Scientific calculators are classified into four types: Basic, Intermediate, Advanced-I, and Advanced-II. They are compared in terms of their capacities, featuring many advantages of the graphic calculator over simple nongraphic calculators. Built-in software packages with the advanced calculators include graphing programs, an equation solver with numerical methods, matrix algebra for solving simultaneous equations, and advanced statistics including a nonlinear least squares regression. Applications in this paper include a simulation of acid-base titration curves, and graphic display of a time course of concentrations of reactants and products for a chemical reaction with first-order kinetics. Ready demonstrations of graphic results from a quantitative chemical problem are particularly advantageous with the advanced graphic calculators.
Supplement
Acid-Base Titration Curve with a Graphic Calculator
This is a source program to generate an acid-base titration curve with the model TI-85 graphing calculator. Helpful explantions are given in parentheses. Some editing or minor modifications might be necessary to be useful for other types of calculators from different manufacturers.
:ClDrw
clear a previous drawing on the screen
:0.00
->
xMin
set a lower limit for the volume of the base, VB
:50.0
->
xMax
set an upper limit for the volume of the base
:5.00
->
xScl
tick marks in the x-axis for the volume
:0.00
->
yMin
set a lower limit for the pH
:14.0
->
yMax
set an upper limit for the pH
:1.00
->
yScl
tick marks in the y-axis for the pH
:25.0
->
VA
input of the volume of the acid
:0.100
->
MA
input of the concentration of the acid
:0.100
->
MB
input of the concentration of the base
:10E-14
->
KW
input of the ion-product of water
:CA=MA*VA/(VA+x)
calculate total concentration of the acid in the mixture at any time during the titration)
:CB=MB*x/(VA+x)
calculate total concentration of the base in the mixture
:PH=-log(0.5((CA-CB)+ ((CA-CB)2+4KW)^0.5))
calculate pH according to the general formula
:y1=PH
store the calculated pH values into an array of variable y1
:DrawF y1
draw a function y1
:End
Notes:
TI-80, TI-81, TI-82, and TI-83 do not allow a variable name with two charactors. Thus , MA, MB, VA, CA, CB , KW and PH must be changed to a single character such as M, N, V, A, B, K and P, respectively for those TI models.
Values for MA, MB, and VA can be readily changed to other values if titration at other conditions are desired.
This work and other related work with graphic calcualtors were presented at the 14th Biennial Conference on Chemical Education, Clemson University, Clemson, SC, August 4-8, 1996.
(tit_asc.htm, 10/98, animated, MHK)
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Kim, Myung-Hoon; Ly, Suw-Young; Hong, Tae-Kee. J. Chem. Educ.2000 77 1367.
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