Antacid Effectiveness
Measuring the rate of change in pH of a dilute hydrochloric acid (HCl) solution when antacid tablets are added.
pH Sensor (PS-2102)
Lab Summary
Students will use an Absolute Pressure Sensor to measure the change in pressure inside a container as a small amount of soda water (seltzer) decomposes. Students will determine whether the temperature of soda water affects the rate at which equilibrium is established.
Digestion in the stomach results from the action of gastric fluid, which includes secretions of digestive enzymes, mucous, and hydrochloric acid. The acidic environment of the stomach makes it possible for inactive forms of digestive enzymes to be converted into active forms (i.e. pepsinogen into pepsin), and acid is also needed to dissolve minerals and kill bacteria that may enter the stomach along with food. However, excessive acid production (hyperacidity) results in the unpleasant symptoms of heartburn and may contribute to ulcer formation in the stomach lining. Antacids are weak bases (most commonly bicarbonates, hydroxides, and carbonates) that neutralize excess stomach acid and thus alleviate symptoms of heartburn. The general neutralization reaction is:
Antacid (weak base) + HCl (stomach acid) —› salts + H2O + CO2
The hydrochloric acid solution used in this experiment (0.1 M) approximates the acid conditions of the human stomach, which is typically 0.4 to 0.5% HCl by mass (pH ~ 1).
Hypothesize: How does the ability of a solid antacid tablet to neutralize excess acid compare to the ability of a crushed antacid tablet to neutralize excess acid? Predict what difference there will be, if any, in the time it takes for the reaction to occur.
Published: April 2002
Downloads
- Antacid Effectiveness - PASPORT (34 KB, .zip)
Includes experiment setup, procedures and Datastudio file
- Antacid Effectiveness - ScienceWorkshop (34 KB, .zip)
Includes experiment setup, procedures and Datastudio file
Here's What You Need
U.S. Educator prices shown.
Probeware (PASPORT Systems)
Xplorer GLX (PS-2002) - $349
The Xplorer GLX is a data collection, graphing, and analysis tool designed for science students and educators.
PASPORT pH Sensor (PS-2102) - $79
Has a wide measurement range of 0 to 14 pH. Has a resolution of 0.01 pH. For use with PASPORT Interfaces.
Probeware (ScienceWorkshop Systems)
750 Interface, USB (CI-7650) - $679
The 750 Interface allows students to measure force, temperature, pressure, angular velocity, acceleration, current, and magnetic field with a built-in function generator and oscilloscope mode.
Other Materials
- Glassware: 250-mL beakers (4) , 100-mL graduated cylinder
- Lab stand & buret clamp for sensor
- Magnetic stir bar set-up
- Mallet and wax paper, mortar and pestle, or similar set-up for crushing antacid tablet
- Wash bottle of distilled water
- Antacid tablets: 2 of the chosen brand to be tested (1 to be crushed)
- Hydrochloric acid, 0.1 M solution
- (100 mL needed per antacid test: 50 mL each for whole tablet and for crushed tablet)
- Goggles, gloves, aprons, and/or other protective gear
