We are currently in the process of incorporating green chemistry throughout the chemistry curriculum. In this article we describe how we applied the principles of green chemistry in one of our first-semester general chemistry courses, specifically in relation to the determination of the formula of a hydrate. We utilize a copper hydrate salt that shows both a visual color change upon dehydration and ease of rehydration upon exposure to steam. (Contains 1 table, 1 figure and 1 note.)