Energy changes Flashcards
What is an exothermic reaction?
Releases exit to the surroundings causing a rise in temperature.
Name examples of Exothermic reactions
Combustion
Neutralization reactions
Many oxidation reactions
What is an endothermic reaction?
Absorbs heat from its surroundings causing temperature to decrease.
Name 2 examples of Endothermic reactions
Thermal decomposition
Reaction between citric acid and sodium hydrogen carbonate.
What is Activation energy?
The minimum amount of energy the reactants need to collide with each other and react.
Describe the reaction profile of Exothermic reactions
The products have less energy than the reactants it started with, meaning energy must of been released so it means their is an exothermic reaction
What does the difference between the reactants and products show in a Exothermic reaction ?
Shows the energy released
Where is the activation energy shown from?
The reactants to the top of the curve
Describe the reaction profile of Endothermic reactions?
In this reaction has products have more energy than the reactants, which means the reaction must of taking in energy telling us with is a Endothermic reaction.
What does the distance from the reactants to the products show?
It tells us the energy taken in.
What is the activation energy in a Endothermic reaction?
If is the difference between the Reactants to the top of the curve.
What are exothermic reactions always shown to be?
Negative
What are endothermic reactions always shown to be?
Positive
When we break bonds what does it require?
It requires energy so therefore the reaction is Endothermic.
When we make chemical bonds what happens?
It releases energy so therefore the reaction is Exothermic
What are the three steps you would use to find the overall energy changes in a reaction if you were given the known bond enthalpies for the bonds present in the reactants and products?
1) Find the energy required to break the original bonds
2) Find the energy released by forming the new bonds
3) Find the overall energy change for the reaction using this equation
Because breaking bonds is endothermic what happens with energy?
Energy is gained
Because bond forming is Exothermic what happens with energy?
Energy is lost
