2013. Vol.4, No.7, 446-451
Published Online July 2013 in SciRes (http://www.scirp.org/journal/ce) http://dx.doi.org/10.4236/ce.2013.47064
Copyright © 2013 SciRe s .
Usefulness of Plastic Hoffman Apparatus in Chemistry Classes: A
Case Study of Its Implementation with High School Teachers
Muhamad Hugerat*, Ahmad Basheer, Naji Kortam
SALiS Center, The Academic Arab College for Education, 22 Hachashmal St., Haifa, Israel
Received April 12th, 2013; revised May 13th, 2013; accepted May 22nd, 2013
Copyright © 2013 Muhamad Hugerat et al. This is an open access article distributed under the Creative Com-
mons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, pro-
vided the original work is p roperly cited.
In this article we present simple and feasible idea to introduce electrolysis experiments using accessible
materials in the classroom. We use plastic syringes and pipettes to build different shapes of Hoffman ap-
paratus for electrolysis. This activity was introduced to a group of 20 teachers from the Arab sector in Is-
rael to examine their impressions about the activity and investigate the feasibility of implementing the ac-
tivity in their classrooms.
Keywords: Electrolysis Workshop; Professional Development of Teachers; Case Study; Accessible
Materials; Plastic Apparatus
Professional development of educators at different levels is
described by many researchers as a central lever leading to
change and improve the capabilities and achievements of the
education system (Scandholtz & Scribner, 2006).
Elliote (1999) emphasizes that it is very important to carry-
out local studies, and case studies to examine the interaction be-
tween local and global dimensions related to the development
Teachers can act as powerful mediators in introducing
change. Their decision to implement a new project depends on
their satisfaction from the current situation and their expecta-
tions from the contribution of the project in improving their tea-
ching (Wallace & Louden, 1998; Zidani, Kortam, & Hugerat,
In order to introduce a change, the teacher, himself, must go
through a learning process (Wheeler et al., 1995). In this proc-
ess, the teacher is an active partner in the creation of change.
This involvement is a constructivist teaching model, which is
essential in the introduction of such process.
In a study among elementary school teachers in Israel, Ben-
Chaim et al. (1994) found that training workshops encourage
the implementation of approaches, attitudes and scientific—
technological—and social literacy among the participating tea-
In this article we present simple and feasible idea to intro-
duce the microscale electrolysis experiments using accessible
materials in the classroom. We use plastic syringes and pipettes
to build different shapes of Hoffman apparatus for electrolysis.
We introduce this activity for high school teachers and we ex-
amine the impact of this implementation.
Starting from the last century, electrolysis of water solutions
has been widely demonstrated to students in secondary schools,
or in a first-year college in order to illustrate oxidation-reduc-
tion reactions as well as to demonstrate the use of an external
source of energy for driving non-spontaneous chemical reac-
tions (Hendricks & Williams, 1982; Hugerat, 2006, 2008; Hu-
gerat et al., 2009; Shakhashiri, 1992; Zhou, 1996).
A Hofmann apparatus is an apparatus for electrolyzing water,
invented by August Wilhelm von Hofmann. It consists of three
joined upright cylinders, usually glass. The inner cylinder is
open at the top to allow the addition of water and an ionic com-
pound, such as a small amount of sodium sulfate, to improve
conductivity. A platinum electrode is placed inside the bottom
of each of the two outer cylinders, connected to the positive and
negative terminals of a source of electricity. Gaseous oxygen
forms at the anode and gaseous hydrogen forms at the cathode
when a current runs through the Hofmann’s apparatus. Each gas
displaces water and collects at the top of the two outer tubes
(Hugerat, 2006, 2008; Hugerat & Schwarz, 2008; Hugerat et al.,
2009; Zhou et al., 2005).
Microscale chemistry is the reduction of chemicals use to the
lowest level at which experiments can be effectively performed.
It offers a safer way to perform chemical experiments by using
smaller quan tities of chem icals. Micros cale experiments are con-
ducted without compromising the quality or standard of chemi-
cal applications in educational institutions and the experimental
industry. The Benefits of Microscale Chemistry are: reduces
chemicals use by promoting waste reduction at the source; im-
proves laboratory safety (air quality, reduced exposure, and
spills); saves money; decreases experiment time; teaches stu-
dent s alternatives to conventi onal chemi s try (Singh et al., 1999;
Zhou et al., 2005).
For microscaling, the “Hoffmann Apparatus” the container,
the electrodes, the electrolyte, and the power supply are replac-
ed by smaller units; uses narrow 3-mL test tubes, insulated cop-
per wire (for the anode they are combined with a pencil lead),
diluted sodium hydroxide solution, or sodium sulfate solution
M. HUGERAT ET AL.
with drops of universal indicator is introduced as neutral elec-
trolyte. A cheap AC/DC adaptor or a 9-Volt battery is used as
power supply (Hugerat, 2006, 2008; Hugerat et al., 2009; Hu-
gerat & Schwarz, 2008; Zhou et al., 2005).
The workshop is one of the good ways to expose teachers to
innovations in building new devices on chemistry experiments.
It also opens new horizons for teachers to be more creative in
the construction of their own devices to use disposable materi-
als that have no adverse impact on the environment (Thompson
& Soyibo, 2002). The general idea behind this article is to in-
vestigate the effect of implementing the activity “Plastic Huff-
man Apparatuses” with teacher participants in the Academic
Arab College for Education in Israel. The main idea of the
workshop is to expose simple activity for electrolysis, such as
“plastic Hoffman apparatus” for teachers and to encourage tea-
chers to be active and creative in building their apparatuses.
The workshop for teachers took place in the laboratory of the
Academic Arab College for Education in Israel during Decem-
The workshop consisted of four meetings of eight contact
hours each. During the workshop, selected topics in electrolysis
were introduced (Table 1). The main topic was electrolysis
through the implementation of an activity titled “Plastic Huff-
The participants in the workshop were 20 teachers from the
Arab sector in Israel; public and private high schools. Their par-
ticipation in the workshop was mandatory; they were selected
from different schools by the science inspector. They earned
hours toward their recertification.
The activity was presented in a full day (4 days) session of
eight hours (every day) in which the participants were intro-
duced to the concept of electrolysis and different methodologies
designed to enhance their content knowledge about the topic
and the pedagogical content knowledge to implement this topic
in their classrooms. The last two meeting focused on the useful-
ness of plastic Huffman apparatuses for electrolysis (Table 1).
The last meeting in the workshop focused on the creativity of
teachers, the teachers were asked to build thei r own plastic Huff-
man apparatuses using plastic and disposables materials.
This activity was introduced to a group of 20 teachers to col-
lect their impressions about the activity and investigate the fea-
sibility of implementing the activity in their classrooms. Fol-
lowing the activity, the researchers presented the participants
with a paper survey to collect their impressions about the activ-
ity, their previous knowledge about the topic of electrolysis and
their predictions of the benefits to their students through the
implementation of this activity in their classrooms.
Syllabus of the course o f the workshop.
Type of presentation Topics Hours
Lecture and Demonstration Introduction to Electrolysis 8
Demonstration and Active
Demonstration and Active
Creative and Active Experimentation
Creativity: Design of Plastic
Huffman Appa ratuses
The following represents the series of experiments imple-
mented during the activity.
Plastic Hoffman Apparatuses for Electrolysis
Advantages of doing these demonstrations:
Students are encouraged to experiment and develop their
own electrolysis experience. Experiments can be done qui-
The creativity of students will be stimulated: They can find
individual solutions for a given problem. Their independ-
Micro-scale saves time. It leaves more opportunities for
conversation, reflection and evaluation while protecting the
environment by using small amounts of chemicals: fewer
chemicals, less waste (less is more).
Micro-scale saves money: special laboratory materials are
replaced by disposable items commonly found in daily life,
or easily acquired.
Increasing sensitivity to the environment: becoming aware
of problems related to consumption, recycling and raw ma-
terials used in daily life.
Plastic Syringe Hoffman
Materials and chemicals
Two 5-ml plastic syringe, wooden test tube stand, bottom of
a disposable plastic cup container, two blunted hypodermic nee-
dles as electrodes, 2 insulated copper wires with crocodile clips,
9 V battery, sodium sulphate solution in red cabbage extract.
1. Connect the two plastic syringes from the bottom as
shown in Figures 1 and 2.
2. Pierce the disposable plastic cup container on the wooden
stand from the downside with the two blunted needles.
3. Totally fill the two plastic syringes with the electrolyte
(sodium sulphate solution in red cabbage extract).
4. Carefully turn the bottles upwards down and place them
tightly on the needles.
5. Add 5 ml of the electrolyte solution to the disposable plas-
tic cup container.
Scheme of the pla stic Huf fman apparatus.
Copyright © 2013 SciRe s . 447
M. HUGERAT ET AL.
Plastic Syringe Huffman apparatus experim ent.
6. Connect the needles acting as electrodes to the power sup-
ply (9 V battery).
Although the power source (9 V battery) used is relatively
weak, electrodes should not be handled while cells are operat-
ing. Care should be exercised when testing the hydrogen gas
with a burning splint, be care ful of explosive hydrogen and oxy -
gen mixtures. Handle the sodium sulfate with care; they can
cause skin irritation. Wear gloves and goggles throughout the
experiments. Be careful during your work with the sharp nee-
dles, we suggest to cut the narrow part of the needle.
Observations and Explanations. Electrolysis of water is a
key chemical reaction, which is very often demonstrated for
students. When an electrical current (DC) is passed through a
water solution, oxygen gas and hydrogen ions are produced at
the anode while hydrogen gas and hydroxide ions are released
at the cathode side; see the equations (Hendricks & Williams,
1982; Hugerat, 2006; Shakhashiri, 1992; Zhou, 1996).
The plant pigments presents in red cabbage, anthocyanin,
turn to red in acidic solutions, purple in neutral solutions, and
green to yellow in basic solutions. It can be clearly observed
after a few minutes of electrolysis that the color of the indicator
turns as the following (Figure 2):
The intensity of the color depends on the change in the pH of
the solution near the electrodes. As a result of electrolysis of
water, bubbles of hydrogen gas as well as hydroxide ions ac-
cumulate in the cathode side. On the other hand, bubbles of
oxygen gas and also hydrogen ions are produced in the anode
side, and the volume ratio is 2:1 (H2/O2) (Figure 2).
Microscale Electrolysis in Two 3-ml Plastic Pipettes
In this experiment the two half-cells are two 3-ml plastic pi-
pettes (Figure 3), pierced by two injection needles, which have
been closed before by heating and compressing their plastic
ends. The pipettes are completely filled with a concentrated so-
dium sulfate solution in a red cabbage extract and placed into a
50-ml plastic cub with an electrolyte. This plastic cub acts as a
salt bridge and as a stand (Figure 3). A 9-Volt battery is used
as power supply.
Observations and Explanations
1. The indicator changes its colour to green in the cathode
pipette; and to red in the anode pipette.
2. Two gases develop in a volume ratio 2 (cathode) to 1 (an-
3. A fascinateur phenomenon can be demonstrated when the
DC connections between both electrodes is reversed. Due to re-
versing the polarity of both electrodes. The initially anode be-
come the cathode and the initially cathode is converted to anode.
As a consequence of this change, acid-base neutralization oc-
curs in the surrounding of each electrode due to the electrolysis
of water. After changing the polarity equal volumes of gases
Two 3-ml plastic pipettes electrolysis experiment.
Copyright © 2013 SciRe s .
M. HUGERAT ET AL.
are formed in both pipettes.
4. After piercing the pipette heads with small closed hypo-
dermic needles these gases can be ignited by the spark of a
piezoelectric device: Fixing the pipette during the reaction re-
sults in a strong reduction of the gas volume. Water synthesis
of oxyhydrogen gas in the pipette head. As the reactants disap-
pear and the product is a liquid the volume is reduced very
2HO2H O l
Electrolysis in One Pipette
In this experiment the cell is 3-ml plastic pipette, pierced by
two injection needles, which have been closed before by heat-
ing and compressing their plastic ends, the two injection nee-
dles acting as electrodes. The pipette is completely filled with a
concentrated sodium sulfate solution in a red cabbage extract
and placed into one hole of a plastic 6-well plate; the end of the
long tail of the plastic pipette dipped inside an another hole of
the plastic 6-well plate which contain soap solution (Figure 4).
A 9-Volt battery is used as power supply.
Observations and Explanations. When an electrical current
(DC) is passed through a water solution, oxygen gas is produc-
ed at the anode while hydrogen gas produced at the cathode.
These gases transferred through the long tail of the pipette to
arrive to the soap solution and we observed bubbles over the
soap solution. A simple method to check these gases (hydrogen
and oxygen) is to bring a source of fire to the bubbles; immedi-
ately a weak sound of explosion is heard. This is a safety ex-
periment because the amount of hydrogen and oxygen which
we produced during the electrolysis are very small.
20 school teachers participated in this workshop doing this
activity. Following the activity, the researchers presented the
participants with a paper survey to examine their impressions
about the activity, their previous knowledge about the topic of
electrolysis and their predictions of the benefits to their students
through the implementation of this activity in their classrooms.
Electrolysis in one pipette in 6-well plate.
Some of the results from the analysis of the survey are:
1. Regarding previous knowledge about electrolysis, the ma-
jority of them stated that they gained this knowledge through
formal education. And they have no idea about new develop-
ments about new apparatuses from the new science education
journals, especially apparatuses from disposables materials such
as plastic apparatuses.
2. When the teachers were asked if they taught electrolysis in
their cla ssrooms, the majority stated that they teach electrolysi s
using conventional methods. Some of them wrote that they us-
ed conventional Hoffman apparatus.
3. When they were asked to describe briefly whether the ex-
periments presented in this workshop has helped them to un-
derstand the process of electrolysis in a better way. Most of
them have answered that after the activity the concept of elec-
trolysis became much clearer for them and that they can explain
it to audiences clearly. As an anecdotal remark, one of the tea-
chers stated that at the beginning of the workshop she had a
very little knowledge on the subject, and doing these experi-
ments has enlightened her about the topic and how to present it
to her students. Most of the participants concluded that using
these electrolysis experiments would allow their students to vi-
sualize what occurs during electrolysis. In the same manner,
teachers commented that the experiments were presented in
such a way that it is easy to implement and does not need a
science laboratory. Some of them also expressed a clear gain in
content knowledge using specific language to explain what
occurred in the electrolysis, such as the production of acid/base
in the anode/cathode and the liberation of O2 and H2.
4. When they were asked about the accessibility to dispos-
able materials to implement the activity, the teachers believe
that using disposable materials and a natural indicator such as
red cabbage juice makes the experiments simpler, so they can
think about other materials that they can use and if they do not
have all the materials, they will be able to find a way to obtain
them or provide alternate materials with which the experiment
can be performed. Figure 5 shows an experiment which was
designed by one of the teachers participating in the workshop.
In the last part of the workshop, as we noted at the beginning
was the important part which teachers were asked to design
new equipment apparatus. As seen in the experiment (Figure 5)
one the teacher built very simple experimental equipment ap-
paratus for electrolysis. He took a syringe and used two needle
electrodes, a battery of nine-volt current source, coffee cup as a
stand and salt bridge and followed the electrolysis of tap water.
As shown in this electrolysis device, he collected in the syringe
oxygen and hydrogen gas. The teacher tested for oxygen and
hydrogen when used with a match, the test is very safe because
Plastic syringe apparatus for electrolysis designed by a participating
teacher in the workshop.
Copyright © 2013 SciRe s . 449
M. HUGERAT ET AL.
of the small amount of gas generated. The teacher could also
give an explanation for the product has a greenish yellow color
(which is chlorine) and the solid brown is rust. More creative
experiments using plastic materials were designed by other tea-
chers in the workshop.
5. When they were asked about the possibility to implement
this activity in the next academic year, the teachers expressed
their intentions to implement some of these electrolysis activi-
ties in their classroom.
6. The teachers believe that these activities will enhance the
learning process in their classroom, claiming that today most of
their students are visual learners and this kind of activity will
motivate and engage them in the learning process of these con-
cepts and wil l encourage them to do resea rch in the future.
7. When they were asked to express the main reasons that
would motivate them to implement this activity in their class-
room, the participants stated in general that:
This activity is very simple and the materials are accessible.
We can think about other accessible and disposable materi-
als that were presented in this workshop by the researchers.
The experiments can be carried out quickly. Our student
can repeat these activities in any place, such as home, be-
cause the materials are accessible, disposable, simple and it
is so easy to design such appa ratus.
The students will be engaged and will feel part of the dis-
covery process and they can easily design their own appa-
The creativity of the students will definitively be simulated.
Analysis of teachers’ statements that came from a paper sur-
vey to check their impressions about the activity has detected a
range of professional descriptions reflecting changes in cogni-
tive, pedagogical and emotional dimension, on the one hand,
and various dilemmas, fears and doubts on the other.
The substantial improvement in the ability of teachers shows
the high skill of teachers to process appropriate activities for
students while going up a “step” in their professional develop-
ment. The study findings indicate that, during the course, the
teachers went through an evolutionary and professional change
expressed in a transition from scientific evidence of their spe-
cial field of knowledge, the type of experiments and materials
they used and the conceptualization of all this, to the acquisi-
tion and implementation of work methods, other ways of deal-
ing and thinking, in a different approach. The findings also in-
dicate that there was progress in their will and ability to deal
with the development and processing of materials originating in
the spirit of this approach. Teachers indicated that they gained,
as a result of the course, self-confidence and high skill of lo-
cating and processing other topics in chemistry that can be
combined during experiments with materials available and not
The change that occurred in the perception of teachers as a
result of the course can be attributed to two factors combined
together. The first is raising teachers’ awareness of the need
and importance of processing such experiments; and the second,
the way teachers were exposed as learners of events during the
course in the context of Hoffman apparatus for electrolysis im-
proved their skills and abilities to the possibility of future de-
velopment of experiments and similar activities.
Some teachers are found in the midst of change process re-
flected in the fact that they are implementing teaching appro-
aches and content in real and not easy manner, caught between
the school reality that does not always allow making real change,
and the desire to change. The real “test” of change in the atti-
tude of teachers will be the implementation in the coming years.
Awareness of the need for change and its nature already exists,
based on the teachers’ statements and the way they began to re-
alize it, as reflected in the findings of this study.
After the significant developmental change expressed by
many teachers following their planning, implementation and
evaluation, it appears that, among teachers, a rise in the motiva-
tion to change was observed; in addition to recognizing the
importance and profound understanding of the entire process. A
possible outcome of teacher development at this stage will be
the involvement of school teaching teams, where they function
as agents of change to their colleagues. Continuation of the pro-
cess of teacher development depends on the teacher himself, on
the school support and the offered academic accompaniment.
The implementation of these activities with teachers from
high school, and the analysis of the data collected from the
participants corroborate the position of this paper. Although
electrolysis can be a difficult subject to teach and perform ex-
periments (given the common lack of resources available to
teachers in high schools), teachers are motivated to experiment
with and introduce these approaches in their classrooms and,
with it, the content knowledge of the subject. The presented
simple and familiar apparatus should make these experiments
safely available at all levels in chemistry classes. Teachers that
have conducted the aforementioned described experiments with
plastic Hoffman apparatus have shown excitement and fun es-
pecially when observing visually occurring electrolysis. We be-
lieve that these workshops motivate the teachers to be more
creative in designing new apparatuses in teaching and learning
chemistry, and encouraging their students to be more active
learning and creative in their classes.
The research described in this paper, has clear implications
for action at school. This action depends on several factors,
where teachers constitute the central link in the success. Expec-
tations to make a real and comprehensive scientific change in
the education system depend largely on the ability of profes-
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