Heat energy changes Flashcards
Exothermic reaction
Heat energy is given out and the reaction mixture or the surroundings increase in temperature
Endothermic reactions
Heat energy is taken in and the reaction mixture or the surroundings decrease in temperature
Measuring temperature changes
You use:
- Thermometer
- Lid with hole
- Polystyrene cup
- Beaker for support
- Reaction for mixture
Bonds and energy
When a chemical reaction happens, the bonds that hold the atoms together are broken. The atoms come together in different arrangements to form the products
Breaking bonds is endothermic (energy is needed)
Making bonds is exothermic (energy is released)
Reaction profiles
Energy profile diagrams model the energy changes that happen during reactions
Exothermic reaction profile
The energy level of the reactants is greater that the energy level of the products
The energy change of the reaction is negative
Endothermic reaction profile
The energy level of the reactants is lower than the energy level of the products
The energy change of the reaction is positive
Activation energy
The minimum energy needed to start a reaction
