CE3171-302 - LabReport3NAradillas

Lab Report #2: Page 1 of 8 TEXAS TECH UNIVERSITY DEPARTMENT OF CIVIL, ENVIRONMENTAL AND CONSTRUCTION ENGINEERING Lab Report #3: Alkalinity and Potentiometric Titration CE 3171 – Environmental Engineering Lab Section: 302 Team Number: 4 Instructor: Dr. Chongzheng Na Authors: Nohemi Aradillas Ryan Donnelly Mitchell Lester Victor Martinez Jack Millen Christian Teddy Date of Experiment: 09/29/23 Date of Submission: 10/06/23

Lab Report #2: Page 2 of 8 TABLE OF CONTENT Introduction ................................................................................................................................................... 3 Objectives ..................................................................................................................................................... 3 Materials/Methods ........................................................................................................................................ 3 Results/Calculations ...................................................................................................................................... 5 Discussion ..................................................................................................................................................... 8 LIST OF FIGURES Figure 1: Titration Set Up ............................................................................................................................. 5 Figure 2: Lake Water - Volume of Acid V. pH ............................................................................................ 6 Figure 3: Tap Water - Volume of Acid V. pH .............................................................................................. 6 LIST OF TABLES Table 1: Volume ........................................................................................................................................... 5 Table 2: Titration of Lake and Tap Water .................................................................................................... 5 TEAM MEMBER CONTRIBUTION STATEMENT: Ryan Donnelly wrote the Introduction and Objective. Nohemi Aradillas wrote the materials/methods and results/calculations section. wrote the Results/calculations. Christian Teddy & Victor Martinez wrote Discussion. All members discussed the results and contributed to the lab experiment.

Lab Report #2: Page 4 of 8 Erlenmeyer (1825 – 1909). Add a magnetic stirring bar to the flask, place it on the stirring plate, and turn it on to start mixing. Calibrate the pH probe with standard pH buffers. Insert the pH probe into the water sample and record the initial pH. Record the initial volume of the acid in the burette. If the pH of the water sample is greater than 8.3, add 0.02 N 𝐻 2 𝑆? 4 (where N is normality; 1 N = 0.5 mol L-1) drop by drop into the water sample. Record the volume of acid added and the corresponding pH. Continue to titrate the sample until the pH reaches 8.3. Record the volume of acid added as VP. If the initial pH of the sample is less than 8.3, skip Steps 6-7 and proceed to Step 8. In this case, take VP = 0. Continue adding acid until the pH of the water sample reaches 4.5. Record the total volume of acid added (since the beginning of the titration process) as VT. Finally, rinse the pH probe, store it in the vial, dispose of the water samples properly, and clean the lab. It is crucial to follow these instructions carefully to ensure a safe and accurate experiment.

Lab Report #2: Page 5 of 8 Figure 1: Titration Set Up Results/Calculations Table 1: Volume Initial Volume: 26.1mL Final Volume: 35.5mL Total Volume: 9.4 mL Table 2: Titration of Lake and Tap Water Sample Name Lake Water Sample Name Tap Water Volume of Acid(mL) pH Volume of Acid(mL) pH 0(=Vp) 8.22 0(=Vp) 6.95 2.00 7.53 2.00 6.30 4.00 6.76 5.00 6.00 5.00 6.35 6.00 5.75

Lab Report #2: Page 7 of 8 Total Alkalinity = 𝑉 𝑇 ∗𝑁∗50,000 𝑉 𝑠𝑎?𝑝?𝑒 OH - Alkalinity = 0 𝐶? 32− Alkalinity = 2𝑉 𝑝 ∗𝑁∗50,000 𝑉 𝑠𝑎?𝑝?𝑒 𝐻𝐶? 3− Alkalinity = 𝑉 𝑇 −2𝑉 𝑝 ∗50,000 𝑉 𝑠𝑎?𝑝?𝑒 Where: N – normal concentration of sulfuric acid (in units of N or equivalent/L) V P – volume of acid required to decrease pH to 8.3 V T - volume of acid required to decrease sample pH to 4.5 V sample - volume of sample Lake Water: Total Alkalinity = 6.75∗0.02∗50,000 9.4 = 718.09? OH - alkalinity = 0 𝐶? 32− alkalinity = 2(0)∗(0.02)∗50,000 9.4 = 0 HC ? 3− alkalinity = 6.75−2(0)∗50,000 9.4 = 0 Tap Water: Total Alkalinity = 9.40∗0.02∗50,000 9.4 = 1000? OH - alkalinity = 0 𝐶? 32− alkalinity = 2(0)∗(0.02)∗50,000 9.4 = 0

Lab Report #2: Page 8 of 8 HC ? 3− alkalinity = 9.4−2(0)∗50,000 9.4 = 0 Discussion The purpose of this experiment was to measure the pH of tap water which was pretty much 7 which means tap water was neutral. The other part of this lab was to determine the volume of acid we need to add to the water solution to get the pH reduced from 7 to 4.5. We ended up adding drop by drop 9.4mL of acid to have the result we wanted. We can conclude acid makes the pH of a solution drop. The lake water was more acid but needed less volume(6.75mL) of acid to decrease the pH from 8.4 to 4.55. We can conclude the lake water decreases faster its pH than tap water with acid being added to the solution. In contrast, tap water tends to resist more due to higher alkalinity value (1000 N). This leads to adding more acid to lower its pH level to 4.56. Then as for lake water the total alkalinity (718.09 N) is lower resulting in less acid to be added to reach a pH level of 4.55. We used those volumes to determine the alkalinity for different water.