If acetaldehyde is photolysed completely at 300C, the final pressure is almost exactly double the initial pressure. One mole of aldehyde, therefore, gives two moles of products and the pressure change at any time during the reaction is a measure of the progress of the reaction. It is convenient to monitor the reaction by following this pressure change, and by the analysis of decomposition products.
Instructions for this experiment are available for reference in a folder in the Lower Teaching Laboratory. You may obtain a personal copy from the technician in that laboratory, or download a copy in PDF format (7 pages).
Updated May 10, 2002.