Great Heat Mystery

Purpose: Observe what happens when you combine calcium chloride (CaCl2), sodium bicarbonate (NaHCO3), phenol red and water? Materials goggles chemical-resistant gloves 100 mL graduated cylinder 80 mL water 3.6g CaCl2 3.6g NaHCO3 phenol red eyedropper cups (more than 60 mL) Ziploc® bags Hypothesis: if you combine calcium chloride, sodium bicarbonate and water then _______________________ Safety: Goggles

Procedure Part 1: 3. 6 g Sodium Bicarbonate 3 Procedure Part 1: 3.6 g Sodium Bicarbonate 3.6 g Calcium Chloride 80 ml water 6 ml universal indicator Record color and temperature changes

Procedure Part 2: 3.6 g Sodium Bicarbonate 40 ml Water 6 ml universal indicator 3.6 g Calcium Chloride 40 ml of water Temperature

Questions 1. Was your hypothesis correct? Why or why not? 2. What is the universal indicator used for? 3. List the three things that indicated that there was a chemical reaction going on in this experiment. 4. What type of chemical reaction was the mixing of the sodium bicarbonate and the calcium chloride? Endothermic or Exothermic (circle one) 5. Use a Periodic Table to determine which elements are in each compound

Use the balance to measure 3.6g of sodium bicarbonate into a cup. 2. Use the balance to measure 3.6g of calcium chloride into a cup. 3. Use the graduated cylinder to carefully measure 80 mL of water. Pour it into the Ziploc bag. (Be sure that no water spills) 4. Add 2 eyedropper-full squirts of phenol red to the Ziploc bag. Observe what occurs. (Color changes from red to yellow or orange, gas forms, and temperature changes (hot, then cold). Students may be able to observe the formation of a new substance, calcium carbonate, which will precipitate out of the water solution.)

1. Use the balance to measure 3.6g of sodium bicarbonate into a cup. 2. Use the balance to measure 3.6g of calcium chloride into a cup. The Great Heat Mystery Lab EDUCATOR MATERIALS 2 3. Carefully add the sodium bicarbonate to the bag. Then add 40 mL of water to the bag. Finally, add 2 eyedropper-full squirts of phenol red to the bag. What happens to the temperature? (If measuring with a thermometer, they may notice a 1-2 degree decrease in temperature.) 4. Use the graduated cylinder to carefully measure 40 mL of water. Pour it into the cup with the calcium chloride. Add 2 eyedropper-full squirts of phenol red to the Ziploc bag. Observe what occurs. (Cup contents turn hot.) 5. Not all of the calcium chloride may be dissolved at this point. Add the calcium chloride solution to the bag and seal it immediately. (Do not let the bag fully expand, or the bag may burst and the contents would spill onto you or students.) What happens? (Gas is formed, temperature changes (slightly colder) and color changes) 6. Students may be able to observe the formation of a new precipitate, calcium carbonate. Carefully swish the contents together to mix them. What do you feel? 7. Dump the contents down the drain, rinse out the bag and dry it with paper towel. 8. Wash your hands and answer the questions.