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General Chemistry Collection
pH Titration Simulator
Windows-compatible computers
User’s Guide
Introduction
Hardware and Software Requirements
Installation
Getting Started
User Directions
Selecting Solutions
Titration Simulation
Tasks
Acknowledgment
Troubleshooting
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pH Titration Simulator
pH Titration Simulator
N. Popadopoulos and M. Limniou
Department of Chemistry, Aristotle University, 54006 Thessaloniki, Greece
Introduction
pH Titration Simulator is a Windows compatible computer program that simulates a pH titration. Students can run realistic experiments and receive sample
data as part of the process of learning how to carry out a titration, practicing
procedures as thoroughly and as often as needed.
The aqueous acid–base titration is one of the most widely used laboratory exercises for a first course in introductory or analytical chemistry. Laboratory experiments give students practical experience and technical competence in manipulation, observation, data collection, processing and analysis of data, interpretation of observations, problem solving, team work, experiment design, and
communication and presentation. However, laboratory training is expensive, it
requires academic and technical staffing, instruments, consumable materials
and laboratory experiments take up a great deal of staff and student time. Simulations can help in developing laboratory skills. Computer simulations offer a
learning experience that complements both classroom instruction and traditional laboratory experiences.
With pH Titration Simulator, students can select an acid, its concentration, the
concentration of the base, and an indicator to be used in a simulated a titration.
They can control the rate at which base is added to the acid from a burette. As
the solution’s pH changes, students can see the changes in color for the chosen
indicator. After each addition of acid or base, the computer calculates the pH,
the concentrations of each of the acidic and basic forms of the indicator, and the
corresponding absorption (according to Beer's law), and displays the approximate color of the solution. Students can develop a clear understanding of how
changes in pH affect the color that is observed in the solution, the pH span in
which the indicator changes its color, and at what pH the major change occurs.
This allows students to understand that each particular indicator is useful in
detecting changes at a specific pH value. The simulation of several different
titrations involving strong and weak acids can complement this, so that students understand the uses of the different indicators that are available. The
program also includes a section that introduces students to the theory and use
of the pH meter. A detailed understanding of these concepts would necessarily
involve a large number of experiments, which may not be feasible in the available laboratory time. Computer simulation provides an extremely versatile way
to ensure that students can have experience with a wider variety of indicators
and titrations than would be possible in the laboratory. At the end of the experiment, data that are displayed graphically on the computer screen can be stored
on disk and reexamined with the aid of spreadsheet software.
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pH Titration Simulator
Hardware and Software Requirements
Hardware and software requirements for pH Titration Simulator are shown in
Table 1.
Table 1. Hardware and software requirements for pH Titration Simulator.
Computer
CPU
RAM
Drives
Graphics
Operating
System
Windows
Compatible
Pentium
≥ 64 MB
CD-ROM;
Hard Drive
SVGA;
≥ 256 colors;
≥ 800 × 600
Windows XP,
2000, Me, 98
Installation
Installation instructions for the General Chemistry Collection CD-ROM are
found in the ReadMe.wri file located at the root level of the General Chemistry
Collection CD-ROM and in the General Chemistry Collection User’s Guide,
User_Dir.pdf, located in the Documentation folder. pH Titration Simulator is
included in the Typical installation for the CD or it may be installed separately
using a Custom installation.
☞
You may be able to run pH Titration Simulator directly from the General Chemistry
Collection CD-ROM, but some versions of the Windows operating system have trouble
doing so. For that reason, the pH Titration Simulator program is installed to the
hard drive by the JCE Software Setup program.
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pH Titration Simulator
Getting Started
To start pH Titration Simulator, click the Start button, then select JCE Software
from the Programs menu. From the JCE Software menu select General Chemistry Collection, then pH Titration Simulator. From the pH Titration Simulator
submenu, select pH Titration Simulator. Alternatively, locate and double-click
the titr.exe icon inside the pH Titr folder on your hard drive.
The opening window, shown in Figure 1, appears when the program is run.
Click the picture of the burette to go to the Solutions window, shown in Figure 2.
Figure 1. The opening screen for pH Titration Simulator.
You can also click Introduction for a brief written introduction to titration or
The Authors to learn about the authors of the program.
Instructions are provided by clicking the Show Instructions button on the Solutions or Titration Simulator windows (See Figs. 2 and 3) and in the User’s Guide.
Suggested exercises that can be done using pH Titration Simulator are available by clicking the Task button (See Figs. 2 and 3).
For background information, click the Theory button (See Figs. 2 and 3).
To quit the program, return to the opening window by clicking the back-pointing arrow buttons (see Figs. 2 and 3). Then click the Exit button (see Fig. 1).
User Reproducible
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pH Titration Simulator
User Directions
Selecting Solutions
The Solutions window, shown in Figure 2 allows you to select the acid, indicator,
and solution concentrations that you want to work with in your titration. The
window consists of three panels.
Figure 2. The Solutions window.
Select a Sample
On the left side of the screen is the Select a sample to titrate panel. Select an
acid by clicking one of the labeled flasks on the left side of the window. The
selected acid is highlighted with red text. The acid selected in Figure 2 is hydrochloric acid. Adjust the concentration of the acid to a value from 1 × 10–4 to 1 ×
10–2 M using the sliding control.
Select an Indicator and Titrant Concentration
The panel on the right side of the window allows you to select an indicator and
set the concentration of the titrant. If you do not want to use a visual acid–base
indicator in your titration, click the radio button in front of no indicator. If you
do want to use an indicator, click the radio button in front of Select an indicator, then click one the labeled flasks. The level of indicator solution in the flask
will fall when it is selected. The indicator selected in Figure 2 is phenolphthalein.
The base used as titrant is sodium hydroxide (NaOH) and cannot be changed.
You can, however, adjust the concentration of the titrant from 1 × 10–4 to 1 × 100
M using the sliding control.
☞
Be sure to select concentrations of acid and base that will allow you to complete a
titration. Consider that you must use a 100 mL sample of acid and that the burette
used in the simulation holds 50 mL of NaOH solution and cannot be refilled.
The panel at the bottom of the screen contains five control buttons. Click the
back-pointing arrow to return to the opening screen. Click the Theory button to
go to window that offers a selection of detailed explanations of titration, acids,
and indicators. Click the Show Instructions button to see on-screen instructions
for this window. The button label changes to Hide Instructions when clicked.
User Reproducible
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pH Titration Simulator
Click it again to remove the on-screen information. Click the Tasks button to see
several suggested assignments that can be done with pH Titration Simulator.
When all the selections are complete in the upper panels of this window, click
the Start Titration button to begin the titration.
Titration Simulation
The Titration Simulator window, shown in Figure 3 appears when you click the
Start Titration button on the Solutions window.
Figure 3. The Titration Simulator Window.
Click the off/on buttons to turn on the Magnetic stirrer and Digital pH meter.
The burette can be operated manually or automatically using the Burette Controller located in the upper left corner of the window.
For manual operation of the burette, first click the radio button in front of Manual
on the Burette Controller. Then, click the Big drop or Small drop button to add
titrant from the burette to the acid solution in the beaker. Clicking Big drop
adds 0.50 mL of titrant. Clicking Small drop adds 0.05 mL of titrant.
For automatic operation of the burette, click the radio button in front of Automatic on the Burette Controller. Titrant will be added automatically in 0.50 mL
drops. To stop the automatic addition, click the radio button in front of Manual.
After each drop of titrant is added, the pH is displayed by the Digital pH meter
and a point is plotted in the chart on the right side of the window. If an indicator
is used, the color of the solution is also adjusted.
When the titration is complete, you can save the data plotted in the chart by
clicking the save data button. You will be prompted to provide a name for the
data file and a location where is should be stored. The data are saved as a
comma-delimited text file that can be opened for further analysis with a spreadsheet application such as Microsoft Excel.
If you would like to repeat the same titration, perhaps adding titrant at a different rate, click the Repeat button. If you would like to run a different titration,
click the New experiment button, and you will be returned to the Solutions
window (Fig. 2) where you can select new solutions.
User Reproducible
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pH Titration Simulator
Tasks
Figure 4. The Tasks window.
Several assignments that can be completed with pH Titration Simulator can be
viewed on-screen by clicking the Task button. The Task window is shown in Figure 4.
Click an icon at the top of the window to see a description of a task you can
complete with pH Titration Simulator. The Tasks are also described below.
User Reproducible
1.
Leveling Effect: Titrate 100 mL of 0.01 M nitric acid and 100 mL of 0.01 M
hydrochloric acid with sodium hydroxide solution. Compare the titration curves
and explain your observations.
2.
Indicator: Find suitable indicators for titration of the following acids, and explain why you choose each indicator:
malonic acid
sulfuric acid
hydrochloric acid
3.
Stereochemistry: Titrate the acids listed below. Compare the titration curves
and explain your observations.
fumaric acid
malic acid
malonic acid
4.
Dissociation of Acids: Titrate 100 mL of 0.01 M solutions of the acids listed
below. Compare the titration curves and explain your observations.
sulfuric acid
phosphoric acid
tartaric acid
5.
Acid Strength: Titrate 100 mL of 0.01 M solutions of the acids listed below.
Compare the titration curves and explain your observations.
acetic acid
formic acid
hydrochloric acid
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pH Titration Simulator
Acknowledgment
The authors thank Robert de Levie of Bowdoin College for providing the algorithm for the pH calculation and for his advice and suggestions for improving
the program.
Troubleshooting
If you experience any difficulty in running pH Titration Simulator, first verify
that you have the minimum hardware and software required to run the program. Hardware and Software requirements for pH Titration Simulator may be
found on Page 3.
Problem Reports
If the problem is not addressed in the User’s Guide and all required hardware
and software are present and in working order, contact the JCE Software office
for technical assistance. For quickest response, call, send a FAX, or an email
message.
Telephone: 800-991-5534 (USA only) or 608-262-5153
FAX: 608-265-8094
Email: [email protected]
Regular office hours are Monday–Friday, 9:00 a.m. to 5:00 p.m. (Central Time).
An answering machine is available at all times. Your message should include
the following information:
• Your name
• How we may contact you (telephone number or email address)
• The best time to reach you by telephone
• Title of the program
• A description of the problem
• A description of your computer system (model, RAM, operating system version, etc.)
If you do not receive a response to a telephone message or email within two
working days, please contact the office again during office hours and request
that your call be transferred (or email message be forwarded) immediately to a
technical editor.
Online Assistance
A technical support section is available on our WWW site at
http://jchemed.chem.wisc.edu/JCESoft/ where you will find a list of technical
questions we have received and answers or solutions for each program we publish. Also, JCE Forums, http://jchemed.chem.wisc.edu/cgi-bin/webx, includes
online discussions of JCE Software publications. If you have WWW access, it
may save you time to check these sites first if you encounter any difficulties.
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