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Chem 1LE W23 - Thong Minh Tran Project #4: Gatorade Buffer Capacity/Original Investigation PDF Version generated by Thong Minh Tran on Feb 28, 2023 @09:47 PM PST Table of Contents Original Investigation ............................................................................................................................................................................................................................................. 2

Original Investigation Thong Minh Tran - Feb 28, 2023, 9:46 PM PST Assignment #OI4 - Original Investigation Project #4 You cannot edit this entry after submission. Turnitin Similarity Score 66 Grade Not yet graded Submitted on Feb 28, 2023, 09:46 PM PST Warning: POSTING COURSE MATERIALS VIOLATES UNIVERSITY POLICY. According the UC Office of General Counsel and the University Committee on Educational Policy it is a violation of the student code of conduct to post course materials on any website or file sharing service where it could be viewed by other students. Removal of this warning will result in a zero for this assignment. Kim Edwards - Mar 14, 2022, 3:36 PM PDT Objective Kim Edwards - Mar 14, 2022, 3:27 PM PDT The purpose of this lab is to determine the optimal concentration of titrant to titrate Gatorade, the buffer capacity of Gatorade, and the conjugate base/acid ratio of Gatorade. This can be accomplished by performing titration on Gatorade with different concentrations of the proper titrant, determined from the initial pH of the Gatorade. The titration data will be plotted and the buffering region will be used to calculate the buffer capacity and the Henderson-Hasselbach equation is used to calculate the acid/base ratio of the Gatorade sample. I hypothesize that the titrant with lower concentration is appropriate for sufficient data set because the reaction will be slower and the buffering region is more clear. Thong Minh Tran - Feb 28, 2023, 9:46 PM PST Project #4: Gatorade Buffer Capacity/Original Investigation 2 of 9

Safety Moment Kim Edwards - Mar 14, 2022, 3:27 PM PDT Exposure Routes Inhalation 1. You are done pumping gas and pulling the nozzle out of the car’s tank but the gas continues to flow spraying you in the face. Your eyes start to burn and you have to remove your contacts. 2. You choose a beaker without realizing it has a small star crack in the bottom. The beaker is filled halfway with methanol and placed on the hotplate which is turned on to heat the solution. The beaker shatters as you pick it up, cutting your hand. 3. You are distracted when you enter the lab and forget to cover your laptop keyboard with plastic wrap. Later that day you are at the library studying and you realize a solid is on your trackpad. You lick your finger to wet the trackpad in an attempt to remove the solid. It doesn’t come off the first time, so you lick the finger again. Your mouth becomes numb. 4. It’s your turn to clean the bathroom at the apartment. You start out using ammonia, but the smell is terrible, so you switch to bleach without washing away all the ammonia. Pretty soon you eyes are watering and you are coughing badly. What chemical or physical properties or procedure steps in the lab might increase the possibility of exposure by each route? (Hint: If you have absorption, skin is arranged in a system of stacked lipid bilayers. What does that indicate about the polarity of your skin surface?) Aqueous or gaseous chemicals that emit vapor would increase the possibility of exposure for chemical inhalation. How do you minimize exposure via this route? To minimize chemical inhalation, ensure that all chemical containers are properly sealed and use the fume hood when dealing with liquid or vapor chemical. What do you do if you are exposed to a hazardous chemical via this route? Get fresh air and seek medical professionals. Which of the following incidents was your exposure route most likely? Describe the exposure & aftermath in terms of the first 3 questions. Situation number 4 corresponds the most to inhalation because the bleach vapor is being inhaled, which caused watering eyes and cough. Thong Minh Tran - Feb 28, 2023, 6:31 PM PST Project #4: Gatorade Buffer Capacity/Original Investigation 3 of 9

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Procedures & Observations Kim Edwards - Mar 14, 2022, 3:27 PM PDT Procedures: Observations: Checking pH Probe Accuracy 1. Obtain 2 pH probes for two pairs of students in each group. Plug the pH probe into LabQuest 3 using channel 1 port or USB port. Set 1: LabQuest# 58, pH Probe# 32 Set 1: LabQuest# 8, pH Probe# 21 2. Take pH probe out of storage solution and rinse with DI water. Blot dry with Kim wipes. pH 7 buffer is liquid, yellow, transparent, and odorless. 3. Obtain about 10mL of pH 7 buffer in a 50 mL beaker. pH reading has 2 significant digits. 4. Dip the entire bulb of pH probe into the buffer and wait the reading to stabilize. The pH should be 7 +/- 0.4. Use new pH probe if reading is off. Finding Buffer Capacity 5. Obtain 10mL of Gatorade and record the pH Gatorade pH= 3.05 Gatorade is liquid, red, transparent, and odorless. 6. Decide the titrant based on the pH of the Gatorade Since the pH of the Gatorade is 3.05 which is acidic, the titrant would be NaOh which is basic. 7. Obtain two 250 mL beakers, each holding 25mL of Gatorade 8. For titrants, perform five-fold dilution once to obtain 2 solutions of titrants with different concentration. Transfer 20 mL of stock solution in to a 100mL Graduated cylinder with a 10mL volumetric pipet. Add DI water until the total volume reach 100mL. Measure the pH for the NaOH stock solution and the diluted solution NaOH solution is liquid, colorless, transparent, and odorless. Stock solution: 0.5M NaOH Diluted solution: 0.1M NaOH M *V = M * V V = (M * V )/M V =(0.1M*100mL)/0.5M V = 20mL pH of 0.5M NaOH= 13.63 pH of 0.1M NaOH= 12.46 9. There will be 2 different solutions, one for each titration Titration 1: Gatorade with 0.5 M NaOH Titration 2: Gatorade with 0.1 M NaOH 10. To prepare buret for titration, add about 10mL of DI water into buret, turn the stopcock to close position and observe for leaks. 11. Pre-rinse buret with the titrant to be delivered twice. Close stopcock and use a funnel to add <5mL of titrant while holding the buret in front of face. Tilt and rotate buret to wet the interior surface. Place buret in buret stand and drain titrant into a waste beaker. Close buret. 12. Fill the buret with titrant above the 29mL mark and drain into a beaker to remove air bubles and the initial volume reaches 30.00mL. Record initial volume: Thong Minh Tran - Feb 28, 2023, 9:32 PM PST conc conc dil dil conc dil dil conc conc conc Project #4: Gatorade Buffer Capacity/Original Investigation 4 of 9

13. To perform the titration, place the beaker with the buffer solution onto a magnetic stir plate and add a small Teflon bar. Adjust the stirrer to a slow stirring speed. 14. Clamp the pH probe to the side of the beaker to not collide with the stir bar and impact to the beaker. 15. On Labquest3, select Sensors>Data collection>Events with Entry. Type "Acid Added" or "Base Added" in Name field and change unit to mL and press OK. Press Go when ready to collect data. One pH is stabilized, press Keep. Press 0 for entry and press OK again. 16. For NaOH titrant, repeat the process until a repeatedly high pH is reached (pH>12). For HCl titrant, repeat the process until a repeatedly low pH is reached (pH<3). 17. When finished, press Stop and ask Ta to check the graph. 18. Add title and axis label to the graph. 19. To clean up, drain all titrant into waste beaker. Rinse pH probe with DI water and place into storage solution. Retrieve the stir bar from the solution using the magnetic stir bar retriever. Rinse beaker, buret, and stir bar with DI water from squeeze bottle. 20. Calculate the buffer capacity for Gatorade Sample Calculations: The buffering region is between 1mL and 10mL of titrant added. β=Δmoles /ΔpH β=Δvolume *Concentration /ΔpH β=(10mL-1mL)*(1L/1000mL)*0.1M / (6.45-3.34) β= 2.90*10 21. Obtain the pKa by locating pH of the solution at the volume halfway from the equivalence point. Since the equivalence point is when 12mL of titrant added, the pKa of the Gatorade is the pH of the analyte solution at 6mL of titran added. pKa= 5.02 22. Use the pKa from step 20, the pH from step 5, and the Henderson-Hasselbach equation to calculate the conjugate acid/base ratio pH = pKa + log ([A ]/ [HA]) [A ]/ [HA]=10 [A ]/ [HA]=10 [A ]/ [HA]= 0.0107 [HA]/[A ] = 1/0.0107= 93.33 23. Transfer remaining Gatorade into the waste beaker. Add Citric acid or Sodium bicarbonate into solution and check pH with pH paper. Pour the solution down the drain once the pH is around 7. titrant titrant titrant 4 - - pH-pKa - 3.05-5.02 - - Project #4: Gatorade Buffer Capacity/Original Investigation 5 of 9

Dilution Plan: Solution Concentration of solution being diluted (M_conc) (M;molar) Final solution Concentration (M_dil)(µM; molar) Graduated Cylinder Volume (V_dil)(mL) A 0.5 0.1 100 Titration Curves: For 0.50M NaOH titrant: For 0.10M NaOH: Thong Minh Tran - Feb 28, 2023, 9:27 PM PST Project #4: Gatorade Buffer Capacity/Original Investigation 6 of 9

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For Group Data Tables and Graphs: https://docs.google.com/spreadsheets/d/1P5e7M1QYLS7RyVir-daArkhvKbbrGfIao19LayDPACQ/edit#gid=1925661601 For Class Data: https://docs.google.com/spreadsheets/d/138c3DojtX1okAbZrJZyjlHlQffrBKTxndxr41znoSQk/edit#gid=1747521696 Thong Minh Tran - Feb 28, 2023, 8:26 PM PST Project #4: Gatorade Buffer Capacity/Original Investigation 7 of 9

Poster Kim Edwards - Mar 14, 2022, 3:27 PM PDT Thong Minh Tran - Feb 28, 2023, 9:37 PM PST Project #4: Gatorade Buffer Capacity/Original Investigation 8 of 9

Critique & Claim Evaluation Kim Edwards - Mar 14, 2022, 3:27 PM PDT Original Investigation : Gatorade will be available in the lab. What concentration of titrant is appropriate for a sufficient data set? What is the buffer capacity and HA/A - or B - /HB ratio of your Gatorade sample? Groups Gatorade Gatorade pH Titrant(s) β [HA]/[A-] Concentration pKa 1 red 3.05 NaOH 2.90E-04 93.3 0.1 5.02 2 red 3.41 NaOH 4.23E-04 38.9 0.1 5 3 red 3.54 NaOH 2.60E-03 n/a 0.1 5 4 red 3.5 NaOH 5.58E-04 31.6 0.1 5 5 red 3.7 NaOH 0.23 33.89 0.125 5 6 red 3.42 NaOH 3.00E-04 38 0.25 5 The concentration of titrant that is appropriate to titrate Gatorade is 0.10M of NaOH. The buffer capacity of Gatorade is 0.00029 and the [HA]/[A ] ratio is 93.33. This is the original claim and was not changed after the Argumentation section. All the other groups also used the red Gatorade and most groups used the 0.1M NaOH as titrant. Our acid/base ratio is 93.33 which is higher compared to most of the other groups with their values around 30, this is because our initial pH of Gatorade is lower compared to the other groups which resulted in a higher acid/base ratio. Our value of buffer capacity is still unaffected by the initial pH and is comparable to other groups. Thong Minh Tran - Feb 28, 2023, 9:43 PM PST - Project #4: Gatorade Buffer Capacity/Original Investigation 9 of 9

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