A pH Calculator, a Virtual Titrator, a Real Titration Data Analyzer, a Distribution Diagram Generator - that's CurTiPot, the all-in-one freeware to learn, teach and work with chemical equilibrium of acids, bases, salts and buffers at home, classroom, interactive "dry lab", routine or research laboratory. Features of this powerful suite of MS Excel spreadsheets embrace:
* pH calculation of any aqueous solution of strong and weak acids, bases, salts, buffers and mixtures of up to 7 polyprotic systems (>40 species), with buffer capacity and activity coefficient estimation;
* Simulation and overlay of acid-base titration curves of any complexity, with or without random errors in pH and/or volume. Valuable for teaching, generation of unlimited titration exercises and evaluation of the feasibility and accuracy of new titrations.
* Analysis of pH vs. volume data from simulated and real potentiometric titration curves by two methods: i) graphical representation of curves, assisted by cubic splines interpolation and smoothing of derivative curves, for accurate evaluation of inflections (end-points); ii) determination of concentrations and refinement of pKa values by multiple nonlinear regression (based on the Solver supplement of Excel), essential for difficult titrations with undefined inflections, e.g., acid rain.
* Generation of acid-base species distribution diagrams and curves of buffer capacity, protonation level and average charge as a function of pH and added volume of titrant, with isoelectric point detection.
* Expandable database with pKa values of 250 acids and bases.
Simply unzip the curtipot_.xls file, open it with Microsoft Excel, enable macros and start learning, working and teaching. No install/uninstall required, all macros are removed by closing the file. The software is completely free for educational and non-commercial not-for-profit use.

Requirements: Microsoft Excel (1997 to 2007)

What's new in this version: New alerts for cases of pH calculation with impaired accuracy ; Mean (average) charge calculations and curves vs. pH with detection of isoelectric point (pI or IEP).