C3.2: Energetics Flashcards
What is the energy change in exothermic reactions?
Energy given out
What is the energy change in endothermic reactions?
Energy taken in
What is the temp change in exothermic reactions?
Temp increases
What is the temp change in endothermic reactions?
Temp decreases
Examples of exothermic reactions
Combustion or neutralisation
Examples of endothermic reactions
Electrolysis
What happens to bonds when energy is taken in?
Break bonds
What happens to bonds when energy is released?
Bonds are made
How do we know whether a reaction profile shows an endothermic reaction?
If less energy is released in forming bonds in the products than is taken in when breaking bonds in the reactants
How do we know whether a reaction profile shows an exothermic reaction?
If more energy is released in forming bonds in the products tthan is taken in when breaking bonds in the reactants
What does a reaction profile diagram show?
Shows how energy in the reactants and products changes during a reaction
Includes activation energy
What is activation energy?
The minimum energy that is needed to start a reaction
How do you draw reaction profiles?
Check notes
What is a bond energy?
The amound ot energy needed to break one mole of a covalent bond
Different bonds have different bond energies
How can you calculate energy change?
Add together all the bond energies in reactants and products
Energy in - energy out
When calculating energy change, what type of reaction is it when my bond energy is positive?
Endothermic reaction
When calculating energy change, what type of reaction is it when my bond energy is negative?
Exothermic
