Theoti Acid Base Titration Simulator Example Graphs

This page contains screen captures of Theoti performing various tasks. The graphics are quite large, so they may take a long time to load. They do quite clearly demonstrate some of the strong point of Theoti, though, so the wait may be worth your while. Otherwise, you may want to go back to the Theoti homepage.

What's on this page?

• Animated Simulation example
• Calculation Assumptions example
• Indicator Concentrations Comparison example
• Carbon Dioxide Concentrations Comparison example
• Guided Tour example
• Lessons example

Animated Simulation example

Screen snap shot of an animated simulation. Drops of titrant are gradually being added to the analyte solution. The stopcock in the insert in the titration setup display (right middle) can be opened or closed with the mouse to increase or decrease titration speed.

Indicator colours in the indicators rack and the beaker will change as more titrant is added.

The simulation can be used to show the necessity of making small volume steps near the equivalence point.

Calculation Assumptions example

Titration of 100ml of 0.100M H₃PO₄ with 1.00M NaOH. Solid curve has no assumptions, dotted curves assume [H₃O⁺]>>[OH^-] (v < 20ml), and that earlier equilibriums can be ignored (v > 20ml). It's seen that in almost all cases the assumptions cause no severe error.

Indicator Concentrations Comparison example

Curves created by varying the amount of methyl red added to the analyte solution. While the amounts shown here are extreme, the effect of adding too much indicator is clearly shown, demonstrating the need not to let the measurement be influenced by the method used to measure it.

Carbon Dioxide Concentrations Comparison example

Demonstration of the effect carbon dioxide dissolved in a sodium hydroxide titrant solution can have on the titration of an acetic acid solution. In laboratories sodium hydroxide titrant solutions are often kept several days. During that period an increasing amount of carbon dioxide will dissolve in the solution. The graph shows that the transition range of phenolphthalein moves to increasingly higher volume coordinates, resulting in an increasing error in calculated acetic acid concentration.

Guided Tour example

Example of Theoti performing the Guided Tour. The help screen at right asks a question, in this case "which pKa would you use to indicate a strong acid". The user can pick one of four answers (-infinity, -5, 0, and 19). As soon as one of the answers is picked, Theoti draws a titration curve using the pKa that was chosen.

Also shown in the help window are scroll bars which can be used to gradually vary the pKa of both the analyte and the titrant. In the screen shot shown the pKa of the analyte has been varied from -5 to 2.70, giving curves that start at increasingly higher pH values.

Lessons example