Establishing the Effect of Solvent Polarity on Carotenoid Extraction: A Small-Scale Solid–Liquid Extraction and Alkene Identification Experiment for Senior High School Students

We present a small-scale, inquiry-based experiment for senior high school students that explores the effect of solvent polarity on the extraction of carotenoids and the identification of unsaturation through qualitative chemical tests. Using 3 g of diced carrot and three solvents─heptane, ethanol, or water─students conducted solid–liquid extractions, followed by bromine water and potassium permanganate testing. These visual tests detect the presence of unsaturated carotenoids based on color changes associated with electrophilic addition or oxidation reactions. Heptane, a nonpolar solvent, proved most effective in extracting carotenoids, while ethanol showed moderate effectiveness and water was ineffective due to its high polarity. This visually engaging and pedagogically robust experiment reinforces key organic chemistry concepts such as solubility, molecular polarity, and functional group reactivity within a 2 h lab session designed for classroom implementation.