Endo vs. Exo Agenda Thought Questions Explorations Notes

What is heat energy? What does it do to atoms?

What does the word “exit” mean? Is getting kicked out of class a positive or negative experience?

What does the prefix “endo” mean?

“Thermasilk” is a brand-name shampoo. What does the prefix “therm” mean?

If a reaction is “exothermic”, what do you think is happening?

What happens when atoms break their bonds with other atoms? With fireworks, which side of the reaction is the heat energy?

Calculators 1 calculator per group Make sure everything is hooked up Press the apps button Choose Data Mate Read temperature reading

Exploration Lab Take a small amount, ~ pea size sample, of the chemicals setting out and add water to dissolve them. Insert the temperature probe of the calculator to measure temperature Shake the chemicals to help the reaction. Determine whether the sample gets hotter or colder. What type of rxn is this? (endo or exo)

Post Lab No formal lab report. Answer the following ?’s and hand in at end of class or tomorrow. Why did you need to shake the chemicals? How did you know if it was endothermic or exothermic?

Energy of Chemical Reactions Date:

Activation energy All reactions require energy to get started. Match

Exothermic Energy is RELEASED during the reaction. Exits the system. Products have less energy than reactants Example reactions: Fireworks, digestion, combustion reactions

Energy Diagram for Exothermic Rxns Time ENERGYENERGY

Endothermic Energy is ABSORBED! Absorbed energy is usually heat or electricity. Products have more energy than reactants. Examples: Cooking, cold packs

Energy Diagram for Endothermic Rxns Time ENERGYENERGY