LAB 4- REPORT TEMPLATE - pH of Foods - Vinegar Ammonia & Baking Soda - Fall 20232

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1080

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Chemistry

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Dec 6, 2023

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Biochemistry in the Kitchen LIFE 1080 LAB EXERCISE 4 –REPORT TEMPLATE- pH of Foods - Vinegar, Ammonia & Baking Soda (Acids, Bases, pH and Buffering Capacity) Report Due Date: Oct 2, 2023 – Monday by 10 pm (Note: Exam 1 is TUESDAY, Oct 3, 2023) INSTRUCTIONS: Answer the Questions posed in the Assignments highlighted in yellow. SAVE your completed Assignment as a word.docx or a pdf . CLICK on Lab 3 Report ASSIGNMENT in the Bb Folder “Lab EXERCISES and ASSIGNMENTS”. This will OPEN the Assignment. - Press “ Browse My Computer ” (halfway down the page) to UPLOAD your completed file onto Blackboard. - Select the file you want to upload by double clicking on that file name . - THIS REPORT REQUIRES GRAPHS, TABLES and DRAWINGS, that must be UPLOADED as SEPARATE FILES to the Supplemental Folder (or you may embed these in the word.docx). o press “ Browse My Computer ” again, and select each of these files to upload with a double-click. - If you want to make comments to me about your lab report (such as questions you might have after completing the lab report), you can type in your question in the “Comments” box. PRESS on the SUBMIT button (lower right corner of the page) when you have finished uploading your report and any supplemental files (or comments). 1

Exercise 4A - Calculating pH from adding known amounts pf HCl or NaOH to distilled water. Part A1- HCl - Using a pipetteman micropipette (see above), ADD To Beaker 1: o 1  l (microliter) of the 1 M HCl solution. This is “one millionth” or 1x10 -6 of a liter that you are putting into the 1 liter of what previously was pure water.  Calculate what the H + - ion concentration should be upon addition of this 1  l of the 1 M HCl solution  _______1x10^-6__________  Calculate what the pH should be upon addition of this 1  l.  ____6_____________ o Repeat this experiment by starting over and instead adding 10  l of the 1 M HCl solution to 1 liter of water. You are adding “one one-hundred thousandth” or 1x10 -5 of a liter to the 1 liter of pure water.  Calculate what the H + - ion concentration should be after adding 10  l of 1 M HCl  ____ 1x10^-5 _____________  Calculate what the pH should be.  ______5___________ o Repeat this experiment again by starting over and instead adding 100  l of the 1 M HCl solution. You are adding “one ten-thousandth” or 1x10 -4 of a liter of the 1 M HCl.  Calculate what the H + - ion concentration should be.  ____ 1x10^-4 _____________  Calculate what the pH should be.  ______4___________ o Repeat this experiment again by starting over and instead adding 1ml (1 milliliter - also known as 1000  l) of the 1 M HCl solution to 1 liter of pure water.  Calculate what the H + - ion concentration should be now.  ______ 1x10^-3 ___________  Calculate what the pH should be.  _______3__________ Part A2- NaOH Now, Using a pipetteman micropipette (see above), To Beaker 2 full of pure water ADD: o 1  l (microliter) of the 1 M NaOH solution to 1 liter of water.  Calculate what the – OH ion concentration should be.  ______ 1x10^-6 ___________  Calculate what the H + - ion concentration should be now.  ______ 1x10^-8 ___________  Calculate what the pH should be.  _______8__________ 2

o Repeat this experiment again by starting over and instead adding 10  l of the 1 M NaOH solution.  Calculate what the – OH ion concentration should be.  _____ 1x10^-5 ____________  Calculate what the H + - ion concentration should be now.  _______ 1x10^-9 __________  Calculate what the pH should be.  ______9___________ o Repeat this experiment again by starting over and instead adding 100  l of the 1 M NaOH solution.  Calculate what the – OH ion concentration should be.  ______ 1x10^-4 ___________  Calculate what the H + - ion concentration should be now.  _____ 1x10^-10 ____________  Calculate what the pH should be.  ______10___________ o Repeat this experiment again by starting over and instead adding 1000  l (1 ml – “milliliter”) of the 1 M NaOH solution.  Calculate what the – OH ion concentration should be.  _____ 1x10^-3 ____________  Calculate what the H + - ion concentration should be now.  ______ 1x10^-11 ___________  Calculate what the pH should be.  _______11__________ Exercise 4B - Measuring the pH of Common Foods and Household Items Analysis/Assignment (Part B - 20 pts) : - Plot each of these foods and household substances on the right-hand side of the pH chart on the next page 3

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4 - 3 – Lemon Juice 2.07 - 4 – Lime Juice 2.10 - 2 – Distilled Vinegar 2.18 - 8 – Premier Protein Drink 2.63 - 6 – Bai Bubbles Blackberry Flavored Sparkling Water 2.64 - 19– Frank’s Red Hot Sauce 2.64 - 5 – Bai Mango Flavored Water 2.74 - 14 - Diet Pepsi 2.79 - 17 – White Wine 3.00 - 13 – Fresh Squeezed Grapefruit Juice 3.06 - 12 – Fresh Squeezed Orange Juice 3.22 - 18 – Red Wine 3.51 - 7 – Brewed Tea 3.75 - 11 – Kefir 3.86 - 10 – Chobani Drinkable Yogurt 4.20 - 26 – Suave Shampoo 4.27 - 16 – Pellegrino Sparkling Water 4.79 - 15 – Chicken Broth 5.39 - 21 – Egg Yolk – Only – separated from egg white 6.46 - 9 - Whole Milk 6.80 - 1 – Distilled Water – “Control” 7.02 - 23 – Car Windshield Washer Solution 7.12 - 25 – 2% Dishwasher Soap 7.81 - 27 – Baking Soda - 0.5 M Sodium Bicarbonate 8.14 - 20 – Egg White – Only – separated from Yolk 8.99 - 24 – Windex Glass Cleaner 10.94 - 22 – Household Ammonia 11.72 Plot pH of Substances Here (put in order of Most Acidic (At Top) to Most Alkaline (at Bottom)

- Looking at the pH of Windex Glass Cleaner, and comparing that to your Chart, what would you guess is the principle “active” ingredient of Windex Glass Cleaner ? o _____The ammonia has a very high pH level so that is the principle active ingredient_________________________ Exercise 4C – Titration pH of Acetic Acid using 1.0 M NaOH or 1.0 M HCl Analysis/Assignment (Part C - 30 pts) : - Plot these results on graph paper laid out as the example provided below. o Note: start plotting at the blue line, with amt NaOH added proceeding to the right (of zero) on the x-axis , and amt HCl added proceeding from the blue line to the lef ( of zero – as a negative number) past the y-axis). o The y-axis should be “Observed pH” - Indicate the “Effective Range” over which Acetic Acid “resists” pH change  From pH ____3.75_________ to pH ______5.5___________ - Based on this graph, estimate where “the balance point” is between the uncharged form of acetic acid and the charged ionic form of acetic acid – that is AT WHAT pH is there 50% ionic form and 50% molecular form?  Balance point is at pH________around 4.75______________________ - Indicate (draw on your graph) in which quadrant the uncharged molecular form predominates o ____lower left______________ - Indicate (draw on the graph below) in which quadrant the charged ionic form predominates o _______upper right___________ TAKE A PICTURE OF YOUR GRAPH AND SAVE AS A JPEG or PDF FILE UPLOAD YOUR GRAPH onto Bb Assignment 4 along with your Lab Report 4 5

Exercise 4D – Addition of Vinegar (5% Acetic Acid) to 0.5 M Sodium Bicarbonate (Na + HCO - 3 ) Analysis/Assignment (Part D - 10 pts) : o What form of carbonic acid/bicarbonate predominates before the acetic acid is added, the uncharged molecular form (H 2 CO 3 ) or the charged ionic form (HCO - 3 )?  _______HCO-3 ionic form______________ o What happens to the carbonic acid/bicarbonate as the vinegar (acetic acid) is added? What form does it change to? Hint: compare the “balance point” of H 2 CO 3 /HCO — 3 (6.8) with the “balance point” of Acetic Acid (determined in part C, above).  ____Since the balance point of the bicarbonate is 6.8 and the balance point of the acetic acid is only 4.76, some of the ionic form will chance to the uncharged molecular form________________ o EXPLAIN - Why the solution “bubbles”/“foams” when the vinegar is added?  __________It bubbles because the uncharged molecules decompose in the water__ ______________________________________________________ o What chemical substance is the gas comprising the bubbles?  _____Carbon Dioxide_________________ o ” What do you think the pH of the solution is after the bubbling ceases? ( Hint: if you add more acetic acid, it would still bubble again –what area/quadrant do you think you are in if you made a graph for bicarbonate/carbonic acid similar to the one your made for acetic acid/acetate in part C )  _________Because it can still bubble again it would be in the buffer range between 6-6.8__________________ ( Hint: look below - note what happens when more vinegar is added… ) Bubbling ceases Add another splash of Vinegar 6

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Exercise 4E – Buffers against pH Change in Foods Analysis/Assignment (Part E - 20 pts) : - List the likely “buffering agent(s)” in each of these products. o Bai Water Mango  ____Malic Acid________________  ___Citric Acid______ / ___Na Citrate________ o Bai Sparkling Blackbery Water  ___Citric Acid______ / ___Na Citrate________  ____Malic Acid________________  ______Ascorbic______________ o Pure Leaf Brewed Tea  _______Citric Acid_____________ o Premier Protein Drink  _____Phosphoric Acid_____________ o Diet Pepsi  ______ Phosphoric Acid ____________  ______Citric Acid____________ o Vlassic Zesty Dill Pickles  _____Vinegar (acetic acid)_____________ o Suave Strawberry Enhancing Shampoo  ____Na Benzoate______________  _____Citric Acid_____________ o Frank’s Red Hot Sauce  _____Vinegar (Acetic Acid)_____________ - Why do some foods list “citrate” and others list “citric acid”? What pH do you think each are trying to main pH at?  Citric acid - close to pH ___3_____________  Sodium Citrate - close to pH ___5________ - Why does soda list “phosphoric acid” and other foods list” Sodium Mono-phosphate and sodium di-phosphate”? What pH do you think each are trying to main pH at?  Phosphoric acid - close to pH ____2_______ 8