Student Exploration ph Analysis

Name: Date: 4-29-21 Student Exploration: 7.1.2 - pH Analysis Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: acid, acidic, alkaline, base, indicator, neutral, pH 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? sour B. What does it feel like if lemon juice gets in your eye? burns 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? slippery, smooth B. What does soap taste like? sour, bad C. What does it feel like if soap gets in your eye? burns 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 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. Wait until the animation is finished. 1. Indicators change color in acids or bases. What is the color of the pH paper? orange, coral pink, blue, yellow 2. Compare the paper to the pH color chart. What is the pH of ammonia? 11 3. Is ammonia acidic or alkaline? Activity A: alkaline Get the Gizmo ready: Measuring pH ● Click Reset. ● Check that the 0-14 paper is selected. 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). Material in the tube Baking soda Bleach Coffee Cola Drain cleaner Hand soap Juice (lemon) Juice (orange) Juice (tomato) Milk Milk of magnesia Oven cleaner Saliva (human) Shampoo Stomach acid Vinegar Water (distilled) Water (ocean) 0-14 pH indicator paper pH value Acidic, alkaline, or neutral? 8 al 11 al 5 ac 2 ac 13 al 9 al 2 ac 3 ac 5 acn 7 al 10 al 13 ac 6 ac 6 ac 1 ac 4 ac 7 n 8 al 2. Summarize: Compare all the acidic substances and all the alkaline substances. A. In general, what types of substances tend to be acidic? (What pattern do you see?) juices, acids B. What types of substances tend to be alkaline? cooking supplies, cleaners Activity B: You don’t need to use the Gizmo for this! Predictions Goal: What happens to the pH when you mix substances together 1. Using your results from Activity A, what do you think the pH would be of lemon juice combined with cola? I say nothing much but ph is going to go down because they have almost the same ph but cola is a alkaline drink and there are not much alkaline juices and if they are both there they the ph will move down to a neutral 2. Think about the amount of hydrogen ions in lemon juice. Are there more, less, or the same amount of hydrogen ions in cola? More because there is a stronger chemical in juice 3. Using your results from Activity A, what do you think the pH would be of baking soda combined with tomato juice? 13.5 4. Do you think pH takes the average of the pHs or adds them together? (Again, think about concentration of hydrogen ions). adds on them 5. Explain your reasoning to the above question: because I feel like if the ph levers are mixed together they get to add to each other 6. Using at least 3 materials from your list, combine them to get a pH of 5. List the 3 ingredients and their pHs below: Baking soda ph 8, coffee ph 5, and milk ph 7 7. How did you get your answer? Explain your reasoning to the above question. because you can find out when you are testing for the Acidic, alkaline, or neutral?