This lecture focuses on exercises related to instrumental chemistry, specifically carboxymethyl cellulose as an ion exchanger. The instructor explains the polymer structure of cellulose, the substitution process with carboxymethyl groups, and the protonation state for ion exchange. The lecture covers pH considerations for effective cation exchange, calculations involving the Anderson-Acelpbach formula, and practical implications for biological materials. Additionally, it discusses UV-visible spectroscopy, Lambert-Beer law applications, and the importance of pH in protein retention on carboxymethyl cellulose. The lecture concludes with infrared spectroscopy analysis and identification of functional groups in organic molecules.