19b. Impact of Surface Area on Reaction Rate
Hypothesis
Increasing the tablet surface area will increase the rate of reaction between water and Alka-Seltzer®.
Method
A glass was filled with water at room temperature, and the temperature recorded. An Alka-Seltzer® tablet was added to the water, and the vigor of the reaction was noted.
The glass was emptied and rinsed, and filled again with water at room temperature, and the temperature recorded.
An Alka-Seltzer® tablet which had been broken into two equally sized pieces was added to the water, and the vigor of the reaction was noted.
This process was repeated using a tablet broken into four equally sized pieces, and again with a tablet that had been ground into a powder.
Diagram
Results
The water temperature was 20°C for all four tests.
The tablet that had been broken into two pieces reacted slightly more vigorously than the whole tablet.
The tablet that had been broken into four pieces reacted slightly more vigorously than the tablet that had been broken into two pieces.
The powdered tablet reacted very vigorously. The water bubbled much more violently, and the reaction finished much more quickly.
Conclusion
Breaking the Alka-Seltzer® tablets into smaller pieces increases their surface area. This increases the rate of molecular collisions between the reactants, and therefore the reaction rate increases.