Printer Friendly

The modification of general chemistry laboratories for use by students with disabilities.

Traditional modifications for individuals with disabilities in laboratory settings have relied on disability-specific accommodations. The purpose of this project was to develop a methodology for inclusion of students with disabilities with a focus on modifying classroom activities rather than requiring the student to adapt to traditional methodology. A General Chemistry laboratory exercise has been modified to make it completely safe for students who have physical disabilities. While only materials available in supermarkets are used, there is no diminution of the chemical principles being taught. There are considerable advantages in both cost and ease of waste disposal compared to traditional experiments. A typical first year chemistry class containing forty students obtained satisfactory results performing the experiment. A student with cerebral palsy who uses a wheelchair (who was not a science major) experienced no difficulties in performing the required experimental manipulations. The philosophies and practicalities of these types of modifications are discussed along with implications for increased accessibility to laboratory settings.


With the passage of the Americans with Disabilities Act (ADA) of 1990, the United States has become a leader in the inclusion of people with disabilities. The ADA has had, and will continue to have, profound affects in all walks of life. This is particularly true in all levels of education due to the need to modify programs and physical accessibility (ANSI, 1986; Redden, Davis and Brown, 1978).

Chemistry and other laboratory sciences are areas where people with physical disabilities have experienced particular difficulties (Crosby, 1981). These difficulties have included obvious prejudices and serious physical barriers. Laboratory benches are usually at an inappropriate height for a person who uses a wheelchair. Dangers associated with the handling of hot, corrosive or toxic materials are often increased for students with poor manual dexterity or reduced vision (Reese, 1990).

One solution to these problems has been to design special benches which are wheelchair accessible and have a number of safety features which contain spills, etc. These benches are expensive (about $5,000) and can only be used by one student in an individual laboratory period (Larsen, Buchanan and Torrey, 1978). In addition, it may be difficult to install them in many small laboratories. Even affluent colleges and universities would probably find it difficult to justify the expense to accommodate a few students per year. Difficulties of these types have led to less inclusion of the student with disabilities than is clearly desirable (e.g., see Swanson and Steere, 1981 and Blumenkoph, Swanson and Larson, 1981).

The primary objective of the authors of this project is to design experiments that would safely illustrate important chemical procedures for all students. Safe has been defined in this context to mean the following: if the entire experimental equipment were to be spilled on a student sitting in a wheelchair there would be no chemical or physical dangers, although the person might get wet. In addition, commonly available inexpensive materials obtainable in most supermarkets are employed that would produce few eventual waste disposal problems.

The philosophy of inclusion concerning students with disabilities can be illustrated by a possible first year college chemistry experiment which is equivalent to one of the traditional laboratory exercises. It should be noted that this exercise can be performed by all students, not just those students with a disability. This is optimal because every student in the laboratory does exactly the same thing whether disabled or not. There are several novel features of the experiment which is described below.


Inexpensive materials such as table salt, sugar and bicarbonate of soda were purchased from a local supermarket. The total cost for the entire experiment for forty students was less than four dollars. All beakers, testtubes etc. were made from unbreakable plastic. Protected thermometers containing alcohol rather than mercury were employed. A metal and plastic digital thermometer with a large easily readable dial was available for students with impaired vision. Further, as all chemicals are obtained from a supermarket, the problems of the disposal of the chemical waste are greatly minimized. Because of the essentially non-hazardous nature of the experiment it could be performed by any student in a seated position on a common folding table. The ease with which an instructor can assist a student from the opposite side of a relatively narrow folding table is clearly demonstrated in the accompanying photograph.

Chemical Procedures

Solutions in which a solute is dissolved in a solvent have lower melting points than the pure solvents. This depression in melting point is directly related to the concentration of the solute. This information can be related to many important chemical phenomena such as the determinations of molecular weight, degrees of ionization and the relationships between empirical and molecular formulas. From an experimental point of view, however, an exercise in which the melting points of both the solution and the pure solvent are measured is always required prior to performing any calculations. Procedures of this type are presented in most high-school and freshman college chemistry texts.

Sienko, Plane and Marcus's laboratory manual [1984] is currently employed in the Auburn University at Montgomery. This text includes a standard experiment entitled Molecular Weight from Freezing Point Lowering. In this experiment, a beaker containing water is placed on a metal stand and heated with a Bunsen burner. A testtube containing naphthalene is placed in the resultant boiling water.

After the naphthalene has melted, the test tube is removed from the water and as the liquid cools the temperature at which the solid is reformed is recorded with a thermometer. This procedure is repeated with sulfur dissolved in the molten naphthalene in order to determine the difference between the melting points.

Numerous hazards are involved in this experiment. This is especially true for a student with limited vision or limited mobility. The metal on the Bunsen burner reaches temperatures that would immediately cause severe bums on contact. A beaker of boiling water is supported by a metal gauze on a metal stand. Liquid naphthalene (which has the consistency of a liquid wax) would adhere to skin on contact. Consequently, there are many opportunities for a seated student. This would be especially true for a student who uses a wheelchair who had to stretch to reach the equipment on a standard laboratory bench. In addition broken glassware and the mercury contained in the thermometer could pose additional hazards.

An experiment has been designed using the melting point of ice that produces data that is as valid and as accurate as the data obtained from the above experiment. The glassware has been replaced by plastic beakers and test tubes. A metal and plastic digital thermometer with a large easily readable dial or protected alcohol thermometers are employed. This equipment costs about $30 per student and could be utilized for other experiments. Students without disabilities could continue to use the normal glassware, which would produce essentially identical experimental results. A mixture of ice, salt and water is placed in a plastic beaker in order to achieve temperatures below -10 [degrees] C. Water is now used as the pure solvent. The freezing point of pure water in a plastic test tube placed in the ice/salt/water mixture can now be used to calibrate the thermometer. A variety of suitable solutes such as sodium chloride, sugar, and sodium bicarbonate are available at nominal cost in any supermarket. A solution containing one of these solutes that would freeze at about -5 [degrees] C is prepared. This temperature is again achieved by placing the solution in a plastic test tube in the ice/salt/water mixture. The measured freezing points can be employed to calculate any of the phenomena resulting from traditional experiments. All of the materials employed are non-toxic and non-corrosive and could, in fact, be safely ingested in small quantities. High temperatures are not employed. At the worst an accident would result in cold water containing salt, sugar or sodium bicarbonate being spilled under conditions where no broken glass was present. Side benefits for the described procedure include the facts that the employed materials are considerably less expensive than chemicals purchased from supply houses and the not trivial costs of disposal of waste chemical materials have been eliminated. Detailed experimental instructions are given in the Appendix.

Experimental testing under classroom conditions

The above experimental procedures have been tested using a volunteer student with a physical disability who uses a wheel-chair and who had no knowledge of chemistry. The procedure was also tested with a third quarter General Chemistry class. In designing the experiment, the authors questioned whether a person seated in a wheelchair at a folding table could physically perform the manipulations necessary to successfully do the experiment. The results show that the student using a lightweight hemi wheelchair had no difficulty whatsoever in performing the experimental procedure. The student's performance of the mechanical manipulations was comparable to the students in the regular laboratory surroundings.

In the case of the General Chemistry class, the authors were interested in obtaining some indication of typical student results from this experiment. We found that three quarters of the class were able to estimate molecular weights with sufficient accuracy to identify the correct unknown material out of several possibilities. The average 8% error observed by this group of students was superior to the usual results for the experiment performed with boiling water in the regular first year chemistry course. (It should be noted that freezing point depression and boiling point elevation experiments always have relatively large errors because results are dependent upon the accurate measurement of small temperature changes.)

To validate the modified experimental procedures, a laboratory section of a general chemistry course will be taught. It is anticipated that at least two of the thirty students enrolled will have a disability and all students will perform exactly the same experimental procedures. A laboratory manual will be developed that includes most or all of the topics commonly encountered in a one-year college or high school chemistry course sequence. It should be noted that many health and engineering areas do not require further chemistry courses beyond that point. In most universities only a very small percentage of students taking chemistry courses actually obtain degrees in the subject. Almost all university chemistry departments possess the resources to individually tailor their courses to meet the needs of chemistry students with disabilities. This is not the case in high schools or large university service courses. Modified experiments involving low costs and very low safety risks are particularly beneficial for accommodating students with disabilities at these academic levels.


Modifications to laboratory settings and chemistry experiments for individuals with motor and vision disabilities produces equivalent results when compared to a class of non-disabled students. This is an example of a methodology for inclusion of students with disabilities where the focus is in modifying classroom activities rather than requiring any student to engage in traditional and possibly unsafe laboratory activities.


American National Standards Institute. (1986). Providing accessibility and usability for physically handicapped people. (ANSI A117.1-1986), Washington, D.C.: ANSI.

Blumenkoph, T.A., Swanson, A.B. and Larsen, R.P. (1981). Mobility-handicapped individuals in the college chemistry curriculum. Journal of Chemical Education, 58, 213.

Crosby, G.A. (1981). Attitudinal barriers to the physically handicapped. Journal of Chemical Education, 58, 205.

Larsen, R.P., Buchanan, R. and Torrey, F.R. (1978). The handicapped student in the science Laboratory. In M. Coons and M. Milner (Eds.), Creating an Accessible Campus (Chapter 7). Washington, D.C.: Association of Physical Plant Administrators of Universities and Colleges.

Redden, M.R., Davis, C.A. and Brown, J.W. (1978). Science for handicapped students in higher education, (Publication 78-2), Washington, D.C.: American Association for the Advancement of Science.

Reese, K. M. (1990). Teaching chemistry to physically handicapped students. Washington D.C.: American Chemical Society, American Chemical Society Committee on the Handicapped.

Sienko, M.J., Plane, R.A. and Marcus, S.T. (1984). Experimental chemistry. New York: McGraw-Hill Inc.

Swanson, A. B. and Steere, N. V. (1981). Safety considerations for physically handicapped individuals in the chemistry laboratory. Journal of Chemical Education, 58, 234.

Authors' Notes

The authors wish to sincerely thank Trisha P. Colley for her help and enthusiasm in performing the experiment. Thanks are also due to Debbie West and Carolyn Johnson (AUM library) for assistance in locating several of the articles in the Bibliography. We are indebted to C[H.sub.2]M Hill for financial support for this project.


Determination of Concentrations by Freezing Point Depression Experiments

A solution has a lower freezing point than a pure solvent. The depression in freezing point is proportional to the molal concentration of particles in solution. For example, a one molal sodium chloride solution would contain two moles of ions per 1,000 grams of solvent. Consequently, the sodium chloride solution would produce twice the depression of a one molal solution of a non-ionizing solute such as sugar.

A. Preparation of 1.0 molal Sodium Chloride Solution

Weigh 5.85 grams of sodium chloride. Dissolve this salt in 100 mls of pure water. (Note that the final solution does not have a volume exactly equal to 100 mls.)

B. Preparation of Ice Bath

Place about a one-inch depth of crushed ice in a one liter beaker. Cover this ice with about a one-half-inch layer of table salt. Repeat this procedure twice in order to obtain a total depth of approximately five inches for the salt/ice mixture. Add the minimum amount of water that will just allow the mixture to be stirred easily. The temperature of this mixture should be at or below -10 [degrees] C.

C. Determination of Freezing Point of Salt Solution

Fill a test tube to a depth of about three inches with water at room temperature. Place the test tube in the ice bath. While stirring gently, record the temperature of the water at thirty-second intervals. Continue until the temperature remains constant for four consecutive readings. This temperature will give the freezing point of water as indicated by your thermometer. (Note that it is common for the water to super-cool below 0 [degrees] C before stabilizing at the actual freezing point.) Temperatures should be estimated to the nearest one quarter of a Celsius degree.

Repeat the experiment with the sodium chloride solution. In this case plot the recorded temperatures against time. The actual freezing point of the solution is obtained in the region after the super-cooling has stopped. The difference between the freezing points of the pure water and the one molal sodium chloride solution is equal to the molal freezing point depression constant for water.

D. Analysis of Unknown Sodium Chloride Solution

Repeat the experiment with the supplied sodium chloride solution of unknown concentration. Use the obtained freezing point depression to estimate the molal concentration of sodium chloride in the unknown solution.
COPYRIGHT 1994 National Rehabilitation Association
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1994, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Author:Teggins, John
Publication:The Journal of Rehabilitation
Date:Jul 1, 1994
Previous Article:Towards access, accountability, procedural regularity and participation: the Rehabilitation Act Amendments of 1992 and 1993.
Next Article:Focus groups: a tool for consumer-based program evaluation in rehabilitation agency settings.

Related Articles
An Introduction to Universal Design.
Inclusion: What Can Teachers Do?
Access to scientific careers.
A winning combination: collaboration in inclusion.
Successful preparation of teachers of students with disabilities.
A review of literature on mathematics instruction for elementary students with learning disabilities.
Understanding learning disabilities.

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters