This module is designed to demonstrate the effect on the pH of a sample of pure water and a sample of a buffer upon addition of a small quantity of an acid or a base. It allows addition of successive amounts of the acid or base. The simulation has been setup to allow user input for the following: 1. To select whether an acid or base is to be added to the samples of water and the buffer. 2. The volume, molarity of the acid or base to be added. 3. Choice of the buffer solution from a set of four buffers. 4. Choice of indicator.
Type of Material:
Simulation, to be used as a demo in the classroom, or as a mini tutorial/homework
Simulation which could be used by the instructor as a demo in the classroom, or as a mini tutorial/homework assignment for a student or group of students. Extensive discussion of the chemical concepts before and after use of the simulation would be helpful.
Standard access to the web using netscape or I.E. is sufficient, no additonal software or platform is needed
Identify Major Learning Goals:
1. Understanding the effect on the pH of an unbuffered solution upon addition of an acid or base. 2. Understanding the effect on the pH of a buffer solution upon addition of an acid or base (how it resists changes in pH) 3. Understanding range and capacity of a buffer and the conditions under which the capacity of the buffer can be broken. 4. Graphical representation of pH data
Target Student Population:
Students in chemistry courses at the high school level, and introdutory chemistry courses at the college level
Prerequisite Knowledge or Skills:
Knowledge of acids, bases, buffers, pH, titrations, molarity are needed. There is no background or introductory information given,
at all, and that could be a problem for a new user.
The concept trends and results are correct qunatitatively and qualitatively. The results are shown as numeric values; changes in pH of the sample solution shown by changes in color of the indicator uesd; and plotting of the resulting pH values as a graph giving visul results.
The results are displayed in many formats: numerically, graphically, and visually, with little to no explantion or labeling. This may be confusing and or overwhelming to students if they do not understand what the information is telling them.
The title is misleading, it is not really a general acid base titration module. This deals specifically with the specific effect of additon of acid or base to samples of pure water and various weak acid/base buffers. Also there is either a typographical error or a content error in the choices of buffers: "hypochlororate". This substance does not exist!
Potential Effectiveness as a Teaching Tool
This is an extremely reusable learning tool. However, it requires extensive background provide by the teacher to be of use to students. The graphics are good, interactive, and is versatile enough to be used in a variety of ways and contexts (with the appropriate supplementary background or assignment).
There is no introductory or background material and the instructor would need to write a detailed assignment before assigning or using this as an effective teaching/learning tool
Ease of Use for Both Students and Faculty
The module behaves robustly (will not crash with many students using it), accepts values from user input for a number of varialbes, and gives results quickly and accurately. The module is easy to use, once the main concept of its use is understood.
The module is not immediately intuitive for students to use. There are no titles, instructions or descriptions to help a beginning user to get started. There is no narrative giving the concepts or theory on which the experiments are based.
Other Issues and Comments:
This is a thorough simulation module that behaves very well even under deliberately extreme conditions such adding large quantities of the acid or base to test the robustness of the module. It gives good graphical and numeric results to allow better understanding of the concepts of pH, buffers, acids and bases.
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