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Enriched Biology Chemical Reactions Lab Name________________________Per____ Date_________ Introduction: Energy takes many forms: heat, light, chemical, and mechanical. Plants rely on light energy for photosynthesis to make sugar. Both plants and animals use chemical energy in sugars to function. Chemical reactions can release or absorb energy. Photosynthesis absorbs light energy, and cellular respiration releases energy. Purpose: In this lab, you will determine if a specific chemical reaction is releasing or absorbing energy. You will measure the temperature of the reaction. Exothermic reactions release energy. Endothermic reactions absorb energy. If it’s an exothermic reaction, the temperature will _______________. If it’s endothermic reaction, the temperature will _________________. The two reactions will be Baking Soda + Vinegar Sodium acetate + Carbonic acid Carbonic Acid Carbon dioxide + water Calcium Chloride + Water Calcium Oxide + Hydrochloric Acid Materials: (2) 250 ml beaker Baking soda Quick Check Thermometer Calcium chloride vinegar stirring rod water stop watch Procedure: Create the Set-up: 1. Place the Quick Check temperature sensor-ring stand setup on the lab table. 2. Obtain two 250ml beakers. Label one CaCl2 and the other beaker Baking Soda using label tape. Place the tap on the upper area of the beaker. 3. Fill the Baking Soda beaker with 100 ml of vinegar. Carefully place the Baking Soda beaker underneath the temperature sensor. Lower the temperature sensor so that the tip of the thermometer is beneath the surface of the vinegar. Allow the thermometer to sit in the vinegar for several minutes. Then record the temperature on the table. 4. Proceed to the balance station. Using a spatula and weigh boat, measure out 2 grams of baking soda. Place the weigh boat on the balance. Wait for its mass, and then press the ‘zero’ button to tear the mass. Now you will see a reading of 0.00 grams. 5. Carefully add baking soda to the weigh boat until it reads 2 grams. Remove the weigh boat and from the balance. Return to your beaker-thermometer set-up. 6. Re-check the temperature of the vinegar. Be sure that you can easily read the temperature because you will be trying to take a temperature reading every 20 seconds. This will require team work. One person reads the thermometer and the other reads the stop watch and records. Determine who will do each job. Start the Baking Soda and Vinegar Trial: 7. Simultaneously add the 2 grams of baking soda to the beaker of vinegar and start the timer. Record temperature every 20 seconds for 3 minutes. Use the stirring rod to stir the solution. Do not hit the sides of the beaker or thermometer. 8. After the 3 minutes are up, raise the thermometer and carefully remove the beaker from underneath the thermometer. Empty the beaker in the sink and place the dirty beaker in appropriate place. 9. Use a damp paper towel to wipe off the thermometer. Complete Data Table. 10. Proceed to run the Calcium Chloride reaction using the technique as for the Baking Soda reaction. Setup Calcium Chloride Reaction: 11. Fill beaker with 100ml of tap water. Place beaker under the thermometer. Lower the thermometer into the water. Allow the thermometer to sit in the water for several minutes. 12. Measure out 15 grams calcium chloride on a weigh boat using the balance. Carefully, carry it back to the lab table. Run the Calcium Chloride Reaction (Goggles Must Be Worn! Zero for Lab if not worn) 13. Determine who will read the thermometer and who will read the stop watch. Record the initial temperature of the water in the Table. 14. Simultaneously add the 15 grams of calcium chloride to the beaker of water and start the timer. Record temperature every 20 seconds for 3 minutes. Use the stirring rod to stir the solution. Do not hit the sides of the beaker or thermometer. WARNING: DO NOT TOUCH THE BEAKER. DO NOT PUT FACE IN THE BEAKER. 15. After the 3 minutes are up, allow the calcium chloride beaker solution to sit for 5 minutes. While waiting, complete the data tables. 16. Read board for calcium chloride and general cleanup. Data Table 1 Title ___________________________________________________________ Time (seconds) Temp (oC) Baking Temp (oC) Calcium Soda + Vinegar chloride + water 0 20 40 60 80 100 120 140 160 180 Data Table 2 Title ___________________________________________________________ Reaction Initial Temp (oC) Final Temp (oC) Change Temp (oC) Heat Release or Absorbed ? Baking Soda + Vinegar Calcium chloride + Water Analysis: Identify which reaction was exothermic and endothermic using data. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________