#IL4 Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco_Project #4_ Gatorade Buffer Capacity_In-Lab #4

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Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation Alejandra Aileen Suarez-Chocoteco - May 29, 2024, 11:40 AM PDT Assignment #IN4 - In-Lab Project #4 You cannot edit this entry after submission. Turnitin Similarity Score Generating score… Grade Not yet graded Submitted on May 29, 2024, 11:40 AM PDT 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 03, 2023, 4:39 PM PST FUNDAMENTAL SKILLS SECTION Kim Edwards - Mar 03, 2023, 4:39 PM PST Objective Kim Edwards - Mar 03, 2023, 4:39 PM PST In this experiment, we determine how well the Henderson-Hasselbach(HH) equation predicts the pH of the ammonia/ammonium buffer solutions and determine the buffer capacity of the titration with 0.75M and 0.250M of HCl. We will create a 1:1 ratio ammonia/ammonium buffer solution to test its buffer capacity concerning 0.075M and 0.250M of HCl with a LabQuest3 and pH probe; with the results, we will solve for buffer capacity. To determine how well the HH equation predicts the pH of the buffer, we will solve for percent error to compare the pH of the HH equation with the actual pH taken with the pH probe. Alejandra Aileen Suarez-Chocoteco - May 28, 2024, 3:01 PM PDT Chemicals & Supplies Kim Edwards - Mar 03, 2023, 4:39 PM PST 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 1/16

Chemical Identity Chemical Name Formula Molar Mass (g/mol) Physical States (s, l, g, aq) Mass (g) Moles Volume (mL) Concentration (M) Constants Acetic Acid CH COOH 60.052 aq 0.10 Sodium Acetate C H NaO 82.03 aq 0.10 Ammonia NH 17.031 aq 0.10 Ammonium Hydroxide NH OH 35.04 aq 0.10 Supply List: Stirring plate, LabQuest3, pH probe, clamp, 250 mL Beakers (±2,5), 10.00mL volumetric pipet (±0.02), 50.00mL buret (±0.05), and 10.00mL graduated cylinder (±0.2). Alejandra Aileen Suarez-Chocoteco - May 27, 2024, 7:40 PM PDT 3 2 3 2 3 4 Safety Kim Edwards - Mar 03, 2023, 4:39 PM PST Chemical Hazards (Please add the GHS symbols with the lowest category numbers) Chemical Name GHS Symbol #1 Associated Precautionary Statement GHS Symbol #2 Associated Precautionary Statement Acetic Acid Keep away from heat and hot surfaces. Wash face, hands, and any exposed skin thoroughly after handling. Sodium Acetate It may be corrosive to metals Keep only in the original container. Ammonia Flammable under gaseous conditions Causes sever skin burns and eye damage Ammonia Hydroxide It causes severe skin burns and eye damage. Wash skin thoroughly after handling. Dispose of content to an approved waste disposal plant. Alejandra Aileen Suarez-Chocoteco - May 15, 2024, 1:07 AM PDT 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 2/16

Safety Moment: Part1: Corrosives, Observations: When the sponge reacts with the sulfuric acid, it fumes, and small amounts of fume form with time. When neutralized with the sodium bicarbonate, the reaction begins to fizz. Q? What are the sponges made out of? How does this relate to your skin's composition and corrosive safety? The sponge is made out of natural fibers like cellulose. This relates to our skin's composition as it holds the same integrity of skin as it is what makes up cell walls in plants. So, the sponge mimics how the sulfuric acid would react if our skin were exposed. The safety demonstration shows how corrosive sulfuric acid is to the skin. Part 2: Safe Glove Removal, Our TA showed us how to remove our gloves properly when contaminated. He used two fingers to pinch the center of the glove, then removed the glove only halfway to expose the clean inside. With the clean side, pinch the other glove and remove it completely. Alejandra Aileen Suarez-Chocoteco - May 15, 2024, 8:41 AM PDT Procedures & Observations Kim Edwards - Mar 03, 2023, 4:39 PM PST 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 3/16

Procedures Observations Before Procedure: Ensure proper PPE is worn during the lab procedure. The lab equipment includes a lab coat, nitrile gloves, and safety goggles. Then, grab two LabQuest3, two pH probes, a pH 7 buffer solution, and glassware to set up the procedure. Assigned Ratios: Group 1: (acid : base) Ammonia/ Ammonium 1:1 Qualitative: Ammonium Chloride, ammonium hydroxide, and hydrochloric acid were all clear, transparent, and odorless aqueous solutions. Checking pH Probe Accuracy: Pick two probes from the front of the room, then plug the pH probe into the LabQuest3. Then, remove the probe from the storage solution, rinse it with deionized water, and blot dry with a Kimwipe. Take 10.00 mL of the pH 7 buffer in a 30.00 mL beaker, ensuring the entire probe is in the buffer. Wait until the reading stabilizes; it should read pH 7 +/- 0.4. pH Probe Procedure: 1) Remove the probe from the storage solution, rinse the probe 2) Calibrate the probe using 2 or 3 buffers, rinse the probe 3) Place the probe in the solution being measured 4) Observe the readout of the sample solution pH on the meter 5) Rinse the probe, then place it in the storage solution * The pH should be within 0.4 (+ or -) of the 7.0 pH * Probe should be tested with 10.00mL of pH 7 buffer solution Qualitative: The pH 7 buffer was a yellow translucent liquid solution and was odorless. Quantitative: Test probe pH: 7.12 Taking pH measurement of buffers: Stockroom: 0.10M of acetic acid, sodium acetate, ammonium chloride, and ammonium hydroxide. 1) Measure out 10.00 mL of each solution and record their pH 2) We will be assigned a buffer mixture ratio (acid/base volume) 3) Take 50 mL of BLANK buffer and record its pH with the probe Assigned: Ammonia/Ammonium Hydroxides pH of ammonium hydroxide was 11.00 pH of ammonium chloride was 5.55 pH ammonium hydroxide/ammonia buffer solution is 9.30 Finding The Buffer Capacity: Then, split the ammonia/ammonium hydroxide buffer solution into two equal solutions of 25.00 mL in a 250 mL Beaker. Titration 1: ammonia/ammonium hydroxide buffer with 0.075M of HCl Titration 2: ammonia/ammonium hydroxide buffer with 0.250M of HCl Bure Preparation Steps for Titration: Step 1: Prerinse with a small amount of titrant Step 2: Fill above the 0.00mL marker Titrant Concentration (M) [HCl] pH 0.075 0.250 0.075M HCl Titrant: Initially, 20.00 mL of 0.075 HCl Titrant was in the buret. Later, 15.00 mL of the 0.075 HCl Tritrant was added, for a total of 35.00 mL of 0.075 HCl Titrant. Graph Above: Labquest plot of the 0.075M HCl titrant 0.250M HCl Titrant: Alejandra Aileen Suarez-Chocoteco - May 27, 2024, 9:24 PM PDT 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 4/16

Step 3: Drain below the 0.00mL to remove air in stopcock Step 4: Record the initial volume to the hundredth place Step 5: Remove hanging drops with tissue Step 6: Open the stopcock to add titrant to the analyte Step 7: Close the stopcock, touch the buret tip to the inside of the analyte beaker/ﬂask Step 8: Record the final volume to the hundredth place Step 9: Drain the buret into a waste container Step 10: Wash Buret with dilute soap and then deionized water. Titration: Step 1: Fill the buret with 20.00mL of the HCl (titrant) and the 250mL beaker with 50mL of the 1:1 ratio ammonia/ammonium hydroxide buffer solution Step 2: Step up the Events Entry mode, label the event with "Acid added" and set units to mL Step 3: Take the pH of the buffer solution, press keep, and label the unit to 0mL Step 4: Then add 1mL to the buffer solution, press keep, and label the unit to 1 mL Step 5: Repeat steps by adding 1 mL and record the pH for each milliliter added. * repeat the steps with 0.250 HCl titrant 20.00 mL of 0.250 HCl titrant was added, but only 7.00 mL was used. Graph Above: Labquest plot of the 0.250M HCl titrant Henderson-Hasselbalch (HH) equation: pH = pKa + log([A ]/[HA ]) Theoretical pH: pH = pKa + log([A ]/[HA ]) pKa = -log(Ka) Percent Error: % error = [(theoretical pH) - (actual pH) / (actual pH)] * 100 Buffering Capacity: β = Δmoles titrant ΔpH Henderson-Hasselbalch (HH) equation: pH = pKa + log([A ]/[HA ]) Theoretical pH: pH = pKa + log([A ]/[HA ]) pKa = -log(Ka) pH of Ammonia/Ammonium Buffer Solution: Theoretical: pH = pKa + log([Base]/[Acid]) pKa= 9.24 pH = 9.24 + log ([0.1]/[0/1]) pH = 9.24 Actual: pH = 9.30, according to the pH probe. pH = 9.03, according to the pH probe. * We created two buffer solutions, one for each titration, but one had a slightly different pH. This could have been because of a human error. Percent Error: 1) % error = [(theoretical pH) - (actual pH) / (actual pH)] * 100 % error = [(9.24 - 9.30) / (9.30)] * 100 = - 0.6% 2) % error = [(theoretical pH) - (actual pH) / (actual pH)] * 100 % error = [(9.24 - 9.03) / (9.03)] * 100 = 2.3% - + - + - + - + 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 5/16

Qualitative: Based on the low percent errors, we can conclude that the Henderson-Hasselbach equation accurately predicts the pH of the ammonia/ammonium buffer solution. Buffering Capacity: β = Δmoles titrant ΔpH Titration 1: (0.075M HCl) Began with 1.00mL of HCl Ended at 35.00mL of HCl (V )(C ) = (mol ) (0.001 L)(0.075 M) = (mol ) (mol ) = 0.000075 mol HCl (V )(C ) = (mol ) (0.035 L)(0.075 M) = (mol ) (mol ) = 0.002625 mol HCl Δmol = (mol ) - (mol ) Δmol = (0.002625 mol) - (0.000075 mol) Δmol = 0.00255 mol ΔpH = (pH ) - (pH ) ΔpH = (9.24) - (2.81) ΔpH = 6.43 β = Δmol / ΔpH = 0.00255 mol / 6.43 = 0.000396579 = 0.0003966 for the ammonia/ammonium buffer titrated with 0.075M of HCl Titration 2: (0.250M HCl) Began with 1.00 mL of HCl Ended at 7.00 mL of HCl (V )(C ) = (mol ) (0.001 L)(0.250 M) = (mol ) (mol ) = 0.00025 mol HCl (V )(C ) = (mol ) (0.007 L)(0.250 M) = (mol ) (mol ) = 0.00175 mol HCl Δmol = (mol ) - (mol ) Δmol = (0.00175 mol) - (0.00025 mol) Δmol = 0.0015 mol ΔpH = (pH ) - (pH ) ΔpH = (8.68) - (1.89) initial titrant initial initial initial final titrant final final final titrant final initial titrant titrant final initial titrant initial titrant initial initial initial final titrant final final final titrant final initial titrant titrant initial final 5/29/24, 11:43 AM Chem 1LC S24 - Alejandra Aileen Suarez-Chocoteco/Project #4: Gatorade Buffer Capacity/In-Lab #4: Fund Skills & Orig Investigation - LabA… https://mynotebook.labarchives.com/entries/print_page/MTM2NjE0Ni42fDEwNTA4ODIvMTA1MDg4Mi9Ob3RlYm9vay8zNjU5NjkyNTg5fDM0Njc5MTAuNTk… 6/16

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