Acid and Bases Lab Peter Andres Emily Foley 20 September 2020 Objectives: The objective of this lab was to determine the pH values of various household objects. The pH of a solution can be determined using pH stirps or a pH sensor. The strips require a colored key and judgment of the eye to roughly estimate the pH, while the pH sensor uses a computer to find the pH. pH is a scale used to specify whether a liquid is acidic or basic, on a scale from 0 to 14, with anything below a 7 being acidic and anything above 7 being basic. Acidic liquids have a higher concentration of H+ ions, while Bases have a lower concentration of H+ ions. Procedures: The experiment was started by taking 1 mL of each solution and placing them in 7 separate test tubes. A stirring rod was used to collect a small amount of each liquid and drop it on a pH paper. The pH of each liquid was estimated by the color of the pH strip and recorded in table 1. Then a pH sensor is placed into each test tube, and cleaned between each use, and the recorded values placed in table 1 in correlation to the data collected with pH strips. This concluded the first part of the experiment; the second part was watched on a video. A large test tube was filled with 20- 25 mL of Deionized water. NaHCO3, or sodium bicarbonate, powder was drawn into a short stemmed pipette, and 2 mL of HCL, or hydrochloric acid, was drawn into a long stemmed pipette. The HCL was slowly added to the short stemmed pipette and the gas produced was collected into a short stemmed pipette and placed into a test tube. Record the data on the pH
sensor for two minutes of slowly squeezing the pipette. This process was repeated for each chemical, with the pH sensor cleaned after each one. Data and Results: Table 1
Solution pH value from pH paper pH value from sensor Vinegar 2 2. Soft Drink 5 3. Lemon Juice 2 2. Ammonia 10 10. Drain Cleaner 11 13. Detergent 10 10. Baking Soda 9 9. This table shows the recorded value of each household object from pH strips compared to the pH value recorded with the pH sensor. Table 2
Gas Initial pH Final pH Change in pH
Initial [H+] Final[H+] Change[H+ > CO2 5 4 -1 1^-6 7^-5 7^- NO2 5 2 -6 1^-6 4^-3 4^- SO2 6 2 -3 5^-7 2^-3 2^- This table shows the data recorded with the pH sensor when sodium bicarbonate and HCL was added to each chemical.
