Energetics Flashcards
Exothermic reaction
-Releases heat
-Energy released to surroundings
-Energy lost by chemicals
Endothermic reaction
-Takes in heat
-Energy taken in from the surroundings
-Energy gained by chemicals
Do products end with more or less energy than the reactants in an exothermic reaction?
Less
(Energy is released to the surroundings)
Do products end with more or less energy than the reactants in an endothermic reaction?
More
(Energy is taken in from the surroundings)
What does ‘BendoMexo’ stand for?
-Breaking bonds is endothermic
-Making bonds is exothermic
(Every reaction has both parts but if stronger bonds are broken/ made, it determines if the reaction is endo/ exothermic)
Calorimetry
Working out the energy changes for a reaction
Bond energy
The amount of energy it takes to break or make a bond
Enthalpy change
The overall energy change in a reaction
Activation energy (Ea)
The energy needed to break bonds in the reactants
When do energy changes take place?
When:
-Salts dissolve in water
-Neutralisation reactions
-Displacement reactions
-Precipitation reactions
Energy equation
Mass x Specific heat capacity x Change in temp
What is delta H?
The energy change
(Measured in Kj/mol)
How do you calculate moles (of limiting reagent) for a solid?
Mass/ RAM
How do you calculate moles (of limiting reagent) for a solution?
Concentration x volume/1000
How do you calculate delta H?
Energy - 1000/ moles
