pH Analysis Quad Color Indicator

Date: Name: ______________________________________ _________02/04/2021_______________ Student Exploration: pH Analysis: Quad Color Indicator Vocabulary: acid, acidic, alkaline, base, indicator, neutral, pH .) Prior Knowledge Questions + 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? _Bitter,Sour,Tart. _______________________________________ B. What does it feel like if lemon juice gets in your eye? _It causes the eyes to burn if it were to come into contact with the eye. ________________________ 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? _Soft, moist, slippery._____________________________________________ B. What does soap taste like? _acid,bitter.____________________________________________ C. What does it feel like if soap gets in your eye? _It also burns the eyes if came into contact. _____________________________ Warm-up The strength of an acid or base is measured on the pH scale. The term “pH” is short for “potential of hydrogen.” It is a measure of how many excess H+ ions there are in a solution. The pH scale runs from 0 to 14, with 0 representing the highest concentration of hydrogen ions. Acidic substances have a pH below 7, while alkaline substances (bases) have a pH above 7. Pure water has a pH of 7 and is considered neutral. The pH Analysis: Quad Color Indicator Gizmo allows you to find the pH of a variety of liquids. In the Gizmo, check that the Substance in the tube is Ammonia, and click Test. 1. Indicators change color in acids or bases. What are the colors of the pH paper? _____Yellow,blue,red,orange._________________________________________________ ___________________ 2. Compare the paper to the pH color chart. What is the pH of ammonia? __11______________ Is ammonia acidic or alkaline? _____alkaline.___________________________________________ Activity A:  Click Reset.  Check that the 0-14 paper is selected. Measuring pH 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 alkaline Hand soap 9 Juice (lemon) 2 acidic Juice (orange) 3 acidic Juice (tomato) 4 acidic Milk 7 neutral Milk of magnesia 11 alkaline Oven cleaner 13 alkaline Saliva (human) 7 neutral Shampoo 7 neutral 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? __Juice, Coffee, Soda, Stomach acid and vinegar. _____________________ ___________________________________________________________________ B. What types of substances tend to be alkaline? __Oven Cleaner, drain cleaner, hand soap, bleach, baking soda (cleaning supplies) milk of magnesia and water (ocean) ____________________________ Activity B: More accurate pH  Click Reset.  Select the 4.5-7.5 paper. 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) Coffee 5 pH value (4.5 to 7.5 paper) 5 (acidic) Milk 7 6.5 (acidic) Oven cleaner 13 7.5 (neutral to alkaline) Saliva (human) 7 6.5 (acidic) Shampoo 7 7 (neutral) Stomach acid 1 4.5 (acidic) Water (distilled) 7 7 (neutral) 2. Analyze: Compare the pH values in each column. A. How do these values compare? Some values stay the same while others less than or more when using two different types of paper. _________________________________________ ___________________________________________________________________ B. What is an advantage of using the 4.5-7.5 paper? __ the 4.5-7.5 paper is a lot more accurate than the 0-14 paper because it helps you have better accuracy than playing a guessing game when the colors on the pH paper are similar to more than one color on the pH color chart. ______________________ ___________________________________________________________________ C. What is a disadvantage of using the 4.5-7.5 paper? _You will not know the exact ph. value on a regular scale. _________________________ ___________________________________________________________________ 2019 D.Given the results from two kinds of indicator paper, which substances appear to be neutral (pH = 7)? Water distilled and shampoo. _____________________________________________________ 2019