Alka-Seltzer Experiment Chemistry 173 6/7 B

Phenomenon Alka-Seltzer Dissolving in water Water causes the citric acid and sodium bicarbonate to react, releasing carbon dioxide which disperses the aspirin throughout the water Measured: Dissolution Time Definition of Dissolved: The tablet is no longer visible

Experiment One Manipulated Variable: Shaking or Stirring the Solution Hypothesis: If shaken/stirred, the time will decrease substantially.

Data Trials Stirring (s) Shaking (s) Normal(s) 1 47.5 48.3 52.55 2 45.3 40.8 53.89 3 41.7 44.7 46.14 4 40.5 47.3 51.74 Standard Dev. 3.23 3.35 2.95 Mean 43.8 45.4 51.1

Graphical Analysis: Stirring

Graphical Analysis: Shaking

Discussion • The data supports the initial hypothesis overall because according to the data table the time decreases substantially compared to the initial test • Difficulties: human and physical error • For a future experiment, we would try to be more accurate as far as timing and measurement

Experiment Two Manipulated Variable: Amount of Water Hypothesis: If we add water to the beaker, then the reaction time of the alka-seltzer ½ tablet and water will not change.

Data Trial 100 mL 150mL 200mL 1 47.8 47.7 47 2 48.8 49.3 43 3 48 49 49.4 4 49.5 44.2 45.2 Avg 48.525 47.55 46.15 St. Dev 0.780491 2.338803 2.714774 *All data measured in seconds unless noted *All data should be rounded to 3 significant figures *Numbers like 47 and 48 are actually 47.0 and 48.0 150 mL 200 mL *Avgs~ 48.5 47.6 46.2

Graphical Analysis

Discussion Hypothesis Difficulties Things to change Supported (for the most part) Change in reaction time insignificant (basically +/- 1 sec. per 50 mL) Difficulties ½ tablet hard to get exact Didn’t clean out beaker perfectly-not perfect tap water Manual timing Exact water amount Things to change Use full tablet to eliminate ½ tablet problems More exact timer More time to work on lab-more trials, cleaner beaker, better data, etc.

Experiment Three Manipulated Variable:Water or Tablet first? Hypothesis: The order of operations for dissolving alka-seltzer tablets will NOT affect the time it takes to dissolve the tablet.

Data Water Then Tablet (s) Tablet Then Water (s) 50.3 48.7 52.4 50.1 49.1 54.2 51.7 47 Mean: 51.7 Mean: 49.4 Standard Deviation: 1.67 Standard Deviation: 1.76

Graphical Analysis

Discussion Our findings for the order or operations experiment is that it doesn't matter if you put the water or Alka-Seltzer in first. This is because the standard deviation we calculated was 2 seconds and the difference between our two means is 2 seconds. Our initial hypothesis was that the order wouldn't make a difference in the time it takes to dissolve the tablet, and we were happy to see that this was true supported by our data. The only difficulty we encountered when conducting our experiment was that the tablet would partially dissolve in the beaker that was supposed to be dry (for the tablet then water portion) because there was leftover water in it from using it in the other portion of our trials. We fixed this by simply drying out the beaker with a paper towel. There are no things that we would change for a future experiment.

Experiment Four Manipulated Variable: Type of Liquid Hypothesis: Because the alka-seltzer table was designed for water, it will dissolve faster in water than in any other liquid.

Diet Pepsi Caffeine Free Data Water Coca-Cola Diet Pepsi Caffeine Free Fruit Punch Time to Dissolve (S) 52.55 56.17 57.61 97.88 53.89 56.62 56.49 98.7 46.14 57.07 86.94 51.74 Mean 56.4 57.1 94.5 Standard Deviation 0.225 0.457 5.36

Graphical Analysis

Discussion Supported hypothesis Problems: Next time: Inexact tablet sizes Hard to see tablet Hard to determine when dissolved Next time: Use whole tablets Get a light to illuminate tablet Conduct more trials

Experiment Five Manipulated Variable: Temperature of the Water Hypothesis: Our hypothesis was that the water at 29.5 degrees Celsius would dissolve the Alka-Seltzer tablet faster than the water at 19.5 degrees Celsius (normal temperature of tap water), which would dissolve the tablet faster than the water at 9.5 degrees.

Data Temp. (degrees Celsius) Time for reaction to stop (s) (Trial 1) Trial 2 (s) Trial 3 (s) Water in beaker (mL) Avg. time (s) Standard Deviation Hot Water 29.5 28.8 25.3 29.1 150 27.7 2.11 Tap Water 19.5 51.0 53.4 48.6 2.4 Cold Water 9.5 82.9 86.1 81.7 83.6 2.27

Graphical Analysis

Discussion Our data does support our initial hypothesis. Just as we predicted, the tablet dissolved significantly faster with warmer water. Some difficulties we encountered in our experiment included getting the water to exactly the right temperature, determining when the tablet was completely dissolved, and stopping the timer at the precise moment. In future experiments, I would perhaps change the temperatures used in the experiment or the size of the Alka-Seltzer tablets (use whole tablets instead of half).

Experiment Six Manipulated Variable: Size of Tablet Hypothesis:

Data Halves Sixths Crushed Time to Dissolve(s) 45.17 49.39 20.15 50.7 50.63 14.03 59.9 52.12 17.96 49.74 54.65 18.67 49.58 42.88 18.81 45.68 49.82 21.85 Average 50.13 49.92 18.58 Standard Deviation 5.303517 3.938765 2.6193772

Graphical Analysis

Discussion Compared to a half tablet, dividing the tablet into sixths does not seem to make much of a difference. The averages are close, and the standard deviation allows for overlap. Therefore, it would not be practical for a consumer to divide the tablet into sixths. However, crushing the tablet does seem to result in a reduction in dissolving time.

Overall Conclusion What should remain the same What could be changed Pour a normal sized glass of water, then put in tablet Water is best Amount of water, order don’t matter Traditional is more convenient What could be changed Use warm water Should stir water Consumer could crush tablet first