Energy Changes Flashcards
(20 cards)
What is an exothermic reaction?
A reaction that releases energy to the surroundings
What is an endothermic reaction?
A reaction that absorbs energy from the surroundings
In an exothermic reaction does the temperature of the surroundings increase or decrease?
Increase
In an endothermic reaction does the temperature of the surroundings increase or decrease?
Decrease
What happens to energy in an exothermic reaction?
It is transferred from the system to the surroundings
What happens to energy in an endothermic reaction?
It is transferred from the surroundings into the system
What does a reaction profile show?
The relative energy of reactants and products during a chemical reaction
In a reaction profile where are the products in an exothermic reaction?
Lower than the reactants
In a reaction profile where are the products in an endothermic reaction?
Higher than the reactants
What is the activation energy of a reaction?
The minimum energy needed to start a reaction
How is activation energy shown on a reaction profile?
As the height of the curve from reactants to the peak
What is bond breaking in terms of energy?
An endothermic process
What is bond making in terms of energy?
An exothermic process
What is the overall energy change in a chemical reaction?
The difference between energy in to break bonds and energy out from forming bonds
What does a negative overall energy change indicate?
The reaction is exothermic
What does a positive overall energy change indicate?
The reaction is endothermic
What does a larger activation energy mean for a reaction?
The reaction is slower or requires more energy to start
What is the unit for energy change in bond energy calculations?
kJ/mol
What must happen to bonds in reactants before a reaction can happen?
They must be broken using energy
What must happen to atoms after bonds in reactants are broken?
New bonds must form to make products
