Chapter 7- Energy Changes Flashcards
What happens to energy during a chemical reaction?
It is neither created or destroyed
What is an exothermic reaction. (Exits)
Energy is transferred from the reacting substances to their surroundings. It heats up the surroundings
What is an endothermic reaction. (Enters)
A reaction where energy is transferred from the surroundings to the reacting substances they cool down the surroundings
Give an example of a product which uses exothermic reaction in it.
Hand warmers or heating drink cans
Give an example of a product which uses endothermic reactions.
Cold packs for sports injuries
What happens to the atoms during a endothermic reaction
The bonds break
Breaking bonds aBsorbs energy
Energy has to be supplied to break down the bonds, so energy has to be taken in from the surroundings
What happens in an exothermic reaction
Bonds are made
foRming bonds Releases energy when bonds are made energy is released to the surroundings
What happens to the energy when new bonds are formed?
It is released
What happens to the energy in exothermic reactions?
The energy released when new bonds are formed is greater than the energy absorbed when bonds are broken
What happens to the energy in an endothermic reaction?
The energy released when new bonds are formed is less than the energy absorbed when bonds are broken
How do you calculate the overall energy change in a reaction?
Using bond energies
What is bond energy?
The energy needed to break the bond between the bond between the atoms
