#
HypCal

## Determination of stability constants and formation enthalpies
from calorimetric data

Written by |

Peter Gans |
Protonic Software |

Antonio Sabatini |
University of Florence |

Alberto Vacca |
University of Florence |

For further details concerning the way the program works see P. Gans, A. Sabatini
and A. Vacca, *Simultaneous Calculation of Equilibrium Constants and Standard
Formation Enthalpies from Calorimetric Data for Systems with Multiple equilibria
in solution*, J. Solution Chem., (2008) **37**, 467-476.
(requires Acrobat reader)

This program (updated from HypDH to HypCal) enables the calculation of

- either formation enthalpies using previously
determined stability constants
- or formation enthalpies and
stability constants

in systems where one or more complexes are in equilibrium in solution with
a set of reagents. It is a Windows application. Key features are as follows

- There are no restrictions on the number of reagents or equilibria
- Typically HypCal uses calorimetric titration data;
multiple titration curves can be treated simultaneously
- Data import may be from a file containing titre, corrected heat
^{*}
data pairs
- Batch data may also be used
- Data is imported from ASCII files containing titration volume, corrected
heat data pairs
- Heats may be expressed in Joules or calories
- Stability constants may be fixed at "known" values, or refined
- Formation enththalpies may be fixed at "known" values, or refined
- Data may be fitted interactively on-screen before refinement
- Refinement is by a stabilised non-linear least-squares method with Jacobian
calculated by means of analytical formulae
- Reaction entropy may be calculated

^{*} Corrected heat is the heat developed in a titration step, corrected
for all non-chemical effects such as heat of dilution, calorimeter effects etc.

This example shows a system with three reagents and eight complexes Stability
constants and reaction enthalpies for all complexes except ML, MLH and M_{2}L
(M = MeHg^{+}, L = gly^{-}) have been determined in separate
experiments. The formation enthalpies are "live", that is, they change
with every change of stability constant.

Stability Constants home page