Endothermic Exothermic LAB Prelab Endothermic reaction chemical reaction

Endothermic Exothermic LAB

Pre-lab • Endothermic reaction: chemical reaction that takes in heat energy Energy of reactants < Energy of products • Exothermic reaction: chemical reaction that releases heat energy Energy of reactants > Energy of products

Pre-lab • • Activation Energy: amount of energy needed to break old bonds and make new ones Catalyst: lowers the activation energy needed for a reaction to go

Supplies/ Materials Chloride • Ziplock bag • Vitamin C powder • Baking soda • Water • Calcium • Measuring tools • Phenol red indicator

Procedure/ Method Reaction #1 1) Measure 1 tsp baking soda, 1 tsp vitamin c, 15 m. L water 2) In ziplock bag, mix dry solids together first. Then add water. Gently mix. Then close bag. Record observations. *WARNING: bag may not be large enough for reaction. Carefully open bag as needed.

Procedure/ Method Reaction #2 1) Empty contents from bag into sink. Rinse bag out with water until clean. 2) Measure 1 tsp baking soda, 1 tsp calcium chloride, 10 m. L phenol red

Procedure/ Method Reaction #2 3) In ziplock bag, mix solids first. Then add phenol red. Gently mix. Then close bag. Record observations. *WARNING: bag may not be large enough for reaction. Carefully open bag as needed. 4) Throw bag away in trash can by the door

Data Table COOLER OR SIGNS OF WARMER AFTER CHEMICAL MIXING? REACTION #1 REACTION #2

Post-lab Which reaction (#1 or #2) was the exothermic reaction? How could you tell? You don’t have to copy this slide down, but please answer in complete sentences.