10.5923.j.jlce.20170501.03
Journal of Laboratory Chemical Education 2017, 5(1): 9-12
DOI: 10.5923/j.jlce.20170501.03
High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
Zahra Arzani1,*, Hassan Hazarkhani2
1
Office of Teaching and Training, Karaj, Iran
Department of Chemistry, Organization for Educational Research and Planning, Tehran, Iran
2
Abstract Teaching high school chemistry is a difficult task in developing countries. The materials in laboratories should
be cheap and accessible. Moreover, waste recovering systems do not exist in most of these countries. Therefore, it is
imperative to instill in students the habit as well as the need to feel responsible for what waste their activities will produce. In
this manuscript we explain a method to determine the presence of Fe2+ and Cu2+ ions in unknown solutions with cheap
equipment. This can be used to illustrate the Beer–Lambert law and also emphasizes environment protection. Each
experiment takes 2 hours of a group.
Keywords Green Chemistry, High School, Introductory Chemistry, Colorimetry, Hands-On Learning
1. Introduction
It has been shown that teaching chemistry is not very
popular. In fact it could be irrelevant in the eyes of students
which find it difficult to learn [1-4]. Therefore, it is essential
to combine the teaching of chemistry with experiments that
grab students’ attention and excite them about the subject. In
third world countries the problem is exacerbated by the need
for cheap equipment given low budgets and scarce resources
[5]. Furthermore, environment pollution is also a growing
concern causing a lot of problems in the world. Thus, school
chemical experiments should be arranged in a way that is
safer for the environment. Students also should be sensitive
to what will be left after these experiments as waste. It is to
be hoped that as a result, this will become a habit for their
daily activities as well.
In this regards, one of the useful experiment is
microfluidic analysis. Microfluidics is the science and
technology of systems that process or manipulate small
amounts of fluids using channels with dimensions of tens to
hundreds of micrometer [6]. Unfortunately this work is not
well known among high school teachers. There are reports
for different paper-based microfluidic analytical devices
(μPADs) in literature [7-10] but the cheapest and easiest one
is recommend by Wang and at al., [11-13] which can be
used in high school chemistry laboratories. The main
advantage of this method is showing chemistry in real
life with simple equipment and using very small amount of
* Corresponding author:
zarzani2111@yahoo.com (Zahra Arzani)
Published online at http://journal.sapub.org/jlce
Copyright © 2017 Scientific & Academic Publishing. All Rights Reserved
compounds.
Colorimeter and determination of ion concentration in
unknown samples is one of the popular undergraduate
laboratory works in universities. Whereas doing so in high
school, requires expensive spectroscopy equipment.
Potentially, this can be achieved using a form of colorimetry
in which comparisons of depth of color are made by
eyeballing without necessarily using a colorimeter [15]. In
this method, a set of solutions will be prepared and the color
of the unknown tube will be compared with them in order to
find which matches best. Kohl et al. [22] used digital images
of solutions (food dye, sports drinks, and Iron chloride).
Kuntzleman at el. [25] left samples in a cardboard box,
allowed light to pass through it, and used a cell phone as the
light detector. Moreover, Rice at el. [23] also used a cell
phone camera as a simple, low cost experimental technique
for teaching molecular diffusion.
We tried to repeat nitrite ion determination with a paper
microfluidic device which Wang and et al [11] proposed.
However, we encountered two main problems. First,
N-(1-naphthyl) - ethylene diamine and p-amino benzene
sulfonamide which are used as mixed indicators for the
nitrite ion, were not familiar to high school students. Second,
preparing these compounds was not so easy. Therefore, we
decided to use the method for iron ion determination in an
iron tablet.
The body relies on the iron ion in order to produce
hemoglobin, a protein which helps red blood cells deliver
oxygen throughout the body. Furthermore, iron deficiency
can lead to anemia. It is the most common nutritional
deficiency in the world, and women are among those at
greatest risk. By doing this experiment, as well as teaching
chemistry concepts, we also wanted to achieve two goals:
Zahra Arzani et al.: High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
10
first, we wanted to emphasize using minimum amounts of
compounds and therefore produce less waste, second; we
wanted to explain the importance of iron tablet intake for
women.
4,7-diphenyl-1,10-phenanthroline reacts with Fe2+
forming a complex with a deep red color which absorbs light
at wavelength 533 nm and can be used to illustrate the
Beer–Lambert Law [14]. 4,7-diphenyl-1,10-phenanthroline
is not familiar for high school student, therefore the iron (II)
in sample and known solutions was converted to iron (III) by
potassium permanganate in an acidic solution which then
turned into a red color by a potassium thiocyanate solution.
A camera-phone was used as the detector for the assay.
In the next experiment, the concentration of an unknown
copper (II) ion was determined by a set of known
concentrations and their color changes after using an
ammonia solution. Ammonia evaporates after the solution
dries, therefore, instead of a paper microfluidic device, a
simple plastic sheet was used [5]. Again, a camera-phone is
used as the detector for this assay. These two experiments are
very simple and data collection is fast and easy. It can be
done in all high school laboratories.
2. Materials
The unknown sample was an iron tablet which was
manufactured by Rouz Darou laboratories in Tehran. A
Whatman filter paper was used. Drawing a circle by a
permanent marker pen on the filter paper made hydrophobic
barriers constraining the reactions in defined areas. A
camera–phone was used to capture images of reaction and
the Adobe Photoshop 7.0 ME software was employed to get
the gray values of the detection areas from the collected
images.
2.2. Sample Preparation
Standard solutions with concentrations of 0.020, 0.016,
0.012, 0.008 and 0.004 mol.L-1 were prepared from solid iron
(II) sulfate heptahydrate (FeSO4.7H2O M = 278.0146 g /
mole) by dissolving 0.278 g in a 50 mL volumetric flask
(solution A). Students were required to dilute this solution
following the procedures described in table 1 and calculate
the molarity of each test tube. An iron tablet was carefully
weighed and its color peel was removed with a sharp knife.
The white tablet was then grinded in a mortar and dissolved
into a 50 mL volumetric flask (solution B).
Table 1. Preparing solutions in test tube
Test
tube
Volume of
standard
solution A
(mL)
Volume of
distilled
water (mL)
Fe2+ ion
Mol.L-1
Volume of
Tablet
solution
(mL)
1
1.0
4.0
0.004
0
2
2.0
3.0
0.008
0
3
3.0
2.0
0.012
0
4
4.0
1.0
0.016
0
5
5.0
0.0
0.020
0
6
0.0
0.0
X
5
No.
2.3. Procedures for Determination of Iron Ions
Using a clean dropper the solution of each test tube with
known concentration was carefully dropped onto six outer
circles. The same volume of tablet solution was dropped onto
the central circle. After a few seconds, an image was
captured by a camera phone.
2.1. Fabrication of the Paper-Based Device
As Wang and et al. recommended, a filter paper
(Whatman No.1) was used. This provides a good medium for
the colorimetric reaction to take place. Filter papers were
placed into a dry glass petri dish in a fume hood; a solution of
potassium thiocyanate was poured into the dish to
completely soak the papers. The papers were taken out and
left in the hood for an hour to become dry. With a permanent
marker, six circles were drawn onto the dried filter paper
(Figure 1).
Figure 2. The relationship between percentage of grayscale and iron
concentration
2.4. Procedures for Determination of Copper (II) Ions
Figure 1. Drawing a Pattern in filter paper
Standard solutions with concentrations of 0.04, 0.032,
0.024, 0.016 and 0.008 mol.L-1 were prepared from solid
copper (II) sulfate pentahydrate (CuSO4.5H2O M = 249.5 g
/ mole) by dissolving 0.249 g in a 25 mL volumetric flask
(solution A). Students were required to dilute this solution
similar to what is described in table 2 and by using a dropper,
and then calculate the molarity of solution in each watch
glass. One mL of solution is equal to 25 drops. In addition, a
solution with unknown concentration was given to students.
Journal of Laboratory Chemical Education 2017, 5(1): 9-12
Table 2. Preparing solutions in watch glasses
No.
Drops of
standard
solution A
Drops of
distilled
water
Drops of
unknown
Cu2+ ion
(mol/L)
1
1.0
4.0
0.0
8.0 × 10−3
2
2.0
3.0
0.0
3
3.0
2.0
0.0
4
4.0
1.0
0.0
5
5.0
0.0
0.0
40.0 × 10−3
6
0.0
0.0
5.0
X
16.0 × 10−3
24.0 × 10−3
32.0 × 10−3
Six circles were drawn onto a paper and it was placed
under a plastic cover. Two drops of each solution was added
to corresponding numbers. (Figure 3).
11
value (%). By using this data, the concentration of iron ion
was found to be 0.017 mol. L-1 in tablet sample, which means
there is 47.6 mg Fe2+ in each tablet. The 4.8% difference
between the written value in tablet box and the
experimentally determined iron ion concentration is readily
rationalized given the approximations implicit to this
methodology.
The equation for copper ion concentration was expressed
as y = 1100x + 38.4 where x represents the copper ion
concentration (mol. L-1), and y represents the gray value with
the correlation coefficient 0.989 and standard error of the
estimation 1.673.
4. Hazards
The potassium thiocyanate solution is toxic and should be
used only in a chemical fume hood. It can be absorbed
through the skin. Potassium thiocyanate is a skin and eye
irritant and is toxic when ingested. Eye contact will cause
redness and pain. Skin contact will cause localized
irritation. Ingestion will cause headache, nausea, vomiting,
dizziness and faintness [16-19].
Potassium permanganate solution can cause skin
irritation. Flush with water immediately [20].
5. Conclusions
Figure 3. Drops of solutions on a sheet of plastics
2 drops of Ammonia solution was carefully dropped onto
the central each circles. After a few seconds, an image was
captured by a camera phone (figure 4).
It is obvious that teaching chemistry with experiments
increases enthusiasm and motivation among students. In
most high schools in developing countries there are not
enough facilities to achieve this goal; therefore in this article
we proposed two simple experiments: paper-based
microfluidic analytical devices for iron ion detection and
plastic sheet instead of microplate for copper ion detection.
All the equipment are simple and easy to use. Furthermore
the experiment reduces disposal and students learn more
about protecting the environment. Above all, by doing this
experiment, as well as teaching chemistry concepts, the
importance of iron tablet intake will be explained.
ACKNOWLEDGEMENTS
Figure 4. Copper solutions with ammonia
Special thanks are owed to the principle of the beheshty
high school in Karaj for facilitating access to laboratory
supplies.
3. Results
According to figure 2, the relation between the
concentration of the iron ion and the intensity of the gray
color is linear with the correlation coefficient 0.909 and
standard error of the estimation 3.5777. The linear equation
was expressed as y = 1550x + 38.6 where x represents the
iron ion concentration (mol. L-1), and y represents the gray
REFERENCES
[1]
Holbrook J. Making chemistry teaching relevant, Chemical
Education International, 2005, Vol. 6, No. 1,
www.iupac.org/publications/cei
[2]
Woldeamanuel, M. What makes chemistry difficult? Journal
of Chemical Education, 2014, 4(2), Special Issue (Part I).
12
Zahra Arzani et al.: High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
[3]
Carter, C.S.; Brickhouse, M.W. What makes chemistry
difficult? Alternate Perceptions, Journal of Chemical
Education, 1989, 66(3), 223-225.
[4]
Nakhleh, M.B. Why some students don’t learn chemistry,
Chemical Misconceptions, Journal of Chemical Education,
1992, 69(3), 191-196.
[5]
Arzani, Z. Chemical waste management in high school,
International Journal of Sustainable Development, 2012, 05:
02, (©Ontario International Development Agency ISSN:
1923-6654 (print). ISSN 1923-6662 (online). Available at
http://www.ssrn.com/link/OIDA-Intl-Journal-Sustainable-De
v.html
[6]
Whitesides, G. M. The Origins and the future of microfluidics.
Nature. 2006, 442 (7101), 368−373.
[7]
Martinez, A. W.; Phillips, S. T.; Butte, M. J.; Whitesides, G.
M. Patterned paper as a platform for inexpensive, low-volume,
portable bioassays, Angew. Chem., Int. Ed. 2007, 46, pp.
1318–1320.
[8]
[9]
Lu, Y.; Shi, W. W.; Jiang, L.; Qin, J. H.; Lin, B. C. Rapid
prototyping of paper-based microfluidics with wax for
low-cost, portable bioassay, Electrophoresis, 2009, 30, pp.
1497-1500.
Li, X.; Tian, J. F.; Nguyen, T.; Shen, W. Paper-based
microfluidic devices by plasma treatment, Analytical
Chemistry, 2008, 23, pp. 9131-9134.
[10] Bruzewicz, D. A.; Reches, M.: Whitesides, G. M. Low-Cost
printing of poly(dimethylsiloxane) Barriers To Define
Microchannels in Paper, Analytical Chemistry, 2008, 80, pp.
3387-3392.
[13] Cain, L.; Wu, Y.; Xu, C.; Chen, Z. A Simple paper-based
microfluidic device for the determination of the total amino
acid content in a tea leaf extract. J. Chem. Educ. 2013, 90 (2),
232−234.
[14] Housecroft Catherine E.; Constable Edwin C. -Chemistry: an
introduction to organic, inorganic, and physical, 4th Edition
-Pearson Academic, 2009; page 383.
[15] http://www.nuffieldfoundation.org/practical-chemistry/colori
metric-determination-copper-ore- (accessed Aug 2015)
[16] Material Safety Data Sheet, potassium thiocyanate,
http://avogadro.chem.iastate.edu/MSDS/KSCN.htm
((accessed Sep 2015)
[17] Potassium thiocyanate,
https://en.wikipedia.org/wiki/Potassium_thiocyanate
((accessed Sep 2015)
[18] http://www.rsc.org/images/loc/2012/pdf/T.5.138.pdf
(accessed Oct 2015)
[19] http://www.ihcworld.com/royellis/ABCSafe/chemicals/potas
sium-thiocyanate.htm (accessed Sep 2015)
[20] Material Safety Data Sheet, Potassium permanganate,
http://avogadro.chem.iastate.edu/MSDS/KMnO4.htm
(accessed Sep 2015)
[21] Kohl S. K.; Landmark, J. D.; Stickle, D. F. Demonstration of
Absorbance using color image analysis and colored solutions.
J. Chem. Educ. 2006, 83, 644−646 .
[22] Kehoe, E.; Penn, R. L. Introducing colorimetric analysis with
camera phones and digital ameras: An activity for high school
or general chemistry. J. Chem. Educ. 2013, 90, 1191−1195
[11] Wang, B.; Lin, Z. ; Wang M. Fabrication of a paper-based
microfluidic device to readily determine nitrite ion
concentration by simple colorimetric assay, J. Chem. Educ.
2015, 92, 733−736 .
[23] Rice N. P., Beer M. P. and Williamson M. E., A Simple
educational method for the measurement of liquid binary
diffusivities
[12] Nie, J.; Zhang, Y.; Lin, L.; Zhou, C.; Li, S.; Zhang, L.; Li, J.
Low- Cost fabrication of paper-based microfluidic devices by
one-step plotting. Anal. Chem. 2012, 84 (15), 6331−6335
http://www.ncbi.nlm.nih.gov/pubmed/22881397
[24] Kuntzleman T.S. and Jacobson E. C., Teaching beer’s law
and absorption spectrophotometry with asmart phone: A
substantially simplified protocol J. Chem. Educ. 2016, 93,
1249−1252
DOI: 10.5923/j.jlce.20170501.03
High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
Zahra Arzani1,*, Hassan Hazarkhani2
1
Office of Teaching and Training, Karaj, Iran
Department of Chemistry, Organization for Educational Research and Planning, Tehran, Iran
2
Abstract Teaching high school chemistry is a difficult task in developing countries. The materials in laboratories should
be cheap and accessible. Moreover, waste recovering systems do not exist in most of these countries. Therefore, it is
imperative to instill in students the habit as well as the need to feel responsible for what waste their activities will produce. In
this manuscript we explain a method to determine the presence of Fe2+ and Cu2+ ions in unknown solutions with cheap
equipment. This can be used to illustrate the Beer–Lambert law and also emphasizes environment protection. Each
experiment takes 2 hours of a group.
Keywords Green Chemistry, High School, Introductory Chemistry, Colorimetry, Hands-On Learning
1. Introduction
It has been shown that teaching chemistry is not very
popular. In fact it could be irrelevant in the eyes of students
which find it difficult to learn [1-4]. Therefore, it is essential
to combine the teaching of chemistry with experiments that
grab students’ attention and excite them about the subject. In
third world countries the problem is exacerbated by the need
for cheap equipment given low budgets and scarce resources
[5]. Furthermore, environment pollution is also a growing
concern causing a lot of problems in the world. Thus, school
chemical experiments should be arranged in a way that is
safer for the environment. Students also should be sensitive
to what will be left after these experiments as waste. It is to
be hoped that as a result, this will become a habit for their
daily activities as well.
In this regards, one of the useful experiment is
microfluidic analysis. Microfluidics is the science and
technology of systems that process or manipulate small
amounts of fluids using channels with dimensions of tens to
hundreds of micrometer [6]. Unfortunately this work is not
well known among high school teachers. There are reports
for different paper-based microfluidic analytical devices
(μPADs) in literature [7-10] but the cheapest and easiest one
is recommend by Wang and at al., [11-13] which can be
used in high school chemistry laboratories. The main
advantage of this method is showing chemistry in real
life with simple equipment and using very small amount of
* Corresponding author:
zarzani2111@yahoo.com (Zahra Arzani)
Published online at http://journal.sapub.org/jlce
Copyright © 2017 Scientific & Academic Publishing. All Rights Reserved
compounds.
Colorimeter and determination of ion concentration in
unknown samples is one of the popular undergraduate
laboratory works in universities. Whereas doing so in high
school, requires expensive spectroscopy equipment.
Potentially, this can be achieved using a form of colorimetry
in which comparisons of depth of color are made by
eyeballing without necessarily using a colorimeter [15]. In
this method, a set of solutions will be prepared and the color
of the unknown tube will be compared with them in order to
find which matches best. Kohl et al. [22] used digital images
of solutions (food dye, sports drinks, and Iron chloride).
Kuntzleman at el. [25] left samples in a cardboard box,
allowed light to pass through it, and used a cell phone as the
light detector. Moreover, Rice at el. [23] also used a cell
phone camera as a simple, low cost experimental technique
for teaching molecular diffusion.
We tried to repeat nitrite ion determination with a paper
microfluidic device which Wang and et al [11] proposed.
However, we encountered two main problems. First,
N-(1-naphthyl) - ethylene diamine and p-amino benzene
sulfonamide which are used as mixed indicators for the
nitrite ion, were not familiar to high school students. Second,
preparing these compounds was not so easy. Therefore, we
decided to use the method for iron ion determination in an
iron tablet.
The body relies on the iron ion in order to produce
hemoglobin, a protein which helps red blood cells deliver
oxygen throughout the body. Furthermore, iron deficiency
can lead to anemia. It is the most common nutritional
deficiency in the world, and women are among those at
greatest risk. By doing this experiment, as well as teaching
chemistry concepts, we also wanted to achieve two goals:
Zahra Arzani et al.: High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
10
first, we wanted to emphasize using minimum amounts of
compounds and therefore produce less waste, second; we
wanted to explain the importance of iron tablet intake for
women.
4,7-diphenyl-1,10-phenanthroline reacts with Fe2+
forming a complex with a deep red color which absorbs light
at wavelength 533 nm and can be used to illustrate the
Beer–Lambert Law [14]. 4,7-diphenyl-1,10-phenanthroline
is not familiar for high school student, therefore the iron (II)
in sample and known solutions was converted to iron (III) by
potassium permanganate in an acidic solution which then
turned into a red color by a potassium thiocyanate solution.
A camera-phone was used as the detector for the assay.
In the next experiment, the concentration of an unknown
copper (II) ion was determined by a set of known
concentrations and their color changes after using an
ammonia solution. Ammonia evaporates after the solution
dries, therefore, instead of a paper microfluidic device, a
simple plastic sheet was used [5]. Again, a camera-phone is
used as the detector for this assay. These two experiments are
very simple and data collection is fast and easy. It can be
done in all high school laboratories.
2. Materials
The unknown sample was an iron tablet which was
manufactured by Rouz Darou laboratories in Tehran. A
Whatman filter paper was used. Drawing a circle by a
permanent marker pen on the filter paper made hydrophobic
barriers constraining the reactions in defined areas. A
camera–phone was used to capture images of reaction and
the Adobe Photoshop 7.0 ME software was employed to get
the gray values of the detection areas from the collected
images.
2.2. Sample Preparation
Standard solutions with concentrations of 0.020, 0.016,
0.012, 0.008 and 0.004 mol.L-1 were prepared from solid iron
(II) sulfate heptahydrate (FeSO4.7H2O M = 278.0146 g /
mole) by dissolving 0.278 g in a 50 mL volumetric flask
(solution A). Students were required to dilute this solution
following the procedures described in table 1 and calculate
the molarity of each test tube. An iron tablet was carefully
weighed and its color peel was removed with a sharp knife.
The white tablet was then grinded in a mortar and dissolved
into a 50 mL volumetric flask (solution B).
Table 1. Preparing solutions in test tube
Test
tube
Volume of
standard
solution A
(mL)
Volume of
distilled
water (mL)
Fe2+ ion
Mol.L-1
Volume of
Tablet
solution
(mL)
1
1.0
4.0
0.004
0
2
2.0
3.0
0.008
0
3
3.0
2.0
0.012
0
4
4.0
1.0
0.016
0
5
5.0
0.0
0.020
0
6
0.0
0.0
X
5
No.
2.3. Procedures for Determination of Iron Ions
Using a clean dropper the solution of each test tube with
known concentration was carefully dropped onto six outer
circles. The same volume of tablet solution was dropped onto
the central circle. After a few seconds, an image was
captured by a camera phone.
2.1. Fabrication of the Paper-Based Device
As Wang and et al. recommended, a filter paper
(Whatman No.1) was used. This provides a good medium for
the colorimetric reaction to take place. Filter papers were
placed into a dry glass petri dish in a fume hood; a solution of
potassium thiocyanate was poured into the dish to
completely soak the papers. The papers were taken out and
left in the hood for an hour to become dry. With a permanent
marker, six circles were drawn onto the dried filter paper
(Figure 1).
Figure 2. The relationship between percentage of grayscale and iron
concentration
2.4. Procedures for Determination of Copper (II) Ions
Figure 1. Drawing a Pattern in filter paper
Standard solutions with concentrations of 0.04, 0.032,
0.024, 0.016 and 0.008 mol.L-1 were prepared from solid
copper (II) sulfate pentahydrate (CuSO4.5H2O M = 249.5 g
/ mole) by dissolving 0.249 g in a 25 mL volumetric flask
(solution A). Students were required to dilute this solution
similar to what is described in table 2 and by using a dropper,
and then calculate the molarity of solution in each watch
glass. One mL of solution is equal to 25 drops. In addition, a
solution with unknown concentration was given to students.
Journal of Laboratory Chemical Education 2017, 5(1): 9-12
Table 2. Preparing solutions in watch glasses
No.
Drops of
standard
solution A
Drops of
distilled
water
Drops of
unknown
Cu2+ ion
(mol/L)
1
1.0
4.0
0.0
8.0 × 10−3
2
2.0
3.0
0.0
3
3.0
2.0
0.0
4
4.0
1.0
0.0
5
5.0
0.0
0.0
40.0 × 10−3
6
0.0
0.0
5.0
X
16.0 × 10−3
24.0 × 10−3
32.0 × 10−3
Six circles were drawn onto a paper and it was placed
under a plastic cover. Two drops of each solution was added
to corresponding numbers. (Figure 3).
11
value (%). By using this data, the concentration of iron ion
was found to be 0.017 mol. L-1 in tablet sample, which means
there is 47.6 mg Fe2+ in each tablet. The 4.8% difference
between the written value in tablet box and the
experimentally determined iron ion concentration is readily
rationalized given the approximations implicit to this
methodology.
The equation for copper ion concentration was expressed
as y = 1100x + 38.4 where x represents the copper ion
concentration (mol. L-1), and y represents the gray value with
the correlation coefficient 0.989 and standard error of the
estimation 1.673.
4. Hazards
The potassium thiocyanate solution is toxic and should be
used only in a chemical fume hood. It can be absorbed
through the skin. Potassium thiocyanate is a skin and eye
irritant and is toxic when ingested. Eye contact will cause
redness and pain. Skin contact will cause localized
irritation. Ingestion will cause headache, nausea, vomiting,
dizziness and faintness [16-19].
Potassium permanganate solution can cause skin
irritation. Flush with water immediately [20].
5. Conclusions
Figure 3. Drops of solutions on a sheet of plastics
2 drops of Ammonia solution was carefully dropped onto
the central each circles. After a few seconds, an image was
captured by a camera phone (figure 4).
It is obvious that teaching chemistry with experiments
increases enthusiasm and motivation among students. In
most high schools in developing countries there are not
enough facilities to achieve this goal; therefore in this article
we proposed two simple experiments: paper-based
microfluidic analytical devices for iron ion detection and
plastic sheet instead of microplate for copper ion detection.
All the equipment are simple and easy to use. Furthermore
the experiment reduces disposal and students learn more
about protecting the environment. Above all, by doing this
experiment, as well as teaching chemistry concepts, the
importance of iron tablet intake will be explained.
ACKNOWLEDGEMENTS
Figure 4. Copper solutions with ammonia
Special thanks are owed to the principle of the beheshty
high school in Karaj for facilitating access to laboratory
supplies.
3. Results
According to figure 2, the relation between the
concentration of the iron ion and the intensity of the gray
color is linear with the correlation coefficient 0.909 and
standard error of the estimation 3.5777. The linear equation
was expressed as y = 1550x + 38.6 where x represents the
iron ion concentration (mol. L-1), and y represents the gray
REFERENCES
[1]
Holbrook J. Making chemistry teaching relevant, Chemical
Education International, 2005, Vol. 6, No. 1,
www.iupac.org/publications/cei
[2]
Woldeamanuel, M. What makes chemistry difficult? Journal
of Chemical Education, 2014, 4(2), Special Issue (Part I).
12
Zahra Arzani et al.: High School Chemistry Activities with an Environmental
Concern: Cost-Effective Colorimetric Ion Analysis
[3]
Carter, C.S.; Brickhouse, M.W. What makes chemistry
difficult? Alternate Perceptions, Journal of Chemical
Education, 1989, 66(3), 223-225.
[4]
Nakhleh, M.B. Why some students don’t learn chemistry,
Chemical Misconceptions, Journal of Chemical Education,
1992, 69(3), 191-196.
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