Universita di Messina Salita Sperone Dipartimento di Chimica Industriale e Ingegneria dei Materiali 31 (Casella Postale 29) 98166 Sant'Agata di Messina Italy 31 (Casella Postale 29) 98166 Sant'Agata di Messina Italy
A small ultraviolet-visible absorption spectrometer which uses fibre optic coupled immersion probes has been incorporated
into a laboratory scale reaction calorimeter. The combined instrument has been tried out using the hydrolysis of acetic anhydride
as a test reaction. With the calorimeter operating in the isoperibolic mode good agreement is found for the pseudo-first order
reaction rate constant as determined from spectroscopic and calorimetric measurements. Experiments have been made in order
to follow the reaction indirectly using optical pH measurements with acid-base indicators. The possibility of determining
the temperature dependence of the rate constant in a single experiment has also been investigated.