SEEING CHEMICAL REACTIONS THROUGH SOUND
104 Chemistry Research building
Day Phone: 814-865-5855
This lecture discu4ses the Audible Submersible Light Sensor developed at Penn State University allowing students with visual impairments to hear chemical reactions in the laboratory.
The goal of the Independent Laboratory Acce55 for the Blind (ILAB) project is to raise the expectations of blind and visually impaired (VI) students as well as educators of these students, in order to encourage them to pursue careers in Science, Technology, Engineering, and Mathematics (STEM) professions. These new tools and procedures will enable blind and VI students to perform chemistry laboratory experiments without sighted assistance. This will change the laboratory methodology for these students to a more active and independent role.1 2
The laboratory tools are being developed at Penn State, Truman State, and at the Indiana School for the Blind (ISB). These tools will be pilot tested at
, and then used in the high school
chemistry laboratory at ISB. A series of knowledge-based and attitudinal
assessments (involving a control group that takes the course in the traditional
way) will be performed to determine the educational value of unassisted
laboratory experiments for blind and VI students.3
why This work is Important:
1. To give blind high-school students an increased role in participation in science laboratory classes; specifically, chemistry.
2. A more independent laboratory experience is integral in fostering interest in
• 3. According to the American Chemical Society (ACS), less than 0.5% of employed chemists have a reported disability. An even smaller percentage of them are blind or visually impaired.4
4. By developing new tools to aid blind students in visual laboratory observations, both interest and independence for this population of students will be enhanced.5
Audible Submersible Light Sensor
This device is a simple hand-held, submersible light sensor that converts the light intensity at a photoconductive probe to an audible signal in real time. The sensor fits inside a test tube and is also compatible with other standard glassware. A test tube can be suspended over a light box by means of a standard ring stand when used in conjunction with the light box, the sensor measures the light intensity and converts it to an audible tone through headphones or external speakers when a chemical reaction occurs, the amount of light transmitted through the solution changes. The change in pitch signals a color change or the formation of a precipitate. By using a talking timer in conjunction with the light sensor, a blind student can determine the time course of the reaction. This method allows the student to be more actively involved in the data acquisition process. Under the traditional method of working with a partner, the blind student would simply be told how long the reaction took, and what color change was observed. This new approach creates a more hands on laboratory experience.6 7
A number of chemical reactions such as precipitations, acid base titrations, and numerous others can be observed with this tool. Understanding the occurrence of precipitate formation in the chemistry laboratory is pedagogically important. Precipitation is used to teach concepts in chemical equilibrium, the periodic properties of the elements, and chemical kinetics. Precipitation is also one of the key observations in the qualitative analysis of chemical compounds.
color changes are used in many experiments, such as titrations, to detect chemical changes. The submersible light sensor is being tested in these kinds of reactions using indicators that cause substantial changes in the amount of light transmitted. Methyl red, phenolphthalein, and bromthymol blue are common indicators that can be used with this tool to determine ranges or to detect the end point in acid-base reactions.
Another reaction that can be monitored using the submersible light sensor is the iodine clock Reaction. This reaction involves the reaction of iodide with hydrogen peroxide in the presence of thyosulfate; using starch as an indicator. This reaction when performed in a test tube has a series of distinct color changes. The timing of these color changes is sensitive to the concentrations of the reagents used, and hence the reaction is known as the clock reaction. The audible tones from the sensor can be measured on a chromatic tuner to quantify the color changes that occur in this reaction.
Further development and testing of audible tools such as the submersible light sensor will allow for blind and visually impaired students to have a more hands on laboratory experience. The goal of this project is to create a suite of tools and adaptations that will allow blind and VI students to work completely unassisted in the laboratory. Future work on this project will focus on additional tool developments that will further enhance blind and VI students’ laboratory experience in chemistry as well as in other physical sciences.
1 Mallouk, Thomas E. “Techniques and Tools to Enhance Blind and visually Impaired
students Participation in High school Level and General chemistry Laboratory
classes” NSF Award Abstract - #0435656
2 Mallouk, Thomas E. “Independent Laboratory Access for the Blind” August 8, 2005
3 supalo, Cary A. “Blind students can succeed in chemistry classes” Future
• Reflections, summer/Fall 2002. http://www.nfb.org/fr/fr8/frsfO210.htm.
4 Miner, Dorothy, Rob Nieman, Anne B. swanson and Michael woods, Editors. “Teaching
chemistry to students with Disabilities”, 4th Edition, 2001.
http //membership. acs. org/c/cwD/Teachchem4. pdf
6 chemistry Laboratory Manual, Prentice Hall, wilbraham,
D.; Matta, Michael S.