Topic 4: Energies Flashcards
Enthalpy change def
Heat or energy change under constant pressure. ΔH
Standard conditions (enthalpy)
Temp. 298K
Pressure 100KPa
Exothermic
Gives out heat, negative enthalpy change
Endothermic
Takes in heat, positive enthalpy change
Enthalpy change unit
KJmol^-1
Energy Level Diagram for Exothermic
Reactants at higher energy level than products. Reactants higher, products lower on diagram.
Energy Level Diagram for Endothermic
Reactants are at lower energy than products. Reactants higher, products lower on diagram.
Activation Energy on energy level diagram
Difference between highest peak and the products, much larger for endothermic
Activation Energy
The minimum amount of energy required in order for a successful collision to occur which will cause the reaction to happen.
Enthalpy change calc using bond dissociation energies
enthalpy to break bonds - enthalpy to make bonds
break - make
Calorimetry
DO THIS LATER ABI
q in calorimetry and equation and units
heat change (J) careful with this as not in kj
m in calorimetry and equation and units
Mass (Mass of water usually) (g)
c in calorimetry and equation and units
Specific heat capacity (JK^-1g^-1)
ΔT in calorimetry and equation and units
Temperature change (K) (As its change in temp, don’t have to convert to K)
