Copper(I) sulfide (Cu2S) and copper(II) sulfide (CuS) of 98%, respectively, +99% purity were obtained from Aldrich.
Nitrogen and synthetic air were obtained from Hoek Loos.The nitrogen was of 99.9% purity and the composition of
the air was 21% oxygen and 79% nitrogen. The calibration gas for the IR analyzer was prepared by Praxair and had a
calibrated composition of 424 ppm SO2 ±9 ppm. The gross composition of the sample could be determined from the mass
balances. The remaining sulfur content of the sample was determined using the data gathered by the IR and the effluent
gas flow rate. The oxygen content of the sample could subsequently be determined from the total mass of the sample as
measured by the microbalance and the mass of sulfur in it as determined from the integrated results of the IR. The gross
composition of the sample could be used to determine the (relative) amounts of the components present in the sample
during the experiment. As a check of the sulfur mass balance the total amount of sulfur dioxide emitted by the sample
was used. On average the total amount of sulfur brought into the reactor as Cu2S matched the amount leaving the reactor
as determined by the sulfur dioxide analyzer within 10%. As a check on the total mass balance, the mass of the completely reacted sample was compared with the original mass of the unreacted sample. Since the molar masses of
the reagent (Cu2S) and the desired end product (CuO) are known the mass that the sample should have at the end of an
experiment can be calculated.