This document is an instructional module package prepared in objective form for use by an instructor familiar with the titremetric method and the nomographic method of determining free carbon dioxide concentrations of a water sample. Included are objectives, an instructor guide, student handouts, and transparency masters. A video tape is also available from the author. This module considers chemistry and principles of dissolved carbon dioxide, the preparation of standards and reagents, calculation of free carbon dioxide and the nomographic determination of free carbon dioxide. (Author/RH)