R. W. Ramette, Flexible Software 805 Highland Avenue, Northfield, MN 55057
Hardware: IBM PC Components: 1 dis* and nstruction sheets Level and Subject: College analytical chemistry Cost: $25.00
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Summary Ratings: Category Ease of Use: Subject Matter Content: Pedagogic Value: Student Reaction:
Good
Gwd Good Gmd
Revlew FABTIC, The Final Acid-Base Titration Curve Program, is a well done simulation program that permits the calculation and plotting of an almost unlimited variety of acid-base pH titration curves. It will also calculate the pH of any mixture of aeid and base solutions. Titratian curves can be calculated for strong or weak aeid andlor base samples and can be done for single or multicomponent svstems. Concentrations of samoles and titram a i well as ,ample volumei ran he varA. The curws can Ihe calculated with ur uithwt ~ o n 4 e r n t i u nuf ionu strength cffects and with or without gaussian errors in the calculated pH values ("with" simulates experimental curves mare closely). The pH intervals calculated can he selected and the only restriction is an upper limit on the number of values that can be determined for each curve (Xlt~,. hlw~alculatedolcmy ultn the pH values are the firat drri\nrne curve rdpH d\'i and the bulfrr capavtry rdV dpH). There is an extensive library of acids and bases on the program disk from which to choose, including t h e amino acids, and many are listed under several common names. Choosing compounds not on the list is an easy operation. The information that must be provided are the number of ionizable protons, the charge of the most pratonated species and the appropriate pK, values. These data can be added to the library if desired. Choosing ionic acids or bases from the library does take some manipulation, however. Far instance, to create a sample of 0.1 M carbonate to be titrated requires choosine a mixture of 0.1 M carbonic acid sen it is not possible to delete them from the mixture although it is possible to delete incorrectly chosen or typed compounds names. Calculation parameters can be changed repeatedly and unrealistic values are ignored. There are sufficient prompts and clearly written help screens to allow for educated parameter choices. Once the calculations are initiated (by pressingthe ESC key) the pH and associated values scroll upscreen as they are calculated. Thus the user can see that the program is running. This can prove useful because sometimes an inappropriate
choice of mixture and parameters can result in a long, slow iteration process. In such cases the operation can he aborted with a sin& The calculated curves can .. kevstroke. , he swed on the procram disk or a separatr d ~ r krf d r w e d . Otherwise they d r C savrd on a temporary file on the program disk. The titration curves are plotted from the stored data by a separate program. The user is given the option of plotting one curve or overlaying several. For this purpose there are eight different curve markings available (narrow or thick line and six circle sizes). Unforronorry thrrr is no wnv ro lahel the rurvrc or create n legend on the plotted graph so confusion about which curve is which can result unless the user keeps his or her own record. Also, once the curves t o be plotted are chosen and loaded there is no way to delete them or add others. For the graph the user is given the option of including the first derivative andlor huffer capacity curves and can choose the volume and pH range t o be plotted as well as the size of the plot up to a maximum of seven by five inches. A title of up to 80charaeters can be given to the graph. Once the graph is plotted it is an easy process to return to the parameter screen to vary the platting conditions until a suitable graph is obtained. The graphs are plotted quickly and quietly. When thegraph is plotted there is a cursor that can be moved in three user chosen increments of volume and pH and the pH1volume location of the cursor is recorded on the screen. The cursor can also he used to select a segment of the curve to be plotted on an expanded scale. This expansion can be repeated as often as desired although curves expanded too much are not very useful. Once an appropriate curve is obtained it is possible to clear the screen of extraneousdata 2nd rheeursornnd gjhtainn hard cbpy o i t h r gmphond irstltle using the PIlINT SCREEN nmmand. Thr
