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pH Analysis Questions and Answers

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Prior Knowledge Questions (Do these BEFORE using the Gizmo .) 1. Acids are substances that produce hydrogen ions (H+) when dissolved in water. Lemon juice is an example of an acid. A. What does lemon juice taste like? A lemon is sour B. What does it feel like if lemon juice gets in your eye? It burns because of the acidity 2. Bases are substances that produce hydroxide ions (OH-) when dissolved in water. Hand soap is an example of a base. A. What does soap feel like? It’s sudsy, slippery, and lathers B. What does soap taste like? It tastes chemically C. What does it feel like if soap gets in your eye? It also burns your eye Gizmo Warm-up 1. Indicators change color in acids or bases. What is the color of the pH paper? Orange, pink, blue, and yellow 2. Compare the paper to the pH color chart. What is the pH of ammonia? 11 is the pH 3. Is ammonia acidic or alkaline? Ammonia is alkaline Goal: Find the pH of 18 common substances. 1. Test: Use the Gizmo to find the pH of each of the available substances. Classify each substance as acidic (pH < 7), alkaline (pH. > 7), or neutral (pH = 7). 0-14 pH indicator paper Material in the tube pH value Acidic, alkaline, or neutral? baking soda 8 alkaline bleach 11 alkaline coffee 5 acidic Cola 2 acidic drain cleaner 13 alkaline hand soap 9 alkaline juice (lemon) 2 acidic juice (orange) 3 acidic juice (tomato) 5 acidic milk 7 neutral milk of magnesia 10 alkaline This study source was downloaded by 100000796615030 from CourseHero.com on 07-07-2021 06:56:24 GMT -05:00 https://www.coursehero.com/file/87344326/pH-Analysis-Gizmodocx/ This study resource was shared via CourseHero.com oven cleaner 13 alkaline saliva (human) 6 acidic shampoo 6 acidic stomach acid 1 acidic vinegar 4 acidic water (distilled) 7 neutral water (ocean) 8 alkaline 2. Summarize: Compare all the acidic substances and all the alkaline substances. A. In general, what types of substances tend to be acidic? Citrus juices, certain fruits…liquids. B. What types of substances tend to be alkaline? Cleaning supplies Goal: Find the pH of substances in a more accurate way. 1. Test: Before you begin testing with the 4.5-7.5 paper, list the pH values of the substances below that you found using the 0-14 pH indicator paper. Then find the pH of each substance with the 4.5-7.5 paper. 4.5-7.5 pH indicator paper Material in the tube pH value (0 to 14 paper) pH value (4.5 to 7.5 paper) Coffee 5 5 Milk 7 6.5 Oven cleaner 13 7.5 Saliva (human) 6 6.5 Shampoo 6 7 Stomach acid 1 4.5 Water (distilled) 8 7 2. Analyze: Compare the pH values in each column. A. How do these values compare? The values are almost the same B. What is an advantage of using the 4.5-7.5 paper? There is a smaller range of alkaline and acidic, more accuracy C. What is a disadvantage of using the 4.5-7.5 paper? The range can be too small to properly get some of the amounts pH D. Given the results from two kinds of indicator paper, which substances appear to be neutral (pH = 7)? Milk, distilled water, and shampoo

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