Quantifying the soda geyser

Although the science behind the soda geyser demonstration is well known, describing the microscopic origins of this dramatic, sticky demonstration can be difficult. In this experiment, an apparatus was designed to contain the reaction, thereby allowing for quantitative analysis of the amount of CO ₂ released after dropping in various initiating objects. The exploratory studies were tested with a moderate sized group of 12-17 year old participants at a summer learning event, and their data confirmed that the difference in the surface area of the initiators was a primary factor for the release of dissolved gas. Additional studies were performed to relate the soda temperature to the amount of dissolved CO₂. In this laboratory experiment, students gained a greater understanding of surface area and its effect on gas nucleation and bubble formation as well as gas solubility its temperature dependence. The experimental approach provided a dramatic yet contained format for students to form and test their own hypotheses about the chemical processes behind this popular classroom demonstration.