Mixing cream of tartar (potassium bitartrate, KHC4H4O6), baking soda (sodium bicarbonate, NaHCO3), and water results in a chemical reaction that produces carbon dioxide (CO2) gas and water, leading to fizzing. Cream of tartar is an acidic compound with a pH of approximately 3.557 in a saturated solution, indicating that it is not fully neutralized. When combined with baking soda, which is a base, the reaction between the acid and the base generates CO2, causing the characteristic fizzing. This interaction exemplifies a typical acid-base reaction, where the acid (cream of tartar) reacts with the hydrogen carbonate (baking soda) to release gas.