The acid-base neutralization in this lab simulates what happens when antacids are taken to alleviate indigestion. Students collect the carbon dioxide produced from the reaction, using the water displacement method. Through graphical analysis of the volume of gas collected over time, students determine the effect that changing the concentration of hydrochloric acid has on the reaction rate. Materials are sufficient for 15 student pairs. General lab equipment and labware (ring stands, clamps, beakers, graduated cylinders) are needed but not supplied