,
and the language used.
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3 305-316
[3] Wiji W, Liliasari L, Sopandi W and Martoprawiro M A 2014 Kemampuan Berpikir Logis dan
Model Mental Kimia Sekolah Mahasiswa Calon Guru Cakrawala Pendidikan 147-156
[4] Jansoon N and Coll R K 2009 Understanding Mental Models of Dilution in Thai Students Int. J.
Env. Sci. Educ. 4 2 147-168
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and their understanding of the sub-microscopic level Chemistry education research and
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[6] Wang C Y 2007 The role of mental-modeling ability, content knowledge, and mental models in
general chemistry students' understanding of molecular polarity (Doctoral dissertation,
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[11] Katmiati S 2017 Identifikasi Miskonsepsi, Troublesome Knowledge, dan Threshold Concept
Berdasarkan Profil Model Mental Siswa pada Materi Reaksi Kimia Menggunakan Tes
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[13] Meyer J and Land R 2003 Threshold concepts and troublesome knowledge: Linkages to ways of
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[14] Meyer J H and Land R 2006 Threshold concepts and troublesome knowledge: An introduction.
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[15] Cousin G 2006 An introduction to threshold concepts Section 1 : Introduction to a threshold
concepts An introduction to threshold concepts Planet 1835 4-5
[16] Park E J and Light G 2009 Identifying Atomic Structure as a Threshold Concept: Student mental
models and troublesomeness Int. J. Sci. Educ. 31 2 233–258

International Conference on Mathematics and Science Education 2019 (ICMScE 2019)
Journal of Physics: Conference Series1521 (2020) 042068
IOP Publishing
doi:10.1088/1742-6596/1521/4/042068
6






[17] Male S A and Baillie C A 2011 Engineering Threshold Concepts Proc. SEFI Annu. Conf. 251–
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