Abstract:
This thesis describes some investigations into the nature of the transient pink color which develops when a basic mixture of copper(II) nitrate and dimethylglyoxime is oxidized by potassium persulfate. This reaction is known informally as the "red flash". Experiments were first performed to try to prolong the reaction by continual addition of some of the reactants. The success of these experiments indicated that hydroxide, dimethylglyoxime, and persulfate were consumed by the reaction, but not copper(II). Some aspects of the stoichiometry were next investigated. The stoichiometric ratio of hydroxide consumed to sulfate produced was measured and found to be slightly greater than 1.
An attempt was also made to identify some of the products, using HPLC. It was established that butanedione monoxime is a product. Butanedione may also be a product but the HPLC detector could not access the 190 nm region needed. The feasibility of monitoring both absorbance and pH during the red flash by interfacing to a computer was then investigated. Some 19 runs were performed. These indicated that the reaction goes through several steps, some of which are pH-dependent. The initial step in which a colored species is first produced appears to be second order with respect to copper(II). The rate is also dependent on persulfate concentration but not enough data could be collected to establish the order with respect to this component.
