Virtual chemistry lab for acid-base titration 

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Methods 

Description of the program

The program consists of two parts: information and experiment.  The information part is designed to provide the basic concepts of acids, bases and titration for students and general Internet users. To help non-major students understand the background information of the simulation program, a concise introduction is given before the simulation program on my web site. It starts with examples of acid and base solutions in everyday life to inform students that the concepts they are going to explore are related to their lives and to foster students' healthy attitude toward natural phenomena.  The definitions and equations of acids and bases follows the introduction helping students understand the meaning and functions of acids and bases without introducing many unfamiliar scientific terms and concepts.  The last portion of the information covers the background knowledge of acid-base titration.  It includes the principles and procedures of acid-base titration. 

Above the simulation program, a guide for using the program is provided.  Even though the interface of the program is not complicated, it is thought to be nice to provide a manual for it.  The guide describes not only the interface of the program, but also the general principles and methods of the titration procedure.  Students can see this manual before starting the program and anytime they run the program because it is on the same web page. 

The simulation is designed to take advantage of simulation programs: color changes of mixed solution, pH curve drawn from user's data, various sets of acids and bases.  To make this program accurate and similar to real chemistry experiments, I simulated the actual chemical reactions for acid-base titration so that students will get the accurate results even when they use a notorious combination for titration - weak acid and weak base.  Here are short descriptions of the simulation program. 
 

  • Introduction and signing in. There is short greeting, and users type their names for certification later. 
  • Step 1. Choosing a solution for erlenmeyer flask: A user can choose either acid or base solution for titration. The program also allows users to decide the concentration and volume of the solution. 
  • Step 2. Choosing a solution for burette: Same interface to the step 1 is applied to this step, but if a user chose a acid solution in step 1, the program guides a user to choose a base solution in this step. 
  • Step 3. Choosing an indicator for titration: An indicator plays a crucial role for determining the equivalence point. So for helping users to make a more accurate selection, a figure is provided showing color vs. pH of several indicators. 
  • Step 4. Titration of acid-base solutions with an indicator and a pH meter: A user can titrate the chosen solutions by moving a scrolling bar to set the drop speed of the solution from the burette. When the solution is added to the erlenmeyer flask, students can monitor the changes of pH value and the color of solution as well as the change of the volume of the solutions. If users think they missed the equivalence point (the end point), they can perform the same experiment again by clicking the button "Titrate again". 
  • Step 5. View titration curve from their data: The titration curve can be used for determining the equivalence point like an indicator. The difference is that the titration curve can show how accurately the experiment was performed The steeper the slope of the titration curve at equivalence point is, the more accurate the data are. While or after users titrate, they can view the titration curve from their data. 
  • Step 6. Getting the results and error percents: After finishing the titration procedures, students enter their data and get error percent for it. 
  • Certificate. Students get different certificates according to their lab results and error percent. 


This program does not provide quizzes or grading systems for teachers like commercial chemistry software (Smith & Stovall, 1996) since it has only one experiment simulation. However, there is a print option on every step and if teachers want to know how accurately their students have performed the simulated lab, they can ask students to print out their lab results pages so that they can record how well students perform their virtual experiment. 

The software has its own explanation about titration and it can be used for homework as well. After students learn and share the principles of acid-base titration, they can do their lab without guidance of teachers. If a teacher gives this lab as an assignment to let students acquire related knowledge and skills, it may encourage students to create their own labs and learn cooperatively. 
I have two versions of the program; a Visual Basic version and a Java version. The Visual Basic version is the first version of the software and it has more background images than the Java version. It is downloadable for a Windows machine, and it can be saved in a local hard disk and used repeatedly without spending time for downloading every time. Without using space in a local hard disk, Java version can run on web browsers. As Java depends on the network connection and the connection is usually slow, I limited the use of background images and minimize the file size to reduce the loading time. 

Subject

For a formative evaluation of the program, a graduate student of College of Education at University of Illinois participated in evaluating the program.  Although her major is not science education, she has experience with evaluating instructional software and curriculum and she is also interested in educational applications of technology.  Therefore, her evaluation was thought appropriate for the modification of the program.  The author interviewed her and received some comments after she finished the program.

The subjects for the summative evaluation of the program are three undergraduate students who are taking an introductory educational psychology class at University of Illinois.  They usually use computer two to eight hours a day for word processing, emailing, web browsing, and graphic.  They did actual chemistry labs at high school, but they were not able to remember the exact concepts of acids and bases, nor the titration procedure.  So, they were able to compare the program with their previous actual labs and they were classified into general users with some background knowledge.  One of them took an introductory college-level chemistry class that requires the students to do both actual acid-base titration lab and the counterpart virtual chemistry lab.  Therefore, she was able to compare my titration simulation program with the titration program given in the course as well as with the actual lab.  Another student also has used simulation programs for his physiology class and he evaluated advantages and disadvantages of my program as a simulation program.

Questions

After monitoring the students going through the program, the author interviewed them to ask several questions to examine the educational effects of the program.  The questions can be divided into three categories: understanding, interface, and comparison.  In the understanding part, the students were asked if the program helped understand acid-base concepts and titration procedure, and how it helped the understanding.  In the interface part, the students were asked if it was easy to follow the program and how this program can be improved.  The comparison part was designed to compare the virtual chemistry lab program I developed with the actual chemistry titration lab as well as with other simulation programs including another chemistry simulation program one student has used.

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Abstract
Introduction
Methods
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Discussion
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