Alka-Seltzer Form

Alka-Seltzer Form

Purpose: The purpose of this experiment was to determine if changing the form of Alka-Seltzer when added to the water, affects the time it takes for the cap to burst.

Introduction:
Alka-Seltzer is a remedy for indigestion that is dissolved in water and ingested by mouth. The active ingredient is sodium bicarbonate, which is baking soda. Alka-Seltzer reacts with water to produce carbon dioxide gas. In an enclosed space, like a film canister, the pressure of the gas increases until the film canister’s lid pops off, and the lid flies into the air.
The purpose of this experiment was to examine changes in the dependent variable (the time until burst) as we changed the independent variable (the form of Alka-Seltzer).
The hypothesis was that if the form of the Alka-Seltzer (the independent variable) is changed to increase the surface area initially coming in contact with the water speeding the creation of carbon dioxide gas, then the time until the cap burst (the dependent variable) would decrease.

Methods/Procedures:
The following items were used in the experiment:
- Graduated cylinder - used to measure water
- Film canister (lid and tube) – container for water, Alka-Seltzer, and carbon dioxide gas
- 120ml of room temperature water – 10ml added to each tablet
- 12 Alka-Seltzer tablets – One tablet used per test Procedure:
Step 1: To keep each test reasonably the same, the same amount of water was used in each test. 10ml of room temperature water (always the same temp.) was put into the film canister.
Step 2: One of the remaining four forms of Alka-Seltzer (1 whole tablet, 2 half tablets, 4 quarter tablets, or one powdered tablet) was added to the water.
Step 3: The cap was then sealed onto the canister. At nearly the same moment, a stopwatch was started.
Step 4: The stopwatch was stopped at nearly the moment the cap burst of the canister.
Step 5: The data of which of the four forms the Alka-Seltzer was in, which number that test was for that form (1-3), and the amount of time it took for the cap to burst for that test was recorded.
Step 6: The previous 5 steps are then repeated until all 12 tests are completed.

Results: All the times for each Alka-Seltzer form were around the same. As each of the four forms increased the amount of surface area of the Alka-Seltzer that was exposed to the water initially, the time until the cap burst decreased. (See Fig 1) The Whole tablet took the most time to burst, the two halves were quicker, the four fourths were quicker still, and the powder was the fastest of all. (See Fig 2) So it can be assumed that:
Assumption: - “The more surface area of the Alka-Seltzer was exposed to water, the faster the carbon dioxide gas was created and the faster the cap burst.”

Discussion:
As we changed the form of Alka-Seltzer changed from 1 whole tablet, to 2 halves, to 4 fourths, and then to one powdered tablet, the amount of time it took for the cap to burst decreased from 7.69s to 1.42s. The largest time (7.69 seconds) occurred with the largest form of Alka-Seltzer (1 whole tablet). The smallest time (1.42 seconds) occurred with the smallest form of Alka-Seltzer (one powdered tablet). The smaller the form of Alka-Seltzer, the smaller the time it took to burst. There were no outliers in the data set; each value followed the same trend. Some factors that could have caused error are; that the water amount wasn’t exactly precise, the stopwatch didn’t start at exactly the same time the cap was closed, the cap wasn’t closed at the exact time the Alka-Seltzer touched the water, the stopwatch was not exact, the stopwatch didn’t stop the second the cap popped off, each test didn’t use the exact same mass of Alka-Seltzer, and the canister’s shape changed slightly between each test. To reduce these sources of error, much more sophisticated and exact equipment would have to be used to measure everything precisely.

Conclusion:
Our hypothesis was that, that if the form of the Alka-Seltzer is changed to increase the surface area initially coming in contact with the water, then the time until the cap burst would decrease. It was shown that this hypothesis was true.

Bibliography

(1) - Bayer Corporation, . N.p.. Web. 28 Oct 2013. .

FIG 1

Test 1
Test 2
Test 3
1 Whole
7.69s
6.94s
7.21s
2 Halves
5.20s
5.61s
5.31s
4 Fourths
4.93s
4.99s
5.07s
Powder
2.07s
2.63s
1.42s

Figure one shows the results that were recorded for each of the 3 tests for each of the 4 forms.

FIG 2

Figure two shows that the whole tablets took the most time to burst, the halves were quicker, the fourths were even faster, and the powder was the quickest of all.