Classic Endothermic Reaction: Alka-Seltzer^® & Water

Measuring the temperature change resulting from an endothermic reaction of Alka-Seltzer tablets with water.

Lab Summary

Students will measure the temperature change resulting from the endothermic reaction of Alka-Seltzer tablets with water. They will also observe physical evidence of the reaction and determine if the temperature of the water causes a difference in the rate of reaction.

Alka-Seltzer neutralizes the acids in the gastrointestinal system by combining with hydrochloric acid in the stomach. It reduces gastric acidity and thereby reduces the activity of pepsin. Alka-Seltzer contains both citric acid (C₆H₈O₇ -- anhydrous) and sodium bicarbonate (baking soda -- NaHCO₃). When you drop a tablet in water, the acid and the baking soda react, producing the famous fizz. You can think of an Alka-Seltzer tablet as compressed baking soda mixed with a little aspirin.

Endothermic reactions absorb heat energy. Because of this, the surroundings lose heat to the reaction and a temperature decrease can be recorded.

Hypothesize: What affect does the temperature of water have on the rate of reaction and temperature change when combined with Alka-Seltzer?

Published: November 2002

Downloads

• Classic Endothermic Reaction - PASPORT (24 KB, .zip)

  Includes experiment setup, procedures and Datastudio file

• Classic Endothermic Reaction - ScienceWorkshop (24 KB, .zip)

  Includes experiment setup, procedures and Datastudio file

Here's What You Need

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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.

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PASPORT Temperature Sensor (PS-2125) - $30

Durable stainless steel temperature sensor with a wide measurable range. For use with PASPORT Interfaces.

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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.

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Temperature Sensor (CI-6605A) - $39

Used for measuring the temperature of liquids, air, and other materials.

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Other Materials

• (2) Alka-Seltzer tablets
• (2) 250-mL beakers
• Tap Water
• Refrigerator