BIO 2 Lab Week one Assignment two

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Southern New Hampshire University *

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Feb 20, 2024

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Name: _Paul S. Nomsule_____________________________ Date: __01/15/2024____________________________ BIO 120L Module One Lab Report: Introduction to Science: Scientific Method Activity 1 – For BIO 120L pH Versus Time to Dissolve pH is the measure of how acidic or basic a substance or solution is and is measured on a scale of 0 to 14. A pH less than 7 is considered acidic (has more free H + ions), a pH greater than 7 is considered basic (has more free OH - ions), and a pH of 7 is considered neutral (relatively equal H + and OH - ions). An Alka-Seltzer tablet contains sodium bicarbonate (NaHCO 3 ) and citric acid (C 6 H 8 O 7 ). When this tablet is dissolved in water, a chemical reaction occurs. When the tablets are dissolved in water, the sodium bicarbonate forms bicarbonate ions (HCO 3 - ) and the citric acid forms hydrogen ions (H + ). These ions can then react to form water and carbon dioxide. Therefore, the general equation for this reaction is as follows: HCO 3 - (aq) + H + (aq) à H 2 O (l) + CO 2 (g) Alka-Seltzer tablets are used to temporarily relieve the symptoms of heartburn, acid indigestion, and sour or upset stomachs. As you are completing this experiment, think about the equation shown above and the purpose of taking Alka-Seltzer to relieve the symptoms of the above- mentioned ailments. You will learn more about pH and buffers next week in your Chemistry of Life: pH and Buffers lab, but this will be a great primer to start you off! Materials Included in the materials kit :  Alka-Seltzer tablets, 5 packs Needed from the equipment kit :  Beaker, 250 mL

1  Bogen Indicator Solution  1M sodium hydroxide  1M hydrochloric acid  Thermometer  Wax pencil Needed but not supplied :  3 clear plastic cups  Medium-sized bowl  1 8.5” x 11” sheet of blank white paper  Stopwatch, kitchen timer, or cell phone with stopwatch application  Sharp knife, scalpel, or scissors  Spoon or another stirring device Part I. Setting Up the Experiment Water with varying pH will be prepared with approximately the same amount of water in each vessel. 1. Add 2000 mL of tap water to a bowl. Allow water to reach room temperature. 2. Label three clear plastic cups, each with one of the following labels: a. pH 4 b. pH 7 c. pH 10 3. Obtain a timing device such as a cell phone or stopwatch. 4. Open three Alka-Seltzer packages and carefully break/cut each Alka- Seltzer tablet into two equal halves, giving you 12 halves total. Tip: To break the Alka-Seltzer tablets into equal portions, take a sharp knife, scalpel, or scissors and lightly score a line across the back of the tablet. Repeat this process several times along the same line. Using light pressure, break the tablet in half along the line. Part II. Running the Experiment 1. Use the 250-mL beaker to measure 200 mL of room temperature water and pour it into the cup labeled pH 4. Repeat this for the cups labeled pH 7 and pH 10. 2. Add 10 drops of Bogen Indicator Solution to each cup of water. Carefully stir the water until the drops are evenly distributed in the cups. Place the blank sheet of white paper behind your clear plastic cups to make it easier to see the color change. 3. Add one drop of 1M hydrochloric acid to the cup labeled pH 4. Carefully stir the water until the drop is evenly distributed in the cup. The water should now appear red in color. © 2016 Carolina Biological Supply Company

2 4. Add one drop of 1M sodium hydroxide to the cup labeled pH 10. Carefully stir the water until the drop is evenly distributed in the cup. The water should now appear blue to violet in color. 5. The color of the water in the pH 7 cup should appear slightly yellow to green. 6. Carefully drop half of an Alka-Seltzer tablet into each cup. 7. Immediately start the timer. 8. Observe the Alka-Seltzer tablets as they begin to dissolve in each cup. 9. When the last piece of tablet disappears in each cup, record the time to the nearest second for that cup in Data Table 1 (Run No. 1). 10. Once all tablets have dissolved and times have been recorded, pour the Alka-Seltzer solutions from each cup down the drain and rinse out the cups with clean water. Run the faucet for at least one minute after disposing the solutions to make sure any acidic or basic residues are eliminated. Part III. Repeating the Experiment 1. Repeat Part II for two additional trials at each pH. Use exactly 200 mL of water in each cup and follow the same procedures to obtain the various pH levels (pH 2, pH 7, and pH 10). 2. When the last piece of tablet disappears in each cup, record the time to the nearest second for that cup in Data Table 1 (Run No. 2 and Run No. 3). 3. For each pH level, calculate the average for the three trials and record that in Data Table 1 (Avg.). © 2016 Carolina Biological Supply Company

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