# Design Lab Water and Alka-Seltzer Essay

Colin Lee

Dr.Cooper

Chemistry 12

Introduction: Alka-seltzer contains three active ingredients, aspirin, sodium hydrogen carbonate and citric acid. It is used for headaches, migraines, and cold and flu symptoms. Alka-Seltzer is usually taken when dissolved in a glass of water. When placed in water a series of chemical reactions result into Sodium citrate and Sodium acetylsalicylate. The sodium citrate would act as the antacid for stomach pains, and the sodium acetylsalicylate would act as the pain reliever.

Research Question: This investigation will determine the how the amount of water (independent variable) affects the amount the amount of time (dependent variable) it takes for the Alka-Seltzer to dissolve.

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This error yielded a much larger error than 0.22s so we must use +/- 8.22 as our absolute error.

Qualitative Observations

* Tablet was chipped

* When the tablet was dropped water splashed out

* Hard to know when reaction finished

* The mass of Alka-Seltzer might have been different

Analysis:

The attached graph shows the proportionality of the amount of water to the amount of time it took to complete the reaction

In order to figure out the proportionality we must calculate the slope.

Calculation of proportionality constant:

Therefore the equation that represents the proportionality between the amount of water and the reaction time would be:

Where T is time and W is amount of water.

Error Analysis

In order to find error with our proportionality we must add error bars into our graph. [Note: Our error bar in the x direction was set to 3 because the error in the graduated cylinder was 1%, so we took the largest value and used that as our error. The error in the y direction was from using the range method above]

To find the error in the proportionality constant we must use k-high and k-low, being the steepest and shallowest slope. Using these we subtract them and divide by 2.

Therefore the new equation for the proportionality is

Our relative error is now

Conclusion and Evaluation

We determined that the proportionality between the time it took and the amount of water…