endothermic and exothermic reactions 1

Endothermic and Exothermic Reactions Portfolio Directions Directions 1. Design an experiment to verify that new substances are formed and heat is released or absorbed during a chemical reaction. 2. Write experimental procedures using detailed, numbered steps. Do not use paragraphs. Do not use personal pronouns such as you or I. a. Incorrect: I will pour 10 ml of water into the graduated cylinder. I will transfer the water to a separate container. I will add 3g of sugar to the water. b. Correct: i. Pour 10 mL of water into the graduated cylinder. ii. Transfer the water to a separate container. iii. Add 3g of sugar to the water. 3. To plan the experimental procedures, consider the following questions: a. What materials are needed? i. Suggested reactants: ? solids: baking soda, baking powder, antacid tablets, yeas powdered candy straws (Do not use any hazardous solids.) t, ? liquids: milk, vinegar, water, 3% hydrogen peroxide (Do not use bleach, ammonia, or other hazardous liquids.) b. What safety procedures should be followed? (*see example below) c. What observations should be made before the reaction? d. What tests and observations should be conducted after the reaction to determine if new substances are formed? (If heat or flame is used, such as a splint test, be sure to include appropriate safety procedures. See a note about splint tests below.) e. What tests should be conducted to determine if energy is absorbed or released during the reaction? f. How often and for how long should temperature be recorded for each reaction? (for example, once every 30 seconds for 3 minutes) g. What kind of data table is needed? 4. After writing the procedures (including safety procedures) and creating a data table (see example), obtain permission from your Learning Coach to begin. 5. Carry out your experiment. Adult supervision is needed when using a heat source for splint test. 6. Create a lab report with the following sections filled in. Submit a typed copy to your teacher via the Drop Box later in this lesson. a. Experimental Question: How does the absorption and release of energy affect temperature change during a chemical reaction? b. Hypothesis: c. Materials List: d. Safety Procedures*: e. Experimental Procedures: f. Data Table: g. Analysis and Conclusions: (Use the data to explain whether or not the hypothesis was supported by the data. Discuss any circumstances that may have affected the outcome. Answer the experimental question.) Sample Data Table Reaction Observations Before Reaction Observations During Reaction Observations After reaction baking soda + vinegar *Sample Safety Procedures 1. Adult supervision is required. 2. Wear safety goggles, apron, and closed-toed shoes. 3. Do not wear baggy sleeves or dangling jewelry. Tie long hair back. 4. Keep flame away from flammable objects. 5. Do not leave the experiment unattended. 6. Clean up spills immediately. 7. Report any injuries to your Learning Coach or an adult supervisor immediately. A Note about Splint Tests There are two types of splint tests. The one seen in the “Fizz, Foam, and Flames” Discovery Education™ Science Simulation was a test for the production of carbon dioxide gas. To conduct this test, light a wooden coffee stirrer (this is the splint), and lower the flame into the beaker. If carbon dioxide is produced, the flame will be extinguished. A second splint test, called the glowing splint, is a test for the production of oxygen gas. To conduct this test, light a wooden coffee stirrer, make sure an orange glow is visible, and then blow out the flame. The orange glow should still be visible on the wooden splint. Lower the glowing splint into the test tube. If oxygen is produced, the flame will reignite because oxygen fuels a fire.