Lab 2

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Santa Monica College *

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Chemistry

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Apr 26, 2024

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Lab 2 pH and Water lab Results ( estimated time: 2 hours ) Online assignment instructions: You will work individually on the exercise below and turn in your worksheet by the deadline. Note: please complete the worksheet below with some results provided. Although you may engage in general discussions of problems with other students, your professors, or anyone else about your thinking, you must answer all questions on your own. Do not use old lab reports, papers from current or previous biology students as all materials will be part of the Quiz and Exam. Exercise I. pH of common household solutions. pH of common household solutions: Use two methods to determine the pH of various solutions. 1. Use the pH paper handed out and check as many solutions that you can find around your residence. 2. Use one or multiple internet resources to find the pH of at least 20 solutions listed on your lab worksheet. Then, at the end of p. 23, list these sources that you have used to obtain your data. For example: http://www.chemistryexplained.com/A-Ar/Acid-Base-Chemistry.html WORKSHEET: pH and Water Lab Lab Instructor: ______________________ Lab Day & Time: _______________ Student name(s): _________________________________________________________ DATA AND ANALYSIS Substance PH Distilled water 7 Sugar Water 7 Orange Juice 3.9 Regular soda 2.5-3.5 Diet soda 3.70 Flat soda 4.03 Scouring cleanser 10.5 Tomato juice 4.1-4.3 Carbonated Water 4.18-5.87 Apple juice 3.48-3.69 Beer 14 Wine 2.9 Coffee 4.85-5.10

Tea 4.9-5.5 Drain cleaner 12-14 Window cleaner 8-11 Alkaline water 8-9 Dish soap 7-10 Bleach Solution 11-13 Antacid 8.5-10.5 Lemon juice 2-3 Ammonia solution 11-12 pH balanced shampoo 4.5-7 Houseland cleaner 9-11 Laundry Detergent 7-10 Exercise II: Buffer Experiment. Read instructions on p. 15 Buffers and slides #14-16 of the pH/Water lab PowerPoint pdf file in the Lab 2. pH and Water Lab Due 2/23 folder. The results of the experiment are as follow: Buffer Solution Initial pH pH After Adding Acid pH After Adding Base Tap water ___7.5____ ___4.0____ ___12.0____ ____7.0___ ___6.5____ ___7.0____ Answer questions on p. 22. 1. Is a solution with a "low" pH acidic or basic? Yes 2. Which is more concentrated in a "high" pH solution, H+or OH -? The OH- is more concentrated because the H+ decreases the higher the pH gets. 3. Are the reactive qualities of window cleaner due to an excess of H+ or an excess of OH -? H+ 4. Which has more hydrogen ions, wine or water? wine 5. Vinegar is an acetic acid solution. Does its pH agree with this fact (yes or no)? yes 6. Do soaps and cleaners tend to be acidic or basic? basic Milk

7. Did the H+ concentration of diet soda and regular soda differ by a magnitude of 10 times or greater (yes or no)? yes 8. Did the H+ concentration of pure water and sugar water differ by a magnitude of 10 times or greater (yes or no)? yes 9. Did the H + concentration of fresh soda pop and flat soda pop differ by a magnitude of 10 times or greater (yes or no)? yes 10. From questions 7, 8, & 9, would you conclude that the pH of soda pop is strongly influenced by: 1) sugar, 2) carbonation, 3) both, or 4) neither? both 11. How many times more basic is a solution with a pH of 9 than a solution with a pH of 8 (2, 10, 20, 100, or 200)? 10 12. How many times more basic is a solution with a pH of 10 than a solution with a pH of 8 (2, 10, 20, 100, or 200)? 100 13. Did your experimental results agree with the fact that milk is a pH buffer? Yes 14. Did the milk buffer: 1) acid, 2) base, or 3) both in your experiment? Yes 15. Which heats more slowly, ethyl alcohol or water? Ethyl 16. Which cools more slowly, ethyl alcohol or water? Alcohol 17. Which has the higher specific heat, ethyl alcohol or water? Water 18. If your blood and tissue fluid were alcohol instead of water, would you be more likely to get overheated on a hot day, (yes or no)? Yes 19. Assuming organisms function best if their internal temperatures remain relatively constant as outside temperatures change, would a body fluid with a high or low specific heat best? low 20. Palm Springs is almost directly inland from Santa Monica. Which of these places has more water nearby and in the air? Santa Monica 21. Which of these places, Palm Springs or Santa Monica, experiences both hotter and colder temperatures? Palm Springs 22. Other factors being equal, should a humid or dry night get colder? Humid Heat of Vaporization 23. Would death by "drying up" be more likely for an organism composed of alcohol or for one (like us) composed of water? Alcohol 24. Based on the behavior of water with wax, oil, and most plastics, would you say that these substances are polar or nonpolar? Nonpolar 25. Does water hold other ions (such as sodium or chloride) in solution by adhesion or cohesion? Adhesion 26. For the most capillary action to occur, is it necessary for: 1) only the fluid, or 2) both the fluid and the tube to be polar? Both 27. Do your experimental results suggest that a tree could move water more effectively from its roots to its leaves using smaller- or larger- diameter vessels? Smaller 28. Mosquitoes can walk on the surface of water because of adhesion or

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