“baggie blast” activity objective: differentiate between exothermic and endothermic reactions,...

“Baggie Blast” Activity

• OBJECTIVE: DIFFERENTIATE BETWEEN EXOTHERMIC AND ENDOTHERMIC REACTIONS, AS WELL AS BETWEEN ACIDIC AND BASIC SOLUTIONS.

• SEVERAL THINGS HAPPEN WHEN BAKING SODA, CALCIUM CHLORIDE, PHENOL RED, AND WATER ARE MIXED: THE SOLUTION GETS WARM, IT CHANGES IN COLOR FROM RED TO YELLOW, AND A GAS IS PRODUCED. SEVERAL PROCESSES ARE AT WORK IN THIS REACTION.

• THE SOLUTION BECOMES WARM BECAUSE ONE REACTION IS EXOTHERMIC – HEAT IS RELEASED WHEN CALCIUM CHLORIDE (CaCl2) DISSOLVES IN WATER. HEAT IS ACTUALLY ABSORBED WHEN BAKING SODA (SODIUM BICARBONATE OR NaHCO3) DISSOLVES IN WATER. THE REACTION IS DETERMINED BY WHICH CHEMICAL IS PRESENT IN THE MOST AMOUNT IN YOUR BAGGIE.

• PHENOL RED, A pH INDICATOR, IS RED IN BASIC (HIGH pH) SOLUTIONS AND YELLOW IN ACIDIC (LOW pH) SOLUTIONS. WHEN MORE CALCIUM CHLORIDE IS PRESENT IN THE BAGGIE, THE SOLUTION CHANGES COLOR BECAUSE CARBON DIOXIDE DISSOLVES IN WATER TO PRODUCE A WEAKLY ACIDIC SOLUTION.