In this three-component laboratory module, upper-division chemistry students were introduced to the kinetics of the aspirin hydrolysis reaction and determined the concentration of its active pharmaceutical ingredient (acetylsalicylic acid-ASA) using a modern, benchtop ultraviolet-visible (UV-vis) absorption spectrophotometer. In the first component, students prepared analyte solutions from over-the-counter aspirin tablets and a relevant number of standards (n = 9-10) through both serial and parallel dilutions. In the second component, the ASA concentrations of three over-the-counter formulations (325 mg per tablet) were determined with percent differences as small as 1.1% using the Beer-Lambert law and external calibration curves. In the third component, students evaluated the reaction order (pseudo-first order), the rate constant (e.g., k